阅读说明：本技术 具有电导率传感器的气溶胶生成装置和系统 (Aerosol-generating device and system with conductivity sensor ) 是由 I·奇诺维科 于 2020-06-24 设计创作，主要内容包括：一种气溶胶生成系统,包括：用于保持液体气溶胶形成基质的液体存储部分；与所述液体存储部分流体连接的雾化器；电导率传感器；电源；和控制电子器件。电导率传感器包括至少两个电极(104、106),并且被布置成感测来自液体存储部分的液体气溶胶形成基质的电导率。控制电子器件被配置成：控制从电源向雾化器的供电以雾化来自液体存储部分的液体气溶胶形成基质；以及控制从电源向电导率传感器的电极(104、106)的供电,该供电作为交流电压提供给电导率传感器。控制电子器件还被配置成：从电导率传感器接收指示液体气溶胶形成基质的电导率的一个或多个测量值；以及基于来自电导率传感器的测量值中的一个或多个确定液体气溶胶形成基质的尼古丁浓度。(An aerosol-generating system comprising: a liquid storage portion for holding a liquid aerosol-forming substrate; an atomizer in fluid connection with the liquid storage portion; a conductivity sensor; a power source; and control electronics. The conductivity sensor comprises at least two electrodes (104, 106) and is arranged to sense the conductivity of the liquid aerosol-forming substrate from the liquid storage portion. The control electronics are configured to: controlling power to the atomiser from a power supply to atomise the liquid aerosol-forming substrate from the liquid storage portion; and controlling power supply from the power supply to the electrodes (104, 106) of the conductivity sensor, the power supply being provided as an alternating voltage to the conductivity sensor. The control electronics are further configured to: receiving one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from a conductivity sensor; and determining the nicotine concentration of the liquid aerosol-forming substrate based on one or more of the measurements from the conductivity sensor.)

1. An aerosol-generating system comprising:

a liquid storage portion for holding a liquid aerosol-forming substrate;

an atomizer in fluid connection with the liquid storage portion;

a conductivity sensor arranged to sense the conductivity of liquid aerosol-forming substrate from the liquid storage portion, the conductivity sensor comprising at least two electrodes;

a power source; and

control electronics configured to:

controlling the supply of power from the power supply to the atomiser to atomise the liquid aerosol-forming substrate from the liquid storage portion;

controlling power supplied from the power supply to the electrodes of the conductivity sensor, the power being supplied to the conductivity sensor as an alternating voltage;

receiving one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from the conductivity sensor; and

determining a nicotine concentration of the liquid aerosol-forming substrate based on one or more of the measurements from the conductivity sensor.

2. An aerosol-generating system according to claim 1, wherein the control electronics are further configured to control the supply of power from the power source to the atomizer to atomize the liquid aerosol-forming substrate based on the determined nicotine concentration of the liquid aerosol-forming substrate.

3. An aerosol-generating system according to claim 2, wherein the control electronics are configured to: controlling power to the atomizer from the power source to atomize the liquid aerosol-forming substrate based on the determined nicotine concentration of the liquid aerosol-forming substrate by comparing the determined nicotine concentration with a predetermined threshold; supplying a first power to the nebulizer when the determined nicotine concentration is at or below the predetermined threshold; and supplying a second power to the nebulizer that is lower than the first power when the determined nicotine concentration exceeds the predetermined threshold.

4. An aerosol-generating system according to any of claims 1 to 3, wherein the aerosol-generating system further comprises a heater arranged to heat aerosol-forming substrate from the liquid storage portion, and wherein the control electronics are configured to supply power from the power supply to the heater to heat liquid aerosol-forming substrate from the liquid storage portion to a predetermined temperature.

5. An aerosol-generating system according to any one of claims 1 to 4, wherein:

the system further comprises a temperature sensor arranged to sense the temperature of the liquid aerosol-forming substrate from the liquid storage portion; and is

The control electronics are further configured to:

receiving one or more measurements of the temperature of the liquid aerosol-forming substrate at the conductivity sensor from the temperature sensor; and

adjusting the determination of nicotine concentration based on one or more of the temperature measurements.

6. An aerosol-generating system according to any of claims 1 to 5, wherein each electrode of the conductivity sensor is arranged to contact liquid aerosol-forming substrate from the liquid storage portion.

7. An aerosol-generating system according to claim 6, wherein the conductivity sensor comprises two electrodes, and wherein the two electrodes are spaced apart to form a cavity in which liquid aerosol-forming substrate from the liquid storage portion is disposed.

8. An aerosol-generating system according to claim 7, wherein the nebulizer is a thermal nebulizer comprising a plurality of heating elements, and wherein each electrode of the conductivity sensor is formed by a heating element of the nebulizer.

9. An aerosol-generating system according to claim 8, wherein the control electronics are further configured to:

supplying a first power to an electrode of the conductivity sensor to measure the conductivity of the liquid aerosol-forming substrate; and

supplying a second power to a plurality of heating elements of the atomizer to atomize the liquid aerosol-forming substrate, the second power being greater than the first power.

10. An aerosol-generating system according to claim 6, wherein:

the conductivity sensor comprises two inner electrodes and two outer electrodes;

the two outer electrodes being spaced apart to form an outer cavity in which liquid aerosol-forming substrate from the liquid storage portion is disposed;

the two inner electrodes being arranged in the outer cavity between the two outer electrodes and being spaced apart to form an inner cavity in which liquid aerosol-forming substrate from the liquid storage portion is disposed; and is

The control electronics are further configured to:

supplying power from the power source to the outer electrode, the power being supplied to the outer electrode as an alternating voltage; and

receiving one or more measurements indicative of the electrical conductivity of the liquid aerosol-forming substrate from the inner electrode.

11. An aerosol-generating system according to claim 10, wherein the nebulizer is a thermal nebulizer comprising a plurality of heating elements, and wherein each electrode of the conductivity sensor is formed by a heating element of the nebulizer.

12. An aerosol-generating system according to claim 11, wherein the control electronics are further configured to:

supplying a first power to an outer electrode of the conductivity sensor to measure the conductivity of the liquid aerosol-forming substrate; and

supplying a second power to a plurality of heating elements of the atomizer to atomize the liquid aerosol-forming substrate, the second power being greater than the first power.

13. An aerosol-generating system according to any one of claims 1 to 5, wherein the conductivity sensor comprises two electrodes, a first electrode and a second electrode, each electrode forming a coil, wherein the control electronics is configured to supply an alternating voltage to the first electrode and the control electronics is configured to receive one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from the second electrode, and wherein the first electrode is arranged to induce a current in the second electrode when an alternating voltage is supplied to the first electrode.

14. An aerosol-generating system according to claim 13, wherein the first and second electrodes are arranged in the liquid storage portion.

15. A cartridge for an aerosol-generating system, the cartridge comprising:

a liquid storage portion for holding a liquid aerosol-forming substrate;

an atomizer in fluid connection with the liquid storage portion; and

a conductivity sensor arranged to sense the conductivity of liquid aerosol-forming substrate from the liquid storage portion, the conductivity sensor comprising two electrodes arranged in the liquid storage portion, a first electrode and a second electrode, each electrode forming a coil, wherein the first electrode is arranged to induce a current in the second electrode when an alternating voltage is supplied to the first electrode.

Technical Field

The present invention relates to an aerosol-generating system that atomises an aerosol-forming substrate comprising nicotine to generate an aerosol. In particular, the invention relates to an aerosol-generating system comprising a conductivity sensor. The invention also relates to an aerosol-generating device comprising a conductivity sensor and a cartridge comprising a conductivity sensor.

Background

Aerosol-generating systems, such as electronic cigarettes, that operate by heating a liquid formulation to generate an aerosol for inhalation by a user are widely used. Typically these systems include a liquid storage portion that holds the liquid formulation, a heater for vaporizing the liquid formulation, a wick that delivers liquid from the liquid storage portion to the heater, a power source, and control electronics. Some of these systems include a refillable liquid storage portion. Some of these systems include a device portion and a replaceable cartridge. In some systems, the device portion includes a power source and control electronics, and the cartridge contains a liquid storage portion that holds the liquid formulation, a heater for vaporizing the liquid formulation, and a wick that delivers liquid from the liquid storage portion to the heater.

In systems that include a refillable liquid storage portion, liquid formulations having different compositions may be introduced into the liquid storage portion, where the liquid storage portion is refilled. Similarly, in a system comprising a device portion and a replaceable cartridge, different cartridges may contain liquid formulations having different compositions. In particular, different liquid formulations may include different amounts or concentrations of nicotine. Thus, an aerosol generated from one particular liquid formulation may contain a different amount or concentration of nicotine than an aerosol generated from a different liquid formulation.

Disclosure of Invention

It is desirable for the aerosol-generating system to be able to assess the nicotine concentration of the liquid formulation. It is also desirable that the aerosol-generating system is capable of controlling the nicotine concentration of aerosols generated by different liquid formulations. It is also desirable to be able to standardize the manufacture of aerosol-generating systems regardless of the aerosol-forming substrate with which the aerosol-generating system is used.

According to the present disclosure, there is provided an aerosol-generating system comprising: a liquid storage portion for holding a liquid aerosol-forming substrate; an atomizer in fluid connection with the liquid storage portion; a conductivity sensor; a power source; and control electronics. The conductivity sensor comprises at least two electrodes and is arranged to sense the conductivity of the liquid aerosol-forming substrate from the liquid storage portion. The control electronics are configured to: controlling power to the atomiser from a power supply to atomise the liquid aerosol-forming substrate from the liquid storage portion; and controlling power supply from the power supply to the electrodes of the conductivity sensor, the power supply being supplied as an alternating voltage to the conductivity sensor. The control electronics are further configured to: receiving one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from a conductivity sensor; and determining the nicotine concentration of the liquid aerosol-forming substrate based on one or more of the measurements from the conductivity sensor.

The liquid aerosol-forming substrate may comprise three main components, typically nicotine, an aerosol former and water. Advantageously, the present inventors have realised that the electrical conductivity of the liquid aerosol-forming substrate may provide an indication of the nicotine concentration of the liquid aerosol-forming substrate. In particular, the present inventors have realised that a manufacturer of an aerosol-generating device may also manufacture or sell proprietary liquid aerosol-forming substrates having different nicotine concentrations, and provide the aerosol-generating device with a conductivity sensor that may enable the device to determine which proprietary aerosol-forming substrate is received in the device based on the conductivity of the aerosol-forming substrate.

As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form an aerosol. The volatile compounds may be released by heating the aerosol-forming substrate. The volatile compound may be released by moving the aerosol-forming substrate through the passage of the vibratable element.

The aerosol-forming substrate is a liquid aerosol-forming substrate. The aerosol-forming substrate may comprise a mixture of a liquid component and a solid component. The aerosol-forming substrate comprises nicotine. Preferably, the aerosol-forming substrate comprises a nicotine salt. The aerosol-forming substrate may comprise a plant-based material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds which are released from the aerosol-forming substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco containing material. The aerosol-forming substrate may comprise a homogenised plant-based material. The aerosol-forming substrate may comprise a homogenized tobacco material. The aerosol-forming substrate may comprise at least one aerosol-former. The aerosol former is any suitable known compound or mixture of compounds which, in use, facilitates the formation of a dense and stable aerosol and which is substantially resistant to thermal degradation at the operating temperature of the system. Suitable aerosol-forming agents are well known in the art and include, but are not limited to: polyhydric alcohols such as triethylene glycol, 1, 3-butanediol and glycerin; esters of polyhydric alcohols, such as glycerol mono-, di-or triacetate; and fatty acid esters of mono-, di-or polycarboxylic acids, such as dimethyldodecanedioate and dimethyltetradecanedioate. Preferred aerosol formers are polyhydric alcohols or mixtures thereof, such as triethylene glycol, 1, 3-butanediol, and most preferably glycerol. The aerosol-forming substrate may comprise other additives and ingredients, such as flavourants.

In some preferred embodiments, the nicotine is in the form of a nicotine salt. In some particularly preferred embodiments, the nicotine salt may be the only electrolyte present in the liquid aerosol-forming substrate. In some embodiments, the nicotine electrolyte concentration may be significantly higher than the concentration of other electrolytes in the liquid aerosol-forming substrate. Thus, the effect of changes in the concentration of other components of the liquid aerosol-forming substrate on the conductivity of the substrate may be neglected.

A manufacturer of liquid aerosol-forming substrates may manufacture different proprietary aerosol-forming substrates having different concentrations of nicotine. To change the nicotine concentration in the aerosol-forming substrate, manufacturers may increase or decrease the amount of nicotine in a given amount of substrate by conversely decreasing or increasing the amount of solvent (e.g., water) in a given amount of substrate. For example, a manufacturer may produce a low nicotine aerosol-forming substrate comprising a first amount of nicotine and a first amount of water for a given amount of substrate and a high nicotine aerosol-forming substrate comprising a second amount of nicotine greater than the first amount of nicotine and a second amount of water less than the first amount of water for a given amount of substrate. The low nicotine aerosol-forming substrate may have a lower nicotine concentration than the high nicotine aerosol-forming substrate. The low nicotine aerosol-forming substrate may have a first electrical conductivity and the high nicotine aerosol-forming substrate may have a second electrical conductivity greater than the first electrical conductivity. The difference between the first conductivity and the second conductivity may increase as the temperature increases.

The liquid aerosol-forming substrate may typically have a conductivity of between about 1 and about 500 microsiemens/cm at 20 degrees celsius, and preferably between about 1 and about 400 microsiemens/cm at 20 degrees celsius. Preferably, the conductivity sensor is adapted to measure the conductivity of the aerosol-forming substrate within these ranges.

The conductivity sensor may be any suitable type of sensor for sensing the conductivity of the liquid aerosol-forming substrate in the system.

The conductivity sensor may be arranged at any suitable location in the aerosol-generating system. The conductivity sensor may be arranged in the liquid storage portion. The conductivity sensor may be arranged at or around the liquid storage portion. The conductivity sensor may be arranged at or around the atomizer. The conductivity sensor may be arranged between the liquid storage portion and the atomizer. In some embodiments, the conductivity sensor is a separate component from the nebulizer. In some preferred embodiments, the nebulizer comprises a conductivity sensor. In these preferred embodiments, the nebulizer may comprise one or more elements, and the at least one electrode of the conductivity sensor comprises an element of the nebulizer.

The electrodes of the conductivity sensor may have any suitable form. For example, the electrode may be a coil electrode, a ring electrode, or a mesh electrode comprising a plurality of filaments. In some embodiments, the electrodes may be arranged to contact the liquid aerosol-forming substrate. In some embodiments, the electrodes may be arranged such that the electrodes do not contact the liquid aerosol-forming substrate. In other words, the electrodes may be separate from the liquid aerosol-forming substrate.

In some first preferred embodiments, the conductivity sensor comprises two electrodes. These first preferred embodiment conductivity sensors may be referred to as two-point conductivity sensors.

The two electrodes may be spaced apart such that a cavity is formed between the electrodes. For example, the two electrodes may be spaced apart by a distance of between about 1 millimeter and about 20 millimeters. As used herein, the term "cavity" refers to any suitable gap or space between two electrodes, including a two-dimensional space between two perfectly flat electrodes arranged in the same plane and a three-dimensional space between two electrodes. The two electrodes may be arranged such that the liquid aerosol-forming substrate may be disposed in the cavity between the electrodes. Preferably, the two electrodes are arranged to be in contact with the liquid aerosol-forming substrate from the liquid storage portion. The two electrodes may be arranged such that they are electrically insulated from each other when the liquid aerosol-forming substrate is not disposed in the cavity between the two electrodes.

In these first preferred embodiments, the control electronics may be configured to supply power from the power supply to the electrodes at an alternating voltage. The control electronics may also be configured to receive one or more measurements indicative of the electrical conductivity of the liquid aerosol-forming substrate from the electrodes.

In these first preferred embodiments, when a liquid aerosol-forming substrate is disposed in the cavity between the electrodes, application of an alternating voltage across the two electrodes may cause an alternating current to flow between the two electrodes through the liquid aerosol-forming substrate in the cavity between the electrodes. The control electronics may be configured to measure the current between the two electrodes. The control electronics may be configured to measure the voltage between the two electrodes. One or more of the measured current and voltage may be used to determine the conductivity of the liquid aerosol-forming substrate disposed in the cavity between the two electrodes.

In these first preferred embodiments, the control electronics may be configured to supply an alternating voltage to the conductivity sensor at a frequency between about 1kHz and about 500 kHz.

In some second preferred embodiments, the conductivity sensor comprises four electrodes. These second preferred embodiment conductivity sensors may be referred to as four-point conductivity sensors.

The conductivity sensor may comprise two inner electrodes and two outer electrodes. The two outer electrodes may be spaced apart such that an outer cavity is formed between the two outer electrodes. For example, the two outer electrodes may be spaced apart by a distance of between about 5 millimeters and about 20 millimeters. The two inner electrodes may be spaced apart to form a lumen between the two inner electrodes. For example, the two inner electrodes may be spaced apart by a distance of between about 5 millimeters and about 20 millimeters. In some embodiments, two inner electrodes are disposed in the outer cavity between the two outer electrodes. In these embodiments, the two inner electrodes may be spaced apart by a distance of between about 1 millimeter and about 18 millimeters.

The two outer electrodes may be arranged such that the liquid aerosol-forming substrate may be disposed in an outer cavity between the two outer electrodes. The two outer electrodes may be arranged such that they are electrically insulated from each other when the liquid aerosol-forming substrate is not disposed in the outer cavity between the outer electrodes.

The two inner electrodes may be arranged such that the liquid aerosol-forming substrate may be disposed in the inner cavity between the two inner electrodes. The two inner electrodes may be arranged such that they are electrically insulated from each other when the liquid aerosol-forming substrate is not disposed in the inner cavity between the two inner electrodes. The two inner electrodes may also be arranged such that they are electrically insulated from the two outer electrodes when the liquid aerosol-forming substrate is not disposed in the inner cavity between the inner electrodes.

Preferably, the two outer electrodes and the two inner electrodes are arranged to be in contact with the liquid aerosol-forming substrate from the liquid storage portion.

In these second preferred embodiments, the control electronics may be configured to supply power from the power supply to the outer electrode at an alternating voltage. The control electronics may be configured to receive one or more measurements indicative of the conductivity of the liquid aerosol-forming substrate from the outer electrode. The control electronics may be configured to receive one or more measurements indicative of the electrical conductivity of the liquid aerosol-forming substrate from the inner electrode.

In these second preferred embodiments, when a liquid aerosol-forming substrate is disposed in the outer chamber between the two outer electrodes, application of an alternating voltage across the two outer electrodes may cause an alternating current to flow between the two outer electrodes through the liquid aerosol-forming substrate disposed in the outer chamber. When a liquid aerosol-forming substrate is provided in the outer chamber, the liquid aerosol-forming substrate is also provided in the inner chamber between the two inner electrodes. When an alternating current flows between the two outer electrodes, it also flows between the two inner electrodes, thereby establishing an alternating voltage across the two inner electrodes.

The control electronics may be configured to measure a voltage drop between the two inner electrodes. The measured voltage drop between the two inner electrodes may be used to determine the electrical conductivity of the liquid aerosol-forming substrate disposed in the internal cavity between the two inner electrodes. The control electronics may be configured to measure the current between the two outer electrodes. The measured current between the two outer electrodes may be used to determine the electrical conductivity of the liquid aerosol-forming substrate disposed in the outer chamber. In some particularly preferred embodiments, the control electronics are configured to determine the conductivity of the liquid aerosol-forming substrate using a measured voltage drop between the two inner electrodes and a measured current between the two outer electrodes. The electrical conductivity of the liquid aerosol-forming substrate may be proportional to the applied electrical current.

Advantageously, the four-point conductivity sensor may minimize the effect of parasitic resistance on voltage measurements made by the conductivity sensor. Parasitic resistance in the conductivity sensor (e.g., contact resistance between leads in contact with the electrodes) can cause voltage measurements to be erroneous. Advantageously, the four electrode arrangement of the second preferred embodiment enables voltage measurements to be separated from current measurements. Separating the voltage measurement from the current measurement may enable minimizing the effect of parasitic resistance on the voltage measurement.

In the four-point conductivity sensor of the second preferred embodiment, the inner electrodes are arranged such that the current between the inner electrodes is substantially the same as the current driven between the outer electrodes. If the voltage on the inner electrodes is measured to have a high impedance, negligible current may be drawn through the leads connected to the inner electrodes compared to the current between the inner electrodes. Since the current through the lead wire connected to the internal electrode is negligible compared to the current across the internal electrode, the voltage drop due to the parasitic resistance on the lead wire connected to the internal electrode is negligible compared to the voltage drop across the internal electrode. Thus, the measurement of the voltage on the inner electrode may include a minimal or negligible contribution of the parasitic resistance.

In addition, as the measurement of the voltage on the two inner electrodes draws negligible current, the polarization of the liquid aerosol-forming substrate at the two inner electrodes is also negligible, thereby minimizing the effect of the polarization on the voltage measurement in the four-electrode arrangement of the second preferred embodiment.

In these second preferred embodiments, the control electronics may be configured to supply an alternating voltage to the conductivity sensor at a frequency between about 1kHz and about 500 kHz.

In some of these second preferred embodiments, the two inner electrodes may be susceptor elements. As used herein, the term "susceptor element" refers to an element comprising a material capable of converting electromagnetic energy into heat. When the susceptor element is positioned in the alternating electromagnetic field, the susceptor is heated. Heating of the susceptor element may be the result of at least one of hysteresis losses and eddy currents induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material. Thus, applying an alternating voltage to the two outer electrodes to heat the outer electrodes may induce a current in the two inner electrodes. The current induced in the two inner electrodes may be sufficient to heat the two inner electrodes.

The susceptor element may comprise any suitable material. The susceptor element may be formed from any material that is capable of being inductively heated to a temperature sufficient to release the volatile compounds from the aerosol-forming substrate. Suitable materials for the elongate susceptor element include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel-containing compounds, titanium, and composites of metallic materials. Preferably the susceptor element comprises a metal or carbon. Advantageously, the susceptor element may comprise or consist of a ferromagnetic material, such as ferritic iron, ferromagnetic alloys (e.g. ferromagnetic steel or stainless steel), ferromagnetic particles and ferrites.

In some third preferred embodiments, the conductivity sensor comprises two electrodes, a first electrode and a second electrode. Preferably, each electrode forms a coil. The first electrode is arranged to induce a current in the second electrode when an alternating voltage is supplied to the first electrode. The two electrodes may be spaced apart such that a cavity is formed between the electrodes. The two electrodes may be arranged such that the two electrodes are electrically insulated from each other.

Where the first and second electrodes form a coil, the first electrode coil may be wound around the first lumen. A second electrode coil may be wound around the second lumen. The first and second electrodes may be arranged such that the first lumen is aligned with the second lumen. The first lumen and the second lumen may define a lumen. The inner cavity may define a passage through which the liquid aerosol-forming substrate may flow.

The conductivity sensor of these third preferred embodiments may be referred to as an inductive conductivity sensor.

In these third preferred embodiments, the control electronics may be configured to supply an alternating voltage to the first electrode. The control electronics may also be configured to receive one or more measurements indicative of the electrical conductivity of the liquid aerosol-forming substrate from the second electrode.

In these third preferred embodiments, when the liquid aerosol-forming substrate is disposed in the lumen between the first electrode and the second electrode, application of an alternating voltage to the first electrode may generate an alternating current in the second electrode by induction. An alternating voltage applied to the first electrode generates a fluctuating magnetic field that causes an electric current to flow through the liquid aerosol-forming substrate disposed in the internal cavity. The magnitude and direction of the current flowing through the liquid aerosol-forming substrate disposed in the inner chamber affects the alternating current generated in the second electrode. The control electronics may be configured to measure the current or voltage induced in the second electrode. The measured current or voltage may be used to determine the conductivity of the liquid aerosol-forming substrate disposed in the lumen between the first and second electrodes. The current induced in the second electrode may be proportional to the conductivity of the liquid aerosol-forming substrate.

In these third preferred embodiments, the first and second electrodes may be shielded or isolated from the aerosol-forming substrate. In other words, the first and second electrodes may be arranged such that the first and second electrodes are not in contact with the liquid aerosol-forming substrate. The first electrode and the second electrode may be disposed in the conductivity sensor housing. The conductivity sensor housing may define an interior cavity including a first interior cavity and a second interior cavity. The conductivity sensor housing may be made of any suitable material. The conductivity sensor housing may be made of a material that is substantially impermeable to the liquid aerosol-forming substrate. The conductivity sensor housing may be made of an electrically insulating material. Suitable electrically insulating materials include, for example, glass, plastic, and ceramic materials. As used herein, an electrically insulating material means having a temperature of greater than about 1x10 at 20 ℃⁶Ω m, typically about 1 × 10⁹Omega m and about 1x10²¹Materials with volume resistivity between Ω m.

The inductive conductivity sensor may be arranged at any suitable location in the aerosol-generating system. Preferably, the inductive conductivity sensor is arranged in the liquid storage portion. Preferably, the inductive conductivity sensor is arranged in the liquid storage portion and the liquid aerosol-forming substrate contained in the liquid storage portion is able to flow through the lumen between the first and second electrodes.

In these third preferred embodiments, the control electronics can be configured to supply an alternating voltage to the conductivity sensor at a frequency between about 1MHz and about 100 MHz.

In these third preferred embodiments, the first electrode coil may have any suitable number of turns. The second electrode coil may have any suitable number of turns. Preferably, the second electrode coil has the same number of turns as the first electrode coil. The first electrode coil may have any suitable form. For example, the first electrode coil may be a spiral coil or a loop coil. The second electrode coil may have any suitable form. For example, the second electrode coil may be a spiral coil or a loop coil. Preferably, the second electrode coil has the same form as the first electrode coil. Particularly preferably, the first electrode coil and the second electrode coil comprise the same annular coil.

The control electronics control the supply of power from the power source to the electrodes of the conductivity sensor. The power supply to the conductivity sensor is provided as an alternating voltage. The alternating voltage may be supplied to the electrodes of the conductivity sensor at any suitable frequency.

The control electronics are configured to determine the nicotine concentration of the liquid aerosol-forming substrate based on one or more of the measurements from the conductivity sensor. The control electronics can be configured to determine the nicotine concentration in any suitable manner. In one example, the predetermined functional relationship between conductivity and nicotine concentration may be known. Suitable algorithms may be stored in the memory of the control electronics, and the control electronics may be configured to calculate the nicotine concentration by applying the measurement of the electrical conductivity to the stored algorithms. In another example, predetermined aerosol-forming substrate conductivity values for known nicotine concentrations may be stored in a look-up table in the memory of the control electronics, and the measured value of conductivity may be compared to the stored value of conductivity to determine the nicotine concentration of the aerosol-forming substrate. The predetermined aerosol-forming substrate conductivity value for a known nicotine concentration may be determined by calibration, typically performed in the factory before the aerosol-generating system is provided to the user for use.

It will be appreciated that determining an indication of nicotine concentration in a liquid aerosol-forming substrate may not necessarily involve calculation of a nicotine concentration value, or stored values of nicotine concentration stored in a look-up table in a memory of the control electronics. For example, in some embodiments according to the invention, determining the concentration of nicotine in the liquid aerosol-forming substrate comprises using a measurement of the electrical conductivity to determine the specific power supplied to the nebulizer. In these embodiments, the determination of the power supplied to the nebulizer using the measurement of the electrical conductivity is based on a predetermined relationship between the nicotine concentration and the electrical conductivity of the liquid aerosol-forming substrate.

In some embodiments, the control electronics are further configured to control the supply of power from the power source to the atomizer to atomize the liquid aerosol-forming substrate based on the determined nicotine concentration of the liquid aerosol-forming substrate. Advantageously, this may enable the aerosol-generating system to control the amount of aerosol produced by the system based on the nicotine concentration of the aerosol-forming substrate.

Preferably, the control electronics are configured to control the supply of power from the power source to the atomizer to atomize the liquid aerosol-forming substrate based on the determined nicotine concentration of the liquid aerosol-forming substrate by comparing the determined nicotine concentration with a predetermined threshold. The control electronics may also be configured to supply a first power to the nebulizer when the determined nicotine concentration is at or below a predetermined threshold. The control electronics may be further configured to supply a second power to the nebulizer that is lower than the first power when the determined nicotine concentration exceeds a predetermined threshold. Such a configuration may generate a relatively large amount of aerosol during the user experience when the determined nicotine concentration is relatively low, and may generate a relatively small amount of aerosol when the determined nicotine concentration is relatively high. Varying the amount of aerosol generated in the user experience may vary the amount of nicotine delivered to the user during the user experience. Advantageously, this may enable the aerosol-generating system to deliver a consistent amount of nicotine to a user during the user experience, regardless of the nicotine concentration of the liquid aerosol-forming substrate.

The control electronics may be configured to control the power supplied from the power source to the nebulizer in discrete increments. For example, a plurality of discrete power settings may be stored in a look-up table in the memory of the control electronics, each power setting being associated with a particular predetermined nicotine concentration and conductivity, the control electronics may be configured to compare the conductivity measurement to the conductivity values stored in the look-up table, and apply power from the power source to the nebulizer based on the power setting associated with the stored conductivity value matching the conductivity measurement.

The control electronics may be configured to control the power continuously supplied from the power supply to the nebulizer. The control electronics may be configured to control the power supplied from the power source to the atomizer as a function of the conductivity. The predetermined algorithm may be stored on a memory of the control electronics, and the conductivity measurement may be applied to the predetermined algorithm to determine the power to be supplied from the power source to the nebulizer.

The control electronics can be configured to provide power from the power source to the electrodes of the conductivity sensor at any suitable time. Preferably, the control electronics are configured to supply power from the power source to the electrodes of the conductivity sensor before supplying power from the power source to the atomizer to atomize the liquid aerosol-forming substrate. Advantageously, this may enable the control electronics to control the power supplied from the power source to the atomizer based on the determined nicotine concentration of the liquid aerosol-forming substrate.

The electrical conductivity of the liquid aerosol-forming substrate may vary depending on the temperature of the aerosol-forming substrate.

In some embodiments, the aerosol-generating device may comprise a temperature sensor. The control electronics may be configured to receive one or more temperature measurements from the temperature sensor. The control electronics may also be configured to adjust the determination of nicotine concentration based on one or more of the temperature measurements from the temperature sensor.

The temperature sensor may be any suitable type of temperature sensor for sensing the temperature of the liquid aerosol-forming substrate. Suitable types of temperature sensors include thermocouples, thermistors, and resistance temperature sensors, among others.

The temperature sensor may be arranged to sense the temperature of the liquid aerosol-forming substrate. The temperature sensor may be arranged at any suitable position relative to the conductivity sensor. Preferably, the temperature sensor is arranged at or around the conductivity sensor to minimize a temperature difference between the liquid aerosol-forming substrate sensed by the temperature sensor and the liquid aerosol-forming substrate sensed by the conductivity sensor. The temperature sensor may be disposed in the liquid storage portion. The temperature sensor may be arranged at or around the atomizer. The temperature sensor may be arranged between the liquid storage portion and the atomizer. In some embodiments, the temperature sensor is a separate component from the atomizer. In some embodiments, the nebulizer includes a temperature sensor.

The control electronics can adjust the determination of nicotine concentration in any suitable manner based on the temperature measurement.

In one example, the predetermined functional relationship between temperature and conductivity is known. The algorithm may be stored in a memory of the control electronics, and the control electronics may be configured to calculate the nicotine concentration by applying the measurements of the electrical conductivity and the temperature to the stored algorithm.

In another example, at a particular temperature, for a known nicotine concentration, predetermined aerosol-forming substrate conductivity values may be stored in a look-up table in the memory of the control electronics, and the measured values of conductivity and temperature may be compared with the stored values of conductivity and temperature to determine the nicotine concentration of the aerosol-forming substrate.

In some embodiments, the aerosol-generating system may comprise a heater. The heater may be arranged to heat the liquid aerosol-forming substrate from the liquid storage portion. The heater may be configured to heat the liquid aerosol-forming substrate to a predetermined temperature. The power source may be configured to supply power to the heater. The control electronics may be configured to supply power from the power supply to the heater to heat the liquid aerosol-forming substrate from the liquid storage portion to a predetermined temperature.

The heater may be disposed at any suitable location relative to the conductivity sensor. Preferably, the heater is arranged at or around the conductivity sensor to minimise the temperature difference between the liquid aerosol-forming substrate heated by the heater and the liquid aerosol-forming substrate sensed by the conductivity sensor. The heater may be disposed in the liquid storage portion. The heater may be disposed at or around the atomizer. The heater may be disposed between the liquid storage portion and the atomizer. Typically, the heater is arranged upstream of the conductivity sensor such that the heater can heat the liquid aerosol-forming substrate to a predetermined temperature before the liquid aerosol-forming substrate reaches the conductivity sensor. In some embodiments, the heater is a separate component from the atomizer. In some embodiments, the atomizer comprises a heater.

The control electronics can be configured to provide power to the heater from the power source at any suitable time. In some embodiments, the control electronics are configured to continuously supply power from the power supply to the heater to maintain the temperature of the liquid aerosol-forming substrate at a predetermined temperature. In some embodiments, the control electronics are configured to supply power to the heater from the power supply for a predetermined period of time before a conductivity measurement is taken to ensure that the liquid aerosol-forming substrate has sufficient time to reach a predetermined temperature before the conductivity measurement is taken.

The predetermined temperature may be any suitable temperature. Typically, the predetermined temperature is higher than the expected ambient temperature, such that the ambient temperature does not affect the temperature of the liquid aerosol-forming substrate at the conductivity sensor. For example, the predetermined temperature may be at least about 60 degrees celsius, at least about 70 degrees celsius, or at least about 80 degrees celsius. The predetermined temperature is below the boiling point of the liquid aerosol-forming substrate.

In embodiments comprising a heater for heating the aerosol-forming substrate to a predetermined temperature, it may not be necessary to provide a temperature sensor for sensing the temperature of the liquid aerosol-forming substrate, as it may be reasonably assumed that the temperature of the liquid aerosol-forming substrate sensed by the conductivity sensor is at the predetermined temperature.

The aerosol-generating system may comprise a housing. The housing may be formed of any suitable material or combination of materials. Suitable materials include, but are not limited to, aluminum, Polyetheretherketone (PEEK), polyimide (e.g., PEEK)) Modified LCPs such as polyethylene terephthalate (PET), Polyethylene (PE), High Density Polyethylene (HDPE), polypropylene (PP), Polystyrene (PS), Fluorinated Ethylene Propylene (FEP), Polytetrafluoroethylene (PTFE), Polyoxymethylene (POM), epoxy resins, polyurethane resins, vinyl resins, Liquid Crystal Polymers (LCP), and LCP having graphite or glass fibers.

The housing may define a liquid storage portion. The liquid storage portion may be of any suitable shape and size for holding sufficient liquid aerosol-forming substrate for multiple user experiences. For example, the liquid storage portion may have sufficient capacity to allow aerosol to be continuously generated for a period of about six minutes, or for a multiple of six minutes. In another example, the liquid storage portion may have a capacity sufficient to allow a predetermined number of puffs or discrete activations of the nebulizer.

In some embodiments, a porous carrier material may be disposed in the liquid storage portion. The liquid aerosol-forming substrate may be adsorbed or otherwise loaded onto a porous carrier material. The porous carrier material may be made of any suitable plug or body having adsorbent capabilities. For example, a suitable absorbent plug or body may be a foamed metal or plastic material, polypropylene, dacron, nylon fiber or ceramic.

The aerosol-generating system may further comprise a liquid transport element. The liquid transport element may be configured such that, in use, liquid aerosol-forming substrate is transported from the liquid storage portion to the atomiser by capillary action along the liquid transport element. In embodiments in which the liquid storage portion comprises a porous carrier material, the liquid transport element is configured to transport the liquid aerosol-forming substrate from the porous carrier material to the atomiser. The liquid transport element may comprise a capillary material. A capillary material is a material that actively transports liquid from one end of the material to the other. The capillary material may advantageously be oriented in the liquid storage portion to convey the liquid aerosol-forming substrate to the atomizer.

The liquid transport element may comprise any suitable material or combination of materials capable of transporting the liquid aerosol-forming substrate along its length. The liquid transport element may be formed from a porous material, but need not be. The liquid transport element may be formed of a material having a fibrous or sponge-like structure. The liquid transport element preferably comprises a bundle of capillaries. For example, the liquid transport element may comprise a plurality of fibers or filaments, or other fine bore tubes. The liquid transport element may comprise a sponge-like or foam-like material. Preferably, the structure of the liquid transport element forms a plurality of apertures or tubes through which the liquid aerosol-forming substrate may be transported by capillary action. Particularly preferred materials will depend on the physical properties of the liquid aerosol-forming substrate. Examples of suitable capillary materials include sponges or foams, ceramic or graphite based materials in the form of fibers or sintered powders, foamed metal or plastic materials, such as fibrous materials made from spun or extruded fibers, such as cellulose acetate, polyester or bonded polyolefin, polyethylene, dacron or polypropylene fibers, nylon fibers, ceramics, glass fibers, silica glass fibers, carbon fibers, metal fibers of medical grade stainless steel alloys such as austenitic 316 stainless steel, and martensitic 440 and 420 stainless steel. The liquid transport element may have any suitable capillarity for use with different liquid physical properties. The liquid aerosol-forming substrate has physical properties including, but not limited to, viscosity, surface tension, density, thermal conductivity, boiling point and vapour pressure, which allow the liquid aerosol-forming substrate to be transported through the liquid transport element. The liquid transport element may be formed of a heat resistant material. The liquid transport element may comprise a plurality of fiber strands. The plurality of fiber strands may be substantially aligned along the length of the liquid transport element.

In embodiments in which the liquid storage section comprises a porous carrier material, the porous carrier material and the liquid transport element may comprise the same material. Preferably, the porous carrier material and the liquid transport element comprise different materials.

The atomiser may be any suitable type of atomiser. For example, the nebulizer may be an acoustic nebulizer. By using vibration, typically at ultrasonic frequencies, a sonic nebulizer may move an aerosol-forming substrate through a plurality of nozzles to release volatile compounds from the aerosol-forming substrate. In another example, the atomizer may be a thermal atomizer. By heating the aerosol-forming substrate, the thermal atomiser may release volatile compounds from the aerosol-forming substrate.

In some embodiments, the nebulizer includes a conductivity sensor. In these embodiments, the atomizer may include one or more conductive elements. The one or more electrodes of the conductivity sensor may comprise one or more conductive elements of the nebulizer. Advantageously, combining the nebulizer and the conductivity sensor may reduce the number of components of the aerosol-generating system, thereby reducing manufacturing costs and complexity.

In some preferred embodiments, the atomizer is a thermal atomizer. The thermal atomizer may be an electric heater. The thermal atomizer may comprise one or more heating elements. Preferably, the thermal atomizer comprises a plurality of heating elements.

In some particularly preferred embodiments, the atomizer is a thermal atomizer comprising a plurality of heating elements, and each electrode of the conductivity sensor comprises a heating element of the thermal atomizer. In these particularly preferred embodiments, the control electronics may also be configured to supply a first power from the power supply to the electrodes of the conductivity sensor to measure the conductivity of the liquid aerosol-forming substrate; and supplying a second power from the power supply to the plurality of heating elements of the atomizer to atomize the liquid aerosol-forming substrate. The second power is greater than the first power. The first power may be sufficient to enable receipt of a conductivity measurement from the conductivity sensor at the control electronics without raising the temperature of the heating element to a temperature sufficient to release volatile compounds from the liquid aerosol-forming substrate. The second power may be sufficient to raise the temperature of the heating element to a temperature sufficient to release the volatile compound from the liquid aerosol-forming substrate.

The thermal atomizer may comprise a resistive heating coil. The thermal atomizer may comprise a plurality of resistive heating coils.

The thermal atomizer may comprise a resistive heating mesh. The thermal atomizer may comprise a plurality of resistive heating screens.

The resistive heating mesh may comprise a plurality of electrically conductive filaments. The conductive filaments may be substantially planar. As used herein, "substantially flat" means formed in a single plane and not rolled or otherwise conformed to fit a curved or other non-planar shape. The flat heating mesh can be easily handled during manufacturing and provides a robust construction.

The electrically conductive filaments may define interstices between the filaments, and the interstices may have a width of between about 10 microns and about 100 microns. Preferably, the filaments create a capillary action in the void such that, in use, liquid aerosol-forming substrate is drawn into the void, thereby increasing the contact area between the heater assembly and the liquid.

The conductive filaments may form a Mesh having a size between about 160 and about 600 US Mesh (+/-10%), i.e., between about 160 and about 600 filaments per inch (+/-10%). The width of the voids is preferably between about 75 microns and about 25 microns. The percentage of open area of the mesh, i.e. the ratio of the area of the voids to the total area of the mesh, is preferably between about 25% and about 56%. Different types of woven or mesh structures may be used to form the mesh. The electrically conductive filaments may be an array of filaments arranged parallel to each other.

The conductive filaments may have a diameter of between about 8 microns and about 100 microns, preferably between about 8 microns and about 50 microns, and more preferably between about 8 microns and about 39 microns.

The resistive heating grid may cover an area of less than or equal to about 25 square millimeters. The resistive heating grid may be rectangular. The resistive heating grid may be square. The resistive heating grid may have dimensions of about 5 millimeters by about 2 millimeters.

The conductive filaments may comprise any suitable conductive material. Suitable materials include, but are not limited to: such as ceramic-doped semiconductors, "conductive" ceramics (e.g., molybdenum disilicide), carbon, graphite, metals, metal alloys, and composites made of ceramic and metallic materials. Such composite materials may include doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable metal alloys include stainless steel; constantan; nickel-containing alloys, cobalt-containing alloys, chromium-containing alloys, aluminum-containing alloys, titanium-containing alloys, zirconium-containing alloys, hafnium-containing alloys, niobium-containing alloys, molybdenum-containing alloys, tantalum-containing alloys, tungsten-containing alloys, tin-containing alloys, gallium-containing alloys, manganese-containing alloys, and iron-containing alloys; as well as superalloys based on nickel, iron, cobalt, stainless steel,alloys based on ferro-aluminium and alloys based on ferro-manganese-aluminium.Is a registered trademark of titanium metal corporation. The filaments may be coated with one or more insulators. Preferred materials for the conductive filaments are 304, 316, 304L and 316L stainless steel, and graphite.

The resistance of the resistive heating grid is preferably between about 0.3 and about 4 ohms. More preferably, the resistance of the mesh is between about 0.5 and about 3 ohms, and more preferably about 1 ohm.

In embodiments where the thermal atomizer comprises resistive heating coils, the spacing of the coils is preferably between about 0.5 millimeters and about 1.5 millimeters, and most preferably about 1.5 millimeters. The pitch of the coil means the pitch between adjacent coil turns. The coil may comprise less than six turns, and preferably has less than five turns. The coil may have a diameter of between about 0.10 mm and about 0.15 mm, and is preferablyA resistive wire of about 0.125 mm is formed. The resistance wire is preferably formed of 904 or 301 stainless steel. Examples of other suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of other suitable metal alloys include constantan, nickel-containing alloys, cobalt-containing alloys, chromium-containing alloys, aluminum-containing alloys, titanium-containing alloys, zirconium-containing alloys, hafnium-containing alloys, niobium-containing alloys, molybdenum-containing alloys, tantalum-containing alloys, tungsten-containing alloys, tin-containing alloys, gallium-containing alloys, manganese-containing alloys, and iron-containing alloys, as well as superalloys based on nickel, iron, cobalt, stainless steels, nickel-containing alloys, and alloys, nickel-containing alloys, and alloys,Alloys based on ferro-aluminium and alloys based on ferro-manganese-aluminium. The resistive heating coil may also comprise a metal foil, such as an aluminium foil, provided in the form of a strip.

In embodiments where the thermal atomizer comprises resistive heating coils, the resistive heating coils may be wrapped around the liquid delivery material.

The power source may comprise any suitable type of power source. For example, the power source may include a battery. The power source may include a nickel metal hydride battery, a nickel cadmium battery, or a lithium based battery, such as a lithium cobalt battery, a lithium iron phosphate battery, or a lithium polymer battery. The power supply may comprise another form of charge storage device, such as a capacitor. The power source may need to be recharged. The power supply may have a capacity that allows sufficient energy to be stored for use in the aerosol-generating system in a multiple use experience. For example, the power source may have sufficient capacity to allow aerosol to be continuously generated for a period of approximately six minutes or an integral multiple of six minutes. In another example, the power source may have a capacity sufficient to allow a predetermined number of puffs or discrete activations of the nebulizer.

The control electronics may include a microprocessor, which may be a programmable microprocessor, microcontroller or Application Specific Integrated Chip (ASIC) or other electronic circuit capable of providing control. The control electronics may include additional electronic components. The control electronics are configured to regulate power to the heater assembly. Power may be supplied to the heater assembly continuously after system start-up, or may be supplied intermittently, such as on a puff-by-puff basis. Power may be supplied to the heater assembly in the form of current pulses.

The control electronics may advantageously comprise a DC/AC inverter, which may comprise a class D or class E power amplifier. The DC/AC inverter may enable the control electronics to supply an alternating voltage from the power source to the conductivity sensor.

The conductivity sensor may be arranged at any suitable location in the aerosol-generating system.

In some embodiments, the conductivity sensor is arranged in the liquid storage portion. In particular, the inductive conductivity sensor may be arranged in the liquid storage portion.

In some embodiments, the system comprises one or more porous carrier materials for holding and optionally transporting a liquid aerosol-forming substrate. Where the system comprises a porous carrier material comprising a liquid aerosol-forming substrate, one or more electrodes of the conductivity sensor may be arranged at or around the porous carrier material. One or more electrodes of the conductivity sensor may be arranged in contact with the porous carrier material. One or more electrodes of the conductivity sensor may be arranged in contact with an end of the porous carrier material.

In some embodiments, the conductivity sensor is disposed between the liquid storage portion and the nebulizer. In these embodiments, the at least two electrodes of the conductivity sensor may be arranged in or around a flow path of the liquid aerosol-forming substrate extending between the liquid storage portion and the nebulizer.

In some embodiments, the nebulizer may include a conductivity sensor. In other words, at least two electrodes of the conductivity sensor may be comprised in the nebulizer. In some preferred embodiments, the nebulizer comprises a plurality of elements, e.g. heating elements, and at least one of the at least two electrodes of the conductivity sensor may comprise an element of the nebulizer. In some embodiments, each electrode of the conductivity sensor comprises an element of the nebulizer.

In embodiments where the nebulizer includes a conductivity sensor, the control electronics may be connected to the nebulizer and the conductivity sensor in any suitable manner. The control electronics may include an aerosol-generating circuit and a conductivity measurement circuit. The aerosol-generating circuit may control the powering of elements of the atomizer to atomize the liquid aerosol-forming substrate. The conductivity measurement circuit may control the powering of electrodes of the conductivity sensor to measure the conductivity of the liquid aerosol-forming substrate.

In some embodiments, the control electronics comprise separate aerosol-generating and conductivity measurement circuits. In these embodiments, each element of the nebulizer, which is also configured as an electrode of the conductivity sensor, may comprise at least one electrical contact electrically connecting the element to the aerosol-generating circuit, and at least one electrical contact electrically connecting the element to the conductivity measurement circuit. Preferably, each element of the nebulizer, which is also configured as an electrode of the conductivity sensor, comprises two electrical contacts electrically connecting the element to the aerosol-generating circuit, and one electrical contact electrically connecting the element to the conductivity measurement circuit.

In some embodiments, the control electronics comprise a shared aerosol-generating circuit and conductivity measurement circuit. In these embodiments, each element of the nebulizer, which is also configured as an electrode of the conductivity sensor, may comprise at least one electrical contact electrically connecting the element to the aerosol-generating circuit and the conductivity measurement circuit. Preferably, each element of the nebulizer, which is also configured as an electrode of the conductivity sensor, comprises two electrical contacts electrically connecting the element to the aerosol-generating circuit and the conductivity measurement circuit.

In some embodiments, an aerosol-generating system comprises a device and a cartridge. The cartridge may be removably received in the device. Typically, the cartridge includes a liquid storage portion and the device includes a power source and control electronics. In these embodiments, the conductivity sensor may be provided in the device or in the cartridge. In some embodiments, the atomizer is disposed in the device. In some preferred embodiments, the atomizer is disposed in the cartridge.

According to the present disclosure there is provided an aerosol-generating system as described above, comprising a device portion and a cartridge portion, and the cartridge portion is removably received in the device portion. The device portion includes a power source and control electronics, and the cartridge portion includes a liquid storage portion, an atomizer, and a conductivity sensor.

Advantageously, providing the aerosol-generating system with a conductivity sensor in the device or in the cartridge may enable a manufacturer to standardise cartridge manufacture and device manufacture irrespective of the aerosol-forming substrate to be contained in the cartridge or in the liquid storage portion of the device. In other words, providing the aerosol-generating system with a conductivity sensor may enable a manufacturer to produce the same cartridge and the same device regardless of the liquid aerosol-forming substrate to be contained in the liquid storage portion of the cartridge or device. Such standardization may reduce the cost and complexity of manufacturing the cartridge and device.

In some embodiments, the conductivity sensor is disposed in the device. Advantageously, providing the conductivity sensor in the device may reduce the number of components in the cartridge, and in particular may reduce the number of relatively expensive electrical components in the cartridge, thereby reducing the cost and complexity of manufacturing the cartridge.

In some embodiments, the conductivity sensor is disposed in the cartridge. In some preferred embodiments, in which the atomiser is a thermal atomiser comprising a plurality of heating elements and each electrode of the conductivity sensor is formed by a heating element of the atomiser, the conductivity sensor may be provided in the cartridge. In these preferred embodiments, the thermal atomizer is disposed in the cartridge. Such cartridges are commonly referred to as cartomisers (cartomisers). The cartomiser may enable a high level of hygiene to be maintained in the aerosol-generating system, as components in contact with the aerosol-forming substrate may be replaced periodically and the user is not exposed to components in contact with the aerosol-forming substrate.

According to the present disclosure, there is provided a cartridge for an aerosol-generating system, the cartridge comprising: a liquid storage portion for holding a liquid aerosol-forming substrate; an atomizer in fluid connection with the liquid storage portion; and a conductivity sensor arranged to sense the conductivity of the liquid aerosol-forming substrate from the liquid storage portion.

In some particularly preferred embodiments, the conductivity sensor of the cartridge comprises two electrodes arranged in the liquid storage portion, a first electrode and a second electrode, each electrode forming a coil, wherein the first electrode is arranged to induce a current in the second electrode when an alternating voltage is supplied to the first electrode. In other words, the cartridge may comprise an inductive conductivity sensor, as described above.

The cartridge may have a simple design. The cartridge may have a housing defining a liquid storage portion. The cartridge housing is preferably a rigid housing comprising a liquid impermeable material. As used herein, "rigid housing" means a self-supporting housing. The device may also have a housing. Preferably, the device housing is a rigid housing. The cartridge housing and the device housing may be made of the same material. The device may have a cavity for receiving the cartridge.

Where the cartridge includes a nebulizer, the device may include electrical contacts for electrically connecting the power supply and control electronics in the device to the nebulizer in the cartridge. Where the cartridge includes a conductivity sensor, the electrical contacts of the device may electrically connect the control electronics and power source in the device to the conductivity sensor in the cartridge.

The aerosol-generating system may comprise a mouthpiece on which a user may draw to receive an aerosol generated by the aerosol-generating system. In some systems that include a device and a cartridge, the device includes a mouthpiece. In some systems that include a device and a cartridge, the cartridge includes a mouthpiece. Advantageously, providing a mouthpiece on the cartridge may help to maintain a high level of hygiene in the system, as the cartridge may be discarded and replaced more frequently than the device.

It should be understood that features described with reference to one embodiment may also be applied to other embodiments. For example, features described with reference to the cartridge may be equally applicable to aerosol-generating systems, and in particular to aerosol-generating systems comprising a cartridge.

Drawings

The invention will be further described, by way of example only, with reference to the accompanying drawings, in which:

figure 1a shows a schematic view of an aerosol-generating system comprising an aerosol-generating device and a cartridge inserted into the aerosol-generating device;

figure 1b shows a schematic view of the aerosol-generating system of figure 1a, wherein the cartridge is received in an aerosol-generating device;

figure 2 shows a schematic view of an end of a liquid transport element of an aerosol-generating system according to an embodiment of the invention, the end of the liquid transport element having an atomizer and a conductivity sensor;

FIG. 3 shows a schematic diagram of a nebulizer and a conductivity sensor according to another embodiment of the invention;

figure 4 shows a schematic view of an end of a liquid transport element of an aerosol-generating system according to another embodiment of the invention, the end of the liquid transport element having an atomizer and a conductivity sensor;

figure 5 shows a schematic view of an end of the liquid transport element of figure 4 comprising an electrical connection between the nebulizer and the conductivity sensor and the control electronics of the aerosol-generating device;

6a, 6b, 6c and 6d show schematic diagrams of elements of an embodiment of control electronics suitable for use with the nebulizer and conductivity sensor of FIG. 4;

FIG. 7 shows a schematic diagram of a four-point conductivity sensor according to another embodiment of the present invention;

FIG. 8 shows a schematic view of a first side of the four-point conductivity sensor of FIG. 7;

FIG. 9 shows a schematic diagram of an inductive conductivity sensor according to another embodiment of the present invention; and

fig. 10 shows a schematic diagram of a cross-section through the length of the inductive conductivity sensor of fig. 9.

Detailed Description

Fig. 1a and 1b are schematic diagrams of an exemplary aerosol-generating system comprising a cartridge, in which a conductivity sensor according to an embodiment of the invention may be provided. FIGS. 1a and 1b are FIGS. 1a and 1d, respectively, from International patent application publication No. WO 2015/117702A 1.

Figure 1a is a schematic view of an aerosol-generating device 10 and a separate cartridge 20 together forming an aerosol-generating system.

The cartridge 20 contains an aerosol-forming substrate and is configured to be received in the cavity 18 within the device. The cartridge 20 should be replaceable by a user when the aerosol-forming substrate disposed therein is exhausted. Fig. 1a shows the cartridge 20 just before insertion into the device, wherein the arrow 1 in fig. 1a indicates the direction of insertion of the cartridge.

The cartridge 20 includes a generally cylindrical housing 24 having a size and shape selected to be received in the cavity 18. The housing contains a capillary material (not shown) which is immersed in the liquid aerosol-forming substrate. In this example, the aerosol-forming substrate comprises 39 wt% glycerin, 39 wt% propylene glycol, 20 wt% water and a flavourant, and 2 wt% nicotine. Capillary materials are materials that actively transport liquid from one end to the other and may be made of any suitable material. In this example, the capillary material is formed from polyester.

The housing has an open end to which the heater assembly 30 is secured. The heater assembly 30 includes a substrate having an aperture formed therein, a pair of electrical contacts secured to the substrate and separated from each other by a gap, and a plurality of electrically conductive heater filaments spanning the aperture and secured to the electrical contacts on opposite sides of the aperture.

The heater assembly 30 is covered by a removable cover 26. The lid comprises a liquid impermeable plastic sheet that is glued to the heater assembly but can be easily peeled off. Tabs are provided on the sides of the lid to allow a user to grasp the lid when peeling the tabs. It will now be apparent to those of ordinary skill in the art that while gluing is described as the method of securing the impermeable plastic sheet to the heater assembly, other methods familiar to those of skill in the art, including heat sealing or ultrasonic welding, may also be used so long as the lid can be easily removed by the consumer.

The aerosol-generating device 10 is portable and has a size comparable to a conventional cigar or cigarette. The device 10 comprises a body 11 and a mouthpiece portion 12. The body 11 contains a battery 14 (e.g., a lithium iron phosphate battery), control electronics 16, and a cavity 18. The mouthpiece portion 12 is connected to the body 11 by a hinge connection 21 and is movable between an open position as shown in figure 1 and a closed position as shown in figure 1 b. The mouthpiece portion 12 is placed in an open position to allow insertion and removal of the cartridge 20, and in a closed position when the system is to be used to generate an aerosol, as will be described. The mouthpiece portion comprises a plurality of air inlets 13 and outlets 15. In use, the user sucks or sucks on the outlet to draw air from the air inlet 13, through the mouthpiece portion to the outlet 15 and then into the mouth or lungs of the user. An internal baffle 17 is provided to force air to flow through the mouthpiece portion 12 through the cartridge 20 as will be described.

The cavity 18 has a circular cross-section and is sized to receive the housing 24 of the cartridge 20. Electrical connectors 19 are provided at the sides of the cavity 18 to provide electrical connections between the control electronics 16 and the battery 14 and corresponding electrical contacts on the cartridge 20.

The cartridge 20 is inserted into the cavity 18 and the cap 26 is removed from the cartridge. In this position, the electrical connector is placed against the electrical contacts on the cartridge, as will be described. The mouthpiece portion 12 is then moved to the closed position.

Figure 1b shows the system with the mouthpiece portion 12 in the closed position. The mouthpiece portion 12 is held in the closed position by a clip-on mechanism (not shown).

The mouthpiece portion 12 in the closed position maintains the cartridge in electrical contact with the electrical connector 19 so that a good electrical connection is maintained in use regardless of the orientation of the system. The mouthpiece portion 12 may comprise an annular resilient element that engages a surface of the cartridge and is compressed between the rigid mouthpiece shell element and the cartridge when the mouthpiece portion 12 is in the closed position. This ensures that a good electrical connection is maintained despite manufacturing tolerances. Of course, other mechanisms for maintaining a good electrical connection between the cartridge and the device may be employed.

Fig. 2 is a schematic diagram of an exemplary nebulizer and conductivity sensor 100 for an aerosol-generating system (e.g., the aerosol-generating system of fig. 1a and 1 b). The nebulizer and conductivity sensor 200 is configured as a two-point conductivity sensor.

Fig. 2 shows a plan view of a combined nebulizer and conductivity sensor 100 of a cartridge received in an aerosol-generating device and electrically connected to control electronics 110 of the device. The cartridge comprises a liquid storage portion comprising a generally cylindrical body of capillary material 102 in which the liquid aerosol-forming substrate is retained. The atomizer and conductivity sensor 100 shown in fig. 2 is disposed over and in contact with an end of a generally cylindrical body of capillary material 102. The capillary material 102 is configured such that liquid aerosol-forming substrate held in the capillary material is drawn by capillary action to the end of the capillary body in contact with the nebulizer and conductivity sensor 100.

The nebulizer and conductivity sensor 100 includes two electrodes, a first electrode 104 and a second electrode 106. Each of the first electrode 104 and the second electrode 106 includes a resistive heating grid including a plurality of electrically conductive heater filaments. The first electrode 104 is spaced apart from the second electrode 106 such that there is a cavity 108 between the first electrode 104 and the second electrode 106. The cavity 108 between the first electrode 104 and the second electrode 106 is wide enough to electrically insulate the first electrode 104 from the second electrode 106 on the capillary material 102 when no liquid aerosol-forming substrate is present in the capillary material 102.

The first electrode 104 and the second electrode 106 are configured such that the liquid aerosol-forming substrate at the end of the capillary body contacts the first electrode 104 and the second electrode 106.

In the embodiment shown in fig. 2, the first electrode 104 and the second electrode 106 are electrically connected to control electronics of an aerosol-generating device (not shown), such as the aerosol-generating devices of fig. 1a and 1 b. The control electronics of the aerosol-generating device are configured to control the supply of power from the power supply of the device to the first electrode 104 and the second electrode 106.

In this embodiment, the control electronics of the aerosol-generating device comprise a separate conductivity measurement circuit 111 and aerosol-generating circuit 112. Each of the conductivity measurement circuit 111 and the aerosol-generating circuit 112 comprises an electrical contact in the form of a resilient pin contact for providing a reliable electrical connection between the control electronics of the aerosol-generating device and the first electrode 104 and the second electrode 106 when the cartridge is received in the device.

Each of the first electrode 104 and the second electrode 106 is electrically connected to the conductivity measurement circuit 111 through a single electrical contact. Thus, the conductivity measurement circuit includes two electrical contacts, one for each electrode 104, 106.

The conductivity measurement circuit 111 is configured to supply an alternating voltage between two electrical contacts of the conductivity measurement circuit, which in turn establishes an alternating voltage between the first electrode 104 and the second electrode 106. An alternating voltage between the first electrode 104 and the second electrode 106 drives an alternating current on a cavity 108 between the first electrode 104 and the second electrode 106 through the liquid aerosol-forming substrate disposed in the cavity 108. The conductivity measurement circuit 111 is further configured to measure a current between the first electrode 104 and the second electrode 106, and to determine the conductivity of the liquid aerosol-forming substrate disposed in the cavity 108 based on the measured current. The electrical conductivity of the liquid aerosol-forming substrate provides an indication of the nicotine concentration in the liquid aerosol-forming substrate.

Each of the first electrode 104 and the second electrode 106 is also electrically connected to the aerosol-generating circuit 112 by two electrical contacts, respectively. Each of the first electrode 104 and the second electrode 106 is electrically connected to a first electrical contact at a first end of the electrode and to a second electrical contact at a second end of the electrode opposite the first end. The aerosol-generating circuit 112 is configured to supply a voltage between the first and second electrical contacts of each of the first and second electrodes 104, 106. A voltage on the first electrode 104 between the first and second electrical contacts drives a current through the first electrode 104 between the first and second electrical contacts. A voltage on the second electrode 204 between the first and second electrical contacts drives a current through the second electrode 204, driving a current through the second electrode 106 between the first and second electrical contacts. The current through each electrode is adapted to heat the electrode. The aerosol-generating circuit 112 is configured to supply direct current in pulses between the two electrical contacts of each electrode 104, 106. The aerosol-generating circuit 112 is configured to vary the duty cycle of the pulses of direct current to vary the temperature of the electrodes 104, 106.

The conductivity measurement circuit 111 is configured to supply a first power to the first electrode 104 and the second electrode 106, and the aerosol-generating circuit 112 is configured to supply a second power to the first electrode 104 and the second electrode 106. Preferably, the first power is insufficient to heat the heater filaments of the electrodes 104, 106 and is insufficient to vaporise the liquid aerosol-forming substrate in contact with the heater filaments. The second power is sufficient to heat the heater filaments of the first electrode 104 and the second electrode 106 to vaporise the liquid aerosol-forming substrate in contact with the heater filaments. The aerosol-generating circuit 112 is configured to vary the second power based on the conductivity of the liquid aerosol-forming substrate determined by the conductivity measurement circuit 111, which provides an indication of the nicotine concentration in the liquid aerosol-forming substrate.

In this embodiment, the conductivity measurement circuit 111 is configured to supply a first power to the first and second electrodes 104, 106 and to measure the conductivity of the liquid aerosol-forming substrate disposed in the cavity 108 before the aerosol-generating circuit 112 supplies a second power to the first and second electrodes 104, 106 to heat the liquid aerosol-forming substrate. This enables the aerosol-generating circuitry 112 to adjust the second power in response to the nicotine concentration of the liquid aerosol-forming substrate determined prior to each aerosol-generating cycle (e.g. each time the user draws the aerosol-generating system to receive aerosol from the system).

Fig. 3 is a schematic diagram of another exemplary nebulizer and conductivity sensor 200 for an aerosol-generating system. The nebulizer and conductivity sensor 200 is configured as a two-point conductivity sensor.

In this embodiment, the cartridge (not shown) comprises a liquid transport element 202 in the form of a wick having at least one end in contact with the liquid aerosol-forming substrate in the liquid storage portion of the cartridge. The combined nebulizer and conductivity sensor 200 of the present embodiment comprises two electrodes 204, 206 in the form of coils arranged at a portion of the liquid transport material 202 outside the liquid storage portion. The liquid transport material 202 is arranged to draw liquid aerosol-forming substrate from the liquid storage portion to the first coil electrode 204 and the second coil electrode 206 of the combined nebulizer and conductivity sensor 200. Each coil electrode 204, 206 comprises a resistance heating wire wound concentrically in a spiral around a portion of the wick outside the liquid storage portion. The two coil electrodes 204, 206 are substantially identical, wound together around the wick in the same direction and comprise the same number of turns. The second coil 206 is offset from the first coil 204 along the wick such that the cavity 208 is disposed between corresponding turns of the first and second coils 204, 206. The cavity between corresponding turns of the first coil 204 and the second coil 206 is such that liquid aerosol-forming substrate in the wick may be drawn into the cavity 208 and disposed between the coil electrodes 204, 206.

The first coil electrode 204 and the second coil electrode 206 are configured such that the liquid aerosol-forming substrate in the cavity 208 between the first coil electrode 204 and the second coil electrode 206 is in contact with the first coil electrode 204 and the second coil electrode 206.

In the embodiment shown in fig. 3, the first coil electrode 204 and the second coil electrode 206 are electrically connected to control electronics of an aerosol-generating device (not shown), such as the aerosol-generating devices of fig. 1a and 1 b. The control electronics of the aerosol-generating device are configured to control the supply of power from the power supply of the device to the first electrode 204 and the second electrode 206.

In this embodiment, the control electronics of the aerosol-generating device comprise a shared conductivity measurement circuit 211 and aerosol-generating circuit 212. The conductivity measurement circuit 211 and the aerosol generation circuit 212 include shared electrical contacts.

Each of the first coil electrode 204 and the second coil electrode 206 is electrically connected to the aerosol-generating circuit 212 by two electrical contacts, one at each end of the coil electrodes. The aerosol-generating circuit 212 is configured to supply a voltage between contacts at opposite ends of each coil such that a voltage is established across each of the first and second electrodes 204, 206. The voltage on the first electrode 204 drives a current through the first electrode 204 to heat the electrode. The voltage on the second electrode 206 drives a current through the second electrode 206 to heat the electrode. The aerosol-generating circuit 212 is configured to supply direct current in pulses through each of the first electrode 204 and the second electrode 206. The aerosol-generating circuit 212 is configured to vary the duty cycle of the pulses of direct current to vary the temperature of the first and second electrodes 204, 206.

In this embodiment, the conductivity measurement circuit 211 shares electrical contacts with the aerosol-generating circuit 212. Each of the first coil electrode 204 and the second coil electrode 206 is electrically connected to the conductivity measurement circuit 211 by one electrical contact. The conductivity measurement circuit 211 is electrically connected to the first coil electrode 204 by an electrical contact at a first end of the first coil electrode 204 and to the second coil electrode 206 by an electrical contact at a second end of the second coil electrode 206, which is the end of the second coil electrode 206 furthest from the first end of the first coil electrode 204. Thus, the conductivity measurement circuit 211 includes two electrical contacts, one for each coil electrode 204, 206.

The conductivity measurement circuit 211 is configured to supply an alternating voltage between two electrical contacts of the conductivity measurement circuit 211, which in turn establishes an alternating voltage between the first coil electrode 204 and the second coil electrode 206. An alternating voltage between the first coil electrode 204 and the second coil electrode 206 drives an alternating current on a cavity 208 between the first electrode 204 and the second electrode 206 through the liquid aerosol-forming substrate disposed in the cavity 208. The conductivity measurement circuit 211 is further configured to measure a current between the first coil electrode 204 and the second coil electrode 206, and to determine the conductivity of the liquid aerosol-forming substrate disposed in the cavity 208 based on the measured current. The electrical conductivity of the liquid aerosol-forming substrate provides an indication of the nicotine concentration in the liquid aerosol-forming substrate.

The conductivity measurement circuit 211 is configured to supply a first power to the first coil electrode 204 and the second coil electrode 206, and the aerosol-generating circuit 212 is configured to supply a second power to the first electrode 204 and the second electrode 206. Preferably, the first power is insufficient to heat the coil electrodes 204, 206 and is insufficient to vaporise the liquid aerosol-forming substrate in contact with the coil electrodes. The second power is sufficient to heat the first coil electrode 204 and the second coil electrode 206 to vaporise the liquid aerosol-forming substrate in contact with the coil electrodes. The aerosol-generating circuit 212 is configured to vary the second power based on the conductivity of the liquid aerosol-forming substrate determined by the conductivity measurement circuit 211, which provides an indication of the nicotine concentration in the liquid aerosol-forming substrate.

It should be understood that in other embodiments, the first and second coil electrodes 204, 206 may be separately electrically connected to the conductivity measurement circuit and the aerosol-generating circuit of the aerosol-generating device in a similar manner to the first and second electrodes 104, 106 of the nebulizer and conductivity sensor described above with respect to fig. 2.

Fig. 4 and 5 are schematic diagrams of another exemplary nebulizer and conductivity sensor 300 for an aerosol-generating system (e.g., the aerosol-generating system of fig. 1a and 1 b). The nebulizer and conductivity sensor 300 is configured as a four-point conductivity sensor.

Fig. 4 shows a plan view of a combined nebulizer and conductivity sensor 300 of a cartridge, and fig. 5 shows a plan view of a cartridge received in an aerosol-generating device and electrically connected to control electronics 310 of the device.

The cartridge comprises a liquid storage portion comprising a generally cylindrical body of capillary material 302 in which the liquid aerosol-forming substrate is retained. The atomizer and conductivity sensor 300 shown in fig. 4 and 5 is disposed over and in contact with an end of a generally cylindrical body of capillary material 302. The capillary material 302 is configured such that liquid aerosol-forming substrate held in the capillary material is drawn by capillary action to the end of the capillary body in contact with the nebulizer and conductivity sensor 300.

The nebulizer and conductivity sensor 300 includes four electrodes, namely a pair of outer electrodes 304 and a pair of inner electrodes 306. Each of the electrodes 304, 306 comprises a resistive heating grid comprising a plurality of electrically conductive heater filaments.

A pair of outer electrodes 304 are spaced apart such that an outer cavity 308 exists between the outer electrodes 304. The outer cavity 308 between the outer electrodes 304 is wide enough to electrically insulate the outer electrodes 304 on the capillary material 302 from each other when no liquid aerosol-forming substrate is present in the capillary material 302.

A pair of inner electrodes 306 is disposed between the pair of outer electrodes 304 in an outer cavity 308. A pair of inner electrodes 306 is spaced sufficiently from a pair of outer electrodes 304 to electrically insulate the inner electrodes 306 on the capillary material 302 from the outer electrodes 304 when no liquid aerosol-forming substrate is present in the capillary material 302. A pair of inner electrodes 306 are spaced apart such that a lumen 309 exists between the inner electrodes 306. The lumens 309 between the inner electrodes 306 are wide enough to electrically insulate the inner electrodes 306 on the capillary material 302 from each other when no liquid aerosol-forming substrate is present in the capillary material 302.

The liquid aerosol-forming substrate at the end of the capillary body in contact with the atomizer and conductivity sensor 300 contacts the inner electrode 204 and the outer electrode 206.

Providing four electrodes in this arrangement enables the combined atomizer and conductivity sensor 300 of this embodiment to be used as a four-point conductivity sensor, as described in more detail below.

In fig. 5, an inner electrode 304 and an outer electrode 306 are shown in electrical connection with control electronics 310 of an aerosol-generating device (not shown), e.g. the aerosol-generating device of fig. 1a and 1 b. The control electronics 310 of the aerosol-generating device are configured to control the supply of power from the power supply of the device to the outer electrode 304 and the inner electrode 306.

In this embodiment, the control electronics 310 of the aerosol-generating device comprise a shared conductivity measurement circuit and aerosol-generating circuit, as described in more detail below with reference to fig. 6. In this embodiment, the conductivity measurement circuit and the aerosol-generating circuit comprise shared electrical contacts in the form of resilient pin contacts for providing a reliable electrical connection between the control electronics 310 of the aerosol-generating device and the inner electrode 304 and the outer electrode 306. It will be appreciated that in other embodiments, the aerosol-generating circuit and the conductivity measurement circuit may comprise separate electrical contacts.

In this embodiment, each of the inner electrode 304 and the outer electrode 306 are electrically connected to the control circuit 310 by two electrical contacts. Each of the inner electrode 304 and the outer electrode 306 is electrically connected to a first electrical contact at a first end of the electrode and to a second electrical contact at a second end of the electrode opposite the first end.

Fig. 6a-d schematically show some components of an exemplary embodiment of control electronics 310 of an aerosol-generating device incorporating the combined nebulizer and conductivity sensor of fig. 4 and 5.

The control electronics are configured to operate in two different modes, namely a conductivity measurement mode and a heating mode. In the conductivity measurement mode, an alternating voltage is supplied between the two outer electrodes 304 and the voltage across the two inner electrodes 306 is measured. In the heating mode, a pulsed direct current is supplied to each of the inner and outer electrodes 304, 306, respectively, to heat the heater filaments of the electrodes and vaporise the liquid aerosol-forming substrate in contact with the heater filaments.

In this embodiment, the control electronics 310 generally include a DC power supply V_DCA microcontroller 320, and a plurality of transistor switches. The transistor switch is a Field Effect Transistor (FET) controlled by the control electronics to power the combined nebulizer and conductivity sensor according to the conductivity measurement mode and the heating mode.

In FIGS. 6a-d, the first of the outer electrodes is shown as E₁And a second one of the outer electrodes is shown as E₄And a first one of the internal electrodes is shown as E₂And a second one of the internal electrodes is shown as E₃. As shown in FIG. 6a, each electrode E_1-E₄Connected to the control electronics by two electrical contacts spaced at opposite ends of the electrodes. Each electrode E₁–E₄Via a first transistor switch T_1a-T_4aConnected by a first electrical contact to a DC power source. Each electrode is also connected by a second electrical contact to a second transistor switch T_1b-T_4bAnd a third transistor switch T_1c-T_4cIn the middle position. First transistor switch T_1a-T_4aSo that the control electronics can isolate each of the electrodes from the power supply individually when the transistor is off. The second transistor switch T will be discussed in further detail below_1b-T_4bAnd a third transistor switch T_1c-T_4cThe function of (c).

A first transistor and a second transistor T for controlling the electronic device to supply a high-frequency AC switching voltage to the external electrode in a conductivity measurement mode_1a、T_1b、T_4a、T_4bSuch that during a half period the transistor T_1aAnd T_4bConducting and transistor T_1bAnd T_4aIs turned off and during the other half-cycle, the transistor T_1bAnd T_4aConducting and transistor T_1aAnd T_4bAnd (6) turning off.

FIG. 4b shows the transistor T_1aAnd T_4bConnection of the combined nebulizer and conductivity sensor to the power supply in the conductivity measurement mode during the first half of the conduction. The arrangement shown in fig. 4b can be seen as comprising a first drive circuit which operates to drive the outer electrode E₁、E₄A first periodic voltage drop is provided having a selected frequency F and having a magnitude ranging from a first value to a second value lower than the first value.

FIG. 4c shows the transistor T_4aAnd T_1cConnection of the combined atomizer and conductivity sensor to a power supply in a conductivity measurement mode during the second half of the on-state. The arrangement shown in fig. 4c can be regarded as being at the outer electrode E₁、E₄A second periodic voltage drop is provided that is the same frequency and magnitude but opposite polarity as the first periodic voltage drop and is completely out of phase with the first periodic voltage.

The first and second periodic voltage drops have opposite polarities to each other, wherein the opposite polarities refer to the relative positions of the high and low voltage sides in this document, rather than requiring positive and negative voltages. Since the first and second periodic voltage drops are applied from opposite ones of the outer electrodes. Since the first and second periodic voltage drops have opposite polarities and are completely out of phase, the AC voltage is effectively supplied on the outer electrode. The first and second periodic voltage drops may have any suitable waveform. For example, the two waveforms may be square waves that are completely out of phase with each other. Advantageously, the control electronics may be configured to provide a dead time period of at least a few nanoseconds between the end of one voltage drop and the start of the next voltage drop in the opposite direction to avoid burning out the switch.

In the first half period, the second external electrode E₄Second transistor T of_4bIs turned on and is turned on by having a known resistance R₂Provides a path to electrical ground. The microprocessor 220 is configured to measure the resistor R₂Voltage V across₃And can be based on the measured voltage V₃And a known resistance R₂Is determined at the first outer electrode E₁And a second external electrode E₄The current flowing in between.

In the second half period, the first external electrode E₁Second transistor T of_1bIs turned on and is turned on by having a known resistance R₁Provides a path to electrical ground. The control electronics are configured to measure the resistor R₁Voltage V across₁And can be based on the measured voltage V₁And a known resistance R₁Is determined at the second external electrode E₄And a first external electrode E₁The current flowing in between.

During the conductivity measurement mode, the control electronics are also configured to supply two internal electrodes E₂、E₃Second crystal T of_1b、T_2bA base of each of which supplies a voltage so that two internal electrodes E₂、E₃Second transistor T of_1b、T_2bAnd conducting. In the conductivity measurement mode, the control electronics do not supply voltage to any of the third transistors of the inner or outer electrodes, so that all third transistors remain off.

Inner electrode E₂、E₃Second transistor T of_2b、T_3bEach providing a path for an input of a differential amplifier 322 whose output is supplied to the microprocessor 320 to provide the microprocessor 320 with an inner electrode E₂、E₁Voltage V across₂Is measured.

The microprocessor 320 can be configured in a number of different ways to use the measured voltage V₁、V₂And V₃To determine an indication of nicotine concentration in the liquid aerosol-forming substrate between the electrodes of the combined nebulizer and conductivity sensor. In this embodiment, the microprocessor 320 is configured to use the measured voltage V₁、V₃To determine the outer electrode E₁、E₄And for the inner electrode E₂、E₃A determined current and a measured voltage V₂To determine the electrical conductivity of the liquid aerosol-forming substrate and to determine an indication of the nicotine concentration in the liquid aerosol-forming substrate.

In the heating mode, the control electronics supply a high-frequency alternating-current switching voltage to all electrodes E₁、E₂、E₃、E₄First transistor T of_1a、T_2a、T_3a、T_4aSuch that all first transistors periodically alternate between being turned on and off. The control electronics also supply a voltage to all electrodes E₁、E₂、E₃、E₄Third transistor T of₁c、T_2c、T_3c、T_4cA base of each of which turns on the third transistor. Third electrode T_1c、T_2c、T_3c、T_4cProviding a path to electrical ground.

FIG. 4d shows the transistor T_1a、T_2a、T_3a、T_4a、T_1c、T_2c、T_3cAnd T_4cIn the on-state, the connection of the combined atomizer and conductivity sensor 300 to the power supply is in the heating mode. The arrangement shown in fig. 4d may be considered to comprise a thirdA drive circuit operative to supply a current on each of the electrodes.

By periodically switching the first transistor on and off, and by maintaining the third transistor on, the control electronics supply a pulsed direct current on each of the electrodes. The control electronics are configured to control the duty cycle of the pulses to control the temperature to which the electrodes are heated. Preferably, the control electronics are configured to control the duty cycle in the heating mode based on an indication of the nicotine concentration determined in the conductivity measurement mode.

It will be appreciated that in other embodiments, the control electronics of the aerosol-generating device may not be arranged to directly power the inner electrode to heat the inner electrode, but rather the control electronics may be arranged to heat the inner electrode by induction. In these embodiments, an oscillating voltage is applied to the outer electrode, which induces a current in the inner electrode. In order to heat the inner electrode to a sufficient temperature, it is preferred that the inner electrode is a susceptor element formed of a magnetic material such as AISI 4xx stainless steel. Although the outer electrodes may be formed of a magnetic material, this is not a necessary requirement in these embodiments.

Fig. 7 and 8 show schematic diagrams of another exemplary conductivity sensor 400. In this embodiment, the conductivity sensor 400 is not combined with the nebulizer. In this embodiment, the conductivity sensor is configured as a four-point conductivity sensor arranged in the liquid storage portion of the cartridge of the aerosol-generating device.

The cartridge comprises a housing 401 defining a substantially cuboidal liquid storage portion. The housing is formed of a rigid electrically insulating material (e.g., PEEK). Conductivity sensor 400 includes four electrodes, two outer electrodes 404 and two inner electrodes 406. A first one of the outer electrodes 404 and a first one of the inner electrodes 406 are disposed on a first inner surface of the cartridge case 401, and a second one of the outer electrodes 404 and a second one of the inner electrodes 406 are disposed on a second inner surface of the cartridge case 401 opposite to the first surface such that the first outer electrode and the first inner electrode face the second outer electrode and the second inner electrode opposite to the liquid storage portion.

The outer electrode 404 comprises the same ring electrode that defines the outer electrode cavity 407. The inner electrodes 406 comprise identical circular electrodes. As shown in fig. 8, at a first inner surface of the cartridge housing 401, a first outer electrode 404 and a first inner electrode 406 are arranged concentrically, wherein the first inner electrode 406 is arranged in an outer electrode cavity 405 of the first outer electrode 404. Similarly, at a second inner surface of the cartridge housing 401, a first outer electrode 404 and a first inner electrode 406 are arranged concentrically, wherein the second inner electrode 406 is arranged in an outer electrode cavity 405 of the second outer electrode 404. The outer diameter of inner electrode 406 is smaller than the inner diameter of outer electrode 404 such that a cavity is disposed between inner electrode 404 and outer electrode 406. The cavity between inner electrode 404 and outer electrode 406 electrically insulates inner electrode 406 from outer electrode 404 when no liquid aerosol-forming substrate is disposed in the cavity.

As shown in fig. 7, the first inner and outer electrodes at the first inner side of the cartridge housing 401 are aligned with the second inner and outer electrodes at the second inner side of the cartridge housing 401. Thus, the first and second outer electrodes 404 are substantially separated by the width of the liquid storage portion, forming a cavity 408, and the first and second inner electrodes 406 are also substantially separated by the cavity 408, which is formed by the width of the liquid storage portion.

When the liquid aerosol-forming substrate is disposed in the liquid storage portion, the liquid aerosol-forming substrate may be disposed in the cavity 408 and contact the first electrode 404 and the second electrode 406. In this embodiment, the liquid aerosol-forming substrate is free to move in the liquid storage portion. However, in other embodiments, a carrier material may be provided in the liquid storage portion for holding the liquid aerosol-forming substrate. Such carrier materials, which are typically porous, electrically insulating materials, are disposed in the cavity 408 in contact with the inner electrode 404 and the outer electrode 406.

As shown in fig. 7, each of the outer electrodes 404 is electrically connected to the control electronics 410 of the aerosol-generating device. Similarly, each of the inner electrodes 406 is electrically connected to the control electronics 410 of the aerosol-generating device. Each electrode 404, 406 is electrically connected to control electronics 410 by one electrical contact.

The control electronics 410 is configured to supply an alternating voltage to the outer electrodes 404, which may drive an alternating current through the liquid aerosol-forming substrate in the cavity 408 disposed between the first and second outer electrodes 404. The control electronics are configured to measure the current between the first and second outer electrodes 404.

An alternating current driven between the first and second outer electrodes 404 by the control electronics 410 establishes an alternating voltage between the first and second inner electrodes 406. The control electronics 410 are configured to measure the voltage on the first and second inner electrodes. The control electronics are also configured to use the measurements of current and voltage to determine the conductivity of the liquid aerosol-forming substrate disposed in the chamber 408. The control electronics 410 may also determine the nicotine concentration in the liquid aerosol-forming substrate based on the determined conductivity.

It should be understood that in other embodiments, the four-point conductivity sensor 400 may be replaced by a two-point conductivity sensor having a first electrode at a first side of the liquid storage portion and a second electrode at a second side of the liquid storage portion.

In this embodiment, the conductivity sensor 400 is arranged in the liquid storage portion of the cartridge; however, it will be appreciated that in other embodiments the conductivity sensor 400 may be arranged in the liquid storage portion of the aerosol-generating device or in a conduit between the liquid storage portion and the nebulizer.

Fig. 9 and 10 show schematic diagrams of another exemplary conductivity sensor 500. In this embodiment, the conductivity sensor 500 is not combined with the nebulizer. In this embodiment, the conductivity sensor 500 is an inductive conductivity sensor arranged in a liquid storage portion of a cartridge of an aerosol-generating device.

The conductivity sensor 500 comprises two electrodes 504, 506 in the form of loop coils. A first of the coil electrodes is a drive coil 504 wound around a first ring 505 of ferromagnetic material. The second of the coil electrodes is a receive coil 506 wound around a second ring 507 of ferromagnetic material. The receiving coil 506 and the loop 507 are substantially the same as the driving coil 504 and the loop 505, specifically, have the same number of turns and are wound in the same direction.

Each of the drive coil 504 and the receive coil 506 has an internal cavity through which the aerosol-forming substrate may be fluidly passed. The receive coil 506 is axially aligned with the drive coil 504 and spaced apart from the drive coil 504 along the axis such that the receive coil lumen and the drive coil lumen are aligned to substantially form a continuous cylindrical lumen through which the liquid aerosol-forming substrate can flow. The drive coil 504 is arranged and configured to induce a current in the receive coil 506 when an alternating voltage is supplied to the drive coil 504.

Each end of the drive coil 504 and the receive coil 506 is electrically connected to the control electronics 510 of the aerosol-generating device.

The drive coils 504 and ferromagnetic rings 505 and the receive coils 506 and ferromagnetic rings 507 are embedded in an annular cylindrical body 512 of electrically insulating material (e.g. plastics material) which is substantially impermeable to the liquid aerosol-forming substrate. Thus, the body 512 has the form of a cylindrical tube with a lumen 514 extending through the body 512 and being open at both ends. The body 512 is arranged to protect the coil electrode from the liquid aerosol-forming substrate. The body 512 is configured to be arranged in the liquid storage portion of the cartridge such that liquid aerosol-forming substrate in the liquid storage portion can flow through the internal passage 514 and around the outer surface of the body 501.

In use, the control electronics 510 are configured to supply power to the drive coil 504 in the form of an alternating voltage. An alternating voltage in the drive coil 504 generates a magnetic field that induces a current in the liquid aerosol-forming substrate disposed in the inner chamber 514. The current in the lumen 514 is shown by arrows 516 in fig. 7. The current 516 induced in the liquid aerosol-forming substrate also generates a magnetic field that induces a current in the receive coil 506. The electrical conductivity of the liquid aerosol-forming substrate affects the magnitude of the current 516 induced in the liquid aerosol-forming substrate, which in turn affects the magnitude of the current induced in the receive coil 506. The control electronics 510 is configured to measure one or both of the voltage and the current induced in the receiving coil, and is further configured to determine the conductivity of the liquid aerosol-forming substrate based on the measured one or more of the current and the voltage induced in the receiving coil. The control electronics may also determine the concentration of nicotine in the liquid aerosol-forming substrate based on the determined conductivity.