CN112213364A - Preparation method of gas sensor element with nano porous structure - Google Patents
Preparation method of gas sensor element with nano porous structure Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
- G01N27/125—Composition of the body, e.g. the composition of its sensitive layer
- G01N27/126—Composition of the body, e.g. the composition of its sensitive layer comprising organic polymers
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Abstract
The invention discloses a preparation method of a gas sensor element with a nano porous structure, which comprises the following steps: s1, self-assembling a polymer film on the interdigital electrode covered on the micro-heating platform to obtain a template base layer of the interdigital electrode after film covering; s2, obtaining a regular nano template structure by adopting a nano imprinting method, wherein the nano template structure is provided with a nano porous array structure layer, and residual template agent is remained on the nano template structure; s3, removing the nanoimprint residual layer to expose the interdigital electrode layer in an air layer and form a gas-sensitive material film-forming carrier; s4, preparing a metal ion doped oxide film on the gas sensitive material film forming carrier to serve as a gas sensitive material layer; and S5, carrying out reaction on the residual template agent to obtain the gas sensor element with the nano porous structure. The preparation method has the advantages of economy, environmental friendliness, good manufacturability and reproducibility, and can be used for CH4、CO、H2And the detection of toxic and harmful gases such as NO and the like has the characteristics of high sensitivity and quick response.
Description
Technical Field
The invention belongs to the technical field of gas sensors, and particularly relates to a preparation method of a gas sensor element with a nano porous structure.
Background
With the rapid development of modern industry, atmospheric environmental pollution has become a key problem in people's healthy life, so the research and development of sensitive materials with high stability, high sensitivity and rapid response recovery has become a research hotspot of current gas sensors. The porous nano array structure can provide more surface active sites for gas adsorption and reaction due to larger specific surface area, and the sensitivity of the sensor can be obviously improved. Xu et al prepared porous SnO using PS microsphere template based on Czochralski method2Sensitive material (sci. rep.5, 10507); sun et al prepared Cu-doped SnO by plasma etching of PS microsphere template2Porous structure (CN 103529081A). In addition, Hu et al prepared nano vanadium oxide gas sensitive material (CN104181206A) using porous silicon structure.
The conventional method includes a microsphere template method and a porous silicon modification method, and the conventional method is exemplified.
(1) Microsphere template method
For example, in the microsphere template method disclosed in patent document CN103529081A, the microsphere template is usually an aqueous solution of polystyrene microspheres, which is expensive and not suitable for mass production.
(2) Porous silicon modification method
For example, in the porous silicon modification method disclosed in patent document CN104181206A, chemical etching is often used for porous silicon, and a large amount of hydrofluoric acid solvent is required, which is not favorable for environment-friendly development.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art.
Therefore, the invention provides a preparation method of the gas sensor element with the nano-porous structure, which combines the nano-imprinting technology, can overcome the defects of the traditional method and is an economic preparation method with strong reproducibility and manufacturability.
The preparation method of the gas sensor element with the nano-porous structure comprises the following steps: s1, self-assembling a polymer film on the interdigital electrode covered on the chip of the micro-heating platform to obtain a template base layer of the interdigital electrode through the film; s2, obtaining a regular nano template structure by adopting a nano imprinting method on the template base layer, wherein the nano template structure is provided with a nano porous array structure layer, and residual template agent is remained on the nano template structure; s3, removing a nanoimprint residual layer on the nano template structure to expose the interdigital electrode layer in an air layer and form a gas-sensitive material film-forming carrier; s4, preparing a metal ion doped oxide film on the gas sensitive material film forming carrier to serve as a gas sensitive material layer; and S5, removing the residual template agent from the chip to obtain the gas sensor element with the nano porous structure.
According to the preparation method provided by the embodiment of the invention, expensive polystyrene microsphere template is avoided, a cheap polymer film is replaced, a nano-imprinting and etching technology is combined, a porous template structure is constructed on a micro-heating platform, the similar effect of the template and etching technology (CN103529081A) is achieved, and the preparation method has the advantages of simple process and low cost. The preparation method provided by the embodiment of the invention is combined with a nano-imprinting technology, can overcome the defects of the traditional method, and is an economical preparation method with strong reproducibility and manufacturability.
According to an embodiment of the present invention, in step S1, the polymer coating film is self-assembled by one of an LB film method, a solution evaporation method, a spin coating method, or a dip coating method.
According to one embodiment of the invention, the spin coating method comprises the steps of: dissolving a thermoplastic polymer in a solvent to obtain a polymer solution; spin-coating the polymer solution to the micro-heating platform by using a spin-coating method to obtain the polymer film; and heating the interdigital electrode coated with the polymer film after standing.
According to one embodiment of the present invention, step S2 includes the steps of: copying the porous structure of the porous anodic alumina template on the polymer film under a preset pressure; carrying out pressure maintaining operation to obtain the nano porous array structure layer; cooling the porous anodic alumina template; and demolding the porous anodic aluminum oxide template and the chip.
According to an embodiment of the present invention, in the step of cooling the porous anodized aluminum template, a condensed water system of the porous anodized aluminum template is used for cooling. It should be noted that, a cooling method of circulating condensed water can be adopted for the porous anodic alumina template, which belongs to the technical field of convection heat dissipation, and the cooling efficiency can be improved by reducing the temperature of the condensed water medium, increasing the contact area with the template, and increasing the flow speed of the condensed water medium.
According to one embodiment of the present invention, in the step of releasing the porous anodized aluminum template and the chip, the releasing angle is 10 ° to 45 °.
According to an embodiment of the present invention, the nanoimprinting residual layer is removed by a plasma dry etching method in step S3.
According to an embodiment of the present invention, the metal ion-doped oxide thin film is prepared by one of a magnetron sputtering method, a sol-gel method, an atomic layer deposition method, a pulsed laser deposition method, and a chemical vapor deposition method in step S4.
According to one embodiment of the invention, the magnetron sputtering method comprises the following steps: depositing an Ag-doped SnO2 film on the gas-sensitive material film-forming carrier, wherein the thickness of the Ag-doped SnO2 film is 10-400 nm, and the doping concentration is 1-10 at%.
According to one embodiment of the present invention, in step S5, the residual templating agent is removed by ultrasonic cleaning.
According to an embodiment of the present invention, step S5 includes: s51, removing the residual template agent; and S52, sintering the chip with the residual template agent removed at high temperature.
According to one embodiment of the invention, the porous anodic alumina template is a V-shaped porous anodic alumina template obtained through multi-step hole expanding and oxidation, and the aspect ratio of the porous anodic alumina template is 2: 1.
According to one embodiment of the present invention, the nano-imprint method in step S2 includes hot imprint and cold imprint.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a flow chart of a method of making a gas sensor element having a nanoporous structure according to an embodiment of the invention;
FIG. 2 is a schematic diagram of a method of making a gas sensor element having a nanoporous structure according to an embodiment of the invention;
FIG. 3 is a top view of a porous anodized aluminum template according to an embodiment of the invention;
FIG. 4 is a cross-sectional view of a porous anodized aluminum template according to an embodiment of the invention;
FIG. 5 is an electron microscope (SEM) photograph of the gas sensitive material for preparing Al-doped zinc oxide with the novel porous structure in example 2 (finished product completed in S5);
FIG. 6 is the XRD phase analysis result of the gas sensitive material prepared by using the novel porous structure to prepare Al-doped zinc oxide in example 2 (finished product completed by S5);
FIG. 7 is a diagram of a gas-sensitive material prepared by using a novel porous structure and doped with Al and zinc oxide in example 2, wherein the gas-sensitive material responds to CO gas at a temperature of 300 ℃ by an ion doping method (finished product completed by S5);
fig. 8 is a schematic structural diagram of a micro-heating platform according to an embodiment of the present invention.
Reference numerals:
a micro-heating stage 10; interdigital electrodes 11; a separator film 12; a heater 13; a support film 14;
a polymer film 20; a pattern template 30; a sensitive material 40; a porous anodized aluminum template 50; a condensate water system 51; and a thermocouple 52.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
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, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; 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.
A method for manufacturing a gas sensor element having a nanoporous structure according to an embodiment of the invention is described in detail below with reference to the accompanying drawings.
As shown in fig. 1 and 2, a method for preparing a gas sensor element having a nanoporous structure according to an embodiment of the invention includes the steps of:
s1, self-assembling the polymer film on the interdigital electrode covered on the chip of the micro-heating platform to obtain the template base layer of the interdigital electrode through film coating, wherein the micro-heating platform mainly comprises a cantilever beam supporting structure, a micro-heating electrode, an insulating layer, the interdigital electrode and the like. The micro heating plate can adopt two modes of direct current heating and pulse heating to heat the metal heating electrode. Wherein, the direct current heating supplies constant current to the micro-hotplate, and the temperature of the micro-hotplate increases along with the increase of the current; the pulse heating adopts a temperature modulation mode, a pulse voltage or a pulse current is applied to the micro-heating plate for heating, and the same micro-heating plate can work at different temperatures at different time by controlling the size and the period of a pulse signal.
In summary, the pulse heating method can realize dynamic temperature control of the micro-heating electrode by pulse signals, and the temperature is raised to 250-600 ℃ in a short time, which is particularly determined according to the selected gas-sensitive material form, thereby being beneficial to realizing low power consumption of the micro-heating element.
And for wet chemical etching processes: the micro heating plate is divided into a closed diaphragm, a suspended diaphragm, a bridge diaphragm and the like; the redundant silicon-based materials are etched through a wet chemical etching process, and a suspended diaphragm structure is adopted, so that the heat loss generated by heat conduction can be reduced, heat concentration can be realized, and the overall power consumption can be reduced.
S2, obtaining a regular nano template structure by adopting a nano imprinting method on the template base layer, wherein the nano template structure is provided with a nano porous array structure layer, and residual template agent is remained on the nano template structure.
It should be noted that the material of the polymer film can be selected according to the nanoimprint method, for example, the hot embossing technique can select thermoplastic polymer, such as polymethyl methacrylate (PMMA), Polystyrene (PS), etc., specifically, the embossing temperature is generally 30-50 ℃ higher than Tg, for PMMA: tg (glass transition temperature) was 105 ℃. The stamping temperature is 150 ℃; for PS: tg and imprint temperature are close to those of PMMA, but the surface energy is low, so that the material is more suitable for imprinting. The nano-imprinting method includes, but is not limited to, hot imprinting, ultraviolet imprinting technology, and may also include micro-contact imprinting. The hot stamping method is preferred, and has the advantages of high speed, high reproducibility and suitability for large-scale mass production.
And S3, removing the nanoimprint residual layer on the nano template structure to expose the interdigital electrode layer in an air layer and form a gas-sensitive material film-forming carrier.
S4, preparing a metal ion doped oxide film on the gas sensitive material film forming carrier to serve as a gas sensitive material layer.
S5, removing residual template agent from the chip to obtain the gas sensor element with a nano porous structure, wherein the template layer of the polymer base can be removed by a high-temperature sintering method to realize crystallization treatment on the sensitive material so as to improve the sensitivity of the gas sensitive material to gas; and can be cleaned by ultrasonic wave to further remove the template layer.
Therefore, according to the preparation method provided by the embodiment of the invention, the adoption of an expensive polystyrene microsphere template is avoided, a cheap polymer film is replaced, the nano-imprinting and etching technologies are combined, and a porous template structure is constructed on the micro-heating platform, so that the similar effect of the template and etching technology (CN103529081A) is achieved, and the preparation method has the advantages of simple process and low cost. The preparation method provided by the embodiment of the invention is combined with a nano-imprinting technology, can overcome the defects of the traditional method, and is an economical preparation method with strong reproducibility and manufacturability.
As shown in fig. 8, a micro heating platform 10 according to an embodiment of the present invention mainly includes four parts, namely a support film 14, a heater 13, an isolation film 12 and an interdigital electrode 11. The supporting film 14 plays a role in supporting the heater 13 and the interdigital electrode 11, and the mechanical stability of the micro-heating platform 100 is guaranteed; the heater 13 can heat the sensitive material and measure the temperature; the isolation film 12 can prevent the heater 13 and the interdigital electrode 11 from leaking electricity; the interdigital electrode 11 is used to apply a voltage while measuring a resistance value. The micro-heating platform 10 can realize low-power heat supply by reducing the heating area and heat loss; in addition, the response rate can be improved and the power consumption can be reduced by a pulse heating mode. The sensitive material can be synthesized into a sensitive material layer on the interdigital electrode 11 by methods such as magnetron sputtering, sol-gel, Atomic Layer Deposition (ALD), Pulsed Laser Deposition (PLD), and the like, and the purpose of gas detection can be realized by the sensitive property of the sensitive material to gas.
According to an embodiment of the present invention, in step S1, the polymer thin film is self-assembled by one of an LB film method, a solution evaporation method, a spin coating method, or a dip coating method.
Optionally, the spin coating method comprises the steps of: dissolving a thermoplastic polymer in a solvent to obtain a polymer solution, such as polymethyl methacrylate (PMMA), Polystyrene (PS) and the like, wherein the molecular weight of the thermoplastic polymer can be controlled to 8000-; and spin-coating the polymer solution to a micro-heating platform by adopting a spin-coating method to obtain a polymer film, wherein the spin-coating speed can be controlled to be 800r/min-3000r/min, the time can be 5s-60s, the standing time can be not less than 4h, the interdigital electrode coated with the polymer film can be heated after standing, the interdigital electrode can be placed in an oven during heating, the temperature of the oven is controlled to be 110-160 ℃, the time can be 20min-60min, and the purpose of heating is to volatilize residual solvent. It should be noted that the spin coating method has the advantages of rapidness, controllable process, and the like.
In some embodiments of the present invention, step S2 includes the following steps: copying the porous structure of the porous anodic alumina template on a polymer film under a preset pressure which can be 1MPa-5 MPa; carrying out pressure maintaining operation to obtain a nano porous array structure layer; cooling the porous anodic alumina template; and demolding the porous anodic alumina template and the chip, wherein the demolding angle can be 10-45 degrees. When the hot stamping method is selected, the defects of difficult demoulding and the like exist, so that the defects that the demoulding angle is increased and a condensed water reflux system is adopted for improvement.
As shown in fig. 3 and 4, in the step of cooling the porous anodized aluminum template, a condensed water system of the porous anodized aluminum template is used for cooling. Wherein the thermocouple 52 can control the temperature of the condensed water.
Optionally, in the step of demolding the porous anodized aluminum template and the chip, the demolding angle is 10 ° to 45 °.
In some embodiments of the present invention, in step S3, the nanoimprint residue layer is removed by a plasma dry etching method, the hot-pressing residue layer is etched by oxygen plasma etching, and then the distance between the templates is increased to expose the chip layer, thereby forming a porous template, which facilitates deposition of the gas sensitive material. Wherein the oxygen plasma etching is different from the wet etching and does not need HF and NH4F. BHF and other chemical corrosive agents have the advantages of controllable process, environmental friendliness and the like. Wherein, in order to remove the nano hot pressing residual layer, the nano imprinting residual layer, O, can be removed by a reactive ion etcher2The flow rate of (2) can be controlled at 30m3/min-50m3Min, the pressure of the cavity can be controlled at 5Pa and other pressures, and O is excited2Plasma processThe power applied by the daughter is controlled to be 40W-80W, and the etching time is controlled to be 10s-60 s.
According to an embodiment of the present invention, the metal ion doped oxide thin film is prepared by one of a magnetron sputtering method, a sol-gel method, an atomic layer deposition method, a pulsed laser deposition, and a chemical vapor deposition in step S4. It should be noted that the preparation methods of the sensitive material are very many, and only the common methods are exemplified here, and the comparison results of the various methods can be shown in table 1 below.
The sol-gel method has low production cost, does not need a vacuum environment, has high film forming speed, can accurately control the doping concentration, and is one of the preferred schemes for preparing the gas-sensitive thin film material.
TABLE 1 comparison of the requirements and film-Forming Properties of different film preparation methods
As can be seen from table 1, the magnetron sputtering method is a controllable film forming process with good repeatability, but the cost is high (the equipment cost, the target material is expensive, the production period is long), and the sol-gel has the advantages of low cost, no need of high-precision equipment, and the like, but the film forming effect is poor.
Further, the magnetron sputtering method comprises the following steps: deposition of Ag-doped SnO on gas-sensitive material film-forming supports2The film has a thickness of 10nm-400nm and a doping concentration of 1 at% -10 at%. In the process of physically depositing the film in the magnetron sputtering method, the power of Ar plasma is 120w, and can be adjusted to other powers according to the situation, the pressure of the cavity is controlled at 0.8Pa, and the pressure of the cavity can be controlled at other values according to the situation.
According to an embodiment of the present invention, in step S5, the residual template agent is removed by ultrasonic cleaning, and the time of ultrasonic washing may be 30S-10 min.
In some embodiments of the present invention, step S5 includes: s51, removing residual template agent; and S52, performing high-temperature sintering on the chip without the residual template agent, wherein the sintering temperature can be 350-550 ℃, and obtaining the gas-sensitive material layer with good crystallinity by adopting a high-temperature sintering method.
According to one embodiment of the invention, a porous anodized aluminum template (AAO template) is a V-shaped AAO template obtained through multi-step hole expanding and oxidation, and the aspect ratio of the porous anodized aluminum template is 2: 1. It should be noted that the common templates include Si and SiO2Templates, but they are all relatively fragile; and AAO template compares Si and SiO2The template has better heat-conducting property and better performance in cooling and demoulding. Therefore, from the use perspective, the AAO template has obvious advantages. In addition, a V-shaped AAO template obtained by multi-step pore expansion and oxidation is used here. Because the depth-to-width ratio (2:1) of the selected V-shaped AAO template is smaller, the demolding difficulty is smaller.
In some embodiments of the present invention, the nanoimprint method in step S2 is mainly divided into hot imprint and cold imprint, where cold imprint, i.e., ultraviolet light solid imprint, if a porous template with the same structure is to be formed, the processes of spin-coating a photoresist, mask exposure, and etching need to be performed, and the process complexity is high, and meanwhile, a lithography machine is needed, which causes an increase in the manufacturing cost. The method disclosed by the embodiment of the invention aims to prepare the porous template by adopting a nano hot stamping method, and mainly solves the problem that hot stamping is difficult to realize in multiple modes through the design of temperature reduction, a demoulding angle and the like.
The following describes in detail the preparation process according to the examples of the present invention with reference to specific embodiments.
Example 1
The hot stamping technology and the magnetron sputtering method are combined.
First, Polystyrene (PS) plastic particles (molecular weight 15000) were dissolved in toluene solvent to a concentration of 1% mg/ml. The polymer solution was spin coated onto the micro-heating platform using spin coating at 2000r/min for 30 s. Standing at room temperature for 4h, and heating the chip coated with the PS film in an oven at 120 ℃ for 30 min.
Then, copying the porous structure of the AAO porous nano template on a polymer film under the pressure of 2MPa by a nano hot pressing process, wherein the pressure holding time is 10 s. Utilize the porous comdenstion water system of taking certainly of AAO to cool down fast to and the good drawing of patterns angle 30 of preferred design, can help quick drawing of patterns. Wherein the master mold has a thickness of 500nm and an array spacing of 200 nm.
Then, in order to remove the nano-hot-pressing residual layer and reduce the space between the PS templates, a reactive ion etcher, O2The flow rate is controlled at 40m3Min, controlling the pressure of the cavity at 5Pa, exciting O2The power applied to the plasma was controlled at 60w and the etching time was controlled at 30 s.
Next, Ag-doped SnO is deposited on the substrate using magnetron sputtering physical deposition2The film has a thickness of 100nm and a doping concentration of 3 at%. In the process of magnetron sputtering physical deposition of the film, the power of Ar plasma is 120w, and the pressure of the cavity is controlled to be 0.8 Pa.
And finally, placing the sample in toluene for ultrasonic washing for 1min, removing the PS film, and finally annealing for 2h at the temperature of 500 ℃ in the air atmosphere.
Example 2
The hot stamping technology and the sol-gel method are combined.
Firstly, preparing Al-doped ZnO precursor sol.
Specifically, 1.4678g of Zn (CH) are added first3COO)2·2H2O and 0.09g of Al (NO)3)3·9H2O is added into 80ml of absolute ethyl alcohol, and the temperature is kept at 80 ℃ for condensation reflux for 3h (wherein the reflux time can be controlled between 30min and 4h, and is preferably 3 h). Then 0.5875g of LiOH & H was added2O is added into 70ml of absolute ethyl alcohol for ultrasonic oscillation. Then, LiOH & H was added under ice-water bath conditions2The O solution is dropwise added into the precursor solution while stirring rapidly and vigorously, and after 3 hours of reaction (wherein the reaction time can be controlled within 1-5 hours, preferably 3 hours), a transparent and colorless sol solution is finally formed. Aging at room temperatureAfter 24h (wherein the aging time can be controlled between 12h and 48h, and is preferably 24h), the ZnO precursor sol doped with 3 at% Al ions is obtained.
The concentration of ion doping may be controlled to 1 at% to 10 at%, and 3 at% is taken as an example.
Subsequently, using the micro thermal platform coated with the PS thin film in example 1, a sol-gel method was used to spin-coat a 3 at% Al-doped ZnO sol on the substrate, with the rotation speed and time controlled at 800r/min and 10s, respectively. The sample was then annealed at a temperature of 500 ℃ for 2h in an air atmosphere.
Wherein, the rotating speed range can be 400r/min-1000r/min, preferably 800r/min, and the time can be 2s-15s, preferably 10 s. The sintering temperature of the sample can be 350-550 ℃, and the time can be controlled within 1-4 h.
In summary, the method according to the embodiment of the present invention is based on a micro-heating platform technology, combines a nanoimprint technology, and prepares a highly-structured nanoporous array by a noble metal doping method and using spin coating, sputtering, ALD, and other film forming processes, and unlike a porous silicon modification method, the preparation method according to the embodiment of the present invention does not need to use a large amount of hydrofluoric acid solvent, but uses a physical heating polymer film and a demolding method, thereby reducing and avoiding the use of a large amount of strong acid solvents, and being beneficial to environment-friendly sustainable development. That is, the preparation method according to the embodiment of the present invention is economical and environmentally friendly, and is a preparation method with good manufacturability and reproducibility, and can be used for CH4、CO、H2And the detection of toxic and harmful gases such as NO and the like has the characteristics of high sensitivity and quick response.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (13)
1. A method for preparing a gas sensor element with a nano-porous structure is characterized by comprising the following steps:
s1, self-assembling a polymer film on the interdigital electrode covered on the chip of the micro-heating platform to obtain a template base layer of the interdigital electrode through the film;
s2, obtaining a regular nano template structure by adopting a nano imprinting method on the template base layer, wherein the nano template structure is provided with a nano porous array structure layer, and residual template agent is remained on the nano template structure;
s3, removing a nanoimprint residual layer on the nano template structure to expose the interdigital electrode layer in an air layer and form a gas-sensitive material film-forming carrier;
s4, preparing a metal ion doped oxide film on the gas sensitive material film forming carrier to serve as a gas sensitive material layer;
and S5, removing the residual template agent from the chip to obtain the gas sensor element with the nano porous structure.
2. The method of claim 1, wherein in step S1, the polymer coating film is self-assembled by one of an LB film method, a solution evaporation method, a spin coating method, or a dip coating method.
3. The method of claim 2, wherein the spin coating process comprises the steps of:
dissolving a thermoplastic polymer in a solvent to obtain a polymer solution;
spin-coating the polymer solution to the micro-heating platform by using a spin-coating method to obtain the polymer film;
and heating the interdigital electrode coated with the polymer film after standing.
4. The method according to claim 1, wherein step S2 comprises the steps of:
copying the porous structure of the porous anodic alumina template on the polymer film under a preset pressure;
carrying out pressure maintaining operation to obtain the nano porous array structure layer;
cooling the porous anodic alumina template;
and demolding the porous anodic aluminum oxide template and the chip.
5. The method as claimed in claim 4, wherein in the step of cooling the porous anodized aluminum template, a condensed water system of the porous anodized aluminum template is used for cooling.
6. The method of claim 4, wherein in the step of demolding the porous anodized aluminum template and the chip, a demolding angle is 10 ° to 45 °.
7. The method according to claim 1, wherein the nanoimprint residue layer is removed in step S3 by a plasma dry etching method.
8. The method of claim 1, wherein the metal ion-doped oxide thin film is prepared by one of a magnetron sputtering method, a sol-gel method, an atomic layer deposition method, a pulsed laser deposition, and a chemical vapor deposition in step S4.
9. The method of claim 8, wherein the magnetron sputtering method comprises the steps of:
depositing Ag-doped SnO on the gas-sensitive material film-forming carrier2The film has a thickness of 10nm-400nm and a doping concentration of 1 at% -10 at%.
10. The method of claim 1, wherein in step S5, the residual templating agent is removed by ultrasonic cleaning.
11. The method according to claim 1, wherein step S5 includes:
s51, removing the residual template agent;
and S52, sintering the chip with the residual template agent removed at high temperature.
12. The method according to claim 4, wherein the porous anodized aluminum template is a V-shaped porous anodized aluminum template obtained through multi-step hole expanding and oxidation, and the aspect ratio of the porous anodized aluminum template is 2: 1.
13. The method of claim 1, wherein the nanoimprinting method of step S2 includes hot stamping and cold stamping.
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