A multi-parameter perception flexible sensor and a preparation method thereof

Abstract

The application discloses a multi-parameter sensing flexible sensor and a preparation method thereof. The multi-parameter sensing flexible sensor comprises, from top to bottom, an upper insulating layer, an upper electrode layer, a sensitive film, a lower electrode layer and a lower insulating layer. The upper electrode layer comprises, from top to bottom, a first upper electrode, a first substrate and a first lower electrode. The lower electrode layer comprises, from top to bottom, a second upper electrode, a second substrate and a second lower electrode. The sensitive film is sensitive to humidity and pressure. The first upper electrode, the first lower electrode, the second upper electrode and / or the second lower electrode are sensitive to temperature. Temperature, pressure and humidity can be measured simultaneously.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of detection sensor, and particularly relates to a thin film sensor detection device for simultaneously detecting temperature, humidity and pressure parameters and not generating coupling between signals and a preparation method thereof. BACKGROUND

[0002] Human skin is a multi-sensing intelligent sensing system, which can sense various information such as external temperature, humidity and pressure, and transmit them to the nervous system of the brain. The brain processes the information and issues instructions to produce corresponding physiological responses to realize the interaction between human and environment. In recent years, with the rapid development of flexible electronics, flexible thin film sensors with human-like skin have emerged, which can capture temperature, humidity, pressure and other information of the environment or user like human skin. Due to the ability to simulate the sensing function of human skin, flexible thin film sensors have shown broad application prospects in wearable electronics, health monitoring, intelligent robots, environmental monitoring and other fields.

[0003] At present, the flexible sensor with single sensing function cannot meet the application requirements, so it is urgent to develop a multi-parameter sensing flexible sensor device. The existing multi-parameter sensing sensor solutions mainly include direct integration, that is, multiple single-sensing sensors are integrated together in a planar manner or stacked in layers. The disadvantage of this method is that the structure, preparation process and processing circuit are complex; another method is to construct special materials that can detect multiple information and output the same type of signal. The disadvantage of this method is poor signal selectivity and large signal coupling. SUMMARY

[0004] The present application provides a multi-parameter sensing flexible sensor and a preparation method, which can be used for simultaneously detecting temperature, humidity and pressure parameters without generating coupling between signals.

[0005] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0006] A multi-parameter sensing flexible sensor, comprising an upper insulating layer, an upper electrode layer, a sensitive thin film, a lower electrode layer and a lower insulating layer arranged in sequence from top to bottom, wherein the upper electrode layer comprises a first upper electrode, a first substrate and a first lower electrode arranged in sequence from top to bottom; and the lower electrode layer comprises a second upper electrode, a second substrate and a second lower electrode arranged in sequence from top to bottom.

[0007] The sensitive thin film is sensitive to humidity and pressure, and the first upper electrode, the first lower electrode, the second upper electrode and / or the second lower electrode are sensitive to temperature.

[0008] Further, a plurality of through holes are formed in the upper insulating layer and the upper electrode layer, and the through holes in the upper electrode layer are located directly below the through holes in the upper insulating layer.

[0009] Further, the upper and lower insulating layers are both PDMS films.

[0010] Further, the first upper electrode, the first lower electrode, the second upper electrode and the second lower electrode are all silver electrodes.

[0011] A preparation method of a multi-parameter sensing flexible sensor, comprising the following steps:

[0012] S1, preparing an upper insulating layer and a lower insulating layer;

[0013] S2, preparing an upper electrode layer and a lower electrode layer, and punching the upper electrode layer;

[0014] S3, preparing a P(VDF-TrFE) / ZnO / RGO sensitive film;

[0015] S4, sequentially laying the lower electrode layer, the sensitive film, the upper electrode layer and the upper insulating layer on the lower insulating layer, and mutually adhering and curing the upper and lower insulating layers where there are more layers than other layers, to obtain a multi-parameter sensing flexible sensor.

[0016] Further, S1 comprises the following steps:

[0017] S1.1, uniformly mixing PDMS prepolymer and curing agent in a ratio of (10-20):1;

[0018] S1.2, spin coating the solution prepared in S1.1 into a film and curing to obtain the upper and lower insulating layers;

[0019] S1.3, punching the upper insulating layer.

[0020] Further, step S1 comprises the following steps:

[0021] S2.1, uniformly mixing anhydrous ethanol, acetone, terpineol and dibutyl phthalate to obtain solution A;

[0022] S2.2, adding ethyl cellulose to the solution A prepared in S2.1 to obtain solution B;

[0023] S2.3, adding nano-silver powder to the solution B prepared in S2.2 to obtain silver conductive ink;

[0024] S2.4, printing the silver conductive ink on the upper and lower surfaces of the first substrate to form a double-layer electrode to obtain a first electrode layer, and screen printing the silver conductive ink on the upper and lower surfaces of the second substrate to form a double-layer electrode to obtain a second electrode layer, curing and sintering the first electrode layer and the second electrode layer to obtain the sintered first electrode layer and the lower electrode layer, and punching the first electrode layer to obtain an upper electrode layer;

[0025] In the steps S2.1, S2.2, S2.3, the mass ratio of each component of the silver conductive ink is as follows: 25-35% of anhydrous ethanol, 8-10% of acetone, 3.80-4.50% of terpineol, 3.90-4.60% of dibutyl phthalate, 2.30-2.90% of ethyl cellulose, and 45-55% of silver powder.

[0026] Further, in the step S2.4, the silver conductive ink is printed on the upper and lower surfaces of the first substrate and the second substrate by screen printing.

[0027] Further, the step S3 includes the following steps:

[0028] S3.1, adding P(VDF-TrFE) powder into N,N-dimethylformamide solution and stirring uniformly to obtain solution C, wherein the mass fraction of P(VDF-TrFE) powder in the solution C is 25-35%;

[0029] S3.2, adding nano-ZnO powder into the solvent and mixing uniformly to obtain solution D, wherein the mass fraction of ZnO powder in the solution D is 2.5-3.5%;

[0030] S3.3, adding the solution C into the solution D, wherein the ratio of the solution C to the solution D is (0.8-1.2):1, and mixing uniformly to obtain a spinning solution; transferring the spinning solution into a syringe in an electrospinning device, extruding the spinning solution by the syringe, adjusting the electrospinning parameters, so that the extruded spinning solution droplets form a stable jet under the action of the electrostatic field, the jet is stretched by the electric field force, the solution is volatilized and solidified, and a P(VDF-TrFE) / ZnO sensitive film is formed on a collection plate;

[0031] S3.4, placing the P(VDF-TrFE) / ZnO sensitive film obtained in S3.3 into an aqueous graphene oxide solution, so that the graphene oxide in the aqueous graphene oxide solution grows on the surface of the sensitive film;

[0032] S3.5, dissolving ascorbic acid powder in deionized water to obtain solution E, wherein the mass fraction of ascorbic acid powder in the solution E is 5-10%;

[0033] S3.6, placing the sensitive film after soaking in S3.4 into the solution E prepared in S3.5, and drying after reaction;

[0034] S3.7, repeating S3.5 and S3.6 until the reaction is complete, to obtain a P(VDF-TrFE) / ZnO / RGO sensitive film.

[0035] Further, in the step S3.2, the solvent is methyl ethyl ketone.

[0036] Compared with the prior art, the present application has at least the following beneficial technical effects:

[0037] The present application provides a new multi-parameter sensing flexible sensor, which assembles an electrode sensitive to temperature and a sensitive film sensitive to pressure and humidity to form a complete sensor.

[0038] The electrode resistance changes with temperature, and the output resistance signal changes when the temperature changes, constituting a resistance temperature sensor; the sensitive film is affected by pressure and humidity, and outputs a voltage signal and a capacitance signal when the pressure and humidity change, constituting a piezoelectric pressure sensor and a capacitive humidity sensor. The present application uses a double-layer electrode to avoid affecting the monitoring of the capacitive humidity sensor when the sensor is subjected to pressure. When the three environmental parameters change simultaneously, any change in a parameter will only cause a change in the corresponding output signal, and will not affect the output of the other two signals. Since the three output signals are different, the different environmental parameter changes can be quickly and accurately determined from the output signals, so the coupling effect between the signals is small and the signal selectivity is good.

[0039] Further, a through hole is provided in the upper insulating layer and the upper electrode layer to allow the moisture in the environment to quickly penetrate the sensitive film, improving the measurement response speed.

[0040] The preparation method, the prepared multi-parameter sensing flexible sensor structure and the preparation process of the present application are simple, can simultaneously monitor temperature, humidity and pressure changes, and output different measurement signals.

[0041] Further, the silver conductive ink configured in the present application is suitable for screen printing, and the sensitivity and linearity of the printed silver electrode for detecting temperature are good, so the silver conductive ink can be used as a resistance temperature sensor alone.

[0042] Further, the solvent for dissolving the nano-ZnO powder in the present application is methyl ethyl ketone, so that the ZnO powder is dissolved faster and more completely in the solvent, is uniformly dispersed, is more suitable for electrospinning, and avoids that the powder that is not completely dissolved or dispersed blocks the needle during electrospinning. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a schematic diagram of a multi-parameter sensing flexible sensor structure;

[0044] Figure 2 is a schematic diagram of a cross-sectional view of a multi-parameter sensing flexible sensor structure;

[0045] Figure 3 is a schematic diagram of a preparation process of a multi-parameter sensing flexible sensor;

[0046] Figure 4is a multi-parameter perception flexible sensor connection test schematic diagram.

[0047] In the drawings: 1 - upper insulating layer, 2 - upper electrode layer, 3 - sensitive film, 4 - lower electrode layer, 5 - lower insulating layer, 6 - first upper electrode, 7 - first substrate, 8 - first lower electrode, 9 - second upper electrode, 10 - second substrate, 11 - second lower electrode. DETAILED DESCRIPTION

[0048] In order to make the purpose and technical scheme of the present application clearer and more convenient to understand. The following will be further described in detail in combination with the drawings and examples, the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0049] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features with "first", "second" can be explicitly or implicitly included one or more features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more. In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0050] Reference Figure 1 and Figure 2 A multi-parameter perception flexible sensor, comprising, from top to bottom, an upper insulating layer 1, an upper electrode layer 2, a sensitive film 3, a lower electrode layer 4 and a lower insulating layer 5.

[0051] The upper insulating layer 1 and the lower insulating layer 5 are both PDMS films obtained by spin coating and drying of PDMS prepolymer. The upper insulating layer 1 has a hole structure; the upper electrode layer 2 is composed of a first upper electrode 6, a first substrate 7 and a first lower electrode 8 arranged from top to bottom. The upper electrode layer 2 has a hole structure, and the first upper electrode 6 and the first lower electrode 8 are both printed on the upper and lower surfaces of the first substrate 7 by screen printing technology using configured silver conductive ink; the sensitive film 3 is a P(VDF-TrFE) / ZnO / RGO sensitive film obtained by soaking and reducing after electrospinning of the configured spinning solution; the lower electrode layer 4 is composed of a second upper electrode 9, a second substrate 10 and a second lower electrode 11 arranged from top to bottom. The second upper electrode 9 and the second lower electrode 11 are both printed on the upper and lower surfaces of the second substrate 10 by screen printing technology using configured silver conductive ink.

[0052] The silver conductive ink used for printing the first upper electrode 6, the first lower electrode 8, the second upper electrode 9 and the second lower electrode 11 is sensitive to temperature.

[0053] The first substrate 7 and the second substrate 10 are both PI flexible substrates.

[0054] Referring to Figure 4 The two protruding pins of the second lower electrode 11 respectively lead out two wires to be connected to a resistance measuring device, so that the temperature change can be monitored and a resistance signal can be output; the first lower electrode 8 and the second upper electrode 9 respectively lead out one wire, which is connected to a voltage measuring device after connecting a conditioning circuit, so that the pressure change can be monitored and a voltage signal can be output; the first upper electrode 6 and the second lower electrode 11 respectively lead out one wire to be connected to a capacitance measuring device, so that the humidity change can be monitored and a capacitance signal can be output.

[0055] The system can simultaneously monitor the changes of temperature, humidity and pressure, and output different monitoring signals. The sensor structure and process are simple, the signal selectivity is good, and signal coupling does not occur.

[0056] When the environmental temperature changes, the second lower electrode 11 senses the temperature change, and the resistance changes accordingly, so that the resistance measuring device connected thereto outputs a resistance signal; when the sensor is pressed, the sensitive film polarizes and the electric charge is offset, so that a voltage difference is generated between the first lower electrode 8 and the second upper electrode 9, and after being amplified by the conditioning circuit, a voltage signal is output by the voltage measuring device; when the environmental humidity changes, the sensitive film 3 absorbs water molecules in the air, the dielectric constant changes, and the capacitance value between the first upper electrode 6 and the second lower electrode 11 changes, so that the capacitance measuring device connected thereto outputs a capacitance signal.

[0057] Referring to Figure 3 The preparation method of the multi-parameter sensing flexible sensor described above comprises the following steps:

[0058] S1, preparing the upper insulating layer 1 and the lower insulating layer 5.

[0059] S1.1, mixing the PDMS prepolymer and the curing agent in a ratio of (10-20):1, and magnetically stirring them uniformly;

[0060] S1.2, spin-coating the solution prepared in S1.1 into a film, and placing it in an oven for curing to obtain the upper insulating layer 1 and the lower insulating layer 5; the spin-coating parameters mainly include the rotation speed and the time, the rotation speed is 200 r / min, and the rotation time is 30 s; the curing parameters mainly include the curing temperature and the curing time, the curing temperature is 100℃, and the curing time is 60 min.

[0061] S1.3, perforating the upper insulating layer 1;

[0062] S2, preparing the upper electrode layer 2 and the lower electrode layer 4, and perforating the upper electrode layer 2.

[0063] S2.1, weighing appropriate amounts of anhydrous ethanol, acetone, terpineol, and dibutyl phthalate in sequence, mixing them, and magnetically stirring them uniformly to obtain solution A;

[0064] S2.2, weighing an appropriate amount of ethyl cellulose into the solution A prepared in S2.1, magnetically stirring for 30 min, and ultrasonically dispersing for 30 min, or until the ethyl cellulose is uniformly distributed in the solution A, to obtain solution B;

[0065] S2.3, finally weighing an appropriate amount of nano-silver powder into the solution B prepared in S2.2, magnetically stirring for 30 min, and ultrasonically dispersing for 30 min, or until the nano-silver powder is uniformly distributed in the solution B, to obtain silver conductive ink;

[0066] S2.4, screen-printing the prepared silver conductive ink on the upper and lower surfaces of the first substrate to form a double-layer electrode, obtaining the first electrode layer, screen-printing the prepared silver conductive ink on the upper and lower surfaces of the second substrate to form a double-layer electrode, obtaining the second electrode layer, and curing the first electrode layer and the second electrode layer at 100℃ for 60 min and sintering them at 300℃ for 120 min to obtain the sintered first electrode layer and the lower electrode layer 4, and perforating the sintered first electrode layer to obtain the upper electrode layer 2;

[0067] In steps S2.1, S2.2, and S2.3, the mass ratio of each component of the silver conductive ink is as follows: anhydrous ethanol 25%-35%, acetone 8%-10%, terpineol 3.80%-4.50%, dibutyl phthalate 3.90%-4.60%, ethyl cellulose 2.30%-2.90%, and silver powder 45%-55%.

[0068] S3. Preparing the P(VDF-TrFE) / ZnO / RGO sensitive film.

[0069] S3.1. Taking an appropriate amount of P(VDF-TrFE) powder and adding it to an N,N-dimethylformamide solution, and magnetically stirring at room temperature for 60 min to obtain solution C;

[0070] S3.2. Taking an appropriate amount of nano-ZnO powder and adding it to an acetone solution, and magnetically stirring for 60 min and ultrasonic dispersing for 60 min, or until the ZnO powder is uniformly distributed in the acetone solution to obtain solution D;

[0071] S3.3. Adding the solution C prepared in S3.1 to the solution D obtained in S3.2, wherein the ratio of solution C to solution D is (0.8-1.2):1, magnetically stirring for 30 min and ultrasonic dispersing for 30 min, or until the two solutions are uniformly mixed to obtain a spinning solution. The spinning solution is transferred to a syringe in an electrospinning device, the spinning solution is extruded by the syringe, and the electrospinning parameters are adjusted so that the extruded spinning solution droplets form a stable jet under the action of the electrostatic field. The jet is stretched by the electric field force, the solution is volatilized and solidified, and finally deposited on a collection plate to form a P(VDF-TrFE) / ZnO sensitive film;

[0072] The electrospinning parameters include a spinning liquid propelling speed, a spinning voltage, and a receiving distance. The propelling speed is 8-12 μL / min, the spinning voltage is 10.5-14 kV, and the receiving distance is 10-15 cm.

[0073] S3.4. Placing the P(VDF-TrFE) / ZnO sensitive film obtained in S3.3 into a 0.5-1.0% mass fraction graphene oxide aqueous solution, and soaking for 60 min to allow the graphene oxide (GO) to be fully adsorbed onto the P(VDF-TrFE) / ZnO sensitive film;

[0074] S3.5. Dissolving an appropriate amount of ascorbic acid powder in deionized water, and magnetically stirring until uniform to obtain solution E;

[0075] S3.6. Placing the soaked sensitive film in S3.4 into the solution E prepared in S3.5, and taking it out after sufficient reaction and placing it in an oven for drying. Part of the GO on the sensitive film will be reduced to reduced graphene oxide (RGO) by the ascorbic acid in the solution E;

[0076] S3.7. Repeating the operations of S3.5 and S3.6 multiple times until the reaction is complete, and finally obtaining a P(VDF-TrFE) / ZnO / RGO sensitive film.

[0077] S4. Packaging of the sensor

[0078] S4.1, in the actual preparation process, the upper and lower insulating layers 1 and 5 should be larger than the area of other layers. The same material PDMS prepolymer is used to coat the upper and lower insulating layers which are more than other layers. The lower electrode layer 4, the sensitive film 3, the upper electrode layer 2 and the upper insulating layer 1 are laid on the lower insulating layer 5 in turn. The upper insulating layer and the lower insulating layer which are more than other layers are bonded and solidified to obtain a multi-parameter sensing flexible sensor.

[0079] Example 1

[0080] A silver conductive ink for a multi-parameter sensing flexible sensor and a preparation method of an electrode thereof, comprising the following steps:

[0081] S1, a proper amount of anhydrous ethanol, acetone, terpineol and dibutyl phthalate are weighed and mixed, and then magnetically stirred for 5 min;

[0082] S2, a proper amount of ethyl cellulose is added to the prepared solution of S2.1, magnetically stirred for 30 min, and ultrasonically dispersed for 30 min;

[0083] S3, a proper amount of nano-silver powder is added to the prepared solution of S2.2, magnetically stirred for 30 min, and ultrasonically dispersed for 30 min;

[0084] S4, the prepared silver conductive ink is screen printed on the upper and lower surfaces of the PI substrate to form a double-layer electrode, and then low-temperature solidified at 100℃ for 60 min and high-temperature sintered at 300℃ for 120 min;

[0085] In S1, S2 and S3, the mass ratio of each component of the silver conductive ink is as follows: anhydrous ethanol 30%, acetone 8.80%, terpineol 4.30%, dibutyl phthalate 4.30%, ethyl cellulose 2.60%, and silver powder 50%.

[0086] Example 2

[0087] A silver conductive ink for a multi-parameter sensing flexible sensor and a preparation method of an electrode thereof, comprising the following steps:

[0088] S1, a proper amount of anhydrous ethanol, acetone, terpineol and dibutyl phthalate are weighed and mixed, and then magnetically stirred for 5 min;

[0089] S2, a proper amount of ethyl cellulose is added to the prepared solution of S2.1, magnetically stirred for 30 min, and ultrasonically dispersed for 30 min;

[0090] S3, a proper amount of nano-silver powder is added to the prepared solution of S2.2, magnetically stirred for 30 min, and ultrasonically dispersed for 30 min;

[0091] S4, screen printing the prepared silver conductive ink on the upper and lower surfaces of the PI substrate to form a double-layer electrode, low-temperature curing at 100 DEG C for 60 min, and high-temperature sintering at 300 DEG C for 120 min;

[0092] In S1, S2 and S3, the mass ratio of each component of the silver conductive ink is as follows: anhydrous ethanol 25%, acetone 10%, terpineol 3.80%, dibutyl phthalate 3.90%, ethyl cellulose 2.30%, and silver powder 55%.

[0093] Example 3

[0094] A silver conductive ink for a multi-parameter sensing flexible sensor and a preparation method of an electrode thereof, comprising the following steps:

[0095] S1, a certain amount of anhydrous ethanol, acetone, terpineol and dibutyl phthalate are weighed and mixed, and then magnetically stirred for 5 min;

[0096] S2, a certain amount of ethyl cellulose is weighed and added to the prepared solution of S2.1, magnetically stirred for 30 min, and ultrasonically dispersed for 30 min;

[0097] S3, a certain amount of nano-silver powder is weighed and added to the prepared solution of S2.2, magnetically stirred for 30 min, and ultrasonically dispersed for 30 min;

[0098] S4, screen printing the prepared silver conductive ink on the upper and lower surfaces of the PI substrate to form a double-layer electrode, low-temperature curing at 100 DEG C for 60 min, and high-temperature sintering at 300 DEG C for 120 min;

[0099] In S1, S2 and S3, the mass ratio of each component of the silver conductive ink is as follows: anhydrous ethanol 25%, acetone 10%, terpineol 3.80%, dibutyl phthalate 3.90%, ethyl cellulose 2.30%, and silver powder 55%.

[0100] Example 4

[0101] A sensitive film preparation method for a multi-parameter sensing flexible sensor, comprising the following steps:

[0102] S1, a certain amount of poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) powder is weighed and added to a N,N-dimethylformamide solution, and magnetically stirred at room temperature until completely dissolved to obtain solution C. The mass fraction of P(VDF-TrFE) powder in solution C is 25% to 35%;

[0103] S2, a certain amount of ZnO powder is weighed by using a precision balance and added into the acetone solution, wherein the volume ratio of the acetone solution to the N,N-dimethylformamide solution in S1 is (0.8-1.2):1, and the solution is magnetically stirred and ultrasonically dispersed at room temperature until completely dissolved to obtain solution D. In the solution D, the mass fraction of ZnO powder is 2.5%-3.5%.

[0104] S3, the solution C prepared in S1 is added into the solution D prepared in S2, and magnetically stirred until completely dissolved to obtain a spinning solution. The spinning solution is transferred into a syringe in an electrospinning device, and the spinning solution is extruded by using the syringe. The electrospinning parameters are adjusted so that the extruded spinning solution droplets form a stable jet under the action of the electrostatic field. The jet is stretched by the electric field force, the solution is volatilized and solidified, and finally deposited on a collection plate to form a P(VDF-TrFE) / ZnO sensitive film.

[0105] S4, the sensitive film obtained in S3 is placed in a 0.5%-1.0% graphene oxide aqueous solution. The graphene oxide in the solution grows on the surface of the sensitive film, causing the sensitive film to turn yellow. The soaking is continued until the color of the film no longer deepens, at which point the graphene oxide on the sensitive film reaches a saturation point.

[0106] S5, a certain amount of ascorbic acid powder is weighed by using a precision balance and dissolved in deionized water, and magnetically stirred until completely dissolved to obtain solution E. In the solution E, the mass fraction of ascorbic acid powder is 5%-10%.

[0107] S6, the sensitive film after soaking in S4 is placed in the solution E prepared in S5, and after the reaction is complete, it is taken out and dried in an oven.

[0108] S7, the operations of S5 and S6 are repeated several times until the color of the film no longer deepens, i.e., the reaction of ascorbic acid reducing graphene oxide is complete. Finally, a P(VDF-TrFE) / ZnO / RGO sensitive film, i.e., a poly(vinylidene fluoride-trifluoroethylene) / zinc oxide / reduced graphene oxide sensitive film, is obtained.

[0109] The electrospinning parameters in S3 include the spinning liquid propelling speed, the spinning voltage and the receiving distance. The propelling speed is 8-12 μL / min, the spinning voltage is 10.5-14 kV, and the receiving distance is 10-15 cm.

[0110] The sensitive film after reaction in S6 is dried in an oven for 20-30 min.

[0111] The sensitive film after reaction in S6 is dried in an oven at a temperature of 110-125℃.

[0112] Example 5

[0113] A method for preparing a sensitive film for a multi-parameter sensing flexible sensor, comprising the following steps:

[0114] S1, a certain amount of poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) powder is weighed using a precision balance and added to a N,N-dimethylformamide solution, and magnetically stirred at room temperature until completely dissolved, to obtain solution C. Among them, P(VDF-TrFE) powder accounts for 25% of the mass fraction of solution C;

[0115] S2, a certain amount of ZnO powder is weighed using a precision balance and added to an acetone solution, wherein the volume ratio of the acetone solution to the N,N-dimethylformamide solution in S1 is 0.8:1, and magnetically stirred and ultrasonically dispersed at room temperature until completely dissolved, to obtain solution D. Among them, ZnO powder accounts for 2.5% of the mass fraction of solution D;

[0116] S3, solution C configured in S1 is added to solution D configured in S2, wherein the ratio of solution C to solution D is 0.8:1, and magnetically stirred until completely dissolved, to obtain a spinning solution. The spinning solution is transferred to a syringe in an electrospinning device, and the spinning solution is extruded with the syringe, and the electrospinning parameters are adjusted, wherein the pushing speed is 8μL / min, the spinning voltage is 10.5kV, and the receiving distance is 10cm. The extruded spinning solution droplets form a stable jet under the action of the electrostatic field, the jet is stretched by the electric field force, the solution is volatilized and solidified, and finally deposited on the collection plate to form a P(VDF-TrFE) / ZnO sensitive film;

[0117] S4, the sensitive film obtained in S3 is placed in a 0.5% graphene oxide aqueous solution, and soaked until the film turns yellow and the color no longer deepens;

[0118] S5, a certain amount of ascorbic acid powder is weighed using a precision balance and dissolved in deionized water, and magnetically stirred until completely dissolved, to obtain solution E. Among them, ascorbic acid powder accounts for 5% of the mass fraction of solution E;

[0119] S6, the sensitive film after soaking in S4 is placed in solution E configured in S5, and after the reaction is complete, it is taken out and placed in an oven at a temperature of 100℃ for 30min;

[0120] S7, repeat the operations of S5 and S6 several times until the color of the film no longer deepens, i.e. the reaction is complete. Finally, a P(VDF-TrFE) / ZnO / RGO sensitive film is obtained.

[0121] Example 6

[0122] A method for preparing a sensitive film for a multi-parameter sensing flexible sensor, comprising the following steps:

[0123] S1, a certain amount of poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) powder is weighed using a precision balance and added to a N,N-dimethylformamide solution, and magnetically stirred at room temperature until completely dissolved, to obtain solution C. Among them, the mass fraction of P(VDF-TrFE) powder in solution C is 30%;

[0124] S2, a certain amount of ZnO powder is weighed using a precision balance and added to an acetone solution, wherein the volume ratio of the acetone solution to the N,N-dimethylformamide solution in S1 is 1:1, and magnetically stirred and ultrasonically dispersed at room temperature until completely dissolved, to obtain solution D. Among them, the mass fraction of ZnO powder in solution D is 3.0%;

[0125] S3, solution C prepared in S1 is added to solution D prepared in S2, wherein the ratio of solution C to solution D is 1:1, and magnetically stirred until completely dissolved, to obtain a spinning solution. The spinning solution is transferred to a syringe in an electrospinning device, and the spinning solution is extruded with the syringe, and the electrospinning parameters are adjusted, wherein the push speed is 10 μL / min, the spinning voltage is 12 kV, and the receiving distance is 12 cm. The extruded spinning solution droplets form a stable jet under the action of the electrostatic field, the jet is stretched by the electric field force, the solution is volatilized and solidified, and finally deposited on the collection plate to form a P(VDF-TrFE) / ZnO sensitive film;

[0126] S4, the sensitive film obtained in S3 is placed in a 0.8% graphene oxide aqueous solution, and soaked until the film turns yellow and the color no longer deepens;

[0127] S5, a certain amount of ascorbic acid powder is weighed using a precision balance and dissolved in deionized water, and magnetically stirred until completely dissolved, to obtain solution E. Among them, the mass fraction of ascorbic acid powder in solution E is 8%;

[0128] S6, the sensitive film after soaking in S4 is placed in solution E prepared in S5, and after the reaction is complete, it is taken out and placed in an oven at a temperature of 110°C for 25 min;

[0129] S7, repeat the operations of S5 and S6 several times until the color of the film no longer deepens, i.e. the reaction is complete. Finally, a P(VDF-TrFE) / ZnO / RGO sensitive film is obtained.

[0130] Example 7

[0131] A method for preparing a sensitive film for a multi-parameter perception flexible sensor, comprising the following steps:

[0132] S1, a certain amount of poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) powder was weighed using a precision balance and added to a N,N-dimethylformamide solution, and magnetically stirred at room temperature until completely dissolved, to obtain solution C. Among them, the mass fraction of P(VDF-TrFE) powder in solution C is 35%;

[0133] S2, a certain amount of ZnO powder was weighed using a precision balance and added to an acetone solution, wherein the volume ratio of the acetone solution to the N,N-dimethylformamide solution in S1 is 1.2:1, and magnetically stirred and ultrasonically dispersed at room temperature until completely dissolved, to obtain solution D. Among them, the mass fraction of ZnO powder in solution D is 3.5%;

[0134] S3, solution F configured in S1 was added to solution D configured in S2, wherein the ratio of solution C and solution D is 1.2:1, and magnetically stirred until completely dissolved, to obtain a spinning solution. The spinning solution was transferred to a syringe in an electrospinning device, and the spinning solution was extruded with the syringe, and the electrospinning parameters were adjusted, wherein the push speed was 12 μL / min, the spinning voltage was 14 kV, and the receiving distance was 15 cm. The extruded spinning solution droplets formed a stable jet under the action of the electrostatic field, the jet was stretched by the electric field force, the solution was volatilized and solidified, and finally deposited on the collection plate to form a P(VDF-TrFE) / ZnO sensitive film;

[0135] S4, the sensitive film obtained in S3 was placed in a 1.0% aqueous solution of graphene oxide, and soaked until the film turned yellow and the color no longer deepened;

[0136] S5, a certain amount of ascorbic acid powder was weighed using a precision balance and dissolved in deionized water, and magnetically stirred until completely dissolved, to obtain solution E. Among them, the mass fraction of ascorbic acid powder in solution E is 10%;

[0137] S6, the sensitive film after soaking in S4 was placed in solution E configured in S5, and after the reaction was complete, it was taken out and placed in an oven at a temperature of 120°C for 20 min;

[0138] S7, repeat the operations of S5 and S6 several times until the color of the film no longer deepens, i.e. the reaction is complete. Finally, a P(VDF-TrFE) / ZnO / RGO sensitive film is obtained.

[0139] Example 8

[0140] The difference between this example and Example 5 is only the solvent in step S2. In this example, methyl ethyl ketone is used as the solvent, i.e. methyl ethyl ketone is used instead of acetone solution. When this solvent is used, the ZnO powder is dissolved more quickly and completely in the solvent, and is uniformly dispersed, which is more suitable for electrospinning, avoiding the needle being blocked by the powder that is not completely dissolved or dispersed during electrospinning.

[0141] Example 9

[0142] The difference between this embodiment and embodiment 6 is only the solvent in step S2, the solvent used in this embodiment is methyl ethyl ketone, when using this solvent, the ZnO powder is dissolved faster and more completely in the solvent, and the dispersion is more uniform, which is more suitable for electrospinning, avoiding the incomplete dissolution or dispersion of the powder in the process of electrospinning.

[0143] Example 10

[0144] The difference between this embodiment and embodiment 7 is only the solvent in step S2, the solvent used in this embodiment is methyl ethyl ketone, when using this solvent, the ZnO powder is dissolved faster and more completely in the solvent, and the dispersion is more uniform, which is more suitable for electrospinning, avoiding the incomplete dissolution or dispersion of the powder in the process of electrospinning.

[0145] Example 11

[0146] A building method of a multi-parameter sensing flexible sensing system, comprising the following steps:

[0147] S1, the second lower electrode 11 is respectively led out two wires and connected to a resistance measuring device, to form a resistance temperature sensor;

[0148] S2, the first lower electrode 8 and the second upper electrode 9 are respectively led out a wire, connected to a conditioning circuit and then connected to a voltage measuring device, to form a "sandwich" type piezoelectric pressure sensor;

[0149] S3, the first upper electrode 6 and the second lower electrode 11 are respectively led out a wire and connected to a capacitance measuring device, to form a "sandwich" type capacitive humidity sensor.

[0150] Example 12

[0151] A detection method of a multi-parameter sensing flexible sensing system, comprising the following steps:

[0152] S1, the multi-parameter sensing flexible sensing system is built according to the method described in embodiment 8;

[0153] S2, the resistance temperature sensor in the multi-parameter sensing flexible sensing system is used to measure temperature, the piezoelectric pressure sensor is used to measure pressure, and the capacitive humidity sensor is used to measure humidity, so as to avoid signal coupling and other problems.

[0154] The working principle of the application is as follows:

[0155] Firstly, the silver electrode in the application is screen printed by special silver conductive ink. Most of the silver conductive ink on the market is difficult to meet the requirements of being suitable for screen printing technology, and having good sensitivity and linearity of temperature detection. Therefore, the silver conductive ink configured in the application is suitable for screen printing, and the printed silver electrode has good sensitivity and linearity of temperature detection, and can be used as a resistance temperature sensor. When the ambient temperature changes, the resistance of the silver electrode changes, and two lead wires are respectively drawn to output the resistance signal.

[0156] Secondly, in the design and preparation of the sensitive film, P(VDF-TrFE) and ZnO belong to piezoelectric materials and are sensitive to pressure. When the sensitive film is pressed, polarization phenomenon occurs between the upper and lower layers, the charge shifts to generate a voltage difference. Therefore, the sensitive film, the first lower electrode 8 and the second upper electrode 9 form a “sandwich” type piezoelectric pressure sensor, which can output a voltage signal when pressure is applied, in combination with the subsequent conditioning circuit.

[0157] Finally, RGO in the sensitive film is sensitive to humidity. When the ambient humidity changes, the sensitive film absorbs water molecules in the environment, the dielectric constant changes, and the capacitance between the upper and lower plates changes. Therefore, the sensitive film, the first upper electrode 6 and the second electrode 11 form a “sandwich” type capacitive humidity sensor, which outputs a capacitance signal.

[0158] The purpose of the double-layer electrode layer is that when the sensor is subjected to pressure, the sensitive film undergoes polarization phenomenon, and the sensitive film tends to be conductive, which affects the monitoring of the capacitive humidity sensor. Therefore, the piezoelectric pressure sensor and the capacitive humidity sensor cannot share a pair of electrodes, and the PI substrate of the electrode layer is an insulator, which can avoid the mutual influence between the two different parameter monitoring. In addition, the design of the upper insulating layer and the upper electrode layer is mainly for the application of the capacitive humidity sensor, in order to quickly allow the moisture in the environment to infiltrate the sensitive film, so that the upper insulating layer and the upper electrode layer need to be punched.

[0159] The above specific embodiments only describe the preferred embodiments of the application, and do not limit the protection scope of the application. Without departing from the design concept and spirit of the application, various modifications, substitutions and improvements of the technical solutions of the application made by those skilled in the art according to the description and drawings of the application should belong to the protection scope of the application. The protection scope of the application is determined by the claims.

Claims

1. A multi-parameter sensing flexible sensor, characterized in that, The device includes an upper insulating layer (1), an upper electrode layer (2), a sensitive film (3), a lower electrode layer (4), and a lower insulating layer (5) arranged sequentially from top to bottom. The upper electrode layer (2) includes a first upper electrode (6), a first substrate (7), and a first lower electrode (8) arranged sequentially from top to bottom. The lower electrode layer (4) includes a second upper electrode (9), a second substrate (10), and a second lower electrode (11) arranged sequentially from top to bottom. The sensitive film (3) is a P(VDF-TrFE) / ZnO / RGO sensitive film, which is sensitive to humidity and pressure. The first upper electrode (6), the first lower electrode (8), the second upper electrode (9) and / or the second lower electrode (11) are sensitive to temperature. Two wires are led out from the two protruding pins of the second lower electrode (11) to connect to the resistance measuring device to monitor temperature changes and output resistance signals; one wire is led out from the first lower electrode (8) and the second upper electrode (9) to connect to the voltage measuring device after connecting to the conditioning circuit to monitor pressure changes and output voltage signals; one wire is led out from the first upper electrode (6) and the second lower electrode (11) to connect to the capacitance measuring device to monitor humidity changes and output capacitance signals.

2. The multi-parameter sensing flexible sensor according to claim 1, characterized in that, The upper insulating layer (1) and the upper electrode layer (2) are provided with a plurality of through holes, and the through holes on the upper electrode layer (2) are located directly below the through holes of the upper insulating layer (1).

3. The multi-parameter sensing flexible sensor according to claim 1, characterized in that, Both the upper insulating layer (1) and the lower insulating layer (5) are PDMS films.

4. The multi-parameter sensing flexible sensor according to claim 1, characterized in that, The first upper electrode (6), the first lower electrode (8), the second upper electrode (9), and the second lower electrode (11) are all silver electrodes.

5. The method for fabricating a multi-parameter sensing flexible sensor according to claim 1, characterized in that, Includes the following steps: S1. Prepare the upper insulating layer (1) and the lower insulating layer (5); S2. Prepare the upper electrode layer (2) and the lower electrode layer (4), and punch holes in the upper electrode layer (2); S3. Preparation of P(VDF-TrFE) / ZnO / RGO sensitive films; S4. Lay the lower electrode layer (4), sensitive film (3), upper electrode layer (2) and upper insulating layer (1) on the lower insulating layer (5) in sequence. The upper insulating layer (1) and the lower insulating layer (5) are bonded and solidified together in places where there are more layers than other layers, to obtain a multi-parameter sensing flexible sensor.

6. The method for fabricating a multi-parameter sensing flexible sensor according to claim 5, characterized in that, Step S1 includes the following steps: S1.1: Mix the PDMS prepolymer and curing agent evenly in a ratio of (10~20):1; S1.2: Spin-coating the solution prepared in S1.1 into a film and curing it to obtain an upper insulating layer (1) and a lower insulating layer (5); S1.3: Drill holes in the upper insulating layer (1).

7. The method for fabricating a multi-parameter sensing flexible sensor according to claim 5, characterized in that, Step S1 includes the following steps: S2.

1. Mix anhydrous ethanol, acetone, terpineol and dibutyl phthalate evenly to obtain solution A; S2.2 Add ethyl cellulose to solution A prepared in S2.1 to obtain solution B; S2.3 Add nano-silver powder to solution B prepared in S2.2 to obtain silver conductive ink; S2.

4. Silver conductive ink is printed on the upper and lower surfaces of the first substrate to form a double-layer electrode, and a first electrode layer is obtained. Silver conductive ink is screen printed on the upper and lower surfaces of the second substrate to form a double-layer electrode, and a second electrode layer is obtained. The first electrode layer and the second electrode layer are cured and sintered to obtain a sintered first electrode layer and a lower electrode layer (4). The first electrode layer is punched to obtain an upper electrode layer (2). In steps S2.1, S2.2, and S2.3, the mass percentages of each component in the silver conductive ink are as follows: anhydrous ethanol 25%~35%, acetone 8%~10%, terpineol 3.80%~4.50%, dibutyl phthalate 3.90%~4.60%, ethyl cellulose 2.30%~2.90%, and silver powder 45%~55%.

8. The method for fabricating a multi-parameter sensing flexible sensor according to claim 7, characterized in that, In step S2.4, silver conductive ink is printed on the upper and lower surfaces of the first and second substrates using screen printing.

9. The method for fabricating a multi-parameter sensing flexible sensor according to claim 5, characterized in that, Step S3 includes the following steps: S3.1 Add P(VDF-TrFE) powder to N,N-dimethylformamide solution and stir until homogeneous to obtain solution C, wherein P(VDF-TrFE) powder accounts for 25%~35% of the mass fraction of solution C; S3.2 Add nano ZnO powder to the solvent and mix evenly to obtain solution D, wherein the ZnO powder accounts for 2.5%~3.5% of the mass fraction of solution D; S3.3 Add solution C to solution D, with a ratio of solution C to solution D of (0.8~1.2):1, and mix thoroughly to obtain a spinning solution; transfer the spinning solution to a syringe in the electrospinning equipment, and use the syringe to extrude the spinning solution. Adjust the electrospinning parameters so that the extruded spinning solution droplets form a stable jet under the action of the electrostatic field. The jet is stretched by the electric field force, the solution evaporates and solidifies, and is deposited on the collecting plate to form a P(VDF-TrFE) / ZnO sensitive film; S3.

4. Immerse the P(VDF-TrFE) / ZnO sensitive film obtained in S3.3 in an aqueous solution of graphene oxide, so that the graphene oxide in the aqueous solution will grow on the surface of the sensitive film. S3.5 Dissolve ascorbic acid powder in deionized water to obtain solution E, wherein the ascorbic acid powder accounts for 5% to 10% of the mass fraction of solution E; S3.6 Place the sensitive membrane soaked in S3.4 into solution E prepared in S3.5, react, and then dry. S3.7, S3.5 and S3.6 are repeated until the reaction is complete, and a P(VDF-TrFE) / ZnO / RGO sensitive film is obtained.

10. The method for fabricating a multi-parameter sensing flexible sensor according to claim 9, characterized in that, In step S3.2, the solvent is methyl ethyl ketone.

Images