CN114324480A

CN114324480A - Gas sensor array and printing solution modulation method thereof

Info

Publication number: CN114324480A
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: 2022-04-12
Anticipated expiration: 2040-07-21
Also published as: CN114324480B; CN111791623B; CN111791623A; CN114368232A; CN114368232B

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 comprises a sensor array substrate, interdigital electrodes printed on the sensor array substrate by conductive ink at preset intervals, and a gas-sensitive film formed on the corresponding interdigital electrode pattern by the optimized metal oxide particle suspension after the interdigital electrode pattern is volatilized to form a film, wherein the physical property parameters of the conductive ink are based on a spray head of a printing deviceAperture-modulated, the physical property parameter of the conductive ink is related to the print stability parameter by:

γ_inkthe surface tension of the ink is shown, rho is the density of the conductive ink, eta is the viscosity of the ink, D is the aperture of the nozzle, and Z ranges from 1 to 12. The gas sensor array printed by the modulated conductive ink has the advantages of no printing and wire drawing phenomenon, stable printing interval and low defective rate.

Description

Gas sensor array and printing solution modulation method thereof

The invention relates to a divisional application of an invention patent with the application date of 2020, 7 and 21 and the application number of 202010709276.2, and in particular relates to a method and a device for preparing a gas sensor array by ink-jet printing.

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

The traditional metal oxide gas sensor has poor gas selectivity and is easily influenced by interference gas due to the cross response of the traditional metal oxide gas sensor to various gases. The different metal oxide gas sensors are integrated into the sensor array as a plurality of sensing pixels, response modes to different gases or mixed gases can be produced according to the difference response 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 mode identification algorithm or a neural network. The sensor array is not simply a plurality of sensors, and the future technical development trend is more towards simple preparation and high integration of the sensor array.

Most of the existing gas sensors are of a planar structure, an interdigital Electrode (Finger Electrode) or a Source-Drain Electrode Pair (Source-Drain Electrode Pair) is integrated on a single substrate, and a gas sensor material is deposited by sputtering (Sputter), Evaporation (Evaporation), Drop Coating (Drop Casting) and Spin Coating (Spin Coating), and signals of the sensor can be led out to a chip carrier by matching with wire bonding and other modes. 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 quickly, the heat resistance and the vacuum resistance of a substrate are required, although materials can be deposited on a micrometer scale, the method needs to be matched with a Top-down micrometer characteristic preparation process (comprising photoetching, etching and other modes), and the total 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 prepare sensor pixels with micron-sized dimensions; dispensing has the advantage of rapidly fabricating sensor arrays of different characteristics, with no requirement for a substrate, but it is also difficult to fabricate sensor pixels of micron size due to the minimal volume limitation of the dropping device.

Ink jet printing is a material saving deposition technique and the ink used for printing can be a liquid phase material dissolved or dispersed in a solvent. The working principle is as follows: the ink chamber receives a sudden piezoelectric action, which causes the volume of the chamber to decrease, and the ink is ejected from the chamber, and then the ink is ejected under the action of gravity and air resistance and drops to the impacted substrate, and spreads under the action of the acquired momentum, and the ink drops form a pattern to be printed after being evaporated and dried by the solvent as the surface tension auxiliary flow flows along the surface. The ink-jet printing technology can control the size of liquid drops to one millionth of a drop coating device, and can realize the rapid and uniform preparation of sensor pixels with micron sizes. Meanwhile, the substrate material is almost not limited, and the sensor can be prepared on a silicon wafer, a ceramic wafer, a glass wafer and even a transparent resin material. Because the method belongs to the field of Additive manufacturing (Additive manufacturing), an additional characteristic preparation flow is not needed. The ink box can be arbitrarily assembled with different metal oxide suspensions and can be used for preparing a sensor array. In particular, inkjet printing can also print conductive inks to prepare interdigitated electrodes, thereby enabling additive manufacturing from electrode to material. Based on the above advantages, the ink jet printing technology is gradually applied to the preparation of the gas sensor.

For example, chinese patent CN107202823B discloses a method for preparing a microelectrode array sensor by inkjet 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, and 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. 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. The prior art does not have an inkjet printed sensor array for gas detection.

Patent document No. CN108490043A discloses a gas sensor and a method for manufacturing the same, wherein the gas sensor uses a flexible material as a substrate, a nano-carbon material as a gas sensitive material, and a microarray electrode as an electrode layer; the preparation process of the gas-sensitive material layer in the gas sensor is simplified, the gas-sensitive material layer is quickly prepared in a large area by blade coating the water-based dispersion liquid of the gas-sensitive material, the material waste caused by processes such as spraying, spin coating and the like in the prior art is avoided, and the cost is reduced; the microarray electrode is prepared by ink-jet printing, so that the electrode pattern can be customized freely, the current response of the sensor is increased, and the sensor has higher sensitivity. However, it is also difficult to fabricate sensor pixels of micron size.

During the substantial examination of the present parent application, no prior art discloses the step of modulating physical property parameters of the conductive ink based on the orifice diameter of the nozzle of the present invention. Therefore, the invention is novel and inventive.

Furthermore, on the one hand, due to the differences in understanding to the person skilled in the art; on the other hand, since the applicant has studied a great deal of literature and patents when making the present invention, but the disclosure is not limited thereto and the details and contents thereof are not listed in detail, it is by no means the present invention has these prior art features, but the present invention has all the features of the prior art, and the applicant reserves the right to increase the related prior art in the background.

Disclosure of Invention

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

In view of the deficiencies of the prior art, the present invention provides a method for preparing a gas sensor array by inkjet printing, which is characterized by at least comprising: modulating a physical property parameter of the conductive ink and/or a physical property parameter of the metal oxide particle suspension adapted to an aperture of the showerhead based on the aperture of the showerhead. According to the invention, through modulating the conductive ink and the metal oxide particle suspension liquid which are matched with the aperture, the liquid drop with higher printing stability can be obtained, and the phenomena of satellite drop and wire drawing are avoided.

In the process of preparing at least one interdigital electrode on a sensor array substrate in an ink-jet printing mode, fine-tuning pulse voltage variation parameters based on a preset nozzle voltage pulse timing diagram to control liquid drop spraying parameters, and printing the conductive ink on the sensor array substrate at preset intervals. The invention adjusts the initial speed and the dropping frequency of the liquid drop through the pulse voltage, thereby better realizing the printing interval and the printing speed of the interdigital electrode on the substrate.

And after the interdigital electrode patterns are volatilized to form a film, printing the optimized metal oxide particle suspension on the corresponding interdigital electrode patterns so as to form the gas-sensitive film. The prepared metal oxide particle suspension is used for printing, and the uniformity and stability of the gas-sensitive film can be better realized by combining a pulse time sequence, so that the efficiency of manufacturing the gas sensor array is higher, and the defective rate is low.

Preferably, the step of modulating physical property parameters of the conductive ink based on the aperture of the nozzle includes: base of

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

γ_inkthe surface tension of the ink is shown, rho is the density of the conductive ink, eta is the viscosity of the ink, D is the aperture of the nozzle, and Z ranges from 1 to 12. Through the calculation of printing stability and the calculation of the modulation physical property parameters, the physical property parameters of the liquid drops can be modulated in a targeted mode, and the printing material with the stable gas sensor array is obtained.

Preferably, the step of modulating physical property parameters of the conductive ink based on the aperture of the nozzle further comprises: and (3) modulating the surface tension and viscosity of the conductive ink to be modulated in a manner of adding an organic solvent until the surface tension and viscosity of the conductive ink reach the corresponding modulation range. The modulation of the conductive ink sold in the market is beneficial to shortening the modulation time and improving the modulation efficiency, so that the conductive ink with stable property can be quickly obtained, and the production efficiency of the gas sensor array can be improved.

Preferably, the step of optimizing the physical property parameters of the metal oxide particle suspension used for preparing the gas-sensitive film comprises: dispersing at least one metal oxide nano particle into a mixed solution of isopropanol and sec-butyl alcohol mixed according to a certain ratio, 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 aperture 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 always facilitated, and the production efficiency of the oxide particle suspension is also improved.

Preferably, the step of modulating the physical property parameters of the metal oxide particle suspension used for preparing the gas sensitive thin film comprises:

preparing zinc acetate alcohol solution into preset concentration and carrying out ultrasonic dispersion,

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

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

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

and re-dispersing the cleaned zinc acetate alcohol solution into a mixed solution of isopropanol and sec-butyl alcohol, and adding a proper amount of polyvinylpyrrolidone to adjust the viscosity. Through modulation metal oxide particle suspension, can obtain the suspension with inkjet printing equipment shower nozzle aperture looks adaptation, be favorable to obtaining the suspension that printing stability is better to make the gas sensitive film of printing can independently set up, do not have the printing phenomenon of wire drawing, adhesion, improve the sensitivity of the gas sensitive film of gas sensor array. The invention can further greatly reduce the reject ratio of the gas sensor array production.

Preferably, the method further comprises:

and heating the sensor array substrate printed with the interdigital electrode pattern in inert gas at a certain temperature for a certain time so as to volatilize the substrate into a film. The method is favorable for the rapid generation of the interdigital electrode, avoids the mixing effect with the subsequent gas-sensitive film, and improves the production efficiency of products.

Preferably, the method further comprises: after the metal oxide particle suspension is printed on the corresponding interdigital electrodes, the sensor array substrate is treated in an inert gas at a high temperature of 200-400 ℃ for at least one hour. The method is favorable for the rapid generation of the gas-sensitive film 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 ink-jet printing equipment with a pulse piezoelectric adjusting component, wherein the ink-jet printing equipment is provided with conductive ink and/or metal oxide particle suspension liquid, the physical property parameters of which are 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 ink-jet printing mode, fine-tuning pulse voltage variation parameters based on an introduced interdigital electrode pattern and a preset nozzle voltage pulse timing diagram by the ink-jet printing equipment to control liquid drop spraying parameters, and printing the conductive ink on the sensor array substrate at preset intervals; and after the interdigital electrode patterns are volatilized to form a film, the optimized metal oxide particle suspension is printed on the corresponding interdigital electrode patterns by the ink-jet printing equipment 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 printing liquid stability draft, the phenomenon of printing errors caused by droplet 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 physical property parameters of the conductive ink based on the aperture of the nozzle includes:

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

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

γ_inkis the surface tension of the ink, rho is the density of the ink, eta is the viscosity of the ink, and D is that of the nozzle

The aperture, Z, ranges from 1 to 12.

The invention relates to an ink-jet printing device based on a gas sensor array, wherein a method for modulating physical property parameters of conductive ink matched with the aperture of a spray head comprises the following steps: and (3) adding an organic solvent to the surface tension and viscosity of the conductive ink to be modulated until the surface tension and viscosity of the conductive ink reach the corresponding modulation range. The invention directly modulates the conductive ink sold in the market, which is beneficial to shortening the modulation time and improving the modulation efficiency, thereby quickly obtaining the conductive ink with stable property 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: a sensor array substrate, interdigital electrodes printed on the sensor array substrate by conductive ink according to preset intervals, and a gas-sensitive film formed on the corresponding interdigital electrode pattern by the optimized metal oxide particle suspension after the interdigital electrode pattern is volatilized to form a film,

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

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

γ_inkthe surface tension of the ink is shown, rho is the density of the conductive ink, eta 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 liquid drop ejection parameters by finely adjusting the pulse voltage variation parameters based on a preset nozzle voltage pulse timing chart.

Preferably, the modulation method of the surface tension and viscosity of the conductive ink is as follows: and (3) adding an organic solvent for modulation until the surface tension and the viscosity of the conductive ink reach the corresponding modulation range.

Preferably, the manner of evaporating the interdigital electrode pattern into a film includes: and heating the sensor array substrate printed with the interdigital electrode pattern in inert gas at a certain temperature for a certain time so as to volatilize the substrate into a film.

Preferably, the gas-sensitive film is formed in a manner including: after the metal oxide particle suspension is printed on the corresponding interdigital electrodes, the sensor array substrate is treated in an inert gas at a high temperature of 200-400 ℃ for at least one hour.

Preferably, the interval jet of the conductive ink forming the interdigital electrode is controlled in a manner that:

a time sequence chart of the voltage pulse of the spray head is set,

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

or fine tuning the speed and size of the voltage drop to obtain better liquid drop spraying effect, so that the liquid drops are not continuous when falling on the sensor array substrate to obtain accurate spacing distance.

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

when the pulse is less than 22V, the flying speed of the liquid drop is reduced sharply;

when the piezoelectric pulse is larger than 22V, the volume and the speed of the liquid drop are 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 physically characterizing the conductive ink comprises: nozzle-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 the viscosity of the conductive ink, wherein gamma_inkThe surface tension of the ink is shown, rho is the density of the conductive ink, eta 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 quantitative amount of polyvinylpyrrolidone is added to adjust the consistency of the suspension of metal oxide particles, wherein,

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

Preferably, the method further comprises:

and (3) modulating the surface tension and viscosity of the conductive ink to be modulated in a manner of adding an organic solvent until the surface tension and viscosity of the conductive ink reach the corresponding modulation range.

Preferably, the method for preparing the metal oxide particle suspension comprises the following steps:

and re-dispersing the cleaned zinc acetate alcohol solution into a mixed solution of isopropanol and sec-butyl alcohol, and adding a proper amount of polyvinylpyrrolidone to adjust the viscosity.

Drawings

FIG. 1 is a pulse voltage diagram illustrating an operating state of the showerhead of the present invention;

fig. 2 is a partial schematic view 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: a pulsed voltage.

Detailed Description

The following detailed description is made with reference to the accompanying drawings.

Interdigitated electrodes are electrodes having a periodic pattern in their faces, such as fingers or combs, that are used to create a capacitance associated with an electric field that can penetrate the material sample and 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: modulating a physical property parameter of the conductive ink and/or a physical property parameter of the metal oxide particle suspension adapted to an aperture of the showerhead based on the aperture of the showerhead.

S2: in the process of preparing at least one interdigital electrode on a sensor array substrate in an ink-jet printing mode, fine-tuning pulse voltage variation parameters based on a preset nozzle voltage pulse timing diagram to control liquid drop spraying parameters, and printing the conductive ink on the sensor array substrate at preset intervals.

S3: and after the interdigital electrode patterns are volatilized to form a film, printing the optimized metal oxide particle suspension on the corresponding interdigital electrode patterns so as to form the gas-sensitive film.

The conductive ink disclosed by the invention is mainly used for preparing an 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 the silver nano-particles is 25-40%, and the particle size is 50-100 nm. The silver ink is chosen with care to match its viscosity and surface tension to the inkjet printer head. The inkjet printing apparatus is preferably a material inkjet printer. For example, the ink jet printing apparatus is preferably a DMP2800 material ink jet printer

The method for modulating the physical property parameters of the conductive ink based on the aperture of the nozzle comprises the following steps: and determining the modulation range of the surface tension and the 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 the printing stability parameters are:

γ_inkthe surface tension of the ink is shown, rho is the density of the ink, eta is the viscosity of the ink, D is the aperture of the nozzle, and Z ranges from 1 to 12. Preferably, Z is in the range of 1 to 10. When Z is between 1 and 12, canThe formation of longer filaments during printing is reduced and the occurrence of discrete droplets is reduced.

In the numerical 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 droplets to reduce the resolution of printing.

For example, the Z value range of the conductive ink is preferably 2-5, which is beneficial to ensuring the printing stability, improving the electrode printing precision and preventing the adjacent electrodes from short circuit caused by discrete conductive liquid drops.

The preferable Z value range of the metal oxide particle suspension is 2-8, which is beneficial to preventing the suspension from blocking a spray head due to over-concentration, and meanwhile, the moderate concentration can ensure high-flux rapid printing, so that the uniform coverage of oxide particles in a sensing area is realized.

For example, the nozzle aperture D is 21.5um, the ink viscosity is 8-12 mPas, the surface tension is 28-33mN/m, and the ink density is 1g/cm³By way of example, an ink representing this property can achieve stable printing with a Z of 2.5 being calculated. Accordingly, for inkjet printing apparatuses of different-aperture heads, various physical properties of ink can be verified according to the Z design. Under the condition that the aperture of the nozzle is known, the conductive ink can be used for printing as long as the printing stability of the modulated conductive ink is within the range of 1-10.

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 of influence of the interfacial tension on the dispersed phase fluid, 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 the liquid drop can not be disturbed by air flow due to over-low initial speed and can not be deposited at a wrong position.

Therefore, by combining the common calculation of the calculation formula of the printing stability parameters and 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, even the speed range of the liquid drop can be calculated, and the preparation of the conductive ink and the metal oxide particle suspension with better printing stability is facilitated.

Under the condition that the conductive ink is not matched with the aperture of a nozzle of the ink-jet printing equipment, the surface tension and the viscosity of the conductive ink to be modulated are modulated in a mode of adding an organic solvent until the surface tension and the 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 parameters of the interdigital electrode of the present invention are: the width of each interdigital is 100um, the distance between adjacent interdigital is 50um, the number of the interdigital is 10 pairs, and the thickness of the electrode is 500nm-1 um.

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

s11: and introducing a preset interdigital electrode pattern into an ink-jet printer program.

S12: and setting a voltage pulse timing diagram of the spray head. An example of a timing diagram of the voltage pulses of the nozzles is shown in fig. 1.

S13: printing an interdigital electrode pattern on the sensor array substrate once according to a preset liquid drop interval, wherein the sensor array substrate is kept at a normal temperature in the printing process. Preferably, the liquid drop interval is preferably 25um, so that the liquid drops are not adhered, the printed interdigital electrode pattern is clear and not blurred, and the electric conductivity is good. The sensor array substrate is preferably ceramic, polyethylene terephthalate or polyimide.

S14: after the printing of the interdigital electrode is finished, the sensor array substrate is heated for a certain time at a certain temperature in inert gas, and the conductive ink is promoted to volatilize and form a film.

Preferably, after printing, the sensor array substrate is heated in an inert gas at 60 ℃ for 30 minutes to promote the conductive ink to volatilize into a film. At the temperature parameter and the time parameter, the conductive ink has high volatilization speed and short volatilization time, does not influence the physical property of the interdigital electrode, and forms an interdigital electrode pattern which is not deformed and is stable and the conductivity is not reduced.

Shown in FIG. 1 is a voltage pulse timing chart of a head of a conductive ink having a viscosity of 8 mPas and a surface tension of 33 mN/m. Fig. 1 is a pulse voltage timing chart of an operating state.

Preferably, the pulse amplitude is preferably 22V. The drop flight velocity decreases sharply when the pulse is less than 22V. The piezoelectric pulse is set to be 22V, so that stable jetting can be realized, a certain initial speed of liquid drops can be guaranteed, and the requirement of ink-jet printing is met. Preferably, the pulse amplitude may also be greater than 22V. When the piezoelectric pulse is more than 22V, the volume and the speed of the liquid drop are stable.

As shown in FIG. 1, the operating condition of the nozzle for ejecting a single drop of conductive ink requires 24.32us for a complete ejection. Firstly, the voltage is reduced to 0V, the piezoelectric element returns to the original position, and the ink is sucked into a cavity connected with the spray head. At 5.888us, the voltage rises at a constant speed, and the voltage is maintained when the voltage rises to the maximum amplitude, and at the moment, the ink is pushed out of the cavity to the outside of the spray head. The voltage was stepped down from 12.032us to prevent air suck back, first to 40% of the maximum amplitude of the second gradient voltage. At 18.176us, the voltage dropped from the second gradient voltage to the first gradient voltage, 25% of the maximum amplitude, and was maintained at 24.32us, the droplet separated relatively cleanly from the jet. For conductive ink with different viscosity or surface tension, the set voltage magnitude and duration are finally achieved by fine tuning the rising speed of the voltage rising edge. Or the parameters such as speed, size and the like when the voltage is reduced are finely adjusted, so that a better liquid drop spraying effect is obtained, liquid drops are discontinuous when falling on the sensor array substrate, an accurate spacing distance is obtained, and the interdigital electrodes without redundant liquid drops overflowing are avoided. For example, when the solution is too viscous, the voltage rising edge speed can be increased appropriately, and the time of the peak voltage can be prolonged, so that the droplets can be dropped quickly for printing.

As shown in fig. 1, in the showerhead off state, the voltage of the showerhead is maintained at about 25% of the maximum amplitude and remains constant. 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 the metal oxide particle suspension for preparing the gas-sensitive film of the present invention is exemplified by the step of preparing the zinc oxide quantum dot dispersion.

S21: and (3) preparing the zinc acetate alcohol solution into a preset concentration and performing ultrasonic dispersion. Preferably, the concentration of zinc acetate is 20-40 mg/mL.

S22: stirring and heating the zinc acetate alcohol solution in a water bath environment at a certain temperature. Preferably, the alcoholic zinc acetate solution is heated under stirring in a water bath environment of 80 ℃ for 2 hours. The water bath environment is favorable for the stability of the temperature environment. The temperature in this step is not limited to 80 degrees and may be 60 to 90 degrees.

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

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

S25: and re-dispersing the cleaned zinc acetate alcohol solution into a mixed solution of Isopropanol (Isopropanol) and sec-butyl alcohol (2-Butanol), and adding a proper amount of Polyvinylpyrrolidone (Polyvinylpyrrolidone) to adjust the viscosity, so that the viscosity and the surface tension of the zinc oxide quantum dot dispersion liquid are matched with the aperture of the spray head. Preferably, the mixing ratio of Isopropanol (Isopropanol) to sec-Butanol (2-Butanol) is 9: 1.

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

Preferably, the metal oxide particle suspension is not limited to the preparation 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 a gas-sensitive film comprises:

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

Specifically, the metal oxide particle suspension may be prepared by directly purchasing various metal oxide nanoparticles (including tin oxide, indium tin oxide, zinc oxide, titanium oxide, etc.) with a diameter of 100nm or less, re-dispersing into a mixed solution of isopropyl alcohol (isoproapanol) and sec-butyl alcohol (2-Butanol) (9: 1), and adding a proper amount of Polyvinylpyrrolidone (Polyvinylpyrrolidone) to adjust viscosity, so that the viscosity and surface tension of the metal oxide particle suspension match the pore size of the showerhead.

After the metal oxide particle suspension is printed on the corresponding interdigital electrodes, the sensor array substrate is treated in an inert gas at a high temperature of 200-400 ℃ for at least one hour. So set up, be favorable to volatilizing fast of metal oxide particle suspension. The temperature does not destroy the stability of the interdigital electrode. Preferably, after the metal oxide particle suspension is printed on the corresponding interdigital electrode, the metal oxide particle suspension is processed in an inert gas at a high temperature of 200-400 ℃ for 2 hours to form a gas-sensitive film, 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 ink jet printing apparatus is provided with a conductive ink and/or a suspension of metal oxide particles whose physical property parameters are adapted to the pore diameter 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 the variation of the pulse voltage 60 according to the pulse timing chart. The head is provided with a passage for introducing the conductive ink 10 or the metal oxide particle suspension. The conductive ink forms drops 30 with adjustable drop velocity in association with the change in the pulsed voltage. The droplets 30 are dropped onto the sensor array substrate to form interdigitated 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 ink-jet printing mode, the ink-jet printing device finely adjusts pulse voltage variation parameters based on an introduced interdigital electrode pattern and a preset nozzle voltage pulse timing diagram to control liquid drop spraying parameters, so that the dropping speed of liquid drops is matched with the moving speed of the sensor array substrate. And printing the conductive ink on the sensor array substrate according to a preset interval.

And after the interdigital electrode pattern is volatilized to form a film, a prepared metal oxide particle suspension liquid matched with the aperture of the spray head is introduced into the spray head of the ink-jet printing equipment. And printing the optimized metal oxide particle suspension on the corresponding interdigital electrode pattern, so that the metal oxide particle suspension is volatilized to form the gas-sensitive film.

In the present invention, the step of modulating physical property parameters of the conductive ink based on the aperture of the nozzle comprises:

and determining the modulation range of the surface tension and the 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 the content of the first and second substances,

γ_inkthe surface tension of the ink is shown, rho is the density of the ink, eta 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 physical property parameters of the conductive ink based on the aperture of the nozzle further comprises:

and (3) adding an organic solvent to the surface tension and viscosity of the conductive ink to be modulated until the surface tension and viscosity of the conductive ink reach the corresponding modulation range.

After the printing of the interdigital electrode is completed, the type of the prepared metal oxide particle suspension is not limited to one, and can be various. In the printing process of the gas-sensitive film, the metal oxide particle suspension drops according to a preset printing interval, and the interval range of the metal oxide particle suspension comprises at least one interdigital electrode. I.e. an interdigital electrode is present between the same metal oxide particle suspension. After dropping the different kinds of metal oxide particle suspension for two times, at least two gas sensitive films on the sensor array substrate are arranged in a staggered mode. In the same way, the ink jet printing device can print 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 device, the arrangement of the interdigital electrodes and the gas-sensitive film can be matrix array arrangement, or can be a plurality of arrays such as circular array arrangement, staggered array arrangement and the like with equal printing distances.

Preferably, the distance between the interdigital electrodes can be arranged at equal intervals or at non-equal intervals.

According to the invention, through the modulation of the physical property parameters of the conductive ink and the metal oxide particle suspension, the printing stability of the liquid drop is better. The ink-jet printing device based on the gas sensor array can adjust the dropping speed of the liquid drops through the pulse timing diagram and the fine adjustment of pulse parameters, so that the conductive ink is not adhered to the spray head, the formation of longer filaments in the printing process is reduced, and the occurrence of discrete liquid drops is reduced. Therefore, liquid drops are sprayed according to a certain dropping speed, so that the conducting circuit of the printed gas sensor array is clear, the gas-sensitive film is uniformly distributed, the obtained gas sensor array is high in sensing sensitivity, and gas components can be detected more quickly.

It should be noted that the above-mentioned embodiments are exemplary, and that those skilled in the art, having benefit of the present disclosure, may devise various arrangements that are within the scope of the present disclosure and that fall within the scope of the invention. It should be understood by those skilled in the art that the present specification and figures are illustrative only and are not limiting upon the claims. The scope of the invention is defined by the claims and their equivalents. The present description contains several inventive concepts, such as "preferably", "according to a preferred embodiment" or "optionally", each indicating that the respective paragraph discloses a separate concept, the applicant reserves the right to submit divisional applications according to each inventive concept.

Claims

1. A gas sensor array, comprising at least:

a substrate for a sensor array, the substrate having a plurality of sensor elements,

interdigital electrodes printed on a sensor array substrate at predetermined intervals by conductive ink, and

after the interdigital electrode pattern is volatilized to form a film, an air-sensitive film is formed 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 controls droplet ejection parameters by fine-tuning pulse voltage variation parameters based on preset head voltage pulse timing diagrams.

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

and (3) adding an organic solvent for modulation until the surface tension and the viscosity of the conductive ink reach the corresponding modulation range.

4. The gas sensor array according to any one of claims 1 to 3, wherein the interdigitated electrode pattern is evaporated to form a film by:

and heating the sensor array substrate printed with the interdigital electrode pattern in inert gas at a certain temperature for a certain time so as to volatilize the substrate into a film.

5. The gas sensor array according to any one of claims 1 to 4, wherein the gas-sensitive film is formed in a manner including: after the metal oxide particle suspension is printed on the corresponding interdigital electrodes, the sensor array substrate is treated in an inert gas at a high temperature of 200-400 ℃ for at least one hour.

6. The gas sensor array according to any one of claims 1 to 5, wherein the spaced ejection of the conductive ink forming the interdigital electrodes is controlled by:

a time sequence chart of the voltage pulse of the spray head is set,

7. The gas sensor array according to any one of claims 1 to 6, wherein the pulse amplitude of the pulse voltage timing diagram of the conductive ink is preferably 22V;

8. A printing solution preparation method of a gas sensor array is characterized in that the printing solution comprises conductive ink for printing an interdigital electrode pattern and metal oxide particle suspension for printing a gas-sensitive film; wherein the content of the first and second substances,

the step of physically characterizing the conductive ink comprises:

γ_inkis the surface tension of the ink, rho is the density of the conductive ink, eta is the viscosity of the ink, and D is the nozzle

The aperture of (1) and the range of Z is 1-12;

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

10. The method of claim 8 or 9, wherein the method of preparing a suspension of metal oxide particles comprises: