Gas sensor, sensor array module including the same, and mobile device
阅读说明：本技术 气体传感器、包括其的传感器阵列模块和移动装置 (Gas sensor, sensor array module including the same, and mobile device ) 是由 朴光暋 李始勋 林载兴 朴晸浩 于 2021-06-10 设计创作，主要内容包括：提供了一种气体传感器以及包括其的传感器阵列模块和移动装置。所述气体传感器包括：压电式衬底；压电式衬底的上表面上的电极区中的谐振器,谐振器包括叉指换能器电极和连接至叉指换能器电极的叉指换能器焊盘,叉指换能器电极被配置为在电极区的中心区中产生表面声波,表面声波在第一水平方向上传播；压电式衬底的上表面上的电极区的中心区中的感测膜,感测膜包括与目标气体相互作用的感测材料；以及包围压电式衬底的上表面上的电极区的边缘区中的加热器,所述加热器包括被配置为加热感测膜的加热器电极和连接至加热器电极的加热器焊盘,加热器电极和加热器焊盘形成闭合传导回路。(Provided are a gas sensor, and a sensor array module and a mobile device including the same. The gas sensor includes: a piezoelectric substrate; a resonator in an electrode region on an upper surface of the piezoelectric substrate, the resonator comprising an interdigital transducer electrode and an interdigital transducer pad connected to the interdigital transducer electrode, the interdigital transducer electrode configured to generate a surface acoustic wave in a central region of the electrode region, the surface acoustic wave propagating in a first horizontal direction; a sensing membrane in a central region of the electrode region on the upper surface of the piezoelectric substrate, the sensing membrane comprising a sensing material that interacts with a target gas; and a heater in an edge region surrounding an electrode region on the upper surface of the piezoelectric substrate, the heater including a heater electrode configured to heat the sensing film and a heater pad connected to the heater electrode, the heater electrode and the heater pad forming a closed conductive loop.)
1. A gas sensor, comprising:
a piezoelectric substrate;
a resonator located in an electrode region on an upper surface of the piezoelectric substrate, the resonator comprising an interdigital transducer electrode and an interdigital transducer pad connected to the interdigital transducer electrode, the interdigital transducer electrode configured to generate a surface acoustic wave in a central region of the electrode region, the surface acoustic wave propagating in a first horizontal direction;
a sensing membrane located in a central region of an electrode region on an upper surface of the piezoelectric substrate, the sensing membrane including a sensing material that interacts with a target gas; and
a heater located in an edge region surrounding an electrode region on an upper surface of the piezoelectric substrate, the heater including a heater electrode configured to heat the sensing film and a heater pad connected to the heater electrode, the heater electrode and the heater pad forming a closed conductive loop.
2. The gas sensor of claim 1, wherein:
the heater is symmetrical with respect to a first center line passing through a center region of the electrode region and extending in the first horizontal direction, and
the heater is symmetrical with respect to a second center line passing through a center region of the electrode region and extending in a second horizontal direction perpendicular to the first horizontal direction.
3. The gas sensor of claim 2, wherein the heater electrode comprises a plurality of meander patterns, each meander pattern of the plurality of meander patterns comprising:
at least three column conductors extending in the second horizontal direction and arranged adjacent to each other in the first horizontal direction;
a first row conductor connecting a first end of a first of the at least three column conductors to a first end of a second of the at least three column conductors; and
a second row conductor connecting a second end of a second of the at least three column conductors to a second end of a third of the at least three column conductors.
4. A gas sensor according to claim 3, wherein the line pitch between two adjacent column conductors in the first horizontal direction is uniform with respect to all column conductors included in each meander pattern of the plurality of meander patterns.
5. The gas sensor of claim 3, wherein each meander pattern of the plurality of meander patterns comprises:
a main meander pattern disposed adjacent to a central region of the electrode region, the main meander pattern generating a first heat per unit area; and
a sub meander pattern, the sub meander pattern being further from a central region of the electrode region than the main meander pattern, the sub meander pattern generating a second amount of heat per unit area, the second amount of heat per unit area being less than the first amount of heat per unit area.
6. The gas sensor according to claim 5, wherein a first line pitch in the first horizontal direction between two adjacent column conductors included in the main meander pattern is smaller than a second line pitch in the first horizontal direction between two adjacent column conductors included in the sub meander pattern.
7. The gas sensor of claim 5, wherein a first line width of each column conductive line included in the main meander pattern is less than a second line width of each column conductive line included in the sub meander pattern.
8. The gas sensor of claim 2, wherein:
the electrode region includes first and second pad regions disposed adjacent to opposite sides of a central region of the electrode region along the second center line such that the electrode region has a cross shape, and
the interdigital transducer pad is located in the first pad region and the second pad region.
9. The gas sensor according to claim 8, wherein the heater pad is adjacent to one side of the first pad region along the second center line and one side of the second pad region along the second center line, or the heater pad is adjacent to an opposite side of the electrode region along the first center line.
10. The gas sensor of claim 8, wherein the heater electrode comprises:
a first meander pattern and a second meander pattern respectively disposed adjacent to opposite sides of the first pad region in the first horizontal direction; and
third and fourth meander patterns respectively disposed adjacent to opposite sides of the second pad region in the first horizontal direction.
11. The gas sensor of claim 10, wherein each of the first to fourth meander patterns comprises:
at least three column conductors extending in the second horizontal direction and arranged adjacent to each other in the first horizontal direction;
a first row conductor connecting a first end of a first of the at least three column conductors to a first end of a second of the at least three column conductors; and
a second row conductor connecting a second end of a second of the at least three column conductors to a second end of a third of the at least three column conductors.
12. The gas sensor of claim 10, wherein each of the first to fourth meander patterns comprises:
a main meander pattern disposed adjacent to a central region of the electrode region, the main meander pattern generating a first heat per unit area; and
a sub meander pattern disposed farther from a central region of the electrode region than the main meander pattern, the sub meander pattern generating a second amount of heat per unit area, the second amount of heat per unit area being less than the first amount of heat per unit area.
13. The gas sensor of claim 2, wherein:
the electrode region includes first and second pad regions corresponding to opposite ends of the electrode region along the first center line such that the electrode region has a bar shape extending in the first horizontal direction, and
the interdigital transducer pad is located in the first pad region and the second pad region.
14. The gas sensor according to claim 1, wherein the heater electrode includes a first meandering pattern and a second meandering pattern respectively disposed adjacent to opposite sides of the electrode region in a second horizontal direction perpendicular to the first horizontal direction.
15. The gas sensor of claim 14, wherein:
the first meander pattern comprises:
a first main meander pattern disposed adjacent to a first side of a central region of the electrode region in the second horizontal direction, the first main meander pattern generating a first heat per unit area; and
a first sub meander pattern and a second sub meander pattern disposed adjacent to opposite sides of the first main meander pattern in the first horizontal direction, the first sub meander pattern and the second sub meander pattern generating a second amount of heat per unit area, the second amount of heat per unit area being less than the first amount of heat per unit area, and
the second meandering pattern comprises:
a second main meander pattern disposed adjacent to a second side of a central region of the electrode region in the second horizontal direction, the second main meander pattern generating the first heat per unit area; and
third and fourth sub meander patterns respectively disposed adjacent to opposite sides of the second main meander pattern in the first horizontal direction, the third and fourth sub meander patterns generating the second heat per unit area.
16. The gas sensor of claim 1 wherein the resonator and the heater are formed in the same conductive layer on the upper surface of the piezoelectric substrate.
17. A sensor array module comprising:
a bottom substrate;
a driving circuit chip on the bottom substrate; and
a plurality of gas sensors on the drive circuit chip, each of the plurality of gas sensors comprising:
a piezoelectric substrate;
a resonator located in an electrode region on an upper surface of the piezoelectric substrate, the resonator comprising an interdigital transducer electrode and an interdigital transducer pad connected to the interdigital transducer electrode, the interdigital transducer electrode configured to generate a surface acoustic wave in a central region of the electrode region, the surface acoustic wave propagating in a first horizontal direction;
a sensing membrane located in a central region of an electrode region on an upper surface of the piezoelectric substrate, the sensing membrane including a sensing material that interacts with a target gas; and
a heater located in an edge region surrounding an electrode region on an upper surface of the piezoelectric substrate, the heater including a heater electrode configured to heat the sensing film and a heater pad connected to the heater electrode, the heater electrode and the heater pad forming a closed conductive loop.
18. The sensor array module of claim 17, further comprising a temperature sensor and a humidity sensor on the driving circuit chip, each of the temperature sensor and the humidity sensor including a heater having the same structure as a heater included in the plurality of gas sensors,
wherein the driving circuit chip is configured to simultaneously drive the heaters of the plurality of gas sensors, the temperature sensor, and the humidity sensor to implement the same temperature condition with respect to the plurality of gas sensors, the temperature sensor, and the humidity sensor.
19. A mobile device, comprising:
a housing comprising a gas inlet;
a sensor array module comprising at least one gas sensor, the sensor array module being in a first interior space of the housing;
a main board located in a second internal space of the housing;
a connector configured to connect the sensor array module with the main board; and
a partition wall configured to separate the first internal space from the second internal space,
the at least one gas sensor comprises:
a piezoelectric substrate;
a resonator located in an electrode region on an upper surface of the piezoelectric substrate, the resonator including an interdigital transducer electrode and an interdigital transducer pad connected to the interdigital transducer electrode, the interdigital transducer electrode configured to generate a surface acoustic wave in a central region of the electrode region, the surface acoustic wave propagating in the first horizontal direction;
a sensing membrane located in a central region of an electrode region on an upper surface of the piezoelectric substrate, the sensing membrane including a sensing material that interacts with a target gas; and
a heater located in an edge region surrounding an electrode region on an upper surface of the piezoelectric substrate, the heater including a heater electrode configured to heat the sensing film and a heater pad connected to the heater electrode, the heater electrode and the heater pad forming a closed conductive loop.
20. The mobile device of claim 19, further comprising a processor located on the motherboard, the processor configured to generate a heating control signal based on an operating condition of the mobile device to communicate the heating control signal to the sensor array module through the connector,
wherein the sensor array module heats a sensing membrane of the at least one gas sensor with the heater based on the heating control signal to increase a sensing sensitivity of the at least one gas sensor.
Technical Field
Embodiments relate to a gas sensor, a sensor array module including the gas sensor, and a mobile device.
Background
Gas sensors may be used in a variety of applications. For example, a gas sensor may be mounted on the air purifier and used to measure the air quality around the air purifier. In addition, a gas sensor may be included in a portable device such as a mobile phone and used to make a user of the portable device recognize the quality of ambient air.
Disclosure of Invention
Embodiments relate to a gas sensor, including: a piezoelectric substrate; a resonator in an electrode region on an upper surface of the piezoelectric substrate, the resonator including an interdigital transducer (IDT) electrode and an IDT pad connected to the IDT electrode, the IDT electrode configured to generate a surface acoustic wave in a center region of the electrode region, the surface acoustic wave propagating in a first horizontal direction; a sensing membrane in a central region of the electrode region on the upper surface of the piezoelectric substrate, the sensing membrane comprising a sensing material that interacts with a target gas; and a heater in an edge region surrounding the electrode region on the upper surface of the piezoelectric substrate, the heater including a heater electrode configured to heat the sensing film and a heater pad connected to the heater electrode, the heater electrode and the heater pad forming a closed conductive loop.
Embodiments are also directed to a sensor array module comprising: a bottom substrate; a driving circuit chip on the base substrate; and a plurality of gas sensors on the driving circuit chip. Each gas sensor of the plurality of gas sensors may include: a piezoelectric substrate; a resonator in an electrode region on an upper surface of the piezoelectric substrate, the resonator including an interdigital transducer (IDT) electrode and an IDT pad connected to the IDT electrode, the IDT electrode configured to generate a surface acoustic wave in a center region of the electrode region, the surface acoustic wave propagating in a first horizontal direction; a sensing membrane in a central region of an electrode region on an upper surface of the piezoelectric substrate, the sensing membrane comprising a sensing material that interacts with a target gas; and a heater in an edge region surrounding an electrode region on the upper surface of the piezoelectric substrate, the heater including a heater electrode configured to heat the sensing film and a heater pad connected to the heater electrode, the heater electrode and the heater pad forming a closed conductive loop.
Embodiments are also directed to a mobile device comprising: a housing comprising a gas inlet; a sensor array module comprising at least one gas sensor, the sensor array module being in the first interior space of the housing; a main board in a second interior space of the housing; a connector configured to connect the sensor array module with the main board; and a partition wall configured to partition the first internal space from the second internal space. The at least one gas sensor may include: a piezoelectric substrate; a resonator in an electrode region on an upper surface of the piezoelectric substrate, the resonator including an interdigital transducer (IDT) electrode and an IDT pad connected to the IDT electrode, the IDT electrode configured to generate a surface acoustic wave in a center region of the electrode region, the surface acoustic wave propagating in a first horizontal direction; a sensing membrane in a central region of the electrode region on the upper surface of the piezoelectric substrate, the sensing membrane comprising a sensing material that interacts with a target gas; and a heater in an edge region surrounding an electrode region on the upper surface of the piezoelectric substrate, the heater including a heater electrode configured to heat the sensing film and a heater pad connected to the heater electrode, the heater electrode and the heater pad forming a closed conductive loop.
Drawings
Features will become apparent to those skilled in the art by describing in detail example embodiments with reference to the attached drawings, wherein:
FIG. 1 is a plan view of a gas sensor according to an example embodiment.
Fig. 2 is a cross-sectional view of a vertical structure of a gas sensor according to an example embodiment.
Fig. 3 is a diagram for describing a symmetrical structure of a heater included in a gas sensor according to an example embodiment.
Fig. 4 and 5 are plan views of examples of resonators included in a gas sensor according to example embodiments.
Fig. 6 is a graph showing a change in the resonant frequency of the gas sensor according to the load.
Fig. 7 is a plan view of an example of a heater included in a gas sensor according to an example embodiment.
Fig. 8A is a plan view of an example of a meander pattern included in the heater of fig. 7, and fig. 8B is a cross-sectional view of a vertical structure of the meander pattern of fig. 8A.
Fig. 9 is a plan view of an example of a heater included in a gas sensor according to an example embodiment.
Fig. 10A is a plan view of an example of a meander pattern included in the heater of fig. 9, and fig. 10B is a cross-sectional view of a vertical structure of the meander pattern of fig. 10A.
Fig. 11A is a plan view of an example of a meander pattern included in the heater of fig. 9, and fig. 11B is a cross-sectional view of a vertical structure of the meander pattern of fig. 11A.
Fig. 12 to 21 are plan views of examples of heaters included in a gas sensor according to example embodiments.
Fig. 22A, 22B, and 22C are diagrams illustrating degradation and regeneration of a gas sensor according to example embodiments.
Fig. 23 is a block diagram illustrating a gas sensing device according to an example embodiment.
Fig. 24 is a plan view of a sensor array module according to an example embodiment.
Fig. 25 is a cross-sectional view of the sensor array module of fig. 24.
Fig. 26 is a perspective view of a mobile device according to an example embodiment.
Fig. 27 is a diagram showing an example of the layout of the mobile device of fig. 26.
Fig. 28 is a flowchart illustrating a method of operating a mobile device according to an example embodiment.
Fig. 29 is a diagram illustrating an internet of things (IoT) network system, according to an example embodiment.
Detailed Description
Here, the vertical direction Z refers to a direction perpendicular to the upper surface of the piezoelectric substrate, and the first horizontal direction X and the second horizontal direction Y refer to two directions parallel to the upper surface of the piezoelectric substrate. In the drawings, the direction indicated by an arrow and the reverse direction may be considered to be the same direction.
Fig. 1 is a plan view of a gas sensor according to an example embodiment, and fig. 2 is a sectional view of a vertical structure of the gas sensor according to an example embodiment.
Referring to fig. 1 and 2, the gas sensor 10 may include: a piezoelectric substrate PZSUB; a resonator formed in an electrode region ELREG on an upper surface of a piezoelectric substrate PZUB; a sensing film SF formed in a central region CTREG of the electrode region ELREG on the upper surface of the piezoelectric substrate PZSUB; and a heater HTR formed in an edge region EGREG surrounding the electrode region ELREG on the upper surface of the piezoelectric substrate PZSUB.
The central region CTREG may be included in the electrode region ELREG, or a region other than the central region CTREG may be considered as the electrode region ELREG. For convenience of illustration, the resonator is omitted in fig. 1 and 2, and an example embodiment of the resonator will be described below with reference to fig. 4 and 5. In addition, for convenience of illustration, a basic structure of the heater HTR is illustrated in fig. 1, and the heater HTR is omitted in fig. 2. Example embodiments of the heater HTR will be described below with reference to fig. 7 to 21.
As will be described below with reference to fig. 4 and 5, the resonator formed in the electrode region eleg may include an interdigital transducer (IDT) electrode and an IDT pad connected to the IDT electrode. The IDT electrode may generate a Surface Acoustic Wave (SAW) in the central region CTREG so that the SAW may be propagated in the first horizontal direction X.
The sensing film SF formed in the central region CTREG on the upper surface of the piezoelectric substrate PZSUB may include a sensing material that reacts or interacts with a target gas. The sensing material included in the sensing film SF may be variously changed according to the kind of the sensed gas (i.e., the kind of the target gas). In addition, the receptor of the sensing film SF may include various kinds of materials, and the resonance frequency of the resonator may be changed according to the kind or concentration of the gas sensed by the sensing film SF. For example, the sensing membrane SF may be implemented as a polymer.
The heater HTR formed in the edge region EGREG on the upper surface of the piezoelectric substrate PZSUB may include heater electrodes HE1 to HE4 configured to heat the sensing film SF and heater pads PHT1 and PHT2 connected to the heater electrodes HE1 to HE 4.
As shown in fig. 2, the resonator and the heater HTR may be formed in the same conductive layer CONLY on the upper surface of the piezoelectric substrate PZSUB. Accordingly, the resonator and the heater HTR may share at least a portion of the patterning process, and thus the manufacturing cost of the heater HTR may be reduced. The heater HTR may be implemented as a conductive material, such as a metal, having an electrical conductivity or resistivity suitable for the heat to be generated by the heater HTR. In an example embodiment, the heater HTR may be implemented by the same material as that of the wire bonding pad of the gas sensor 10.
The heater HTR included in the gas sensor 10 according to example embodiments may have a basic structure such that the heater electrodes HE 1-HE 4 and the heater pads PHT1 and PHT2 may form a closed conductive loop (e.g., a conductive loop of metal, etc.).
The heaters HTR may be symmetrical with respect to a first center line CLX passing through the central region CTREG and extending in the first horizontal direction X. In addition, the heater HTR may be symmetrical with respect to a second center line CLY passing through the center region CTREG and extending in a second horizontal direction Y perpendicular to the first horizontal direction X.
As described with reference to fig. 3, the heater HTR included in the gas sensor 10 according to example embodiments may effectively heat the sensing film SF in the central region CTREG through the structure of the closed conductive loop and/or the symmetrical structure.
In example embodiments, the heater HTR may include a plurality of zigzag patterns, as will be described below with reference to fig. 7 to 21. Therefore, the amount of heat per unit area of the heater HTR can be effectively increased without increasing the size of the gas sensor 10. According to example embodiments, the heater HTR may include a main meander pattern and a sub meander pattern that generate different amounts of heat per unit area, respectively. By disposing the main meander pattern (which generates more heat per unit area) closer to the central region CTREG than the sub meander pattern (which generates less heat per unit area), the heat generated by the heater HTR can be concentrated on the sensing film SF.
Fig. 3 is a diagram for describing a symmetrical structure of a heater included in a gas sensor according to an example embodiment.
The heater HTR having a structure of a closed conductive loop according to an example embodiment is shown in the left portion of fig. 3, and the heater HTR' having an open conductive loop structure is shown in the right portion of fig. 3.
The resistance of the resistor having a uniform cross section can be expressed by expression 1, and the power consumed by heat per unit time according to joule's law can be expressed by expression 2.
Expression 1
R＝L/(σ×S)
Expression 2
P＝I2×R
In expression 1, R represents the resistance of the resistor, L represents the length of the resistor, S represents the cross-sectional area of the resistor, and σ represents the electrical conductivity of the resistor. In expression 2, P represents power, R represents resistance of the resistor, and I represents current flowing through a cross-sectional area of the resistor.
When the power supply voltage VDD is applied to the first heater pad PHT1 of the heater HTR and the ground voltage VSS is applied to the second heater pad PHT2 of the heater HTR, the same current I may flow from the first heater pad PHT1 to the second heater pad PHT2 clockwise and counterclockwise due to a structure (e.g., a symmetrical structure) of a closed conductive loop. If the resistance of each of the two conductive paths from the first heater pad PHT1 to the second heater pad PHT2 is R, the power P1 of the heater HTR may be represented by expression 3.
Expression 3
P1＝I2×R+I2×R＝2×I2×R
In contrast, the heater HTR ' of the open conductive loop has a single conductive path from the first heater pad PHT1 ' to the second heater pad PHT 2', and the resistance of the single conductive path is 2 × R. Therefore, the current I ' flowing through the open conductive loop of the heater HTR ' is half of the current flowing through the closed conductive loop of the heater HTR, and the power P2 of the heater HTR ' may be represented by expression 4.
Expression 4
P2＝(I/2)2×(2×R)＝(1/2)×I2×R＝P1/4
As a result, the heater HTR having the closed conductive loop may generate four times as much heat as the heater HTR' having the open conductive loop when the same heating voltages VDD and VSS are used. Therefore, the heater HTR according to example embodiments may effectively heat the sensing film SF.
Fig. 4 and 5 are plan views of example embodiments of resonators included in a gas sensor according to example embodiments.
Referring to fig. 4 and 5, each of the resonators RSN1 and RSN2 may include IDT electrodes eldt 1 and eldt 2 and IDT pads PEL1 to PEL 2.
Each of IDT electrodes ELIDT1 and ELID2 can include interlocking comb electrodes, as shown in fig. 4 and 5. The electrodes may be deposited on the surface of the piezoelectric substrate to form a periodic structure. An input signal or voltage applied to at least one of the IDT pads PEL1 to PEL4 may cause a mechanical force generated by a piezoelectric effect, and thus the input signal may be converted into a Surface Acoustic Wave (SAW) propagating in the first horizontal direction X in the upper portion of the piezoelectric substrate. The SAW may be converted again into an output signal or voltage provided through at least one of the IDT pads PEL1 through PEL 4.
The frequency of the SAW is affected by the material deposited on the propagation surface of the piezoelectric substrate, as represented by expression 5.
Expression 5
Δf＝k×(Δm×fo2)/A
In expression 5, Δ f represents a frequency shift, k represents a constant depending on the gas sensor, a represents a propagation area of the SAW, Δ m represents a mass load of a material deposited on the propagation surface, and fo represents a resonance frequency of the resonator.
The frequency shift increases as more target gas is combined with the sensing material of the sensing film SF in the central region CTREG. Thus, the density of the target gas can be determined by measuring the frequency shift.
In example embodiments, as shown in fig. 4, the IDT pads PEL1 to PEL4 may be disposed in the first and second pad regions PDREG11 and PDREG12, wherein the first and second pad regions PDREG11 and PDREG12 are adjacent to both sides (e.g., opposite sides) of the central region CTREG along the second center line CLY. In this case, the electrode regions ELREG1 may have a cross shape when viewed from the vertical direction Z perpendicular to the upper surface of the piezoelectric substrate.
In example embodiments, as shown in fig. 5, the IDT pads PEL1 to PEL4 may be disposed in the first and second pad regions PDREG21 and PDREG22, the first and second pad regions PDREG21 and PDREG22 corresponding to both end portions (e.g., opposite end portions) of the electrode region ELREG2 along the first center line CLX. In this case, electrode region ELREG2 has a bar shape extending in first horizontal direction X when viewed from vertical direction Z perpendicular to the upper surface of the piezoelectric substrate.
Example embodiments may differ from the examples of SAW resonators of fig. 4 and 5. The shape of the heater HTR included in the gas sensor according to example embodiments may be adaptively modified according to the shape of the electrode region.
Fig. 6 is a graph showing a change in the resonant frequency of the gas sensor according to the load.
In fig. 6, the horizontal axis represents frequency, and the vertical axis represents acoustic impedance. A first curve 41 shows the resonant frequency of the gas sensor (i.e. the resonant frequency of the unloaded resonator) when the sensing membrane does not sense the target gas molecules. A second curve 42 shows the resonant frequency of the gas sensor (i.e., the resonant frequency of the loaded resonator) when the sensing membrane senses the target gas molecule. When the sensing membrane senses the target gas molecules, the resonant frequency of the gas sensor may be changed, and thus the frequency of the output signal of the resonator may be changed. Accordingly, the target gas may be sensed or measured by detecting a frequency shift of the output signal of the resonator.
Fig. 7 is a plan view of an example embodiment of a heater included in a gas sensor according to an example embodiment.
Fig. 7 illustrates an example embodiment of a heater HTR1 corresponding to an electrode region ELREG1 having a cross shape as shown in fig. 4. In other words, the IDT pads PEL1 to PEL4 may be disposed in the first and second pad regions PDREG11 and PDREG12, wherein the first and second pad regions PDREG11 and PDREG12 are adjacent to both sides (e.g., opposite sides) of the center region ctre along the second center line CLY.
Referring to fig. 7, the heater HTR1 may include first to fourth zigzag patterns ZZP1 to ZZP4 (corresponding to heater electrodes), a first heater pad PHT1, and a second heater pad PHT 2.
The first and second heater pads PHT1 and PHT2 are respectively disposed adjacent to one side of the first pad region PDREG11 along the second center line CLY and one side of the second pad region PDREG12 along the second center line CLY.
The first zigzag pattern ZZP1 and the second zigzag pattern ZZP2 may be disposed adjacent to both sides (e.g., opposite sides) of the first pad region PDREG11 in the first horizontal direction X. The third zigzag pattern ZZP3 and the fourth zigzag pattern ZZP4 may be disposed adjacent to both sides (e.g., opposite sides) of the second pad region PDREG12 in the first horizontal direction. The first meandering pattern ZZP1 may be connected to the third meandering pattern ZZP3 through a first connection wire CONL 1. The second meandering pattern ZZP2 may be connected to the fourth meandering pattern ZZP4 through a second connecting wire CONL 2.
In this way, the first to fourth zigzag patterns ZZP1 to ZZP4, the first heater pad PHT1, and the second heater pad PHT2 included in the heater HTR1 may form a closed conductive loop, and may be symmetrical with respect to each of the first center line CLX and the second center line CLY.
Fig. 8A is a plan view of an example embodiment of a meander pattern included in the heater of fig. 7, and fig. 8B is a cross-sectional view of a vertical structure of the meander pattern of fig. 8A.
For convenience of illustration, only the first zigzag pattern ZZP1 is shown in fig. 8A and 8B. It will be understood that, among the symmetrical structures of the heater HTR1, the structure of the second to fourth zigzag patterns ZZP2 to ZZP4 may be implemented substantially the same as the first zigzag pattern ZZP 1.
Referring to fig. 8A and 8B, the first zigzag pattern ZZP1 may include a plurality of column conductive lines LNC, a plurality of first row conductive lines LNR1, and a plurality of second row conductive lines LNR 2.
The column conductive lines LNC may extend in the second horizontal direction Y, and may be arranged, for example, to be spaced apart in the first horizontal direction X. A first row conductor LNR1 may be connected to a first end E1 of the column conductor LNC. A second row conductor LNR2 may be connected to the second end E2 of the column conductor LNC.
To form the meander pattern ZZP1, a first row conductor LNR1 may connect the first end E1 of a first column conductor LNC to the first end E1 of an adjacent second column conductor LNC, and a second row conductor LNR2 may connect the second end E2 of an adjacent second column conductor LNC to the second end E2 of an adjacent third column conductor LNC.
For example, referring to fig. 8A, the meandering pattern ZZP1 may comprise three column conductors 21, 22 and 23 which are adjacent in sequence in the first horizontal direction X. The first ends E1 of the intermediate and right column conductors 22, 23 may be connected by a first row conductor LNR 1. The second ends E2 of the intermediate and left column conductors 22, 21 may be connected by a second row conductor LNR 2.
The heat per unit area of heater HTR1 may increase due to the serpentine pattern.
In an example embodiment, as shown in fig. 8A and 8B, the line pitch LTP in the first horizontal direction X between two adjacent column conductors may be uniform with respect to all column conductors included in the first meandering pattern ZZP 1. In addition, the line width LW of the column conductor may be uniform with respect to all column conductors included in the first meandering pattern ZZP 1. As a result, the first zigzag pattern ZZP1 can generate uniform heat per unit area.
Fig. 9 is a plan view of an example embodiment of a heater included in a gas sensor according to an example embodiment.
Fig. 9 illustrates an example embodiment of a heater HTR2 corresponding to an electrode region ELREG1 having a cross shape as illustrated in fig. 4. In other words, the IDT pads PEL1 to PEL4 may be disposed in the first and second pad regions PDREG11 and PDREG12, the first and second pad regions PDREG11 and PDREG12 being adjacent to both sides (e.g., opposite sides) of the center region ctre along the second center line CLY.
Referring to fig. 9, the heater HTR2 may include first to fourth zigzag patterns ZZP1a to ZZP4a (corresponding to heater electrodes), a first heater pad PHT1, and a second heater pad PHT 2.
The first and second heater pads PHT1 and PHT2 are respectively disposed adjacent to one side of the first pad region PDREG11 along the second center line CLY and one side of the second pad region PDREG12 along the second center line CLY.
The first zigzag pattern ZZP1a and the second zigzag pattern ZZP2a may be disposed adjacent to both sides (e.g., opposite sides) of the first pad region PDREG11 in the first horizontal direction X. The third zigzag pattern ZZP3a and the fourth zigzag pattern ZZP4a may be disposed adjacent to both sides (e.g., opposite sides) of the second pad region PDREG12 in the first horizontal direction. The first meandering pattern ZZP1a may be connected to the third meandering pattern ZZP3a by a first connecting wire CONL 1. The second meandering pattern ZZP2a may be connected to the fourth meandering pattern ZZP4a by a second connecting wire CONL 2.
In this way, the first to fourth zigzag patterns ZZP1 to ZZP4, the first heater pad PHT1 and the second heater pad PHT2 included in the heater HTR2 may form a closed conductive loop, and may be symmetrical with respect to each of the first and second center lines CLX and CLY.
Each of the first to fourth zigzag patterns ZZP1 a-ZZP 4a may include a main zigzag pattern ZZM and a sub zigzag pattern ZZS. The main meander pattern ZZM may be disposed adjacent to the central region CTREG, and the main meander pattern ZZM may generate a first amount of heat per unit area. The sub meander pattern ZZS may be disposed farther from the central region CTREG than the main meander pattern ZZM, and the sub meander pattern ZZS may generate a second amount of heat per unit area, which is less than the first amount of heat per unit area.
In an example embodiment, as described with reference to fig. 10A to 11B, the different amounts of heat per unit area of the main meandering pattern ZZM and the sub-meandering pattern ZZS may be achieved by making the line pitch between column conductors in the main meandering pattern ZZM different from the line pitch between column conductors in the sub-meandering pattern ZZS.
In an example embodiment, as described with reference to fig. 11A and 11B, the different amounts of heat per unit area of the main meandering pattern ZZM and the sub-meandering pattern ZZS may be achieved by making the line width of the column conductive line in the main meandering pattern ZZM different from the line width of the column conductive line in the sub-meandering pattern ZZS.
In this way, the heat generated by the heater HTR2 may be concentrated on the sensing film SF disposed in the central region CTREG to reduce power consumption by disposing the main meander pattern (generating more heat per unit area) closer to the central region CTREG than the sub meander pattern (generating less heat per unit area).
Fig. 10A is a plan view of an example embodiment of a meander pattern included in the heater of fig. 9, and fig. 10B is a cross-sectional view of a vertical structure of the meander pattern of fig. 10A.
For convenience of illustration, only the first zigzag pattern ZZP1a is shown in fig. 10A and 10B. It will be understood that, among the symmetrical structures of the heater HTR2, the structure of the second to fourth meandering pattern ZZP2a to ZZP4a may be implemented substantially the same as the first meandering pattern ZZP1 a.
Referring to fig. 10A and 10B, the first zigzag pattern ZZP1a may include a main zigzag pattern ZZM and a sub zigzag pattern ZZS. The meandering structures of the column conductors and the row conductors in the main meandering pattern ZZM and the sub-meandering pattern ZZS are substantially the same as those described with reference to fig. 8A and 8B, and a repeated description is omitted.
As shown in fig. 10A and 10B, a first line pitch LPT1 in the first horizontal direction X of two adjacent column conductive lines LNC included in the main meandering pattern ZZM may be smaller than a second line pitch LPT2 in the first horizontal direction X of two adjacent column conductive lines LNC' included in the sub-meandering pattern ZZS.
A line width LW1 of the column wire LNC included in the main meandering pattern ZZM may be equal to a line width of the column wire LNC' included in the sub meandering pattern ZZS.
The lengths of the row conductive lines LNR1 'and LNR 2' included in the sub meandering pattern ZZS in the first horizontal direction X may be longer than the lengths of the row conductive lines LNR1 and LNR2 included in the main meandering pattern ZZM in the first horizontal direction X because the second line pitch LPT2 is larger than the first line pitch LPT 1.
As the line pitch increases, the length of the current path per unit area decreases, and thus the resistance per unit area can be reduced by expression 1. In addition, as the resistance per unit area decreases, the amount of heat per unit area can be decreased by expression 2. As a result, because the first line pitch LPT1 is smaller than the second line pitch LPT2, the first heat per unit area of the main meandering pattern ZZM may be larger than the second heat per unit area of the sub-meandering pattern ZZS.
In this way, the heat generated by the heater HTR2 may be concentrated on the sensing film SF disposed in the central region CTREG to reduce the power consumption of the gas sensor by arranging the main meander pattern ZZM (generating more heat per unit area) closer to the central region CTREG than the sub-meander pattern ZZS (generating less heat per unit area).
Fig. 11A is a plan view of an example embodiment of a meander pattern included in the heater of fig. 9, and fig. 11B is a cross-sectional view of a vertical structure of the meander pattern of fig. 11A.
For convenience of illustration, only the first zigzag pattern ZZP 1A' is shown in fig. 11A and 11B. It will be understood that, among the symmetrical structures of the heater HTR2, the structure of the second to fourth meandering patterns ZZP2a ' to ZZP4a ' may be implemented substantially the same as the first meandering pattern ZZP1a '.
Hereinafter, the description overlapping with fig. 10A and 10B is omitted.
As shown in fig. 11A and 11B, a first line width LW1 of the column conductive line LNC included in the main meandering pattern ZZM may be smaller than a second line width LW2' of the column conductive line LNC ' included in the sub-meandering pattern ZZS '. Compared to the sub-meander pattern ZZS in fig. 10A and 10B, the heat per unit area of the sub-meander pattern ZZS' can be further reduced by increasing the line width in addition to the line pitch.
As the line width increases, the cross-sectional area of the current path per unit area increases, and the resistance per unit area may decrease by expression 1. In addition, as the resistance per unit area decreases, the heat per unit area can be decreased by expression 2. As a result, the heat per unit area of the sub-meandering pattern ZZS ' of fig. 11A and 11B can be further reduced relative to the heat per unit area of the sub-meandering pattern ZZS of fig. 10A and 10B because the second line width LW2' of the sub-meandering pattern ZZS ' in fig. 11A and 11B is larger than the second line width LW2 of the sub-meandering pattern ZZS in fig. 10A and 10B.
As described with reference to fig. 10A to 11B, the heat per unit area of the meander pattern can be adjusted by the line pitch and/or line width of the conductive lines in the heater.
Hereinafter, the description overlapping with fig. 7 and 11B may be omitted.
Fig. 12 to 21 are plan views of example embodiments of heaters included in gas sensors according to example embodiments.
Referring to fig. 12, the heater HTR3 may include first through fourth zigzag patterns ZZP1b through ZZP4b (corresponding to heater electrodes), a first heater pad PHT1, and a second heater pad PHT 2.
The first and second heater pads PHT1 and PHT2 are respectively disposed adjacent to one side of the first pad region PDREG11 along the second center line CLY and one side of the second pad region PDREG12 along the second center line CLY.
Each of the first to fourth zigzag patterns ZZP1 b-ZZP 4b may include a main zigzag pattern ZZM and a sub zigzag pattern ZZS.
In contrast to the sub-meandering pattern ZZS in the heater HTR2 of fig. 9, the sub-meandering pattern ZZS in the heater HTR3 of fig. 12 may not comprise a meandering structure, but may comprise a single row conductor extending in the first horizontal direction X. Therefore, the sub-zigzag pattern ZZS in fig. 12 can generate lower heat per unit area than the sub-zigzag pattern ZZS in fig. 9.
The heaters HTR4, HTR5, and HTR6 of fig. 13, 14, and 15 are substantially the same as the heaters HTR1, HTR2, and HTR3 of fig. 7, 9, and 12, respectively, except for the location of the heater pad.
Referring to fig. 13, 14, and 15, the first and second heater pads PHT3 and PHT4 may be disposed adjacent to both sides (e.g., opposite sides) of the electrode region elge 1 along the first center line CLX. Each of the first meandering patterns ZZP1, ZZP1a, and ZZP1b may be connected to each of the second meandering patterns ZZP2, ZZP2a, and ZZP2b by a first connecting wire CONL 3. Each of the third meandering patterns ZZP3, ZZP3a, and ZZP3b may be connected to each of the fourth meandering patterns ZZP4, ZZP4a, and ZZP4b by a second connecting wire CONL 4.
Each of the heaters HTR4, HTR5, and HTR6 has a structure of a closed conductive loop and a symmetrical structure to effectively heat the sensing film SF including the sensing material without increasing the size of the gas sensor. In addition, each of the heaters HTR4, HTR5, and HTR6 has a meandering pattern to effectively increase heat per unit area, and the line pitch and/or line width of the meandering pattern may be adjusted to reduce power consumption of the gas sensor.
Fig. 16 to 21 illustrate example embodiments of a heater corresponding to the electrode region ELREG2 having a bar shape as shown in fig. 5. The IDT pads PEL1 to PEL4 may be disposed in the first and second pad regions PDREG21 and PDREG22, the first and second pad regions PDREG21 and PDREG22 corresponding to both end portions (e.g., opposite end portions) of the electrode region ELREG2 along the first center line CLX.
Referring to fig. 16, the heater HTR7 may include first and second zigzag patterns ZZP21 and ZZP22 (corresponding to heater electrodes), a first heater pad PHT5, and a second heater pad PHT 6.
The first and second heater pads PHT5 and PHT6 are respectively disposed adjacent to both sides (e.g., opposite sides) of the electrode region elge 2 along the first center line CLX. The first meandering pattern ZZP21 and the second meandering pattern ZZP22 may be respectively disposed adjacent to both sides (e.g., opposite sides) of the electrode region elgeg 2 in the second horizontal direction Y.
In this way, the first meandering pattern ZZP21, the second meandering pattern ZZP22, the first heater pad PHT5, and the second heater pad PHT6 included in the heater HTR7 may form a closed conductive loop, and may be symmetrical with respect to each of the first center line CLX and the second center line CLY.
As described with reference to fig. 8A and 8B, the line pitch of two adjacent column conductors in the first horizontal direction X may be uniform with respect to all column conductors comprised in the first and second meandering patterns ZZP21, ZZP 22. As a result, the first zigzag pattern ZZP21 and the second zigzag pattern ZZP22 can generate uniform heat per unit area.
Referring to fig. 17, the heater HTR8 may include first and second zigzag patterns ZZP21 and ZZP22 (corresponding to heater electrodes), a first heater pad PHT5, and a second heater pad PHT 6.
The first and second heater pads PHT5 and PHT6 are respectively disposed adjacent to both sides (e.g., opposite sides) of the electrode region elge 2 along the first center line CLX. The first meandering pattern ZZP21 and the second meandering pattern ZZP22 may be respectively disposed adjacent to both sides (e.g., opposite sides) of the electrode region elgeg 2 in the second horizontal direction Y.
In this way, the first meandering pattern ZZP21, the second meandering pattern ZZP22, the first heater pad PHT5, and the second heater pad PHT6 included in the heater HTR8 may form a closed conductive loop, and may be symmetrical with respect to each of the first center line CLX and the second center line CLY.
The first zigzag pattern ZZP21 may include a first main zigzag pattern ZZM1, a first sub-zigzag pattern ZZS1, and a second sub-zigzag pattern ZZS 2. The first main meander pattern ZZM1 may be disposed adjacent to a first side of the central region CTREG in the second horizontal direction Y, and the first main meander pattern ZZM1 may generate the first heat per unit area. The first sub zigzag pattern ZZS1 and the second sub zigzag pattern ZZS2 may be respectively disposed adjacent to both sides (e.g., opposite sides) of the first main zigzag pattern ZZM1 in the first horizontal direction X. The first sub-zigzag pattern ZZS1 and the second sub-zigzag pattern ZZS2 may generate a second amount of heat per unit area, the second amount of heat per unit area being less than the first amount of heat per unit area.
The second zigzag pattern ZZP22 may include a second main zigzag pattern ZZM2, a third sub-zigzag pattern ZZS3, and a fourth sub-zigzag pattern ZZS 4. The second main meander pattern ZZM2 may be disposed adjacent to a second side of the central region CTREG in the second horizontal direction Y, and the second main meander pattern ZZM2 may generate the first heat per unit area. The third sub zigzag pattern ZZS3 and the fourth sub zigzag pattern ZZS4 may be respectively disposed adjacent to both sides (e.g., opposite sides) of the second main zigzag pattern ZZM2 in the first horizontal direction X, and the third sub zigzag pattern ZZS3 and the fourth sub zigzag pattern ZZS4 may generate the second heat per unit area.
As described with reference to fig. 10A to 11B, by adjusting the line pitch and/or line width of the conductive line, the first heat per unit area of the first main meander pattern ZZM1 and the second main meander pattern ZZM2 may be greater than the second heat per unit area of the first sub meander pattern ZZS1 to the fourth sub meander pattern ZZS 4.
In this way, by disposing the first main meander pattern ZZM1 and the second main meander pattern ZZM2 (generating more heat per unit area) closer to the central region CTREG than the first sub meander pattern ZZS1 to the fourth sub meander pattern ZZS4 (generating less heat per unit area), the heat generated by the heater HTR8 can be concentrated on the sensing film SF disposed in the central region CTREG to reduce power consumption.
In contrast to the first to fourth sub-meandering patterns ZZS1 to ZZS4 in the heater HTR8 of fig. 17, each of the first to fourth sub-meandering patterns ZZS1 to ZZS4 in the heater HTR9 of fig. 18 may not include a meandering structure but may include a single row wire extending in the first horizontal direction X. Therefore, the first to fourth sub-zigzag patterns ZZS1 to ZZS4 in fig. 18 may generate less heat per unit area than the first to fourth sub-zigzag patterns ZZS1 to ZZS4 in fig. 17.
The heaters HTR10, HTR11, and HTR12 of fig. 19, 20, and 21 are substantially the same as the heaters HTR7, HTR8, and HTR9 of fig. 16, 17, and 18, respectively, except for the location of the heater pad.
Referring to fig. 19, 20 and 21, the first and second heater pads PHT7 and PHT8 may be disposed adjacent to one side of the first and second zigzag patterns ZZP21 and ZZP22, respectively, along the second center line CLY. The first meandering pattern ZZP21 may be connected to the second meandering pattern ZZP22 through two connecting wires CONL5 and CONL 6.
Each of the heaters HTR10, HTR11, and HTR12 has a structure of a closed conductive loop and a symmetrical structure to effectively heat the sensing film SF including the sensing material without increasing the size of the gas sensor. In addition, each of the heaters HTR10, HTR11, and HTR12 has a meandering pattern to effectively increase heat per unit area, and the line pitch and/or line width of the meandering pattern may be adjusted to reduce power consumption of the gas sensor.
Fig. 22A, 22B, and 22C are diagrams illustrating degradation and regeneration of a gas sensor according to example embodiments.
Generally, for example, the sensing material may be exposed to the outside (e.g., exposed to the outside), such that the gas sensor may operate based on a chemical reaction or interaction of the sensing material and the target gas. In the case of a resonance-based gas sensor, the sensor may be degraded due to the influence of the environment, such as moisture in the atmosphere. For example, in the case of a gas sensor using a SAW, the resonance frequency may vary due to environmental influences.
In a manner of estimating the reliability of a gas sensor, repeatability is an estimate of whether the gas sensor provides the same results under the same conditions. If the gas sensor is affected by the environment such as temperature, humidity, etc., and causes deterioration, the reproducibility may be reduced.
Fig. 22A illustrates the reactivity degradation of the gas sensor due to the exposure to the environment. The two samples were separately placed in dry nitrogen (N)2) Atmosphere and Wet N2The aging and the leaving in the atmosphere were performed for 1 day, 5 days, and 14 days, and the frequency shift Δ f was measured after the sensing film was reacted with toluene gas as an example of the target gas. In dry N2In the case, the reaction amount (frequency shift) was reduced from 120Hz to 110Hz, while in wet N2In the case of the reaction, the reaction rate (frequency shift) was reduced from 105Hz to 70Hz, which was about dry N23 times the case. Without being limited by theory, it is believed that wet N2The greater reduction in the case is due to hydration of the sensing material.
To prevent hydration of the sensing material, the surface of the sensing membrane comprising the sensing material may be coated with a hydrophobic layer. However, it may be difficult to selectively block moisture, and the sensing sensitivity of the target gas may also be reduced. According to an example embodiment, the sensing film may be heated, e.g., periodically or aperiodically, to remove moisture bound to the sensing material, thereby regenerating the reaction volume (e.g., frequency shift) to maintain sensitivity. Because hydration is a reversible chemical reaction, degradation may be reduced or prevented by heating the sensing membrane.
FIG. 22B shows the result of heating to remove hydration of the sensing material. The sample was heated on a hot plate at 200 ℃ for about two minutes. In fig. 22B, T1 is the time point immediately after the sample was made, T2 is the time point after the first regeneration (i.e., heating), T3 is the time point after seven days of aging, and T4 is the time point after the second regeneration. As shown in fig. 22B, the reaction volume (e.g., frequency shift) may be restored after regeneration.
FIG. 22C shows the improvement in repeatability of the gas sensor by periodic regeneration. The gas sensor was heated once in a period of seven days, and the reaction amount was measured after heating. As shown in fig. 22C, the reaction volume (e.g., frequency shift) can be maintained for at least about one month by periodic heating.
Typically, when a heater is formed on the package containing the gas sensor, the entire package is heated to heat the sensing material to a desired temperature. Therefore, power consumption may be increased and other components in the package may be deteriorated.
According to example embodiments, a micro-electromechanical system (MEMS) heater may be implemented on a surface of a piezoelectric substrate PZSUB, and power consumption may be significantly reduced by intensively heating a sensing material using the MEMS heater having a closed conductive loop structure and a symmetric structure.
Fig. 23 is a block diagram illustrating a gas sensing device according to an example embodiment.
Referring to fig. 23, the gas sensing device 60 may include a temperature sensor 110, a first gas sensor 120, a second gas sensor 130, a humidity sensor 140, a pressure sensor 150, and a drift sensor (or drift compensation sensor) 160. The temperature sensor 110, humidity sensor 140, pressure sensor 150, and drift compensation sensor 160 may be environmental sensors. In an example embodiment, the gas sensing device 60 may also include multiple gas sensors or multiple environmental sensors.
In the gas sensing device 60, each of the temperature sensor 110, the first gas sensor 120, the second gas sensor 130, the humidity sensor 140, the pressure sensor 150, and the drift compensation sensor 160 may be implemented as a SAW device, and mounted on the driving circuit chip 200. The first gas sensor 120 may sense a first gas and the second gas sensor 130 may sense a second gas. In example embodiments, the first gas sensor 120 and the second gas sensor 130 may be respectively formed on different wafers, and thus implemented as separate semiconductor dies or semiconductor chips. In example embodiments, the first gas sensor 120 and the second gas sensor 130 may be formed on the same wafer, and thus implemented as a single die or a single semiconductor chip.
The humidity sensor 140 may sense an ambient humidity and output a humidity sensing result. The pressure sensor 150 may sense atmospheric pressure and output an atmospheric pressure sensing result. For example, pressure sensor 150 may have a package-type cavity between the substrate and the SAW device and sense atmospheric pressure. The drift compensation sensor 160 may sense aging of the SAW device and output a drift sensing result. For example, the drift compensation sensor 160 may include a SAW device that is not coated with a sensing film. The drift sensing results can be used to remove the effects of aging of the SAW device from the gas sensing results.
The driving circuit chip 200 may include first to sixth Drivers (DRV)210 to 260, which may correspond to the temperature sensor 110, the first gas sensor 120, the second gas sensor 130, the humidity sensor 140, the pressure sensor 150, and the drift compensation sensor 160, respectively. Each of the sensors 110-160 may include a resonator and a heater as described above, and each of the first through sixth drivers 210-260 may drive the resonator and the heater based on each of the first through sixth control signals CT 1-CT 6.
The first to sixth drivers 210 to 260 may generate first to sixth sensing signals SS1 to SS6 in response to changes in the resonant frequencies of the sensors 110 to 160, respectively.
The driving circuit chip 200 may further include a calibration circuit 270. The calibration circuit 270 may calibrate the second sensing signal SS2 based on the first sensing signal SS1, the fourth sensing signal SS4, the fifth sensing signal SS5, and the sixth sensing signal SS6, and generate the first gas sensing signal GSS1 a. In addition, the calibration circuit 270 may calibrate the third sensing signal SS3 based on the first sensing signal SS1, the fourth sensing signal SS4, the fifth sensing signal SS5, and the sixth sensing signal SS6, and generate the second gas sensing signal GSS2 a. In this way, the influence of temperature, humidity, atmospheric pressure, and drift can be removed from the sensing results output by the first gas sensor 120 and the second gas sensor 130, thereby further improving the accuracy of the sensing results of the first gas and the second gas.
Although fig. 23 shows a case where the calibration circuit 270 is included in the driver circuit chip 200, the calibration circuit 270 may be included in, for example, an Application Processor (AP) or a System On Chip (SOC). In example embodiments, the first to sixth sensing signals SS1 to SS6 may be provided to the AP or the SOC, and the AP or the SOC may calibrate the second and/or third sensing signals SS2 and SS3 based on the first, fourth, fifth and sixth sensing signals SS1, SS4, SS5 and SS6 and generate the first and/or second gas sensing signals GSS1a and GSS2 a.
To improve calibration accuracy, the environmental sensors 110, 140, 150, and 160 and the first and second gas sensors 120 and 130 may be implemented to generate the sensing signals SS 1-SS 6 under the same operating conditions. According to example embodiments, the first and second gas sensors 120 and 130, the temperature sensor 110, and the humidity sensor 140 may include respective heaters having the same structure. The driving circuit chip 200 may simultaneously drive the heaters of the first and second gas sensors 120 and 130, the temperature sensor 110, and the humidity sensor 140 to implement the same temperature condition with respect to the first and second gas sensors 120 and 130, the temperature sensor 110, and the humidity sensor 140, thereby implementing accurate calibration through the calibration circuit 270.
Fig. 24 is a plan view of a sensor array module according to an example embodiment, and fig. 25 is a sectional view of the sensor array module of fig. 24 cut along a line a-a'.
Referring to fig. 24 and 25, the sensor array module or the gas sensing device 60a may include a substrate (PCB)300 and a driving circuit chip 200a mounted on the substrate 300. A first sensor CHIP (CHIP1)110a, a second sensor CHIP (CHIP2)120a, a third sensor CHIP (CHIP3)130a, a fourth sensor CHIP (CHIP4)140a, a fifth sensor CHIP (CHIP5)150a, and a sixth sensor CHIP (CHIP6)160a may be mounted on the driving circuit CHIP 200 a.
Gas sensing device 60a may also include a housing member 400, a drive circuit chip 200a, and sensor chips 110 a-160 a, which may be located over substrate 300. At least one hole H1 may be formed in the case member 400. The gas may be supplied into the gas sensing device 60a through the hole H1 or discharged from the gas sensing device 60a so that the first and second sensing films 122 and 132 on the second and third sensor chips 120a and 130a, respectively, may sense the target gas. The housing member 400 may be referred to as a cover member or a case. In example embodiments, the housing member 400 may be implemented as stainless steel or plastic. In an example embodiment, the top surface of the case member 400 may be implemented in a mesh shape, so that gas may be more actively introduced or exhausted.
The first sensor chip 110a, the second sensor chip 120a, the third sensor chip 130a, the fourth sensor chip 140a, the fifth sensor chip 150a and the sixth sensor chip 160a may correspond to examples of implementations of the temperature sensor 110, the first gas sensor 120, the second gas sensor 130, the humidity sensor 140, the pressure sensor 150 and the drift compensation sensor 160 of fig. 23, respectively.
The temperature sensor chip 110a, the first gas sensor chip 120a, the second gas sensor chip 130a, the humidity sensor chip 140a, the pressure sensor chip 150a, and the drift compensation sensor chip 160a may be respectively formed on different wafers, and thus, may be implemented as a separate semiconductor wafer or a separate semiconductor chip. In this case, as described above, each of the temperature sensor chip 110a, the first gas sensor chip 120a, the second gas sensor chip 130a, the humidity sensor chip 140a, the pressure sensor chip 150a, and the drift compensation sensor chip 160a may include a SAW device (or SAW resonator) and a heater.
The temperature sensor chip 110a may have a package structure that does not expose the SAW resonator to the outside. The first gas sensor chip 120a may include a first sensing film 122 coated on an upper surface of the piezoelectric substrate, and the first sensing film 122 may be exposed to the outside and sense the first gas. The second gas sensor chip 130a may include a second sensing film 132 coated on the upper surface of the piezoelectric substrate, and the second sensing film 132 may be exposed to the outside and sense the second gas. The humidity sensor chip 140a may include a third sensing film 142 coated on the upper surface of the piezoelectric substrate, and the third sensing film 142 may be exposed to the outside and sense humidity. The pressure sensor chip 150a may include a fourth sensing film 152 coated on the upper surface of the piezoelectric substrate and the package cavity, and sensing the atmospheric pressure. The drift compensation sensor chip 160a may be implemented to not include a sensing film to compensate for frequency variation due to aging of the sensor.
The sensor chips 110a to 160a may be electrically connected to an external device through pads BP and bonding wires BW formed on the sensor chip and/or the driving circuit chip 200 a.
Fig. 26 is a perspective view of a mobile device according to an example embodiment, and fig. 27 is a diagram illustrating an example embodiment of a layout of the mobile device of fig. 26.
Referring to fig. 26 and 27, a mobile device 2000 such as, for example, a smart phone, may include a case HCS, a main board 2010, a sensor array module 2020, a camera module CAM, a display panel DPNN, a battery, and the like. The housing HSC may have an open upper surface, and the display panel DPNN may be arranged to occupy the upper surface of the housing HCS. A USB terminal and a headphone or earphone terminal 2040 may be formed at the bottom of the housing HCS. Various elements such as the system chip SOC may be integrated on the motherboard 2010.
Additionally, the housing HCS can include a gas inlet 2050. The sensor array module 2020 may include one or more gas sensors according to an example embodiment. The sensor array module may be disposed in the first internal space of the housing HCS. The main board 2010 may be disposed in the second internal space of the casing HCS, and may be connected to the sensor array module 2020 through the connector CNN 2. The first internal space and the second internal space may be blocked from each other by a partition wall 2030. The gas sensors in the sensor array module 2020 may include heaters having a closed conductive loop configuration as described above.
The motherboard 2010, the camera module CAM and the BATTERY may be mounted in the housing HCS. The camera module CAM may be electrically connected to the main board 2010 through the connector CNN 1. Various components, such as a system on a chip SOC, may be integrated on motherboard 2010.
Fig. 28 is a flowchart illustrating a method of operating a mobile device according to an example embodiment.
Referring to fig. 27 and 28, a processor (e.g., SOC) mounted on the main board 2010 may generate a heating control signal based on an operating condition of the mobile device 2000 (S100).
The processor may transmit the heating control signal to the sensor array module 2020 through the connector CNN2 (S200).
The sensor array module 2020 may heat a sensing film of a gas sensor included in the sensor array module 2020 with a heater of the gas sensor based on the heating control signal to improve sensing sensitivity of the gas sensor (S300).
According to an example embodiment, the processor may set the operating conditions as follows, and may activate the heating control signal when one or more of the following operating conditions are met:
1. when the sensing sensitivity of the gas sensor falls below a reference sensitivity;
2. when a predetermined time elapses after the gas sensor starts to be driven;
3. when the user has not used the included mobile device for a predetermined period of time;
4. at a predetermined time (e.g., an expected time for the user to sleep);
5. when the mobile device is charging.
Fig. 29 is a diagram illustrating an internet of things (IoT) network system, according to an example embodiment.
Referring to fig. 29, an IoT network system 3000 may have an entity including the gas sensor or sensor array module described above with reference to fig. 1-28. As shown in fig. 29, the IoT network system 3000 may include a plurality of IoT devices 3311, 3312, 3313, and 3314.
The internet of things (IoT) may indicate a network of objects utilizing wired and/or wireless communication, and may be referred to as an IoT network system, a Ubiquitous Sensor Network (USN) communication system, a Machine Type Communication (MTC) system, a Machine Oriented Communication (MOC) system, a machine-to-machine (M2M) communication system, a device-to-device (D2D) communication system, and the like. For example, IoT network system 3000 may include IoT devices, access points, gateways, communication networks, servers, and the like. Further, IoT network system 3000 may use transmission protocols, such as User Datagram Protocol (UDP) and Transmission Control Protocol (TCP), and application protocols, such as IPv 6low power wireless personal area network (6LoWPAN) protocol, IPv6 internet routing protocol, restricted application protocol (CoAP), hypertext transfer protocol (HTTP), Message Queue Telemetry Transport (MQTT), and MQTT for sensor networks (MQTT-S), to exchange information between two or more components in the IoT network system.
In a Wireless Sensor Network (WSN), each of the plurality of IoT devices 3311, 3312, 3313, and 3314 may serve as an aggregation node or a sensor node. The sink node may be referred to as a base station. The aggregation node may serve as a gateway for connecting the WSN to an external network (e.g., the internet), and may assign tasks to each sensor node and collect events detected by the respective sensor nodes. The sensor nodes may be nodes in the WSN that may perform processing and collecting sensory information, and may perform communication between nodes connected to each other in the WSN. In an example embodiment, the gas sensor described above with reference to the figures may be included in a sensor node.
The plurality of IoT devices 3311, 3312, 3313, 3314 may include active IoT devices operating with their own power and passive IoT devices operating with externally wirelessly applied power. For example, the active IoT devices may include a refrigerator, an air conditioner, a phone, an automobile, etc., and the passive IoT devices may include a Radio Frequency Identification (RFID) tag or an NFC tag, for example. In example embodiments, the IoT devices 3311, 3312, 3313, 3314 may include passive communication interfaces such as QR codes, RFID tags, and NFC tags, or may include active communication interfaces such as modem and transceivers. Each of the plurality of IoT devices 3311, 3312, 3313, 3314 may collect data by using a sensor such as the gas sensor described above with reference to the drawings, or transmit the collected data, e.g., state information, to the outside via a wired communication interface and/or a wireless communication interface, and may transmit and/or receive control information and/or data via the wired communication interface and/or the wireless communication interface.
In an example embodiment, each of IoT devices 3311, 3312, 3313, and 3314 may form a set according to the characteristics of the respective IoT device. For example, the IoT devices 3311, 3312, 3313, and 3314 may be grouped into home tool groups, home appliance/furniture groups, entertainment groups, or vehicle groups, and each of the IoT devices 3311, 3312, 3313, and 3314 may be collectively included in a plurality of groups. For example, the home toolset (e.g., IoT device 3311) may include heart rate sensor patches, blood glucose measuring devices, lighting devices, hygrometers, surveillance cameras, smart watches, security keyboards, temperature controllers, orientation devices, blinds, and the like. The home appliance/furniture set (e.g., IoT devices 3312) may include home appliances such as robotic cleaners, laundry washers, refrigerators, air conditioners, air purifiers, and televisions, as well as furniture such as beds that include sensors. The entertainment group (e.g., IoT devices 3313) may include multimedia imaging devices such as televisions and smart phones, as well as communication devices.
IoT network system 3000 may also include access point 3310. The plurality of IoT devices 3311, 3312, and 3313 may be connected to the communication network through the access point 3310 or may be connected to other IoT devices through the access point 3310. In an example embodiment, the access point 3310 may be embedded in one IoT device. For example, the access point 3310 may be embedded in a television set, and a user may monitor or control at least one IoT device connected to the access point 3310 via a display of the television set. In addition, the access point 3310 may be included in a mobile phone, and the mobile phone may serve as an IoT device and as the access point 3310 connected to other IoT devices, and may be connected to a communication network through a mobile communication network or a local area wireless network.
IoT network system 3000 may also include a gateway 3320. The gateway 3320 may change protocols to connect the access point 3310 to an external communication network (e.g., an internet network or a public communication network). IoT devices 3311, 3312, and 3313 may connect to external communication networks through gateway 320. In an example embodiment, the gateway 320 may be integrated into the access point 3310. In other cases, access point 3310 may act as a first gateway and gateway 3320 may act as a second gateway. In an example embodiment, the gateway 3320 may be included in one of the IoT devices 3311, 3312, and 3313, and the mobile phone may function as an IoT device as well as a gateway 3320 connected to other IoT devices.
IoT network system 3000 may also include at least one communication network 3330. For example, the communication network 3330 may include the internet and/or a public communication network, and the public communication network may include a mobile cellular network. The communication network 3330 may provide a channel through which to transmit the information collected by the IoT devices 3311, 3312, 3313, 3314.
IoT network system 3000 may also include a server 3340 and a management server 3335 connected to a communication network 3330. The communication network 3330 may transmit data sensed by the IoT devices 3311, 3312, 3313, 3314 to the server 3340. The server 3340 may store or analyze data received through the communication network 3330 and may transmit the analysis result through the communication network 3330. The server 3340 may store information associated with at least one of the IoT devices 3311, 3312, 3313, and 3314 and may analyze data transmitted from the associated IoT device based on the stored information.
As described above, the gas sensor according to example embodiments may effectively heat a sensing material using a heater having a symmetrical structure integrated with a resonator on an upper surface of a piezoelectric substrate without increasing the size of the gas sensor. The gas sensor can effectively prevent deterioration of the gas sensor with low power consumption by locally heating the sensing material, and thus can improve the performance of the gas sensor and the apparatus/system including the gas sensor.
Embodiments may be applied to semiconductor integrated circuits in general, and more particularly, to gas sensors and any electronic devices and systems including the gas sensors. For example, embodiments may be applied to systems such as mobile phones, smart phones, Personal Digital Assistants (PDAs), Portable Multimedia Players (PMPs), digital cameras, video cameras, Personal Computers (PCs), server computers, workstations, notebook computers, digital televisions, set top boxes, portable game machines, navigation systems, wearable devices, internet of things (IoT) devices, internet of things (IoE) devices, electronic books, Virtual Reality (VR) devices, Augmented Reality (AR) devices, and the like.
By way of summary and review, a gas sensor may include a gas sensing device that senses gas according to various principles, and the gas sensing device may have an exposed surface for sensing gas. Due to humidity, heat, and volume accumulation applied to the gas sensing device during use of the gas sensor, the sensitivity of the gas sensing device may change, and accordingly, the accuracy of the gas sensor may decrease.
As described above, example embodiments may provide a gas sensor capable of effectively enhancing sensing sensitivity, a sensor array module and a mobile device including the gas sensor.
The gas sensor according to the embodiment can effectively heat the sensing material without increasing the size of the gas sensor. The gas sensor may include a heater having a symmetrical structure integrated with a resonator on an upper surface of a piezoelectric substrate. The gas sensor can effectively prevent deterioration of the gas sensor with low power consumption by locally heating the sensing material, and thus can improve the performance of the gas sensor and the apparatus/system including the gas sensor.
Example embodiments are disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purposes of limitation. In some instances, features, characteristics and/or elements described in connection with a particular embodiment may be used alone or in combination with features, characteristics and/or elements described in connection with other embodiments, unless specifically stated otherwise, as will be apparent to one of ordinary skill in the art upon filing the present application. Accordingly, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.