CN115368696B

CN115368696B - Transparent stretchable self-powered hydrogen sulfide gas sensor based on gel

Info

Publication number: CN115368696B
Application number: CN202210991096.7A
Authority: CN
Inventors: 吴进; 黄文溪; 韦耀铭
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2022-08-18
Filing date: 2022-08-18
Publication date: 2023-07-18
Anticipated expiration: 2042-08-18
Also published as: CN115368696A

Abstract

The invention belongs to the technical field of sensors, and provides a transparent stretchable self-powered hydrogen sulfide gas sensor based on gel.

Description

Transparent stretchable self-powered hydrogen sulfide gas sensor based on gel

Technical Field

The invention relates to the technical field of sensors, in particular to a transparent stretchable self-powered hydrogen sulfide gas sensor based on gel.

Background

Hydrogen sulfide is a colorless, toxic gas that is commonly produced in industrial activities such as biological decomposition of organic matter, food processing, leather manufacturing, and oil refining. Hydrogen sulfide at a concentration of 0.13ppm in the atmosphere has a significantly unpleasant odor, and human exposure to hydrogen sulfide at a concentration of 20ppm or higher can be life threatening to human health. In addition, in medical diagnostics, hydrogen sulfide is one of the biomarkers of bad breath. In one clinical study, the mean concentration of hydrogen sulfide in exhaled breath of halitosis patients was not less than 20.64ppb, and the mean concentration of hydrogen sulfide in oral cavity of healthy volunteers was not more than 3.36ppb. It can be seen that the effective and accurate detection of ppb levels of hydrogen sulfide is of great importance in the prevention and diagnosis of oral diseases. In addition, with the rapid development of the universe and the internet of things, portable and wearable equipment is greatly concerned worldwide, and the flexible wearable gas sensor can be processed into an electronic nose for real-time health monitoring and toxic gas early warning. Therefore, developing a flexible, portable gas sensor that is capable of detecting low concentrations of hydrogen sulfide would greatly improve one's life.

At present, in medical diagnosis, traditional hydrogen sulfide detection methods include gas chromatography/mass spectrometry, ion chromatography and the like, however, the methods are complex in operation, high in cost and long in time consumption, and real-time detection cannot be realized. In the past decades, researchers have explored a variety of metal oxide semiconductors or nanomaterials to make hydrogen sulfide gas sensors, but most of these materials do not have flexibility or stretchability, have complex manufacturing processes, can only detect hydrogen sulfide at high concentrations (ppm level), and require high operating temperatures (100-500 ℃). Therefore, there is a need to develop a portable stretchable hydrogen sulfide gas sensor capable of detecting low concentration hydrogen sulfide at low operating temperature so as to perform real-time monitoring.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems in the prior art described above. Therefore, the transparent stretchable self-powered hydrogen sulfide gas sensor based on gel provided by the invention can detect low-concentration hydrogen sulfide, can work at room temperature, has flexibility, can be stretched, has a tensile strain of 400%, is transparent, can realize self-powering, can reduce equipment size and energy consumption by self-powering, has a hydrogen sulfide detection limit of ppb level, can be used for preparing wearable equipment, portable hydrogen sulfide gas sensors and the like, and meets the requirements of portability and real-time monitoring of hydrogen sulfide.

A first aspect of the invention provides a transparent, stretchable, self-powered hydrogen sulfide gas sensor based on a gel.

The transparent stretchable self-powered hydrogen sulfide gas sensor based on gel comprises gel and an electrode;

the gel comprises a polymer hydrogel, a solvent and an electrolyte salt;

the polymer network contains-NH ₂ 、-COO ^- 、-SO ₃ ^- And at least one functional group of-OH;

the polymer hydrogel contains at least two polymer networks;

the electrodes are wound or adhered at two ends of the gel;

the electrode includes an anode and a cathode.

The invention adopts gel and electrode to make transparent self-powered hydrogen sulfide gas sensor based on gel, wherein the gel is mainly composed of polymer hydrogel, solvent and electrolyte salt, and the gel has certain strength and support property, so the gel can be used as solid electrolyte; due to the fact that the polymer hydrogel also containswith-NH ₂ 、-COO ^- 、SO ₃ ^- And at least one functional group in-OH, which can be combined with hydrogen sulfide gas, when the gas sensor is connected with external circuit to form complete closed circuit, the gel and electrode form primary cell, anode electron-loss is changed into cation into gel, anode potential is reduced, H in gel ⁺ Electrons are obtained at the cathode, so that a stable potential difference is formed between the anode and the cathode, and the primary battery converts chemical energy into electric energy to realize self-power supply; when the gas sensor contacts hydrogen sulfide, H atoms on the hydrogen sulfide are adsorbed by functional groups on the surface of the gel to form hydrogen bonds, and S atoms on the hydrogen sulfide and atoms on the cathode form weak ionic bonds; because the S-H bond in the hydrogen sulfide is a polar bond, the shared electron is biased towards the S atom with stronger electron attraction capability, so that the S atom is relatively negatively charged; when S atoms and metal atoms of the cathode form weak ionic bonds, the S atoms reduce the potential of the cathode, and the anode potential is lower, so that the S atoms which are relatively negatively charged are difficult to adsorb on the atoms of the anode, and the potential difference between the anode and the cathode is reduced, therefore, the adsorption condition of hydrogen sulfide at the junction of the gel and the electrode and the concentration of the hydrogen sulfide can be reflected by measuring the potential difference between the anode and the cathode, the detection of the low-concentration hydrogen sulfide can be realized, and the room-temperature work can be realized; in addition, the gel is adopted as the main part of the gas sensor, so that the gas sensor is endowed with transparency, stretchability and flexibility, can realize self-powered operation in an aerobic or anaerobic environment, and can be used for preparing wearable equipment, portable hydrogen sulfide gas sensors and the like.

Preferably, the polymer hydrogel is a dual network polymer hydrogel.

Preferably, the dual-network polymer hydrogel is a polyacrylamide-calcium alginate dual-network polymer hydrogel.

Preferably, the solvent comprises a polyol.

Preferably, the polyol is propylene glycol and/or glycerol.

Preferably, the electrolyte salt is one or more of calcium chloride, aluminum chloride and ferric chloride.

Preferably, the mass content of the solvent is 35-65% of the gel mass.

Preferably, the mass content of the electrolyte salt is 0.5-1% of the gel mass.

Preferably, the anode and the cathode are respectively and independently selected from one or more of zinc, silver, copper, iron and porous carbon materials.

Preferably, the porous carbon material is a porous carbon cloth.

Preferably, the anode and the cathode are respectively two metals with different reactivities, or the anode and the cathode are respectively an active metal and an inert nonmetallic material.

Preferably, the anode is zinc and the cathode is silver.

Preferably, the strain of the gel is 0-400%. The gel provided by the invention has good tensile property, and the tensile strain can reach 400%. And the gel helps to increase the sensitivity of the gas sensor of the present invention under appropriate strain.

More preferably, the strain of the gel is 50-100%.

The second aspect of the invention provides a method for preparing a transparent stretchable self-powered hydrogen sulfide gas sensor based on gel.

A preparation method of a transparent stretchable self-powered hydrogen sulfide gas sensor based on gel comprises the following steps:

and winding or adhering the electrodes on two ends of the gel to obtain the transparent stretchable self-powered hydrogen sulfide gas sensor.

Preferably, the method further comprises immersing the gel in an alcohol solution for 1-5 hours, and winding or adhering the electrodes on two ends of the gel.

Preferably, the alcohol solution is glycerol. After glycerol is adopted for soaking the modified gel, the frost resistance, the water retention and the sensitivity of the gas sensor are improved.

Preferably, the preparation method of the gel comprises the following steps:

dispersing polymer monomer in solvent, adding crosslinking agent and accelerator, adding initiator, and adding calcium salt to obtain gel.

Preferably, the crosslinking agent and the accelerator are added and then stirred, and the stirring temperature is 20-50 ℃.

Preferably, after the initiator is added, stirring is carried out, the mixed solution is poured into a glass culture dish after stirring, and the glass culture dish is heated to 60-70 ℃ after being sealed by a preservative film, and the mixed solution reacts for 2-3 hours.

Preferably, the polymer monomers include a first polymer monomer and a second polymer monomer.

Preferably, the mass ratio of the first polymer monomer to the second polymer monomer is 5-10:1.

More preferably, the mass ratio of the first polymer monomer to the second polymer monomer is 8:1.

Preferably, the first polymer monomer is one or more of acrylamide, vinyl alcohol and chitin. The polymers corresponding to the monomers of acrylamide, vinyl alcohol and chitin are respectively polyacrylamide, polyvinyl alcohol and chitosan.

Preferably, the second polymer monomer is alginic acid and/or carrageenan.

Preferably, the crosslinking is made as N, N' -methylenebisacrylamide.

Preferably, the accelerator is tetramethyl ethylenediamine.

Preferably, the initiator is ammonium persulfate.

Preferably, the curing agent is a calcium salt. The method comprises the steps of adding a crosslinking agent, an accelerator and an initiator into a polymer monomer, preparing first polymer network hydrogel, and then adding calcium salt to crosslink a second polymer monomer, so as to prepare gel with a double-network structure, wherein the gel also contains a solvent and electrolyte salt.

Preferably, the calcium salt is calcium chloride.

A third aspect of the invention provides the use of a transparent stretchable self-powered hydrogen sulfide gas sensor based on a gel.

The application of a transparent stretchable self-powered hydrogen sulfide gas sensor based on gel in hydrogen sulfide detection is provided.

Compared with the prior art, the invention has the following beneficial effects:

(1) The transparent stretchable self-powered hydrogen sulfide gas sensor is prepared by adopting gel and electrodes, and a polymer network contains-NH ₂ 、-COO ^- 、-SO ₃ ^- And at least one functional group in-OH, can be combined with hydrogen sulfide gas to be detected, then further twine or adhere electrodes at two ends of gel on the gel, the hydrogen sulfide gas sensor prepared has transparent, stretchable, self-powered, flexible characteristics, the tensile strain can reach 400%, and can work at room temperature, can also reduce the equipment size and energy consumption through self-powered, have good open-circuit voltage stability and long-time gas detection capability, the hydrogen sulfide detection limit reaches ppb level, can detect low-concentration hydrogen sulfide, can work in aerobic or anaerobic environment, overcomes the defect that the existing most metal oxide semiconductor gas sensor needs to work in anaerobic environment, can be used for preparing wearable equipment, portable hydrogen sulfide gas sensors and the like, meets the requirements of portability and real-time monitoring, can be used for halitosis detection and oral disease prevention and the like;

(2) The invention adopts polyacrylamide-calcium alginate double-network polymer hydrogel as double-network polymer hydrogel, which contains a large amount of-NH ₂ 、-COO ^- and-OH functional groups, which facilitate adsorption of hydrogen sulfide molecules; but also has good transparency; compared with single-network hydrogel, the double-network hydrogel has better mechanical properties, which is mainly attributed to a special energy dissipation mechanism of the polyacrylamide-calcium alginate double-network hydrogel, when the hydrogel is stretched, the calcium alginate network with weak mechanical strength is unwound, and the polyacrylamide network with strong mechanical strength maintains the shape of the hydrogel, so that the gas sensor is endowed with good stretching property; in addition, the preparation method of the polyacrylamide-calcium alginate double-network polymer hydrogel is simple, and high temperature (generally, the preparation is carried out at the high temperature of 90 ℃ and above) is not needed;

(3) The transparent stretchable self-powered hydrogen sulfide gas sensor can be prepared by directly winding or adhering the electrodes on the two ends of the gel, has short preparation time, does not need to adopt ultraviolet irradiation and the like, has simple steps and low cost, does not need expensive equipment and complicated operation, has low energy consumption, and is beneficial to large-scale production and application of the hydrogen sulfide gas sensor.

Drawings

FIG. 1 is a schematic diagram of a one-pot synthesis reaction scheme of the dual-network hydrogel prepared in example 1 of the present invention;

FIG. 2 is a schematic diagram showing the charge transfer process of a gas sensor composed of the dual-network hydrogel prepared in example 1 of the present invention, zinc electrode and silver electrode;

FIG. 3 is a drawing showing tensile properties of the dual-network hydrogel prepared in example 1 of the present invention;

FIG. 4 is a graph showing the water retention test of the double-network hydrogels prepared in examples 1 to 4 of the present invention at 25℃and 40% relative humidity;

FIG. 5 is a chart showing freezing point test of the dual-network hydrogel prepared in examples 1-4 according to the present invention after being immersed in glycerol solution for different periods of time;

FIG. 6 is a graph showing the optical transmittance test data of the dual-network hydrogel prepared in example 1 of the present invention;

FIG. 7 is a graph showing the electrochemical performance of a gas sensor formed by the double-network hydrogels prepared in examples 5-10 and different metal electrodes;

FIG. 8 shows the exposure of the gas sensors prepared in example 6 and example 10 of the present invention to different concentrations of H ₂ Response curve at S gas;

FIG. 9 shows the exposure of the gas sensor according to example 10 to low H concentration in nitrogen atmosphere ₂ Response curve at S gas;

FIG. 10 shows the exposure of the gas sensor of example 10 to different background gases and different concentrations of H ₂ A dynamic response curve at S gas;

FIG. 11 shows the exposure of the gas sensors of examples 10-12 of the present invention to different concentrations of H under different strains ₂ Response curve at S gas;

fig. 12 shows the use of the gas sensor of example 10 of the present invention to detect exhaled gas and simulate bad breath in healthy volunteers.

Detailed Description

In order to make the technical solutions of the present invention more apparent to those skilled in the art, the following examples will be presented. It should be noted that the following examples do not limit the scope of the invention.

The starting materials, reagents or apparatus used in the following examples are all available from conventional commercial sources or may be obtained by methods known in the art unless otherwise specified.

Example 1

A preparation method of polyacrylamide-calcium alginate double-network polymer hydrogel comprises the following steps:

(1) 6.222g of acrylamide, 0.7778g of sodium alginate, 0.0038g of N, N' -methylenebisacrylamide and 20.2 mu L of tetramethyl ethylenediamine are added into 42mL of deionized water, and stirred at 25 ℃ until the materials are uniformly mixed to obtain a mixed solution;

(2) Dissolving 0.0374g of ammonium persulfate in 1mL of deionized water to prepare an ammonium persulfate solution, adding the ammonium persulfate solution into the mixed solution, stirring for 20 seconds, uniformly mixing, immediately pouring the mixture into a glass culture dish, sealing the mixture by using a preservative film, and heating the mixture at 65 ℃ for 2 hours to crosslink acrylamide to form polyacrylamide network hydrogel;

(3) Placing polyacrylamide network hydrogel in CaCl of 1mol/L ₂ Soaking in the solution for 3 hours to crosslink sodium alginate to form calcium alginate, so as to obtain the polyacrylamide-calcium alginate double-network polymer hydrogel (or called double-network hydrogel).

Example 2

The polyacrylamide calcium alginate double-network polymer hydrogel obtained in example 1 was immersed in a pure glycerol solution for 1 hour.

Example 3

The preparation process was substantially the same as in example 2, except that the pure glycerol solution was immersed for 2 hours.

Example 4

The preparation process was substantially the same as in example 2, except that the pure glycerol solution was immersed for 4 hours.

Example 5

A transparent stretchable self-powered hydrogen sulfide gas sensor based on gel, comprising the dual-network polymer hydrogel prepared in example 1 and an electrode; electrodes are wound or adhered at two ends of the gel; the anode is copper, and the cathode is silver.

The preparation method comprises the following steps:

A15X 5mm rectangular block of example 1 was taken and wound with copper and silver wires on both ends of the block of example 1.

Example 6

The preparation process was substantially the same as in example 5, except that copper and silver were replaced with zinc and silver, respectively.

Example 7

The preparation process was substantially the same as in example 5, except that copper and silver were replaced with zinc and copper, respectively.

Example 8

The preparation method is basically the same as that of example 5, except that copper and silver are replaced with iron and silver respectively.

Example 9

The preparation process was substantially the same as in example 5, except that copper and silver were replaced with iron and copper, respectively.

Example 10

A15X 5mm rectangular block of example 2 was taken and wound with zinc and silver wires at both ends of the block of example 2.

Example 11

Example 10 was stretched to 50% strain and secured to a glass sheet.

Example 12

The preparation process was essentially the same as in example 5, except that 50% strain was replaced with 100% strain.

Comparative example 1

The comparative example is a single network hydrogel without polyacrylamideI.e. calcium alginate single network hydrogel. Compared with the double-network hydrogel adopted by the invention, the single-network hydrogel lacks-NH ₂ less-OH, for H ₂ S has weak adsorption capacity, and the sensitivity of the prepared gas sensor is low.

Comparative example 2

This comparative example is a single network hydrogel without calcium alginate, i.e., a polyacrylamide single network hydrogel. Compared with the double-network hydrogel adopted by the invention, the single-network hydrogel has less-COO-, -OH and less H-resistance ₂ S has weak adsorption capacity, and the sensitivity of the prepared gas sensor is low.

Product effect test

FIG. 1 is a schematic diagram showing the one-pot synthesis of a double network hydrogel according to example 1 of the present invention, wherein 1-N, N' -Methylenebisacrylamide (MBA), 2-acrylamide, 3-sodium ion (Na ⁺ ) 4-ammonium persulfate, 5-alginic acid, 6-polyacrylamide network, 7-calcium ion (Ca ²⁺ ) 8-calcium alginate network. As shown in figure 1, the invention firstly utilizes acrylamide 2, N' -methylene bisacrylamide 1, sodium alginate 5 and accelerator tetramethyl ethylenediamine to be heated and mixed uniformly in water, then adds initiator ammonium persulfate 4, firstly polymerizes to form a polyacrylamide 6 network, and then cools and soaks CaCl ₂ Solution introduction of Ca ²⁺ Ion, alginic acid in Ca ²⁺ And polymerizing the ions serving as crosslinking points to form a calcium alginate 8 network, and finally forming the polyacrylamide-calcium alginate double-network hydrogel.

As shown in FIG. 2, the gas sensor prepared in the embodiment 1 is structurally schematically shown to form a structure which is formed by combining an active electrode, a double-network hydrogel and an inert electrode in sequence, wherein the active electrode adopts zinc, the inert electrode adopts silver, and the hydrogel adopts polyacrylamide-calcium alginate double-network polymer hydrogel. When the external circuit is connected, the gel and the electrode form a primary cell, zinc is the anode of the primary cell, and the Zn electron loss is changed into Zn ²⁺ Into the hydrogel, the zinc electrode potential is reduced; silver is the cathode of the primary cell, H in hydrogel ⁺ Electrons are obtained at the silver electrode. A stable potential difference is formed between zinc and silver. When the gas sensor contacts hydrogen sulfide, sulfurH atoms on hydrogen sulfide are adsorbed by functional groups on the surface of the double-network hydrogel to form hydrogen bonds, and S atoms on hydrogen sulfide and Ag atoms form weak ionic bonds. Because the S-H bond in the hydrogen sulfide is a polar bond, the shared electron is biased towards the S atom with stronger electron attraction capability, so that the S atom is relatively negatively charged. When S atoms and Ag atoms form weak ionic bonds, the S atoms reduce the potential of Ag, the potential of Zn poles is lower, and S atoms which are relatively negatively charged are difficult to adsorb on the Zn atoms, so that the potential difference between zinc and silver poles is reduced. Therefore, the adsorption of hydrogen sulfide at the interface of the hydrogel and the electrode and the concentration of the hydrogen sulfide can be reflected by measuring the potential difference between the zinc and the silver electrode.

Fig. 3a shows the dual-network hydrogel prepared in example 1 with 0% strain, and fig. 3b shows the dual-network hydrogel prepared in example 1 with 400% strain, and as can be seen from fig. 3, the tensile strain of the dual-network hydrogel prepared in example 1 of the present invention can reach 400%, which indicates that the dual-network hydrogel prepared in the present invention is flexible and has good tensile strain.

As shown in fig. 4, the dual-network hydrogels prepared in examples 1 to 4 were left to stand in an environment of 25 ℃ and 40% relative humidity for 36 hours or more, and a certain volume shrinkage was observed in the dual-network hydrogels prepared in example 1 without glycerol soaking, while the dual-network hydrogels modified in examples 2 to 4 with glycerol soaking remained intact without shrinkage after 36 hours, indicating that the water retention of the dual-network hydrogels was improved by glycerol soaking the modified dual-network hydrogels.

Differential scanning calorimetry analysis was performed on the double-network hydrogels prepared in examples 1 to 4, and the freezing point of the double-network hydrogels was measured. As a result, as shown in FIG. 5, the freezing point of the double-network hydrogel prepared in example 1 was observed to be-18.6 ℃, the freezing point of the double-network hydrogel prepared in example 2 was observed to be-42.4 ℃, and the double-network hydrogels immersed in glycerol for 2 hours and above in examples 3-4 were not observed to be the freezing point at-120-0 ℃, which indicates that the immersion modification of the double-network hydrogel with glycerol according to the present invention is also helpful for improving the freezing resistance of the hydrogel, and the prolonged immersion time is more helpful for improving the freezing resistance of the hydrogel.

As shown in FIG. 6The optical transmittance of the double-network hydrogel prepared in example 1 in the visible light band is 83% or more, and the double-network hydrogel is covered with a gel region "H ₂ The background pattern of the S-shaped pattern is still clearly visible, which indicates that the double-network hydrogel prepared by the invention has good transparency.

Fig. 7a is an open circuit voltage test chart of a gas sensor formed by the double-network hydrogel of examples 5-9 and different metal electrodes, and fig. 7b is an open circuit voltage stability test chart of a gas sensor formed by the double-network hydrogel of example 10 and zinc and silver stored at room temperature. As shown in fig. 7a, the open circuit voltages of the gas sensors prepared in examples 5 to 9 were measured, and the gas sensors made of zinc and silver prepared in example 6 were observed to have high open circuit voltages and stable signals, indicating the possibility of long-term gas detection of the gas sensor prepared in example 6. As shown in fig. 7b, the gas sensor prepared in example 10 maintains the open circuit voltage at about 0.9V for 4 days, which illustrates that the gas sensor of the present invention has good open circuit voltage stability.

FIG. 8a shows the exposure of the gas sensors prepared in example 6 and example 10 of the present invention to different concentrations of H ₂ FIG. 8b shows the dynamic response curve for S gas, for the gas sensor pairs H prepared in examples 6 and 10 of the present invention ₂ S response linear fitting curve. As shown in the dynamic response curves of FIG. 8a, the open circuit voltage of the gas sensor prepared in example 6 and example 10 is rapidly reduced along with the increase of hydrogen sulfide, and when the concentration of hydrogen sulfide is 4ppm, the open circuit voltage variation value of the sensor reaches 153mV, and the gas sensor responds differently to hydrogen sulfide with different concentrations, which indicates that the gas sensor has the capability of detecting hydrogen sulfide with different concentrations. As shown in FIG. 8b, the gas sensor responses prepared in example 6 and example 10 of the present invention have good linear relationship with hydrogen sulfide concentration, and the linearly fitted hydrogen sulfide response curve shown in FIG. 8b shows that the sensitivity (slope) of the dual-network hydrogel prepared in example 6 and the glycerol-modified dual-network hydrogel prepared in example 10 as the gas sensor responses are-13.7 mV/ppm and-25.6 mV/ppm, respectively, showing that the gas sensor prepared in the present invention has higher sensitivity and is subjected to the following stepsThe sensitivity of the hydrogen sulfide gas sensor can be improved after glycerol is modified.

As shown in the dynamic response curve of fig. 9, the gas sensor prepared in example 10 has a remarkable response to 40ppb and 20ppb of hydrogen sulfide in a nitrogen atmosphere, which indicates that the gas sensor of the present invention has an extremely low detection limit of hydrogen sulfide, can detect low concentration of hydrogen sulfide, and has a detection limit of ppb level.

As can be seen from FIG. 10, the gas sensor prepared in the embodiment 10 of the present invention can respond differently to hydrogen sulfide with different concentrations in both air and nitrogen contexts, which illustrates that the gas sensor of the present invention can detect hydrogen sulfide in both aerobic and anaerobic environments, and overcomes the disadvantage that most of the existing metal oxide semiconductor gas sensors need to operate in anaerobic environments.

FIG. 11a shows the exposure of the gas sensors of examples 10-12 of the present invention to different concentrations of H under different strains ₂ S gas dynamic response curve FIG. 11b shows the sensitivity versus strain of the gas sensors prepared in examples 10-12 of the present invention. As shown in the dynamic response curve of FIG. 11a, the open circuit voltages of the gas sensors prepared in examples 10-12 all have significant changes, i.e., the gas sensor of the present invention is responsive to hydrogen sulfide of different concentrations, indicating that the gas sensor of the present invention also has the capability of detecting hydrogen sulfide in a strained state. As can be seen from the results of FIG. 11b, in the gas sensors prepared in examples 10 to 12 (the strains corresponding to examples 10 to 12 are 0%, 50% and 100%, respectively), the higher the strain of the double-network hydrogel, the higher the sensitivity of the hydrogen sulfide gas sensor, indicating that increasing the strain can improve the sensitivity of the gas sensor of the present invention. Wherein sensitivity is defined as the change in open circuit voltage of the sensor caused by hydrogen sulfide per concentration.

As shown in fig. 12, the gas sensor prepared in example 10 was used to detect the exhaled gas and simulated halitosis gas of healthy volunteers, respectively, and it was observed that the open circuit voltage of the gas sensor was increased when the exhaled gas of healthy volunteers was introduced, and the open circuit voltage of the gas sensor was significantly decreased when the simulated halitosis gas was introduced, indicating that the gas sensor of the present invention was able to significantly distinguish the exhaled gas of healthy people from the exhaled gas of halitosis patients. Wherein simulated halitosis gas was prepared by mixing hydrogen sulfide with the gas exhaled from healthy volunteers, and the concentration of hydrogen sulfide after mixing was 0.4ppm.

The above data in fig. 7-12 were all experimental in a room temperature environment and were all self-powered without an external power source, demonstrating that the gas sensor of the present invention can be detected at room temperature and self-powered.

Claims

1. A transparent stretchable self-powered hydrogen sulfide gas sensor, comprising a gel and an electrode;

the gel comprises a polymer hydrogel, a solvent and an electrolyte salt;

the polymer hydrogel is a double-network polymer hydrogel, and the double-network polymer hydrogel is polyacrylamide-calcium alginate double-network polymer hydrogel;

the electrodes are wound or adhered at two ends of the gel;

the electrode comprises an anode and a cathode;

the anode and the cathode are respectively and independently selected from one or more of zinc, silver, copper and iron;

the preparation method of the gel comprises the following steps:

dispersing acrylamide, sodium alginate, a cross-linking agent and an accelerator in a solvent, then adding an initiator to crosslink the acrylamide to form polyacrylamide network hydrogel, and placing the polyacrylamide network hydrogel in a calcium salt solution to crosslink the sodium alginate, thereby obtaining the polyacrylamide-calcium alginate double-network polymer hydrogel.

2. The transparent stretchable self-powered hydrogen sulfide gas sensor according to claim 1, wherein the electrolyte salt is one or more of calcium chloride, aluminum chloride, and ferric chloride.

3. The transparent stretchable self-powered hydrogen sulfide gas sensor according to claim 1, wherein the mass content of the solvent is 35-65% of the gel mass.

4. The transparent stretchable self-powered hydrogen sulfide gas sensor according to claim 1, wherein the mass content of the electrolyte salt is 0.5-1% of the gel mass.

5. A method of making a transparent stretchable self-powered hydrogen sulfide gas sensor according to any of claims 1-4 comprising the steps of:

6. The method of preparing the gel according to claim 5, comprising the steps of:

7. Use of a transparent stretchable self-powered hydrogen sulfide gas sensor according to any of claims 1-4 for hydrogen sulfide detection.