CN112782089A

CN112782089A - Gas sensor based on photoacoustic effect

Info

Publication number: CN112782089A
Application number: CN202011525743.2A
Authority: CN
Inventors: 不公告发明人
Original assignee: Yu Mengjin
Current assignee: Yu Mengjin
Priority date: 2020-12-22
Filing date: 2020-12-22
Publication date: 2021-05-11

Abstract

The invention relates to the field of gas detection, and particularly provides a gas sensor based on a photoacoustic effect, which comprises a cavity wall, a gas inlet, a gas outlet, a light-transmitting hole, an elastic layer, an electric sensitive layer, a source electrode and a drain electrode, wherein the gas inlet and the gas outlet are arranged on opposite side surfaces of the cavity wall, the light-transmitting hole is arranged on the same side as the gas inlet, the elastic layer covers the cavity wall, the elastic layer and the cavity wall form a cavity in a surrounding mode, the electric sensitive layer is arranged on the elastic layer, and the source electrode and. The invention has the advantage of high gas concentration detection sensitivity.

Description

Gas sensor based on photoacoustic effect

Technical Field

The invention relates to the field of gas detection, in particular to a gas sensor based on a photoacoustic effect.

Background

Gas detection, and in particular selective gas detection techniques, have important applications in the medical and industrial fields. The gas detection technology based on the photoacoustic effect has the advantage of strong selectivity and has good prospect in the field of gas sensing. However, the conventional gas sensor based on the photoacoustic effect has low detection sensitivity.

Disclosure of Invention

In order to solve the problems, the invention provides a gas sensor based on a photoacoustic effect, which comprises a cavity wall, a gas inlet, a gas outlet, a light hole, an elastic layer, an electric sensitive layer, a source electrode and a drain electrode, wherein the gas inlet and the gas outlet are arranged on opposite side surfaces of the cavity wall, the light hole is arranged on the same side of the gas inlet, the elastic layer covers the cavity wall, the elastic layer and the cavity wall form a cavity in a surrounding mode, the electric sensitive layer is arranged on the elastic layer, and the source electrode and the drain electrode are arranged on two sides.

Still further, the electrically susceptible layer is a graphene layer.

Further, the elastic layer is an insulating material.

Further, the elastic layer is thin in the middle and thick at the edges.

Furthermore, holes are arranged in the graphene layer.

Furthermore, the number of graphene layers in the graphene layer is more than 1 and less than 10.

Further, the source electrode and the drain electrode are made of gold, silver or platinum.

Furthermore, a porous scattering material is arranged in the chamber.

Further, the porous scattering material is titanium dioxide or zirconium dioxide.

The invention has the beneficial effects that: the invention provides a gas sensor based on a photoacoustic effect, which comprises a cavity wall, a gas inlet, a gas outlet, a light hole, an elastic layer, an electric sensitive layer, a source electrode and a drain electrode, wherein the gas inlet and the gas outlet are arranged on opposite side surfaces of the cavity wall, the light hole is arranged on the same side of the gas inlet, the elastic layer covers the cavity wall, the elastic layer and the cavity wall form a cavity, the electric sensitive layer is arranged on the elastic layer, and the source electrode and the drain electrode are arranged on two sides of the electric sensitive layer. When the gas detection device is applied, gas to be detected enters the cavity through the gas inlet. Periodic laser light is applied to irradiate the gas to be measured in the chamber through the light-transmitting holes. The gas molecules to be detected absorb light with specific wavelength and generate heat, so that the pressure in the cavity is periodically increased, the elastic layer is upwards expanded, the electric sensitive layer is bent, the electric conduction characteristic of the electric sensitive layer is changed, and the gas concentration detection is realized by measuring the change of the electric conduction characteristic of the electric sensitive layer. And after the detection is finished, the gas to be detected is discharged out of the chamber through the gas outlet. The invention has the advantage of high gas concentration detection sensitivity because the conductive property of the electric sensitive layer is closely related to the shape and the internal stress of the electric sensitive layer.

The present invention will be described in further detail below with reference to the accompanying drawings.

Drawings

Fig. 1 is a schematic diagram of a photoacoustic effect based gas sensor.

Fig. 2 is a schematic diagram of yet another photoacoustic effect based gas sensor.

Fig. 3 is a schematic diagram of yet another gas sensor based on the photoacoustic effect.

In the figure: 1. a chamber wall; 2. an air inlet; 3. an air outlet; 4. a light-transmitting hole; 5. an elastic layer; 6. an electrically susceptible layer; 7. a source electrode; 8. a drain electrode; 9. a chamber; 10. and (4) holes.

Detailed Description

To further explain the technical means and effects of the present invention adopted to achieve the intended purpose, the following detailed description of the embodiments, structural features and effects of the present invention will be made with reference to the accompanying drawings and examples.

Example 1

The invention provides a gas sensor based on a photoacoustic effect, which comprises a cavity wall 1, a gas inlet 2, a gas outlet 3, a light hole 4, an elastic layer 5, an electric sensitive layer 6, a source electrode 7 and a drain electrode 8, as shown in figure 1. The chamber wall 1 comprises side and bottom surfaces. The gas inlet 2 and the gas outlet 3 are arranged on opposite sides of the chamber wall 1. In fig. 1, the air inlet 2 is arranged on the left side of the chamber wall 1 and the air outlet 3 is arranged on the right side of the chamber wall 1. The light hole 4 is arranged on the side surface of the cavity wall 1, and the light hole 4 is arranged on the same side as the air inlet 2. The light-transmitting hole 4 is used for introducing additional laser into the cavity wall 1. The light hole 4 is made of transparent material. The elastic layer 5 covers the cavity wall 1, and the elastic layer 5 and the cavity wall 1 enclose a cavity 9. That is, the elastic layer 5 serves as a top surface of the chamber 9. The elastic layer 5 is made of insulating material or elastic material. In practical applications, the elastic layer 5 may be rubber or other organic material. The material of the elastic layer 5 is determined according to the gas to be measured, the gas to be measured cannot corrode the elastic layer 5, and the material of the elastic layer 5 is not limited herein. An electrically susceptible layer 6 is placed on the elastic layer 5. When the morphology of the electrically susceptible layer 6 changes, the conductive properties of the electrically susceptible layer 6 change significantly. Preferably, the electrically susceptible layer 6 is a graphene layer. The number of graphene layers in the graphene layer is more than 1 and less than 10. The graphene layer may be made up of two parts that are exfoliated, both parts containing 1-4 layers of graphene. Thus, when the electrically susceptible layer 6 deforms, the interface between the two parts changes, resulting in a significant change in the conductive properties of the electrically susceptible layer 6. The source electrode 7 and the drain electrode 8 are disposed on both sides of the electrically sensitive layer 6 to measure the conductive characteristics of the electrically sensitive layer 6. Preferably, the source 7 and the drain 8 are placed in the vicinity of the chamber wall 1. Thus, when the elastic layer 5 is deformed and the electrically susceptible layer 6 is deformed, the measured values of the source electrode 7 and the drain electrode 8 change more, i.e., the electrically conductive characteristics of the electrically susceptible layer 6 change more. The source electrode 7 and the drain electrode 8 are made of gold, silver or platinum.

In use, gas to be measured enters the chamber 9 through the gas inlet 2. Through the light-transmitting holes, periodic laser light is applied to irradiate the gas to be measured in the chamber 9. The gas molecules to be detected absorb light with a specific wavelength and generate heat, so that the pressure in the cavity 9 is periodically increased, the elastic layer 5 is expanded upwards, the electric sensitive layer 6 is obviously bent under the limitation of the cavity wall 1, the electric conduction characteristic of the electric sensitive layer 6 is changed, and the gas concentration detection is realized by measuring the change of the electric conduction characteristic of the electric sensitive layer 6. After the detection is finished, the gas to be detected is discharged out of the chamber 9 through the gas outlet 3. The present invention has the advantage of high gas concentration detection sensitivity because the conductive properties of the electrically sensitive layer 6 are closely related to its shape and internal stress.

In addition, the present invention places the graphene layer on the elastic layer 5, that is, the graphene layer is placed outside the chamber 9, so that the graphene layer is easily prepared and regulated. For example, when the gas is periodically irradiated by the excitation light at different temperatures, the change of the conductive characteristics of the graphene layer is measured, so that a plurality of groups of data are obtained, which is equivalent to a sensor array, and higher accuracy is obtained.

Example 2

On the basis of example 1, as shown in fig. 2, the elastic layer 5 is thin in the middle and thick at the edges. Therefore, when the gas to be detected absorbs laser and expands, the elastic layer 5 deforms to a larger extent, so that the conductive characteristic of the electric sensitive layer 6 is changed more, and the gas detection with higher sensitivity is realized.

Example 3

On the basis of example 2, as shown in fig. 3, holes 10 are provided in the graphene layer. As such, the current in the graphene layer is confined to a narrower path. When the graphene layer deforms, the current distribution in the graphene layer changes more obviously, so that the conductive characteristics of the graphene layer change to a greater extent, and gas detection with higher sensitivity is realized.

Example 4

On the basis of embodiment 3, a porous scattering material is disposed in the chamber 9, and the porous scattering material is titanium dioxide or zirconium dioxide. On one hand, the porous scattering material has strong adsorption capacity to the gas to be detected, and absorbs more gas to be detected; on the other hand, the porous scattering material has a limiting effect on incident laser, and the incident laser is gathered in the porous scattering material by the porous scattering material, so that a strong electric field is formed in the porous scattering material. The two effects are beneficial to the gas to be detected to generate larger expansion, so that the electric sensitive layer 6 deforms more, and the gas detection with higher sensitivity is realized.

Furthermore, the porous scattering material is provided with noble metal particles therein. Preferably, the noble metal particles are silver particles. The preparation of silver particles in the porous scattering material is simple and convenient. During preparation, the porous scattering material can be placed in a silver nitrate solution, then the porous scattering material is taken out of the silver nitrate solution, and after silver nitrate in the porous scattering material is decomposed, silver particles can be obtained. The silver particles absorb the incident laser light, and surface plasmon resonance is generated on the silver particles. On one hand, the absorption of incident laser light by silver particles is enhanced; on the other hand, a strong electric field is generated in the vicinity of the silver particles. The two effects are beneficial to the gas to be detected to absorb more laser energy, so that more expansion is generated, the conductive characteristic of the electric sensitive layer 6 is changed more, and the gas detection with higher sensitivity is realized.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims

1. A gas sensor based on a photoacoustic effect is characterized by comprising a cavity wall, a gas inlet, a gas outlet, a light hole, an elastic layer, an electric sensitive layer, a source electrode and a drain electrode, wherein the gas inlet and the gas outlet are arranged on opposite side surfaces of the cavity wall, the light hole is arranged on the same side as the gas inlet, the elastic layer covers the cavity wall, the elastic layer and the cavity wall form a cavity in a surrounding mode, the electric sensitive layer is arranged on the elastic layer, and the source electrode and the drain electrode are arranged on two sides of the electric sensitive layer.

2. The photoacoustic effect-based gas sensor of claim 1 wherein: the electric sensitive layer is a graphene layer.

3. The photoacoustic effect-based gas sensor of claim 2 wherein: the elastic layer is made of an insulating material.

4. The photoacoustic effect-based gas sensor of claim 3 wherein: the elastic layer is thin in the middle and thick at the edges.

5. The photoacoustic effect-based gas sensor of claim 4 wherein: holes are formed in the graphene layer.

6. The photoacoustic effect-based gas sensor of any one of claims 2 to 5 wherein: the number of graphene layers in the graphene layer is greater than 1 and less than 10.

7. The photoacoustic effect-based gas sensor of claim 6 wherein: the source electrode and the drain electrode are made of gold, silver and platinum.

8. The photoacoustic effect-based gas sensor of claim 7 wherein: and a porous scattering material is arranged in the cavity.

9. The photoacoustic effect-based gas sensor of claim 8 wherein: the porous scattering material is titanium dioxide or zirconium dioxide.