CN114324480B

CN114324480B - Gas sensor array and printing solution preparation method thereof

Info

Publication number: CN114324480B
Application number: CN202210020886.0A
Authority: CN
Inventors: 周清峰; 丘勇才
Original assignee: Ai Gan Technology Guangdong Co ltd
Current assignee: Ai Gan Technology Guangdong Co ltd
Priority date: 2020-07-21
Filing date: 2020-07-21
Publication date: 2023-08-29
Anticipated expiration: 2040-07-21
Also published as: CN114368232B; CN114324480A; CN111791623B; CN111791623A; CN114368232A

Abstract

The invention relates to a gas sensor array and a printing solution modulation method thereof, wherein the gas sensor array at least comprises the following components: the sensor array substrate, the interdigital electrode printed on the sensor array substrate according to a preset interval by conductive ink, and the gas-sensitive film formed on the corresponding interdigital electrode pattern by the optimized metal oxide particle suspension after the interdigital electrode pattern volatilizes to form a film, wherein the physical property parameter of the conductive ink is modulated based on the nozzle aperture of the printing device, and the relationship between the physical property parameter and the printing stability parameter of the conductive ink is as follows:γ _ink the surface tension of the ink, ρ is the density of the conductive ink, η is the viscosity of the ink, D is the aperture of the nozzle, and Z ranges from 1 to 12. The gas sensor array obtained by printing the modulated conductive ink has the advantages of no phenomenon of printing wiredrawing, stable printing interval and low defective rate.

Description

Gas sensor array and printing solution preparation method thereof

The invention discloses a method and a device for preparing a gas sensor array by ink-jet printing, which are divided into patent applications, wherein the application date is 7/21/2020, the application number is 202010709276.2.

Technical Field

The invention belongs to the technical field of sensor devices, and particularly relates to a gas sensor array and a printing solution modulation method thereof.

Background

Conventional metal oxide gas sensors have poor gas selectivity due to cross-responses to a variety of gases and are susceptible to interfering gases. The differential multiple metal oxide gas sensors are integrated into the sensor array as multiple sensing pixels, the response modes to different gases or mixed gases can be produced according to the differential responses of the sensors in the array, and the different gases can be effectively distinguished and the concentration of each component in the mixed gases can be detected by utilizing a pattern recognition algorithm or a neural network. The sensor array is not simply a plurality of sensors placed together, and future technology trends are more toward simple fabrication of the sensor array, and high integration.

The existing gas sensor is mostly in a planar structure, and signals of the sensor can be led out to a chip carrier by integrating interdigital electrodes (Finger electrodes) or Source-drain Electrode pairs (Source-Drain Electrode Pair) on a monolithic substrate, depositing gas sensor materials by means of sputtering (spray), vapor deposition (Evaporation), drop Casting (Drop Casting) and Spin Coating (Spin Coating), and combining with modes of wire bonding and the like. In the existing mode of depositing the sensor film, the time required by sputtering and evaporation is long, the sensor array is difficult to prepare rapidly, the heat resistance and the vacuum resistance of a substrate are required, although the material can be deposited on a micrometer scale, the method needs to be matched with a micrometer characteristic preparation flow (comprising modes of photoetching, etching and the like) from Top to bottom, and the overall cost is high; the spin coating can prepare a relatively uniform film, has no requirement on a substrate, but is difficult to prepare different sensors on the same substrate, and is also difficult to prepare sensor pixels with micron-sized; dispensing has the advantage of rapidly preparing sensor arrays of different characteristics, with no requirement for the substrate, but also makes it difficult to prepare sensor pixels of micron size due to the minimal volume limitations of the dispensing device.

Inkjet printing is a material-saving deposition technique in which the ink used for printing may be a liquid phase material dissolved or dispersed in a solvent. The working principle is as follows: the ink cavity receives sudden piezoelectric action, so that the volume of the cavity is reduced, ink is ejected from the cavity, then the ink is ejected and pressed down to an impacted substrate under the action of gravity and air resistance, the ink is diffused under the action of the obtained momentum, along with the flow of surface tension auxiliary flow along the surface, ink drops are evaporated and dried through a solvent, and then a pattern to be printed is formed. The ink jet printing technology can control the size of liquid drops to one part per million of a dripping device, and can realize the rapid and uniform preparation of sensor pixels with micrometer size. Meanwhile, the substrate material is almost unlimited, and the sensor can be prepared on silicon wafers, ceramic wafers, glass wafers and even transparent resin materials. No additional feature preparation flow is needed as it is in the category of additive manufacturing (Additive anufacturing). The cartridge can be optionally assembled with different metal oxide suspensions and can be used to prepare sensor arrays. In particular, inkjet printing may also print conductive ink, preparing interdigitated electrodes, enabling additive manufacturing from the electrodes to the material. Based on the above advantages, the ink jet printing technology is gradually applied to the preparation of gas sensors.

For example, chinese patent CN107202823B discloses a method for preparing a microelectrode array sensor by ink-jet printing, wherein the microelectrode array sensor is composed of a working electrode, a counter electrode and a reference electrode, wherein the working electrode is composed of a substrate layer, a working electrode gold electrode layer, a working electrode printed silver electrode layer, an electrode waterproof layer and a biosensing layer, the counter electrode is composed of a counter electrode gold electrode layer, a counter electrode printed silver electrode layer and a counter electrode waterproof layer, the reference electrode is composed of a reference electrode gold electrode layer, a reference electrode printed silver electrode layer and a reference electrode waterproof layer, and the microelectrode array sensor obtained by the invention can be used as a DO sensor, a temperature sensor, a pH sensor and a conductivity sensor in the field of wastewater treatment, and various water quality parameters can be detected in real time. The microelectrode array sensor has the advantages of compact structure, small size, high precision, quick response, simple preparation process, strong controllability and low cost. The sensor array is suitable for sensing and detecting water quality parameters. There is no prior art sensor array for gas detection that has been ink jet printed.

Patent document with publication number CN108490043a discloses a gas sensor and a method for preparing the same, the gas sensor uses flexible material as substrate, nano carbon material as gas sensitive material, microarray electrode as electrode layer; the preparation process of the gas-sensitive material layer in the gas sensor is simplified and rapidly prepared in a large area by scraping the aqueous dispersion liquid of the gas-sensitive material, meanwhile, the material waste caused by the processes of spraying, spin coating and the like in the prior art is avoided, and the cost is reduced; the electrode pattern of the microarray electrode can be customized arbitrarily by ink-jet printing, so that the current response of the sensor is increased, the sensor has higher sensitivity, and compared with the electrode preparation processes such as photoetching, evaporation method and the like in the prior art, the sensor has the characteristics of simplicity, easiness in operation, low cost and convenience in large-scale preparation. However, it is also difficult to produce sensor pixels of micron-sized dimensions.

During the substantial examination of the present parent, there is no prior art disclosing the step of modulating the physical properties parameters of the conductive ink based on the aperture of the nozzle of the present invention. Thus, the present invention is novel and inventive.

Furthermore, there are differences in one aspect due to understanding to those skilled in the art; on the other hand, since the applicant has studied a lot of documents and patents while making the present invention, the text is not limited to details and contents of all but it is by no means the present invention does not have these prior art features, but the present invention has all the prior art features, and the applicant remains in the background art to which the right of the related prior art is added.

Disclosure of Invention

The term "module" as used herein describes any hardware, software, or combination of hardware and software capable of performing the functions associated with the "module".

In view of the shortcomings of the prior art, the present invention provides a method for preparing a gas sensor array by inkjet printing, which is characterized in that the method at least comprises: the physical property parameters of the conductive ink and/or the physical property parameters of the metal oxide particle suspension adapted to the aperture of the spray head are modulated based on the aperture of the spray head. According to the invention, through preparing the conductive ink and metal oxide particle suspension liquid which are matched with the aperture, liquid drops with higher printing stability can be obtained, and satellite drops and wiredrawing phenomena are avoided.

In the process of preparing at least one interdigital electrode on a sensor array substrate in an ink-jet printing mode, pulse voltage variation parameters are finely adjusted based on a preset nozzle voltage pulse timing diagram so as to control droplet ejection parameters, and the conductive ink is printed on the sensor array substrate at preset intervals. According to the invention, the initial speed and the dropping frequency of liquid drops are regulated by pulse voltage, so that the printing interval and the printing speed of the interdigital electrode on the substrate can be better realized.

And printing the optimized metal oxide particle suspension on the corresponding interdigital electrode pattern after the interdigital electrode pattern volatilizes to form a gas-sensitive film. The uniformity and stability of the gas-sensitive film can be better realized by printing through the prepared metal oxide particle suspension liquid and combining with pulse time sequence, the efficiency of manufacturing the gas sensor array is higher, and the defective rate is low.

Preferably, the step of modulating the physical property parameter of the conductive ink based on the aperture of the nozzle comprises: base group

Determining the modulation range of the surface tension and viscosity of the conductive ink at the aperture of the spray head, the density of the conductive ink to be modulated and the printing stability parameter Z, wherein,

γ _ink the surface tension of the ink, ρ is the density of the conductive ink, η is the viscosity of the ink, D is the aperture of the nozzle, and Z ranges from 1 to 12. By calculation of the print stability and calculation of the modulation physical property parameter, the physical property parameter of the droplet can be modulated in a targeted manner, and a print material having a stable gas sensor array can be obtained.

Preferably, the step of modulating the physical property parameter of the conductive ink based on the aperture of the nozzle further comprises: and modulating the surface tension and viscosity of the conductive ink to be modulated in a mode of adding an organic solvent until the surface tension and viscosity of the conductive ink reach corresponding modulation ranges. The method is beneficial to shortening the modulation time and improving the modulation efficiency by modulating the commercial conductive ink, so that the conductive ink with stable properties is obtained rapidly, and the improvement of the production efficiency of the gas sensor array is facilitated.

Preferably, the step of optimizing physical property parameters of the metal oxide particle suspension for preparing the gas-sensitive film comprises: dispersing at least one metal oxide nanoparticle into a mixed solution of isopropanol and sec-butyl alcohol mixed according to a certain proportion, and adding quantitative polyvinylpyrrolidone to adjust the viscosity of a metal oxide particle suspension, wherein the viscosity range of the metal oxide particle suspension is determined based on the pore diameter of a spray head, the density of the metal oxide particle suspension and a printing stability parameter Z. The optimization can reduce the preparation steps of liquid drops, the method is simple and easy, the implementation of operators is facilitated, and the production efficiency of the oxide particle suspension is improved.

Preferably, the step of preparing the physical property parameter of the metal oxide particle suspension for preparing the gas-sensitive film includes:

the zinc acetate alcohol solution is prepared into preset concentration and is subjected to ultrasonic dispersion,

stirring and heating zinc acetate alcohol solution in a water bath environment with a certain temperature,

after the zinc acetate alcoholic solution is cooled to room temperature, a certain amount of sodium hydroxide alcoholic solution is added and stirred,

after adding 0.1-1mL of oleic acid, centrifuging and washing at least once with alcohol,

the cleaned zinc acetate alcohol solution is redispersed into the mixed solution of isopropanol and sec-butanol, and proper polyvinylpyrrolidone is added to regulate the viscosity. Through modulating metal oxide particle suspension, suspension matched with the aperture of a nozzle of the ink-jet printing equipment can be obtained, suspension with better printing stability can be obtained, so that the printed gas-sensitive film can be independently arranged, the phenomena of wiredrawing and adhesion printing are avoided, and the sensitivity of the gas-sensitive film of the gas sensor array is improved. The invention can further greatly reduce the reject ratio of the gas sensor array production.

Preferably, the method further comprises:

the sensor array substrate printed with the interdigital electrode pattern is heated in an inert gas at a certain temperature for a certain time, thereby volatilizing to form a film. Is beneficial to the rapid generation of the interdigital electrode, avoids the generation of a mixing effect with the subsequent gas-sensitive film, and improves the production efficiency of the product.

Preferably, the method further comprises: after printing the metal oxide particle suspension on the corresponding interdigitated electrode, the sensor array substrate is treated at a high temperature of 200-400 degrees celsius in an inert gas for at least one hour. The method is favorable for rapid generation of Yu Qimin films and improves the production efficiency of products.

The invention also provides an ink-jet printing device based on the gas sensor array, which is characterized by at least comprising an ink-jet printing device with a pulse piezoelectric adjusting component, wherein the ink-jet printing device is provided with conductive ink and/or metal oxide particle suspension with physical property parameters matched with the aperture of a spray head; in the process of preparing at least one interdigital electrode on a sensor array substrate in an inkjet printing mode, the inkjet printing equipment finely adjusts pulse voltage variation parameters based on the imported interdigital electrode pattern and a preset nozzle voltage pulse time sequence diagram so as to control droplet ejection parameters, and the conductive ink is printed on the sensor array substrate according to preset intervals; after the interdigital electrode patterns volatilize to form films, the ink-jet printing equipment prints the optimized metal oxide particle suspension on the corresponding interdigital electrode patterns so as to form the gas-sensitive film. According to the ink-jet printing device, the interdigital electrodes and the gas-sensitive film in the gas sensor array have clear printing areas, and under the condition of stable printing liquid, the phenomenon of printing errors caused by liquid drop wire drawing among the printing areas is avoided, so that the phenomenon of circuit short circuit or signal transmission disorder is reduced, and the gas sensor array with high sensitivity and high detection rate can be obtained. Preferably, the step of modulating the physical property parameter of the conductive ink based on the aperture of the nozzle comprises:

the invention relates to an ink jet printing device based on a gas sensor array, which is matched with the aperture of a spray head, and the method for modulating the physical property parameters of conductive ink comprises the following steps:

determining the modulation range of the surface tension and viscosity of the conductive ink based on the aperture of the spray head, the density of the conductive ink to be modulated and the printing stability parameter Z, wherein,

γ _ink is the surface tension of the ink, ρ is the density of the ink, η is the viscosity of the ink, and D is the nozzle

The pore diameter, Z, ranges from 1 to 12.

The invention relates to an ink jet printing device based on a gas sensor array, which is matched with the aperture of a spray head, and the method for modulating the physical property parameters of conductive ink comprises the following steps: and adding an organic solvent to the surface tension and viscosity of the conductive ink to be prepared until the surface tension and viscosity of the conductive ink reach the corresponding preparation range. The invention directly modulates the commercial conductive ink, which is beneficial to shortening the modulation time and improving the modulation efficiency, thereby rapidly obtaining the conductive ink with stable properties and being more beneficial to improving the production efficiency of the gas sensor array.

The present invention also provides a gas sensor array comprising at least: the sensor array substrate is printed with conductive ink on the interdigital electrode of the sensor array substrate according to preset intervals, and after the interdigital electrode pattern volatilizes to form a film, a gas-sensitive film is formed on the corresponding interdigital electrode pattern by optimized metal oxide particle suspension,

wherein the physical property parameter of the conductive ink is modulated based on the nozzle aperture of the printing device,

the relation between the physical property parameter and the printing stability parameter of the conductive ink is as follows:

γ _ink the surface tension of the ink, ρ is the density of the conductive ink, η is the viscosity of the ink, D is the aperture of the nozzle, and Z ranges from 1 to 12.

Preferably, the conductive ink is used for controlling the droplet ejection parameters based on a preset nozzle voltage pulse timing diagram to fine tune the pulse voltage variation parameters.

Preferably, the surface tension and viscosity of the conductive ink are prepared by the following steps: and adding an organic solvent for modulation until the surface tension and viscosity of the conductive ink reach corresponding modulation ranges.

Preferably, the method for volatilizing the interdigital electrode pattern into a film comprises the following steps: the sensor array substrate printed with the interdigital electrode pattern is heated in an inert gas at a certain temperature for a certain time, thereby volatilizing to form a film.

Preferably, the forming mode of the gas-sensitive film includes: after printing the metal oxide particle suspension on the corresponding interdigitated electrode, the sensor array substrate is treated at a high temperature of 200-400 degrees celsius in an inert gas for at least one hour.

Preferably, the control manner of the interval ejection of the conductive ink forming the interdigital electrode is as follows:

a spray head voltage pulse time sequence chart is set,

fine-tuning the rising speed of the rising edge of the voltage to reach the set voltage and duration;

or the speed and the size of the voltage drop are finely adjusted to obtain a good droplet ejection effect, so that the droplets are not continuous with each other when falling on the sensor array substrate, and an accurate spacing distance is obtained.

Preferably, the pulse amplitude of the pulse voltage timing diagram of the conductive ink is preferably 22V;

the drop flight speed decreases sharply when the pulse is less than 22V;

when the piezoelectric pulse is greater than 22V, the volume and velocity of the droplet are relatively stable.

The invention also provides a printing solution preparation method of the gas sensor array, wherein the printing solution comprises conductive ink for printing the interdigital electrode pattern and metal oxide particle suspension for printing the gas-sensitive film; wherein the step of physical property parameters of the conductive ink comprises: spray head based

The pore diameter, the density of the conductive ink to be modulated and the printing stability parameter Z determine the modulation range of the surface tension and viscosity of the conductive ink, wherein gamma _ink The surface tension of the ink is that ρ is the density of the conductive ink, η is the viscosity of the ink, D is the aperture of the nozzle, and Z ranges from 1 to 12;

the preparation method of the metal oxide particle suspension comprises the following steps:

dispersing at least one metal oxide nano particle into a mixed solution of isopropanol and sec-butyl alcohol according to a certain proportion,

a quantity of polyvinylpyrrolidone is added to adjust the viscosity of the suspension of metal oxide particles, wherein,

the viscosity range of the metal oxide particle suspension is determined based on the pore size of the spray head, the density of the metal oxide particle suspension, and the print stability parameter Z.

Preferably, the method further comprises:

and modulating the surface tension and viscosity of the conductive ink to be modulated in a mode of adding an organic solvent until the surface tension and viscosity of the conductive ink reach corresponding modulation ranges.

Preferably, the preparation method of the metal oxide particle suspension comprises the following steps:

the cleaned zinc acetate alcohol solution is redispersed into the mixed solution of isopropanol and sec-butanol, and proper polyvinylpyrrolidone is added to regulate the viscosity.

Drawings

FIG. 1 is a schematic diagram of pulse voltages for the operation of the spray head of the present invention;

fig. 2 is a schematic partial structure of the ink jet printing apparatus of the present invention.

List of reference numerals

10: a conductive ink; 20: a spray head; 30: a droplet; 40: a piezoelectric transducer; 50: a substrate; 60: pulse voltage.

Detailed Description

The following detailed description refers to the accompanying drawings.

An interdigitated electrode is an electrode having a periodic pattern in the plane, such as a finger or comb, that is used to create a capacitance associated with the electric field of the penetrable material sample and the sensitive coating.

The invention provides a method for preparing a gas sensor array by ink-jet printing, and also provides an ink-jet printing preparation device based on the gas sensor array.

Example 1

The invention provides a method for preparing a gas sensor array by ink-jet printing, which at least comprises the following steps:

s1: the physical property parameters of the conductive ink and/or the physical property parameters of the metal oxide particle suspension adapted to the aperture of the spray head are modulated based on the aperture of the spray head.

S2: in the process of preparing at least one interdigital electrode on a sensor array substrate in an ink-jet printing mode, pulse voltage variation parameters are finely adjusted based on a preset nozzle voltage pulse timing diagram so as to control droplet ejection parameters, and the conductive ink is printed on the sensor array substrate at preset intervals.

S3: and printing the optimized metal oxide particle suspension on the corresponding interdigital electrode pattern after the interdigital electrode pattern volatilizes to form a gas-sensitive film.

The conductive ink provided by the invention is mainly used for preparing the interdigital electrode and providing a conductive channel for a subsequent gas-sensitive film. Preferably, the conductive ink is generally selected from commercially available silver inks. The concentration of silver nano particles is 25-40%, and the particle size is 50-100nm. The choice of silver ink requires attention to its consistency and surface tension matching the inkjet printer nozzle. The inkjet printing device is preferably a material inkjet printer. For example, the inkjet printing apparatus is preferably a DMP2800 material inkjet printer

The method for modulating physical property parameters of the conductive ink based on the aperture of the spray head comprises the following steps: the modulation range of the surface tension and viscosity of the conductive ink is determined based on the aperture of the ejection head, the density of the conductive ink to be modulated, and the print stability parameter Z. Wherein, print stability parameters are:

γ _ink the surface tension of the ink, ρ is the density of the ink, η is the viscosity of the ink, D is the aperture of the nozzle, and Z ranges from 1 to 12. Preferably, Z ranges from 1 to 10. When Z is between 1 and 12, the formation of longer filaments during printing can be reduced, and the occurrence of discrete droplets can be reduced.

In the value range of Z, if the value of Z is close to or less than 1, the ink is too thick to be ejected; if the Z value is close to or greater than 10, a large number of fine discrete droplets are ejected together with the main droplet, thereby decreasing the resolution of printing.

For example, the Z value of the conductive ink is preferably 2-5, which is favorable for ensuring printing stability, improving electrode printing precision and preventing adjacent electrodes from being short-circuited due to discrete conductive liquid drops.

The Z value range of the metal oxide particle suspension is preferably 2-8, which is favorable for preventing the suspension from being too thick to block the spray head, and meanwhile, the moderate concentration can ensure high-flux rapid printing, so that the oxide particles can be uniformly covered in the sensing area.

For example, the nozzle aperture D is 21.5um, the viscosity of the ink is 8-12mPa s, the surface tension is 28-33mN/m, and the ink density is 1g/cm ³ By way of example, an ink having a Z of 2.5, representing this property, can achieve stable printing. Accordingly, for inkjet printing devices with different aperture heads, each physical property of the ink may be verified according to the Z design. With known nozzle apertures, conductive ink can be used to print as long as the print stability of the modulated conductive ink is in the range of 1 to 10.

Preferably, the invention can also judge the speed of the liquid drop according to an interfacial tension ratio calculation formula. The interfacial tension ratio is the ratio between the viscous force and the surface tension of the conductive ink, reflects the degree to which the disperse phase fluid is affected by the interfacial tension, and can predict the possibility of deformation and fracture in the two-phase flow.

N represents the interfacial tension ratio and v represents the velocity of the droplet. N is more than or equal to 1, the stability of the conductive ink is better, and liquid drops cannot be deposited at wrong positions due to the fact that the initial speed is too small and the liquid drops are disturbed by air flow.

Therefore, by combining the calculation formula of the printing stability parameter and the common calculation of the interfacial tension ratio formula, the accurate range of the viscosity and the surface tension of the liquid drop with the printing stability can be obtained, and even the speed range of the liquid drop can be calculated, thereby being beneficial to preparing the conductive ink and the metal oxide particle suspension with better printing stability.

Under the condition that the conductive ink is not matched with the aperture of a nozzle of the inkjet printing equipment, the surface tension and viscosity of the conductive ink to be modulated are modulated in a mode of adding an organic solvent until the surface tension and viscosity of the conductive ink reach the corresponding modulation range, so that the physical property parameters of the conductive ink are matched with the aperture of the nozzle, and the printing stability is improved.

Examples of the parameters of the interdigital electrode of the present invention are: the width of each interdigital is 100um, the distance between adjacent interdigital electrodes is 50um, the number of the adjacent interdigital electrodes is 10 pairs, and the thickness of each electrode is 500nm-1um.

The printing step of the interdigital electrode comprises the following steps:

s11: the predetermined interdigitated electrode pattern is introduced into an inkjet printer program.

S12: setting a spray head voltage pulse time sequence chart. An example of a spray head voltage pulse timing diagram is shown in fig. 1.

S13: and printing the interdigital electrode pattern on the sensor array substrate for one time according to the preset liquid drop distance, wherein the sensor array substrate is kept at normal temperature in the printing process. Preferably, the distance between the droplets is preferably 25um, which is favorable for the non-adhesion of the droplets, so that the printed interdigital electrode patterns are clear, not blurred and good in conductivity. The sensor array substrate is preferably ceramic, polyethylene terephthalate or polyimide.

S14: after the interdigital electrode is printed, the sensor array substrate is heated in inert gas for a certain time at a certain degree centigrade to promote the conductive ink to volatilize and form a film.

Preferably, after printing, the sensor array substrate is heated in inert gas at 60 ℃ for 30 minutes to promote the conductive ink to volatilize and form a film. In the temperature parameter and the time parameter, the volatilization speed of the conductive ink is high, the volatilization time is short, the physical property of the interdigital electrode is not affected, the formed interdigital electrode pattern is stable without deformation, and the conductivity is not reduced.

A voltage pulse timing chart of a jet head of conductive ink having a viscosity of 8mpa s and a surface tension of 33mN/m is shown in fig. 1. Fig. 1 is a pulse voltage timing diagram of an operating state.

Preferably, the pulse amplitude is preferably 22V. The drop flight speed decreases dramatically after the pulse is less than 22V. Setting 22V at the piezoelectric pulse can not only meet stable injection, but also ensure that the liquid drop has a certain initial speed, and meet the requirement of ink-jet printing. Preferably, the pulse amplitude may also be greater than 22V. At piezoelectric pulses greater than 22V, the volume and velocity of the droplet are also relatively stable.

As shown in FIG. 1, the working state of the spray head for spraying single drop of conductive ink is that the whole spray is 24.32us. First the voltage drops to 0V and the piezoelectric element returns to its original position and ink is drawn into the chamber connected to the nozzle. The voltage rises at a constant rate at 5.888us, and the voltage is maintained from the rise to the maximum amplitude, at which time the ink is pushed out of the chamber to the outside of the ejection head. The voltage was stepped down from 12.032us to prevent air from being pulled back, and first down to 40% of the maximum amplitude of the second gradient voltage. At 18.176us the voltage drops from the second gradient voltage to the first gradient voltage, 25% of the maximum amplitude and is maintained at 24.32us, the droplet separates relatively cleanly from the spray head. For conductive inks with different consistencies or surface tension, the set voltage magnitude and duration are finally achieved by fine tuning the rising speed of the rising edge of the voltage. Or fine-tuning the parameters such as the speed and the size when the voltage drops, so as to obtain better droplet ejection effect, ensure that droplets are not continuous with each other when falling on the sensor array substrate, obtain accurate spacing distance and have no interdigital electrode overflowed by redundant droplets. For example, when the solution is too viscous, the rising speed of the voltage can be increased appropriately, the time of the peak voltage can be prolonged, and the liquid drops can be quickly landed for printing.

As shown in fig. 1, in the off state of the head, the voltage of the head is maintained at about 25% of the maximum amplitude and remains unchanged. The maximum amplitude in the present invention is not limited to 22V, but may be other pulse amplitudes set according to actual conditions.

The step of preparing a metal oxide particle suspension for preparing a gas-sensitive film in the present invention is exemplified by the step of preparing a zinc oxide quantum dot dispersion.

S21: the zinc acetate alcoholic solution is configured to a preset concentration and subjected to ultrasonic dispersion. Preferably, the concentration of zinc acetate is 20-40mg/mL.

S22: and stirring and heating the zinc acetate alcohol solution in a water bath environment with a certain temperature. Preferably, the zinc acetate alcoholic solution is heated with stirring in an 80 degree water bath environment for 2 hours. The water bath environment is favorable for stabilizing the temperature environment. The temperature in this step is not limited to 80 degrees and may be between 60 degrees and 90 degrees.

S23: after the zinc acetate alcoholic solution was cooled to room temperature, a fixed amount of sodium hydroxide alcoholic solution was added and stirred. For example, 5-10mL of 0.5-1M sodium hydroxide alcohol solution is added and stirred for 10 minutes, which is favorable for forming zinc oxide quantum dots.

S24: after adding 0.1-1mL of oleic acid, centrifugation is performed and washing with alcohol is performed at least once. Preferably, after 0.1-1mL of oleic acid is added, the mixture is centrifuged and washed for 2-3 times by alcohol, which is more beneficial to improving the purity of the zinc oxide quantum dot.

S25: the washed zinc acetate alcoholic solution is redispersed into a mixed solution of Isopropanol (isopanol) and sec-Butanol (2-Butanol), and an appropriate amount of Polyvinylpyrrolidone (Polyvinylpyrrosidone) is added to adjust the viscosity so that the viscosity and the surface tension of the zinc oxide quantum dot dispersion are matched with the pore diameter of a spray head. Preferably, the mixing ratio of Isopropanol (isopanol) to sec-Butanol (2-Butanol) is 9:1.

Preferably, the metal oxide particle suspension is not limited to being prepared with a zinc acetate alcoholic solution, and any precursor solution containing zinc salt may be used instead of the zinc acetate alcoholic solution.

Preferably, the metal oxide particle suspension is not limited to being prepared with an alcoholic sodium hydroxide solution, and any alkaline precursor solution may be used instead of the alcoholic sodium hydroxide solution.

Preferably, the step of optimizing the suspension of metal oxide particles for preparing the gas sensitive film comprises:

For different suspensions of metal oxide particles, the surface tension and viscosity of the suspensions need to be optimized in the preparation stage of the suspensions, and the suspensions are matched with a spray head. In the actual printing process, all optimized suspensions have less different surface tension and viscosity, and can be printed by using the same voltage pulse.

Specifically, in addition to the zinc oxide quantum dot dispersion liquid, various metal oxide nanoparticles (including tin oxide, indium tin oxide, zinc oxide, titanium oxide, etc.) with diameters within 100nm can be purchased directly, redispersed into a mixed solution (9:1) of Isopropanol (isopanol) and sec-Butanol (2-Butanol), and an appropriate amount of Polyvinylpyrrolidone (Polyvinylpyrrolidone) is added to adjust viscosity so that the viscosity and surface tension of the metal oxide particle suspension liquid match the pore diameter of the spray head.

After printing the metal oxide particle suspension on the corresponding interdigitated electrode, the sensor array substrate is treated at a high temperature of 200-400 degrees celsius in an inert gas for at least one hour. This arrangement facilitates rapid volatilization of the metal oxide particle suspension. The temperature does not deteriorate the stability of the interdigital electrode. Preferably, after printing the metal oxide particle suspension on the corresponding interdigital electrode, the metal oxide particle suspension forms a gas-sensitive film after being processed in inert gas at a high temperature of 200-400 ℃ for 2 hours, and the preparation of the sensor is completed.

Example 2

The invention also provides an ink jet printing device based on the gas sensor array, which at least comprises an ink jet printing device with a pulse piezoelectric adjusting component. Wherein the inkjet printing device is provided with a suspension of conductive ink and/or metal oxide particles whose physical properties parameters are adapted to the aperture of the nozzle head.

As shown in fig. 2, the head 20 of the inkjet printing apparatus is provided with a piezoelectric transducer 40. The piezoelectric transducer 40 adjusts for variations in the pulse voltage 60 according to a pulse timing diagram. A channel is provided in the nozzle for introducing the conductive ink 10 or the suspension of metal oxide particles. The conductive ink forms droplets 30 with an adjustable drop rate in association with the pulse voltage variation. The droplets 30 drop onto the sensor array substrate to form interdigital electrodes arranged at predetermined intervals.

Wherein the conductive ink and a preset pulse timing diagram are introduced to the inkjet printing apparatus prior to printing.

In the process of preparing at least one interdigital electrode on a sensor array substrate in an inkjet printing mode, the inkjet printing device fine-adjusts pulse voltage variation parameters based on the imported interdigital electrode pattern and a preset nozzle voltage pulse timing diagram so as to control droplet ejection parameters, so that the dropping speed of droplets is matched with the moving speed of the sensor array substrate. And printing the conductive ink on the sensor array substrate at preset intervals.

After the interdigital electrode pattern volatilizes to form a film, a nozzle of the ink-jet printing equipment introduces a modulated metal oxide particle suspension which is matched with the aperture of the nozzle. Printing the optimized metal oxide particle suspension on the corresponding interdigital electrode pattern, so that the metal oxide particle suspension volatilizes to form a gas-sensitive film.

In the invention, the step of modulating the physical property parameters of the conductive ink based on the aperture of the spray head comprises the following steps:

the modulation range of the surface tension and viscosity of the conductive ink is determined based on the aperture of the ejection head, the density of the conductive ink to be modulated, and the print stability parameter Z. Wherein, the liquid crystal display device comprises a liquid crystal display device,

γ _ink the surface tension of the ink, ρ is the density of the ink, η is the viscosity of the ink, D is the aperture of the nozzle, and Z ranges from 1 to 12.

Preferably, the step of modulating the physical property parameter of the conductive ink based on the aperture of the nozzle further comprises:

and adding an organic solvent to the surface tension and viscosity of the conductive ink to be prepared until the surface tension and viscosity of the conductive ink reach the corresponding preparation range.

After the completion of the interdigital electrode printing, the kind of the prepared metal oxide particle suspension is not limited to one kind, and may be plural kinds. During printing of the gas sensitive film, droplets of the metal oxide particle suspension are dropped at preset printing intervals, and the interval range of the metal oxide particle suspension includes at least one interdigital electrode. I.e. there is an inter-digital electrode between the same metal oxide particle suspension. After two drops of different kinds of metal oxide particle suspensions, at least two gas-sensitive films on the sensor array substrate are formed in a staggered arrangement. In the same manner, the inkjet printing apparatus is capable of printing a plurality of gas-sensitive films in a plurality of different distribution forms on the interdigital electrodes of the sensor array substrate, thereby forming a sensor array capable of detecting a plurality of gas components simultaneously.

Preferably, in the printing process of the ink-jet equipment, the interdigital electrodes and the gas-sensitive film can be arranged in a matrix array, or can be arranged in a plurality of arrays with equal printing distances, such as circular array arrangement, staggered array arrangement and the like.

Preferably, the distance between the interdigital electrodes can be equidistantly arranged or non-equidistantly arranged.

According to the invention, the printing stability of the liquid drops is better through the modulation of physical property parameters of the conductive ink and the metal oxide particle suspension. According to the gas sensor array-based ink-jet printing device, the dropping speed of liquid drops can be adjusted through pulse timing diagrams and pulse parameter fine adjustment, so that conductive ink is not adhered to a spray head, long filiform substances are reduced in the printing process, and discrete liquid drops are reduced. Therefore, the liquid drops are sprayed according to a certain dropping speed, so that the printed conductive lines of the gas sensor array are clear, the gas-sensitive films are uniformly distributed, the obtained gas sensor array has high sensing sensitivity, and gas components can be detected more quickly.

It should be noted that the above-described embodiments are exemplary, and that a person skilled in the art, in light of the present disclosure, may devise various solutions that fall within the scope of the present disclosure and fall within the scope of the present disclosure. It should be understood by those skilled in the art that the present description and drawings are illustrative and not limiting to the claims. The scope of the invention is defined by the claims and their equivalents. The description of the invention encompasses multiple inventive concepts, such as "preferably," "according to a preferred embodiment," or "optionally," all means that the corresponding paragraph discloses a separate concept, and that the applicant reserves the right to filed a divisional application according to each inventive concept.

Claims

1. A gas sensor array comprising at least:

a sensor array substrate having a plurality of sensor array substrates,

an interdigital electrode printed on the sensor array substrate at a predetermined interval from the conductive ink, and

after the interdigital electrode pattern volatilizes to form a film, forming a gas-sensitive film on the corresponding interdigital electrode pattern by the optimized metal oxide particle suspension,

2. The gas sensor array of claim 1, wherein the conductive ink is used to control droplet ejection parameters based on a preset showerhead voltage pulse timing profile to fine tune pulse voltage variation parameters;

the spray head is provided with a channel for introducing a conductive ink or a suspension of metal oxide particles, which forms droplets with an adjustable dropping speed in connection with a pulse voltage variation.

3. The gas sensor array according to claim 1 or 2, wherein the conductive ink has a surface tension and viscosity modulated by:

and adding an organic solvent for modulation until the surface tension and viscosity of the conductive ink reach corresponding modulation ranges.

4. The gas sensor array of claim 1, wherein the pattern of interdigitated electrodes volatilizes to form a film in a manner comprising:

the sensor array substrate printed with the interdigital electrode pattern is heated in an inert gas at a certain temperature for a certain time, thereby volatilizing to form a film.

5. The gas sensor array of claim 1, wherein the gas sensitive film is formed in a manner comprising: after printing the metal oxide particle suspension on the corresponding interdigitated electrode, the sensor array substrate is treated at a high temperature of 200-400 degrees celsius in an inert gas for at least one hour.

6. The gas sensor array of claim 2, wherein the spaced-apart ejection of conductive ink forming the interdigitated electrodes is controlled in the manner of:

a spray head voltage pulse time sequence chart is set,

7. The gas sensor array of claim 2, wherein the pulse amplitude of the pulse voltage timing diagram of the conductive ink is preferably 22V;

the drop flight speed decreases sharply when the pulse is less than 22V;

8. A method of preparing a printing solution for a gas sensor array, the printing solution comprising a conductive ink for printing an interdigitated electrode pattern and a suspension of metal oxide particles for printing a gas-sensitive film; wherein, the liquid crystal display device comprises a liquid crystal display device,

the step of physical property parameters of the conductive ink comprises the following steps:

γ _ink is the surface tension of the ink, ρ is the density of the conductive ink, η is the viscosity of the ink, and D is the nozzle

The range of Z is 1-12;

9. The method of printing solution preparation for a gas sensor array of claim 8, further comprising:

10. The method of preparing a printing solution for a gas sensor array according to claim 8 or 9, wherein the method of preparing a metal oxide particle suspension comprises: