A piezoelectric gel-based tactile sensing synapse and a preparation method thereof

Abstract

The application discloses a kind of touch perception synapse based on piezoelectric gel and its preparation method, using piezoelectric gel to convert pressure signal into electrical signal;Piezoelectric gel has the advantages of response sensitivity, biocompatibility, piezoelectric signal is obvious, can effectively convert transient pressure signal into voltage signal;By regulating LiTFSI concentration, piezoelectric gel can have different transient response characteristics to pressure, and can be selected for different application scenarios;The first transistor has a large memory window, and has a high sensitivity pressure signal-electrical signal conversion function, which can convert the transient pressure signal into an electrical current signal output, for subsequent processing;The second transistor has a transconductance of up to 104, and can accurately collect and amplify the piezoelectric signal generated by the first transistor;The manufacturing process uses simple processes such as evaporation and spin coating, which is easy to manufacture in large quantities, has a high yield, and is easy to commercialize.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of transistors and sensing technology, and particularly relates to a piezoelectric gel-based tactile perception synapse and a preparation method thereof. BACKGROUND

[0002] Organic electrochemical transistors (OECTs) have attracted extensive attention in the field of bioelectronics due to their unique characteristics and excellent performance. OECTs use organic semiconductors as channel materials, which can not only conduct electrons but also conduct ions, making them an ideal bridge for converting ionic signals into electrical signals. Their high transconductance characteristics enable them to effectively amplify weak signals, while their low driving voltage and high biocompatibility make them valuable in biomedical sensors, neural interfaces, and flexible electronic devices. In addition, due to the similarity between the characteristics of OECTs in ion-electron mixed conduction and the working mechanism of biological neurons, OECTs also have great potential in simulating biological neural systems and developing bionic devices.

[0003] Pressure sensors are an integral part of modern electronic technology and are widely used in medical monitoring, artificial intelligence, robotics, wearable devices, and other fields, especially in the development of bionic electronic skin. Bionic electronic skin can sense external pressure, vibration, and tactile information by mimicking the mechanical sensing function of human skin, providing strong technical support for the development of flexible electronics and artificial intelligence. However, existing pressure sensing technology often faces the trade-off between sensitivity, resolution, and dynamic response capability, and how to further improve the performance of sensors remains an important direction for current technology development.

[0004] Therefore, it is necessary to develop a piezoelectric gel-based tactile perception synapse and a preparation method thereof to solve the above problems. SUMMARY

[0005] The purpose of the present application is to design a piezoelectric gel-based tactile perception synapse and a preparation method thereof to solve the above problems.

[0006] The present application achieves the above-mentioned purpose through the following technical solutions:

[0007] A piezoelectric gel-based tactile sensing synapse comprises a first transistor and a second transistor, a first source, a first gate of the first transistor, and a second source, a second gate of the second transistor are disposed on a substrate, a first semiconductor is disposed above the first source, a first drain is disposed above the first semiconductor, a second semiconductor is disposed above the second source, a second drain is disposed above the second semiconductor, the second gate and the first drain are connected, and a piezoelectric gel is disposed between the first gate and the first source; an ionic liquid gel is disposed between the first gate and the channel and between the second gate and the channel.

[0008] A preparation method of a piezoelectric gel-based tactile sensing synapse comprises the following steps:

[0009] Step 1: drying treatment is performed on the cleaned substrate;

[0010] Step 2: a bottom electrode of a specific shape is evaporated on the dried substrate using a mask method, and the bottom electrode comprises a first source, a first gate, a second source, and a second gate;

[0011] Step 3: a semiconductor material doped with a photo-crosslinking agent is spin-coated on the silicon wafer, and then patterned semiconductor regions are obtained by mask exposure and cleaning;

[0012] Step 4: a top electrode is evaporated using a mask method, and the top electrode comprises a first drain and a second drain;

[0013] Step 5: Ag or AgCl dispersion liquid is added dropwise between the first gate and the second gate, and then annealing is performed to form Ag or AgCl gates;

[0014] Step 6: ionic liquid gel is added dropwise between the first gate and the second gate and the channel, piezoelectric gel is added dropwise between the first gate and the first source, and photo-curing is performed;

[0015] Step 7: the device is packaged.

[0016] Preferably, the thickness of the semiconductor material is 200-500 nm.

[0017] Preferably, the top electrode is gold with a thickness of 80 nm.

[0018] Preferably, the piezoelectric gel is prepared by mixing PVDF-HFP, LiTFSI, and polypropylene carbonate, and by casting.

[0019] Preferably, the semiconductor material is at least one of Pg2T-T, gdpp-g2t, pedot:pss, and BBL.

[0020] Preferably, the crosslinking agent is PEGDA.

[0021] The application has the advantages that:

[0022] In the application, a piezoelectric gel is used to convert a pressure signal into an electrical signal. The piezoelectric gel has the advantages of high response sensitivity, biocompatibility and obvious piezoelectric signal, and can effectively convert a transient pressure signal into a voltage signal.

[0023] In the application, by adjusting the LiTFSI concentration, the piezoelectric gel can have different transient response characteristics to pressure, and can be selected according to different application scenarios.

[0024] In the application, the first transistor has a large memory window and a high-sensitivity pressure signal-electrical signal conversion function, can convert a transient pressure signal into a current signal output, and is convenient for subsequent processing.

[0025] In the application, the second transistor has a transconductance as high as 104, and can accurately collect and amplify the piezoelectric signal generated by the first transistor.

[0026] In the application, the manufacturing process uses simple processes such as evaporation and spin coating, is easy to manufacture in large areas, has a high yield, and is easy to commercialize. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 FIG. 1 is a structural schematic diagram of a tactile perception synapse based on a piezoelectric gel in the application;

[0028] Figure 2 FIG. 2 is a transfer curve of the first transistor in the application;

[0029] Figure 3 FIG. 3 is a transfer curve of the second transistor in the application;

[0030] Figure 4 FIG. 4 is an output response of pressing the gate region of the first transistor in the application;

[0031] Figure 5 FIG. 5 is an output response of pressing the channel region of the first transistor in the application;

[0032] Figure 6 FIG. 6 is an output response of the first transistor under periodic pressure in the application. The output response schematic diagram of applying a periodic force to the channel region of the transistor 1; wherein A is time-pressure; B is time-output current.

[0033] Explanation of reference numerals in the drawings: 1-second transistor, 2-substrate, 3-second source, 4-second semiconductor, 5-second drain, 6-second gate, 7-ionic liquid gel, 8-first transistor, 9-first source, 10-first semiconductor, 11-first drain, 12-first gate, 13-piezoelectric gel. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative work fall within the scope of protection of the present application.

[0036] It should be noted that: similar reference numerals and letters indicate similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0037] In the description of the present application, it should be understood that the terms "upper", "lower", "inner", "outer", "left", "right", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly placed when the product of the present application is used, or the orientation or positional relationship commonly understood by those skilled in the art, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element 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.

[0038] In addition, the terms "first", "second", etc. are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0039] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "provided", "connected" and the like should be understood broadly, for example, "connected" can be fixedly connected, or detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of 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.

[0040] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0041] As Figure 1As shown, a piezoelectric gel-based tactile sensing synapse includes a first transistor 8 and a second transistor 1, a first source 11 of the first transistor 8, a first gate 12, and a second source 3 of the second transistor 1 are disposed on a substrate 2, a first semiconductor 10 is disposed above the first source 9, a first drain 11 is disposed above the first semiconductor 10, a second semiconductor 4 is disposed above the second source 3, a second drain 5 is disposed above the second semiconductor 4, the second gate 6 and the first drain 11 are connected, and a piezoelectric gel 13 is disposed between the first gate 12 and the first source 9; an ionic liquid gel 7 is disposed between the first gate 12 and the channel, and between the second gate 6 and the channel.

[0042] A preparation method of a piezoelectric gel-based tactile sensing synapse includes the following steps:

[0043] Step 1: dry treatment is performed on the cleaned substrate;

[0044] Step 2: a mask method is used to evaporate a bottom electrode of a specific shape on the dried substrate, and the bottom electrode includes a first source, a first gate, a second source, and a second gate;

[0045] Step 3: a semiconductor material doped with a photo-crosslinking agent is spin-coated on the silicon wafer, and then a mask method is used for exposure and cleaning to obtain a patterned semiconductor region;

[0046] Step 4: a top electrode including a first drain and a second drain is evaporated using a mask method;

[0047] Step 5: Ag or AgCl dispersion liquid is added dropwise between the first gate and the second gate, and then annealing is performed to form Ag or AgCl gates;

[0048] Step 6: ionic liquid gel is added dropwise between the first gate and the second gate and the channel, and piezoelectric gel is added dropwise between the first gate and the first source, and then photo-curing is performed;

[0049] Step 7: the device is packaged.

[0050] The bottom electrode is chromium with a thickness of 3 nm and gold with a thickness of 80 nm, the semiconductor layer has a thickness of 200-500 nm, the top electrode is gold with a thickness of 80 nm, and the piezoelectric gel is fixed in a size of 10 mm×3 mm×1 mm (length×width×height) by a PDMS well.

[0051] The piezoelectric gel is mixed by PVDF-HFP, LiTFSI, and polypropylene carbonate, and is formed into a specific shape by a casting method.

[0052] The electrodes are prepared by using a metal mask plate with a pattern to evaporate, which has the advantages of simple operation process, adjustable electrode thickness, uniform film formation, etc. and can ensure the yield in mass production. In order to enhance the adhesion strength of gold and silicon substrate, a certain thickness of chromium is evaporated as a transition layer at the bottom of the gold electrode.

[0053] The semiconductor layer adopts an organic polymer material with good transmission characteristics, good chemical stability and low threshold voltage, such as one or more combinations of Pg2T-T, gdpp-g2t, pedot:pss, BBL, etc. The organic semiconductor layer material of the application is preferably Pg2T-T.

[0054] The gate of the transistor is solidified by dropping Ag / AgCl slurry and annealing at a suitable temperature. The silver / silver chloride gate has a lower chemical potential than gold, which can more effectively drive the ion in the electrolyte with the gate voltage and reduce the threshold voltage.

[0055] The crosslinking agent of the semiconductor layer is PEGDA, which can undergo polymerization under the irradiation of 280nm ultraviolet light, solidify the organic semiconductor material, and form a specific semiconductor pattern.

[0056] Example 1

[0057] The preparation method of the piezoelectric gel-based tactile perception synapse is as follows:

[0058] Step 1: ultrasonic cleaning of the silicon substrate with detergent, deionized water, isopropanol, and then drying treatment;

[0059] Step 2: on the dried silicon substrate, use a metal mask plate with a specific pattern to evaporate a Cr transition layer with a thickness of 3nm and gold as a bottom electrode with a thickness of 80nm.

[0060] Step 3: ultraviolet irradiation treatment of the silicon wafer with the bottom electrode for 10min to enhance the hydrophilicity of the silicon wafer and ensure the adhesion of the semiconductor layer on the silicon wafer.

[0061] Step 4: spin coating the organic semiconductor solution on the silicon wafer treated with ultraviolet light at a speed of 3000rpm. In the present application, Pg2T-T is dissolved in chloroform at a concentration of 10mg / ml to form a solution, and DA is dissolved in chloroform at a concentration of 20mg / ml to form a solution, and then mixed in a volume ratio of 2:1. After spin coating, use 280nm ultraviolet light to pass through the mask plate for 140 seconds, then use chloroform to clean the unexposed part, leaving the patterned semiconductor layer.

[0062] Step 5: use a metal mask plate with a specific pattern to evaporate gold as a top electrode with a thickness of 3nm and 80nm.

[0063] Step 6: Drop Ag / AgCl paste on the gate of the first and second transistors, anneal at 60 degree Celsius for 10 minutes.

[0064] Step 7: Drop electrolyte gel between the Ag / AgCl gate and organic semiconductor of the second transistor, and let it dry naturally at room temperature. The electrolyte gel is prepared by first dissolving PVDF-co-HFP in acetone at 12.5 wt / wt%, and then mixing [EMIM][TFSI] with PVDF-co-HFP at a volume ratio of 9:1. Figure 3 As shown in FIG. 2, the second transistor has an on-off ratio of over 10 5 and a high transconductance of nearly 0.2 S.

[0065] Step 7: Cast piezoelectric gel between the gate and organic semiconductor of the first transistor in-situ through the PDMS well, and let it dry naturally at room temperature. To prepare the piezoelectric gel, dissolve LiTFSI in propylene carbonate at 3 mol / L; dissolve PVDF-co-HFP in acetone at 7.5 wt / wt%, and then mix 5 mL of LiTFSI solution with 33.3 g of PVDF-co-HFP.

[0066] Example 2

[0067] The difference from Example 1 is that in Step 7, LiTFSI is dissolved in propylene carbonate at 2 mol / L.

[0068] Example 3

[0069] The difference from Example 1 is that in Step 7, LiTFSI is dissolved in propylene carbonate at 1 mol / L.

[0070] Example 4

[0071] The difference from Example 1 is that in Step 7, LiTFSI is dissolved in propylene carbonate at 0.5 mol / L.

[0072] First, cast piezoelectric gel with a length of 10 mm, a width of 3 mm, and a thickness of 1 mm, test its piezoelectric effect, use weights to exert different pressures on the piezoelectric gel, connect the pressed area to the positive electrode of the test table, and measure the voltage output of the piezoelectric gel in the non-pressed area. The results are shown in Table 1:

[0073]

[0074] Subsequently, cast piezoelectric gel with a length of 10 mm, a width of 3 mm, and a thickness of 1 mm in the electrolyte region of the first transistor. Measure the transfer curve of the first transistor as shown in FIG. 3. Figure 2

[0075] ​During the test, the source of the first transistor is connected to a 0.5V power supply, the gate of the first transistor is connected to a 0.4V power supply, the drain is left open, the source of the second transistor is connected to a 0.5V power supply, and the drain of the second transistor is connected to ground.

[0076] The following tests were performed on Example 1:

[0077] A pressure of 4N was applied to the channel region of the first transistor for 0.1s, and the change in drain current output from the second transistor was observed as shown in Figure 4 A significant pressure-induced current output was observed, and the drain current remained higher than the initial state after the pressure was removed.

[0078] A pressure of 4N was applied to the channel region of the first transistor for 0.1s, and the change in drain current output from the second transistor was observed as shown in Figure 5 A significant pressure-induced current output was observed, and the drain current remained lower than the initial state after the pressure was removed.

[0079] A sinusoidal pressure of 0-4N was applied to the electrolyte region of the first transistor for 5s, and the change in drain current output from the second transistor was observed as shown in Figure 6 The output current of the second transistor continuously decreased under the action of the periodic pressure.

[0080] The above only describes preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A tactile sensing synapse based on piezoelectric gel, characterized in that: The invention comprises a first transistor and a second transistor, wherein the first source and the first gate of the first transistor, and the second source and the second gate of the second transistor are all arranged on a substrate, the first semiconductor is arranged above the first source, the first drain is arranged above the first semiconductor, the second semiconductor is arranged above the second source, the second drain is arranged above the second semiconductor, the second gate is connected to the first drain, and a piezoelectric gel is arranged between the first gate and the first source; an ionic liquid gel is arranged between the first gate and the channel, and between the second gate and the channel; the piezoelectric gel is characterized in that the piezoelectric gel is made by mixing PVDF-HFP, LiTFSI and polypropylene carbonate and by a casting method.

2. The method for preparing a tactile sensing synapse based on piezoelectric gel according to claim 1, characterized in that: The following steps are involved: Step 1: Drying the cleaned substrate; Step 2: Using a mask method to evaporate a bottom electrode of a specific shape on the dried substrate, the bottom electrode includes a first source electrode, a first gate electrode, a second source electrode, and a second gate electrode; Step 3: Spin-coating a semiconductor material doped with a photocrosslinker onto the silicon wafer, followed by exposure and cleaning using a mask method to obtain a patterned semiconductor region; Step 4: Using a mask method to evaporate the top electrode, the top electrode includes a first drain electrode and a second drain electrode; Step 5: Add Ag or AgCl dispersion to the first gate and the second gate, and then anneal to form Ag or AgCl gates; Step 6: dripping ionic liquid gel between the first gate and the second gate and the channel respectively, dripping piezoelectric gel between the first gate and the first source, and performing photocuring; Step 7: Package the device.

3. The method for preparing a tactile sensing synapse based on piezoelectric gel according to claim 2, characterized in that: The thickness of the semiconductor material is 200-500 nm.

4. The method for preparing a tactile sensing synapse based on piezoelectric gel according to claim 2, characterized in that: The top electrode is gold with a thickness of 80 nm.

5. The method for preparing a tactile sensing synapse based on piezoelectric gel according to claim 2, characterized in that: The semiconductor material is at least one of Pg2T-T, gdpp-g2t, pedot:pss, and BBL.

6. The method for preparing a tactile sensing synapse based on piezoelectric gel according to claim 2, characterized in that: The cross-linking agent was PEGDA.

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