CN113358608B

CN113358608B - Gas sensor and preparation method thereof

Info

Publication number: CN113358608B
Application number: CN202010153708.6A
Authority: CN
Inventors: 王铁; 刘璐
Original assignee: Institute of Chemistry CAS
Current assignee: Institute of Chemistry CAS
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2023-03-21
Anticipated expiration: 2040-03-06
Also published as: CN113358608A

Abstract

The invention provides a gas sensor and a preparation method thereof, relating to the technical field of substance detection and comprising the following steps: a membrane body of a gas sensitive substance, the membrane body comprising active and inert regions which are interlaced with one another. In the technical scheme, the membrane body of the gas sensor is arranged in the form of the active area and the inert area which are staggered with each other, so that the gas molecules to be detected can be effectively promoted to flow on the interface of the gas molecules to be detected, the mass transfer of the molecules to be detected is enhanced, the effect of the molecules to be detected on the surface of the gas molecules to be detected is enhanced, the detection sensitivity is further improved, and the existing use requirements are met.

Description

Gas sensor and preparation method thereof

Technical Field

The invention relates to the technical field of substance detection, in particular to a gas sensor and a preparation method thereof.

Background

In analytical testing work, gas species detection is a very important aspect. Taking the detection of gas substances by a solid substrate as an example, the detection is generally divided into five processes, namely, diffusion of reaction gas in air, adsorption of reaction gas on the surface of the detection substrate, gas-solid reaction, desorption of gas products on the surface of the detection substrate, and diffusion of gas products in air.

Currently, detection conclusions need to be drawn by virtue of well-defined signal changes, which are based on a sufficient amount of reaction, which requires a detection substrate capable of rapidly capturing a large number of target molecules, especially for open systems. Rapid, sensitive and accurate detection is a consistent target and evaluation criterion when analyzing the detection level, and technologists are constantly striving to improve the detection sensitivity and selectivity, which is of great significance for identifying substances such as explosives, disease markers, pollutants and the like. Therefore, with the continuous development of science and technology, the sensitivity of the existing gas sensor cannot meet the existing detection requirement, and needs to be improved still.

Disclosure of Invention

The invention aims to provide a gas sensor and a preparation method thereof, and aims to solve the technical problem that the gas sensor in the prior art is low in sensitivity.

The invention provides a gas sensor, comprising:

a membrane body comprised of a gas sensitive substance, the membrane body comprising active and inert regions that are interlaced with one another.

Further, the membrane body comprises a plurality of unit membranes, and gaps are formed between every two adjacent unit membranes;

the unit film constitutes the active region, and the gap constitutes the inactive region.

Further, the membrane body is provided with a plurality of hole structures, and the surface of the membrane body and the hole structures are mutually staggered;

the surface area of the membrane body constitutes an active area and the pore structure constitutes an inert area.

Further, the pore structure is a circular pore, and the pore diameter of the pore structure is between 0.1nm and 1 cm.

Further, the ratio of the total area of the active regions to the total area of the inert regions is r, and 0-r is less than or equal to 5.

Further, the thickness of the film body is between 1nm and 1 cm.

Further, the gas sensor further includes:

a substrate, the film body covering a surface of the substrate.

The invention also provides a preparation method of the gas sensor, which is used for preparing the gas sensor and comprises the following steps:

dissolving a gas-sensitive substance in a solvent to form a solution, fitting a guide medium having at least one guide projection on the surface of the substrate so that the end face of the guide projection is in close contact with the surface of the substrate;

pouring the solution on the surface of the substrate, wherein the solution forms the active area of the film body through crystallization on the surface of the substrate, and the part of the surface occupied by the guide projection on the substrate forms the inert area due to non-crystallization.

dissolving a gas-sensitive substance in a solvent to form a solution, pouring the solution into a growth tank with at least one guide projection, crystallizing the solution in the growth tank to form an active area of the membrane body, and forming the inert area by crystallizing partial space occupied by the guide projection in the growth tank.

dissolving a gas-sensitive substance in a solvent to form a solution, and printing the solution out of the structure of the active region through a 3D printing device, wherein the solution forms the active region of the membrane body through crystallization.

In the technical scheme, the membrane body of the gas sensor is arranged in the form of the active area and the inert area which are staggered with each other, so that the gas molecules to be detected can be effectively promoted to flow on the interface of the gas molecules to be detected, the mass transfer of the molecules to be detected is enhanced, the effect of the molecules to be detected on the surface of the gas molecules to be detected is enhanced, the detection sensitivity is further improved, and the existing use requirements are met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic view of the diffusion of gas molecules according to one embodiment of the present invention;

FIG. 2 is a fluorescent microscope image obtained in example 1 of the present invention.

FIG. 3 is an atomic force image obtained in example 1 of the present invention.

FIG. 4 shows the percent fluorescence quenching per unit area obtained in example 1 of the present invention.

FIG. 5 is a graph showing the percent of color fading of glyoxal measured for phenol red obtained in example 1 of the present invention.

Reference numerals are as follows:

1. an active region; 2. an inert region; 3. a substrate; 4. gas molecules.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

As shown in fig. 1, the present embodiment provides a gas sensor, including:

a membrane body of a gas sensitive substance, the membrane body comprising mutually interlaced active regions 1 and inert regions 2.

The gas sensitive substance is a substance which can perform specific reaction with some gas substances or some gas substances, and can generate a phenomenon of signal enhancement or signal attenuation after the reaction, such as a p-type organic semiconductor and the like, so that the gas sensitive substance can be used for manufacturing a gas sensor. Referring to fig. 1, although the gas molecules 4 are generally uniformly distributed in the space as they are, once the gas molecules 4 are adsorbed near the active surface, the concentration difference of the gas molecules 4 in the space occurs at the interface of the active surface.

For example, in the case of a membrane structure, once the gas molecules 4 have an adsorption effect on the membrane surface, the concentration of the gas molecules 4 in the portion close to the membrane surface decreases, while the concentration of the gas molecules 4 away from the membrane surface is not affected. In this case, therefore, the direction of the concentration difference of the gas molecules 4 is mainly along the direction perpendicular to the film surface, so that the gas molecules 4 are diffused along the direction of the concentration difference.

Referring to fig. 1, when the active regions 1 (i.e., active surfaces) and the inactive regions 2 (i.e., inactive surfaces) are arranged in a staggered manner, the gas molecules 4 near the surface of the membrane body are adsorbed only on the active regions 1 and the surface of the membrane body, but not on the inactive regions 2. Therefore, the gas concentration in the active region 1 is reduced, while the gas concentration in the inactive region 2 is not changed, and at this time, not only the concentration difference in the direction perpendicular to the active region 1 but also the concentration difference in the direction parallel to the active region 1 are present, and the gas molecules 4 are diffused toward the active region 1 and parallel to the active region 1 at the same time due to the concentration difference in the double crossing, which makes the movement of the gas molecules 4 more vigorous, increases the probability of collision and adsorption of the gas molecules 4 with the active region 1, and promotes adsorption of the gas molecules 4 in the active region 1.

Based on such a film body (i.e., patterning of the film body) composed of the active regions 1 and the inactive regions 2 which are staggered with each other, since the gas molecules 4 are adsorbed only in the active regions 1 and not in the inactive regions 2, even if the absolute value of the adsorbed gas molecules 4 is not necessarily higher than that of the film structure of the all-active regions 1, by disposing the active regions 1 and the inactive regions 2 in a staggered manner with each other, the ratio of the number of gas molecules 4 actually adsorbed by the film body to the adsorption capacity of the film body is increased, that is, the number of gas molecules 4 actually adsorbed to the maximum number of molecules capable of adsorbing gas molecules 4 is increased.

For example, in the prior art, the ratio of the number of gas molecules 4 actually adsorbed by the membrane structure to the maximum molecule number of the gas molecules 4 that can be adsorbed is 30/100=0.3, and after the membrane body is arranged in the form of the active region 1 and the inert region 2 being interlaced with each other, the ratio of the number of gas molecules 4 actually adsorbed to the maximum molecule number of the gas molecules 4 that can be adsorbed is 20/50=0.4, so that after the gas sensor of the present application is arranged in the form of the active region 1 and the inert region 2 being interlaced with each other, the phenomenon change of signal enhancement or signal attenuation is more obvious, and the sensitivity of the gas sensor is further effectively improved.

In conclusion, the membrane body of the gas sensor is arranged in a manner that the active area 1 and the inert area 2 are staggered with each other, so that the gas molecules 4 to be detected can be effectively promoted to flow on the interface, the mass transfer of the molecules to be detected and the adsorption effect of the molecules to be detected on the surface are enhanced, the detection sensitivity is further improved, and the existing use requirements are met.

In one embodiment of the membrane body structure, the membrane body comprises a plurality of unit membranes, and gaps are arranged between adjacent unit membranes; the unit film constitutes the active region 1, and the gap constitutes the inactive region 2.

Therefore, the film body can be a discontinuous structure, that is, after the film body is formed by a plurality of unit films, part of the unit films can be connected, another part of the unit films can be completely disconnected, or all the unit films can be in a structure which is not connected with each other. The membrane body can enable unit membranes to pass through a gas-sensitive substance to form an active area 1, gaps exist between adjacent unit membranes due to the fact that the adjacent unit membranes are not connected, and the gaps can form an inert area 2 due to the fact that the gas-sensitive substance does not exist.

Further, the membrane body is provided with a plurality of pore structures, and the surface of the membrane body and the pore structures are mutually staggered; the surface area of the membrane body constitutes the active region 1 and the pore structure constitutes the inert region 2.

Therefore, the membrane body can also be a continuous structure, namely the membrane body is a complete integral membrane structure, after the membrane body is formed by the gas-sensitive substance, the surface of the membrane body forms an active region 1, and a through hole structure on the membrane body can form an inert region 2 due to the absence of the gas-sensitive substance.

Further, the pore structure is a circular pore, and the pore diameter of the pore structure is between 0.1nm and 1 cm. It should be noted that the pore structure may be a circular pore, a square pore, or any other pore structure with any specification or an irregular pore structure, and various pore structures may realize the division of the active region 1 and the inert region 2 on the membrane body. When the pore structure is a circular hole, the pore diameter of the pore structure can be set between 0.1nm and 1cm, namely the pore structure can be as small as a nanometer level and as large as a centimeter level, and the pore structure can be selected to have any pore diameter level according to the requirement by the technical personnel in the field.

In one embodiment of the pore structure size, the diameter of the pore structure may be between 0.1nm and 1000nm, e.g., 10nm, 100nm, 800nm, etc.; meanwhile, the diameter of the pore structure can be 0.1cm, 0.5cm, 0.8cm and the like. In addition, when the hole structure is a hole structure of other structures, the size of the hole structure can also refer to the size of the circular hole.

In the membrane structure of the two membrane bodies, the ratio of the total area of the active regions 1 to the total area of the inert regions 2 is r, 0-r ≦ 5. Since the sensitivity of the corresponding gas sensor is worse when the area of the inert region 2 is determined and the area of the active region 1 is larger, the ratio of the total area of the active region 1 to the total area of the inert region 2 is limited to be less than 5 by the ratio, so that a better detection effect can be obtained, and the sensitivity of the gas sensor is ensured.

In addition, the thickness of the film body is between 1nm and 1 cm. The same as the size of the pore structure, the thickness of the membrane body can be set between 1nm and 1cm, namely the thickness of the membrane body can be reduced to nano level and increased to centimeter level, and the thickness level of the membrane body can be selected by the technical personnel in the field according to the requirement. In one embodiment of the film body thickness, the film body thickness can be between 0.1nm-1000nm, e.g., 10nm, 100nm, 800nm, etc.; meanwhile, the thickness of the film body can be 0.1cm, 0.5cm, 0.8cm and the like.

Further, the gas sensor further includes: a substrate 3, wherein the film body covers the surface of the substrate 3. The substrate 3 can be a silicon wafer, a glass sheet polydimethylsiloxane film, or the like. Therefore, the film body can be supported by the substrate 3, and the film body can be stably held by covering the substrate 3 with the film body.

In addition, the film body can be made into a self-supporting film structure, for example, the overall strength can be increased by laminating a plurality of film bodies, and the film body can have a self-supporting effect, so that the self-supporting film structure is prepared. The self-supporting film structure can be prepared by other methods in the prior art according to the requirement of the skilled person, so that the film body can be separated from the substrate 3 and exist independently.

The invention also provides a preparation method of the gas sensor, which is used for preparing the gas sensor and comprises the following steps: dissolving a gas-sensitive substance in a solvent to form a solution, fitting a guide medium having at least one guide projection on the surface of the substrate 3 so that the end face of the guide projection is in close contact with the surface of the substrate 3; pouring the solution on the surface of the substrate 3, wherein the solution forms the active region 1 of the membrane body through crystallization on the surface of the substrate 3, and the part of the surface occupied by the guide projection on the substrate 3 forms the inert region 2 because of non-crystallization.

In the preparation method, a guide medium with a guide projection and a substrate 3 are assembled and assembled with each other, a space for applying a solution can be formed between the guide medium and the substrate, after the solution is crystallized in the space, the inert region 2 is formed because the part of the surface occupied by the guide projection on the substrate 3 is not crystallized, and the other crystallized parts form the active region 1.

After the film body is formed by crystallization, the guiding medium is detached from the substrate 3, and the film body is attached to the surface of the substrate 3 and supported by the substrate 3. The guiding medium may be a plate-like structure, a cap-like structure, or any other structure that can be adapted to the substrate 3, wherein the guiding protrusion may be any structure such as a cylindrical structure or a prismatic structure.

The size of the active area 1 can be controlled during the manufacturing process by adjusting the solution concentration adjustment. The high-sensitivity gas sensor prepared by the preparation method has the characteristics that the shape and the size of the active area 1 are effectively controllable, and the high-sensitivity gas sensor can be prepared in a large area. To explain the production method in detail, the following specific examples are given.

Example 1

The p-type organic semiconductor M1 is dissolved in chloroform which is a good solvent of the p-type organic semiconductor to form an M1 solution. The guide medium is modified by fluorosilane, and the integral surface energy of the guide medium is reduced. The polydimethylsiloxane is used as a substrate 3, a poor solvent N, N-dimethylformamide is added into the M1 solution, a guide medium and the substrate 3 are assembled into a whole, and a guide bulge of the guide medium limits the crystallization position of the M1 solution to form an inert region 2, so that the film body is patterned.

The reaction system is kept still at normal temperature and pressure. With the volatilization of the M1 solution, molecules of the p-type organic semiconductor M1 gradually grow into nanofibers. When the solvent M1 is completely volatilized, the film body is obtained.

As shown in fig. 2, the gas sensitive material is an organic p-type semiconductor, and can react with an electron-deficient material to attenuate intrinsic fluorescence. The a-g periods are 82, 85, 90, 100, 120, 160 and 240mm, respectively. The scales of a-g are all 100mm.

In the fluorescence microscopy image of patterned M1, substrate 3 was polydimethylsiloxane. The guide medium limits the M1 solution to the area outside the guide projection during the growth process, and the guide projection is in a cylindrical structure. The structure of the membrane body is complementary to that of the guiding medium, and the gas-sensitive substances are visible to be distributed outside the circumference. In a series of different periods of the guide media, while keeping the diameter and height of the cylinder of the guide media constant, it was found that as the pattern period of the guide media increased, the size of the outer circumferential pattern also increased.

As shown in fig. 3, the a-g periods are 82, 85, 90, 100, 120, 160 and 240mm, respectively. From the height analysis, the height of the active area 1 of the sensor with different periods is mostly between 100nm and 200 nm.

As shown in fig. 4, the fluorescence quenching of the patterned gas sensor is generally higher than that of a film (0 mm) made of the same substance, and as the film period is reduced, the fluorescence quenching percentage is increased, demonstrating that the smaller the period, the higher the gas sensor sensitivity.

As shown in FIG. 5, phenol red was used in the same manner to prepare gas sensors having respective cycle times of 82, 85, 90, 100, 120, 160 and 240mm, and glyoxal vapor was measured, and the film structure (0 mm) of phenol red was compared with the percentage fading of the gas sensor. The percentage of discoloration of the gas sensor is significantly higher than that of a film (0 mm) made of the same substance, and as the period is reduced, the percentage of discoloration increases, demonstrating that the smaller the period, the higher the sensitivity of the gas sensor.

Example 2

The p-type organic semiconductor M1 is dissolved in chloroform which is a good solvent of the p-type organic semiconductor to form an M1 solution. The guide medium is modified by fluorosilane, so that the overall surface energy of the guide medium is reduced. And (3) taking a silicon wafer as a substrate 3, adding a poor solvent ethanol into the M1 solution, assembling the M1 solution, a guide medium and the substrate 3 into a whole, and forming a limit on the crystallization position of the M1 solution by a guide bulge of the guide medium to form an inert region 2 so as to pattern the film body.

Example 3

The p-type organic semiconductor M1 is dissolved in chloroform which is a good solvent of the p-type organic semiconductor to form an M1 solution. The guide medium is modified by fluorosilane, and the integral surface energy of the guide medium is reduced. The polydimethylsiloxane is used as a substrate 3, poor solvent water of the polydimethylsiloxane is added into the M1 solution, a guide medium and the substrate 3 are assembled into a whole, and a guide bulge of the guide medium limits the crystallization position of the M1 solution to form an inert region 2, so that the film body is patterned.

The reaction system is kept still at normal temperature and pressure. With the volatilization of the M1 solution, molecules of the p-type organic semiconductor M1 gradually grow into nanofibers. When the M1 solvent was completely volatilized, the film bulk was obtained.

The invention also provides a preparation method of the gas sensor, which is used for preparing the gas sensor and comprises the following steps: dissolving a gas-sensitive substance in a solvent to form a solution, pouring the solution into a growth tank with at least one guide projection, crystallizing the solution in the growth tank to form an active region 1 of the membrane body, and forming an inert region 2 by non-crystallizing partial space occupied by the guide projection in the growth tank.

In this production method, the produced membrane body is not based on the substrate 3 as a support, but is a separate membrane structure. Therefore, the film body can be forced to be increased by increasing the thickness and the like, so that the prepared film body has self-supporting capacity and forms a self-supporting film structure. Wherein the solution can be poured into the growth chamber, after the solution is crystallized in the growth chamber, the inert region 2 is formed because a part of the space occupied by the guide projection in the growth chamber is not crystallized, and the other crystallized parts form the active region 1. Similarly, the size of the active region 1 can also be controlled by adjusting the solution concentration adjustment during the preparation process. The high-sensitivity gas sensor prepared by the preparation method has the characteristics that the shape and the size of the active area 1 are effectively controllable, and the high-sensitivity gas sensor can be prepared in a large area.

The invention also provides a preparation method of the gas sensor, which is used for preparing the gas sensor and comprises the following steps: dissolving a gas-sensitive substance in a solvent to form a solution, and printing the solution out of the structure of the active region 1 through a 3D printing device, wherein the solution forms the active region 1 of the membrane body through crystallization. According to the preparation method, the 3D printing technology is used, the membrane body is prepared by the 3D printing technology, the position and the size of the active region 1 can be controlled more accurately, the active region 1 is more uniform, and the area of the prepared active region 1 is larger. Meanwhile, the size of the active region 1 can also be controlled by adjusting the solution concentration adjustment. The high-sensitivity gas sensor prepared by the preparation method has the characteristics that the shape and the size of the active area 1 are effectively controllable, and the high-sensitivity gas sensor can be prepared in a large area.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas sensor, comprising: a substrate, a film body covering a surface of the substrate;

the membrane body is composed of gas-sensitive substances, the membrane body comprises an active area with the gas-sensitive substances and an inert area without the gas-sensitive substances, and the active area and the inert area are arranged on the substrate in a staggered mode;

the substrate is polydimethylsiloxane; the membrane body comprises a plurality of independent unit membranes, and gaps are formed between every two adjacent unit membranes;

the unit film constitutes the active region, and the gap constitutes the inactive region;

the ratio of the total area of the active regions to the total area of the inert regions is r, and 0< -r is less than or equal to 5.

2. The gas sensor according to claim 1,

the thickness of the film body is between 1nm and 1 cm.

3. A method for producing a gas sensor according to claim 1, comprising the steps of:

pouring the solution on the surface of the substrate, wherein the solution forms the active area of the film body on the surface of the substrate through crystallization, and the part of the surface occupied by the guide projection on the substrate forms the inert area due to non-crystallization.

4. A method for producing a gas sensor according to any one of claims 1 to 2, comprising the steps of: