阅读说明：本技术 气体感测器 (Gas sensor ) 是由 黄柏恺 蔡明志 简志轩 于 2020-04-22 设计创作，主要内容包括：本发明提供了一种气体感测器,包括：一基板；多个电极,形成于该基板上；以及一金属层,形成于该基板与多个该电极上,其中该金属层包括多个第一分子与多个第二分子,多个该第二分子掺杂于多个该第一分子中,其中每一第一分子包括一金属粒子与多个碳链,多个该碳链连接该金属粒子的表面,以及每一第二分子包括共轭结构。(The invention provides a gas sensor, comprising: a substrate; a plurality of electrodes formed on the substrate; and a metal layer formed on the substrate and the plurality of electrodes, wherein the metal layer comprises a plurality of first molecules and a plurality of second molecules, the plurality of second molecules are doped in the plurality of first molecules, each first molecule comprises a metal particle and a plurality of carbon chains, the plurality of carbon chains are connected with the surface of the metal particle, and each second molecule comprises a conjugated structure.)

1. A gas sensor, comprising:

a substrate;

a plurality of electrodes formed on the substrate; and

a metal layer formed on the substrate and the plurality of electrodes, wherein the metal layer includes a plurality of first molecules and a plurality of second molecules, the plurality of second molecules are doped in the plurality of first molecules, each of the first molecules includes a metal particle and a plurality of carbon chains, the plurality of carbon chains are connected to a surface of the metal particle, and each of the second molecules includes a conjugated structure.

2. The gas sensor according to claim 1, wherein the metal particles in the first molecule comprise gold, silver, copper, tin, palladium, platinum, nickel, cobalt, or aluminum.

3. The gas sensor according to claim 1, wherein the carbon chain of the first molecule has a carbon number between 6-24.

4. The gas sensor according to claim 1, wherein the carbon chain in the first molecule is connected to the surface of the metal particle through an anchoring unit.

5. The gas sensor according to claim 4, wherein the anchor unit includes a sulfur atom, a phosphorus atom, or a nitrogen atom.

6. The gas sensor according to claim 1, wherein the second molecule comprises one or more of a nitrogen-containing cyclic conjugated structure, a sulfur-containing cyclic conjugated structure, or a double bond-containing cyclic conjugated structure.

7. The gas sensor according to claim 1, wherein the second molecule comprises one or more of a nitrogen-containing cyclic conjugated structure, a sulfur-containing cyclic conjugated structure, or a double bond-containing cyclic conjugated structure modified with a functional group.

8. The gas sensor according to claim 1, wherein the ratio of the number of the second molecules to the number of the first molecules is between 1:2 and 1: 100000.

9. The gas sensor according to claim 1, wherein the ratio of the number of the second molecules to the number of the first molecules is between 1:20 and 1: 10000.

10. The gas sensor according to claim 1, wherein the first molecule and the second molecule form a physical mixture.

11. The gas sensor according to claim 7, wherein the first molecule and the second molecule form a covalent bond.

12. The gas sensor according to claim 11, wherein the metal particles in the first molecule are covalently bonded to the functional groups in the second molecule.

13. The gas sensor according to claim 1, wherein the target gas detected by the gas sensor comprises a volatile organic compound gas.

14. The gas sensor according to claim 1, wherein the target gas detected by the gas sensor comprises an amine gas, an oxynitride gas or an explosive gas.

Technical Field

The present invention relates to a gas sensor, and more particularly, to a gas sensor capable of effectively preventing aggregation of nano-metal particles.

Background

Generally, gas sensors can be classified into six types, namely, metal oxide type (metal oxide), conductive polymer type (conductive polymer), photo catalyst type (optical catalyst), quartz crystal micro-balance type (quartz crystal micro-balance), surface acoustic wave type (surface acoustic wave), and chemical resistance type (chemical-resistance).

In the chemical resistance type gas sensor, nano gold particles are often used as the sensing material, however, the material has two major problems, one is that the conductivity of the protective agent (capping agent) for providing stability of nano gold particles is low, which causes the resistance of the nano gold film after film formation to be too high and difficult to control, usually reaching tens to hundreds of Mega ohms, so that the technicians in the field often encounter considerable difficulties in designing the back end signal processing circuit, and the other is the problem of the device lifetime, because the characteristics of nano gold particles are continuously aggregated (aggregation) with time, the rate of change of the resistance value during sensing is continuously reduced, and finally the sensor cannot be used.

Therefore, it is desirable to develop a gas sensor that can effectively prevent the aggregation of nano-metal particles and improve the sensing performance.

Disclosure of Invention

To solve the above disadvantages and shortcomings, the present invention provides a gas sensor.

According to one embodiment of the present invention, a gas sensor is provided. The gas sensor includes: a substrate; a plurality of electrodes formed on the substrate; and a metal layer formed on the substrate and the plurality of electrodes, wherein the metal layer comprises a plurality of first molecules and a plurality of second molecules, the plurality of second molecules are doped in the plurality of first molecules, each first molecule comprises a metal particle and a plurality of carbon chains, the plurality of carbon chains are connected with the surface of the metal particle, and each second molecule comprises a conjugated structure.

In some embodiments, the metal particles in the first molecule include gold, silver, copper, tin, palladium, platinum, nickel, cobalt aluminum.

In some embodiments, the carbon chain in the first molecule has a carbon number between 6 and 24.

In some embodiments, the carbon chain in the first molecule is attached to the surface of the metal particle via an anchor unit.

In some embodiments, the anchoring unit includes a sulfur atom, a phosphorus atom, or a nitrogen atom.

In some embodiments, the second molecule comprises one or a combination of nitrogen-containing cyclic conjugated structures, sulfur-containing cyclic conjugated structures, or double bond-containing cyclic conjugated structures.

In some embodiments, the second molecule comprises

In some embodiments, the second molecule comprises one or more of a nitrogen-containing cyclic conjugated structure, a sulfur-containing cyclic conjugated structure, and a double bond-containing cyclic conjugated structure modified with a functional group.

In some embodiments, the second molecule comprises Wherein the functional group R comprises-O- (CH)₂)_nH、-O-(CH₂CH₂O)_nCH₃、-S(CH₂)_nH、-O-(CH₂CH₂O)_nSH、 n is between 0 and 24.

In some embodiments, the doping concentration ratio of the second molecule to the first molecule is between 1:2 and 1: 100000. In some embodiments, the doping concentration ratio of the second molecule to the first molecule is between 1:20 and 1: 10000. In other words, in some embodiments, the ratio of the number of the second molecules to the number of the first molecules is between 1:2 and 1: 100000. In some embodiments, the ratio of the number of the second molecules to the number of the first molecules is between 1:20 and 1: 10000.

In some embodiments, the first molecule forms a physical mixture with the second molecule.

In some embodiments, the first molecule and the second molecule form a covalent bond.

In some embodiments, the metal particles in the first molecule are covalently bonded to the functional groups in the second molecule.

In some embodiments, the target gas detected by the gas sensor includes volatile organic compound (voc) gas.

In some embodiments, the target gas detected by the gas sensor includes amine gas, nitrogen oxide gas, or explosive gas, such as methane, industrial flammable gas, etc.

The present invention provides a method for preparing a conjugated organic compound, such as porphyrin (porphyrin,) Phthalocyanine (phthalocyanine,) Or naphthalocyanines (naphthalocyanines,) Doping and introducing into the nano metal particles, and further modifying functional groups to increase the bonding stability between the nano metal particles and the nano metal particles. The invention can increase the conductive path by adjusting and optimizing the doping concentration of the organic compound, precisely control the resistance value of the sensor to maintain the resistance value within the required range, effectively reduce the integration difficulty between the sensor and the semiconductor process and the signal processing circuit, and expand the distance between the nano metal particles due to the doped organic compound,in addition, the doped organic compound and the side chain functional group thereof have nonpolar characteristics, so that the doped organic compound and the side chain functional group thereof have certain sensing effect on polar gases and are easy to grab the nonpolar gases, the change of resistance value is increased, the effect of signal amplification is achieved, and the efficiency (sensitivity) of the sensor is further improved.

Drawings

FIG. 1 is a schematic cross-sectional view of a gas sensor provided in an embodiment of the present invention;

FIG. 2 is a schematic view of a metal layer of a gas sensor provided in an embodiment of the present invention;

FIG. 3 is a schematic view of a metal layer of a gas sensor provided in an embodiment of the present invention;

FIG. 4 is a diagram illustrating the physical property (resistance) test results of a gas sensor provided in an embodiment of the present invention;

FIG. 5 is a diagram illustrating the results of a physical property (resistance change) test of a gas sensor according to an embodiment of the present invention;

fig. 6 is a diagram illustrating a physical property (resistance change) test result of the gas sensor according to an embodiment of the present invention.

The main reference numbers illustrate:

10 gas sensor;

12 a substrate;

14 electrodes;

16 metal layers;

18 a first molecule;

20 a second molecule;

22 metal particles;

24 carbon chains;

26, an anchoring unit;

28 a core structure;

30 functional groups.

Detailed Description

In order to clearly understand the technical features, objects and advantages of the present invention, the following detailed description of the technical solutions of the present invention will be made with reference to the following specific examples, which should not be construed as limiting the implementable scope of the present invention.

Referring to FIG. 1, a gas sensor 10 is provided according to one embodiment of the present invention. FIG. 1 is a cross-sectional view of a gas sensor 10.

In FIG. 1, a gas sensor 10 includes a substrate 12, a plurality of electrodes 14, and a metal layer 16. The electrode 14 is formed on the substrate 12. The metal layer 16 is formed on the substrate 12 and the electrode 14, for example, the metal layer 16 is formed on the substrate 12 and the electrode 14 entirely. In some embodiments, substrate 12 may comprise silicon, metal oxide, or other suitable substrate material. In some embodiments, the electrode 14 may comprise gold, silver, copper, or other suitable electrode material. Referring to fig. 2 and 3, different composition patterns of the metal layer 16 are illustrated.

As shown in fig. 2, in some embodiments, the metal layer 16 includes a plurality of first molecules 18 and a plurality of second molecules 20. The second molecule 20 is doped in the first molecule 18. Each first molecule 18 includes a metal particle 22 and a plurality of carbon chains 24 connecting the surface of the metal particle 22. Each second molecule 20 includes a core structure 28.

In some embodiments, the metal particles 22 in the first molecule 18 may include gold, silver, copper, tin, palladium, platinum, nickel, cobalt, or aluminum. In some embodiments, the carbon chain 24 in the first molecule 18 has a carbon number between about 6 and 24. In some embodiments, the carbon chains 24 in the first molecule 18 have a carbon number between about 8 and about 20. In some embodiments, the carbon chains 24 in the first molecule 18 are further attached to the surface of the metal particles 22 by anchoring units (anchors) 26. In some embodiments, the anchoring unit 26 may include a sulfur atom, a phosphorus atom, or a nitrogen atom.

In some embodiments, the core structure 28 of the second molecule 20 may include a nitrogen-containing cyclic conjugated structure, a sulfur-containing cyclic conjugated structure, or a double bond-containing cyclic conjugated structure. In some embodiments, the core structure 28 of the second molecule 20 may include

In some embodiments, the doping concentration ratio of the second molecule 20 to the first molecule 18 is between about 1:2 and about 1: 100000. In some embodiments, the doping concentration ratio of the second molecule 20 to the first molecule 18 is between about 1:20 and about 1: 10000. In other words, in some embodiments, the ratio of the number of the second molecules 20 to the number of the first molecules 18 is between 1:2 and 1: 100000. In some embodiments, the ratio of the number of the second molecules 20 to the number of the first molecules 18 is between 1:20 and 1: 10000.

In some embodiments, the first molecule 18 and the second molecule 20 may form a physical mixture, i.e., no covalent bond is formed between the first molecule 18 and the second molecule 20.

As shown in fig. 3, in some embodiments, the metal layer 16 includes a plurality of first molecules 18 and a plurality of second molecules 20. The second molecule 20 is doped in the first molecule 18. Each first molecule 18 includes a metal particle 22 and a plurality of carbon chains 24 connecting the surface of the metal particle 22. Each second molecule 20 includes a core structure 28 and a plurality of functional groups 30 attached to a surface of the core structure 28.

In some embodiments, the metal particles 22 in the first molecule 18 may include gold, silver, copper, tin, palladium, platinum, nickel, cobalt, or aluminum. In some embodiments, the carbon chain 24 in the first molecule 18 has a carbon number between about 6 and 24. In some embodiments, the carbon chains 24 in the first molecule 18 have a carbon number between about 8 and about 20. In some embodiments, the carbon chains 24 in the first molecule 18 are further attached to the surface of the metal particles 22 by anchoring units (anchors) 26. In some embodiments, the anchoring unit 26 may include a sulfur atom, a phosphorus atom, or a nitrogen atom.

In some embodiments, the second molecule 20 may include a nitrogen-containing cyclic conjugated structure, a sulfur-containing cyclic conjugated structure, or a double bond-containing cyclic conjugated structure modified with a functional group 30. In some embodiments, the second molecule 20 may comprise

In the above formula, R may comprise-O- (CH)₂)_nH、-O-(CH₂CH₂O)_nCH₃、-S(CH₂)_nH、-O-(CH₂CH₂O)_nSH、 n is between 0 and 24.

In some embodiments, the doping concentration of the second molecule 20 in the first molecule 18 is between about 1:2 and about 1: 100000. In some embodiments, the doping concentration of the second molecule 20 in the first molecule 18 is between about 1:20 and about 1: 10000. In other words, in some embodiments, the ratio of the number of the second molecules 20 to the number of the first molecules 18 is between 1:2 and 1: 100000. In some embodiments, the ratio of the number of the second molecules 20 to the number of the first molecules 18 is between 1:20 and 1: 10000.

In some embodiments, the first molecule 18 and the second molecule 20 may form a physical mixture, i.e., no covalent bond is formed between the first molecule 18 and the second molecule 20. In some embodiments, the first molecule 18 and the second molecule 20 may form a covalent bond, for example, a covalent bond is formed between the metal particle 22 in the first molecule 18 and the functional group 30 in the second molecule 20.

In the present invention, since the nano-metal particles in the metal layer 16 are soluble in various organic solvents, the nano-metal particle film can be deposited by means of, for example, dropping or spraying, and in some embodiments, the nano-metal particle film (i.e., the metal layer 16) can also be deposited by using techniques such as inkjet printing, micro-contact printing, dispenser or optical lithography.

In some embodiments, the target gas detected by the gas sensor 10 may include Volatile Organic Compounds (VOCs) such as ethanol, toluene, butanol, or octane. In some embodiments, the target gas detected by the gas sensor 10 may include amine-based gas, nitrogen oxide gas, or explosive gas, such as methane, industrial flammable gas, etc.

The sensing principle of the gas sensor of the invention is that when the sensor contacts organic gas molecules, physical adsorption is generated between the gas molecules and the nano metal particles, and the gas molecules are diffused into gaps between the metal particles, so that the distance between the two metal particles is increased, namely, the paths of electron hopping and tunneling are lengthened, and the conductivity is reduced and the resistance value is increased. Since the acting force between each gas molecule and the nano metal particles is different, the nano metal particles have different physical adsorption capacities for various Volatile Organic Compounds (VOC) gases, and have different sensitivities for different gases due to different degrees of distance changes between the metal particles caused by adsorption of organic molecules. In addition, the invention selects the nano metal particles as the sensing material, which can be applied to the measurement of gas under normal temperature and normal pressure, and the sensing material is reactive to most Volatile Organic Compound (VOC) gas.

The present invention provides a method for preparing a conjugated organic compound, such as porphyrin (porphyrin,) Phthalocyanine (phthalocyanine,) Or naphthalocyanines (naphthalocyanines,) The metal nanoparticles are doped and introduced, and the bonding stability between the metal nanoparticles and the metal nanoparticles is increased by further functional group modification. The invention can increase the conductive path by adjusting and optimizing the doping concentration of the organic compound, precisely control the resistance value of the sensor to maintain the resistance value within the required range, effectively reduce the integration difficulty between the sensor and the semiconductor process and the signal processing circuit, and because the doped organic compound enables the nano metal particles to be integratedThe distance is expanded, thereby effectively slowing down aggregation (aggregation) among the nano metal particles, further prolonging the service life of the element, besides, the doped organic compound and the side chain functional group thereof have a certain sensing effect on polar gas due to the non-polar characteristic, and are easy to grab for the non-polar gas, thereby increasing the change of resistance value, achieving the effect of signal amplification, and further improving the efficiency (sensitivity) of the sensor.

Example 1

Measurement of basic resistance of gas sensor

This example illustrates the effect of doping a metal layer in a gas sensor with conjugated molecules on its basic resistance (baseline resistance). First, a sensor C, a sensor I, a sensor II, a sensor III and a sensor IV are provided. In this embodiment, the metal layer of the gas sensor is mainly composed of nano gold particles with octyl groups connected to the surface, wherein the metal layer of the sensor C is not doped with conjugated molecules, and the metal layers from the sensor I to the sensor IV are further doped with conjugated moleculesIn the conjugated molecule, R is-O- (CH)₂)₃CH₃And the doping concentration ratio is 1:20 (sensor I), 1:100 (sensor II), 1:2000 (sensor III) and 1:10000 (sensor IV), respectively. Then, the basic resistance of the gas sensor is measured, and the measurement results are shown in table 1.

TABLE 1

Gas sensor	Doping concentration	Basic resistance value
			Sensor C	0	～500MΩ
Sensor I	1:20	11.3±1.1MΩ
			Sensor II	1:100	3.01±0.14MΩ
Sensor III	1:2000	0.72±0.02MΩ
			Sensor IV	1:10000	0.28±0.01MΩ

As can be seen from table 1, the basic resistance values of the sensors I to IV doped with the conjugated molecules in the metal layer of the present invention can be precisely controlled, i.e., the basic resistance values of the sensors can be controlled within a desired range by adjusting and optimizing the doping concentration of the conjugated molecules, without generating too large resistance value variability.

Example 2

Device life test for gas sensor

This example illustrates the effect of doping a metal layer in a gas sensor with conjugated molecules on the lifetime of the device. First, a sensor I, a sensor II, a sensor III and a sensor IV are provided. In this embodiment, the metal layer of the gas sensor is mainly composed of nano gold particles with octyl groups connected to the surface, and the metal layers from the sensor I to the sensor IV are further doped with conjugated molecules(R is-O- (CH)₂)₃CH₃) The doping concentration ratio is 1:20 (sensor I), 1:100 (sensor II), 1:2000 (sensor III) and 1:10000 (sensor IV). Then, the lifetime of the gas sensor is tested, and the test result is shown in fig. 4.

In fig. 4, curve 1 shows the change of the resistance of sensor I with time, curve 2 shows the change of the resistance of sensor II with time, curve 3 shows the change of the resistance of sensor III with time, and curve 4 shows the change of the resistance of sensor IV with time. As shown in fig. 4, the functions of the sensor I to the sensor IV can be maintained for more than several months (the resistance value of the sensor varies very slightly with time), and are not affected by the environment and humidity, because the metal layers of the sensor I to the sensor IV are doped with conjugated molecules, the distance between the gold nanoparticles is spread, the aggregation speed between the gold nanoparticles is effectively reduced, and the device lifetime is further prolonged.

Example 3

Sensitivity testing of gas sensors

This example illustrates the effect of doping a metal layer in a gas sensor with conjugated molecules on its sensitivity. First, a sensor C and a sensor II are provided. In this embodiment, the metal layer of the gas sensor is mainly composed of nano-gold particles with octyl groups connected to the surface, wherein the metal layer of the sensor C is not doped with conjugated molecules, and the metal layer of the sensor II is further doped with conjugated molecules(R is-O- (CH)₂)₃CH₃) And the doping concentration is 1: 100. Then, toluene (400-1000ppm) as the target gas was introduced, and the gas sensor was tested for sensitivity by introducing toluene gas at 400ppm, 500ppm, 600ppm, 800ppm and 1000ppm for 100 seconds, 300 seconds, 500 seconds, 700 seconds and 900 seconds, respectively, and the test results are shown in FIG. 5.

In fig. 5, curve 1 shows a change in resistance of the sensor C after contacting the target gas, and curve 2 shows a change in resistance of the sensor II after contacting the target gas. As shown in fig. 5, the resistance of the sensor C is very slightly changed after contacting the target gas regardless of the concentration of the toluene gas introduced, whereas the resistance of the sensor II is very significantly changed after contacting the target gas regardless of the concentration of the toluene gas introduced. Therefore, the sensitivity (sensing performance) of the sensor II doped with the conjugated molecules in the metal layer to the toluene gas is significantly better than that of the sensor C not doped with the conjugated molecules in the metal layer.

Example 4

Gas selectivity testing of gas sensors

This example illustrates the gas selectivity exhibited by a metal layer in a gas sensor doped with conjugated molecules. First, a sensor III is provided. In this embodiment, the metal layer of the sensor III is mainly composed of nano-gold particles with octyl groups connected to the surface, and the metal layer of the sensor III is further doped with conjugated molecules(R is-O- (CH)₂)₃CH₃) The doping concentration is 1: 2000. Then, different target gases, ethanol, toluene, butanol and octane, with concentrations of 400-1000ppm, were introduced, and the gas sensor was tested for gas selectivity, with concentrations of 400, 500, 600, 800, 1000ppm of ethanol, toluene, butanol and octane gas being introduced at 100 seconds, 300 seconds, 500 seconds, 700 seconds, 900 seconds, respectively, with the test results shown in fig. 6.

In fig. 6, curve 1 shows the change of the resistance value of the sensor III after contacting ethanol gas, curve 2 shows the change of the resistance value of the sensor III after contacting toluene gas, curve 3 shows the change of the resistance value of the sensor III after contacting butanol gas, and curve 4 shows the change of the resistance value of the sensor III after contacting octane gas. As shown in fig. 6, the resistance change of the sensor III after contacting different target gases is very different from each other regardless of the target gases introduced. Therefore, the sensor III doped with conjugated molecules in the metal layer can exhibit high selectivity for various target gases, i.e., can distinguish the types and concentrations of different gases.

The features of the above-described embodiments are useful for understanding the present invention by those skilled in the art. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. It should also be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.