A flexible pressure sensor with integrated carbon nanotube transistor and its preparation method

Abstract

The present invention provides a flexible pressure sensor with an integrated carbon nanotube transistor, comprising an elastomeric composite gate electrode, a layered composite dielectric layer, and a floating-gate carbon nanotube transistor. The elastomeric composite gate electrode is a composite of an elastomeric electrode and a metal electrode, the elastomeric electrode being made of polydimethylsiloxane and conductive carbon nanotubes. The outer surface of the elastomeric electrode forms a multi-scale microstructure, and the metal electrode comprises a lower metal layer electrode deposited on the outer surface of the microstructure and an upper metal layer electrode connected to the upper surface of the elastomeric electrode. The layered composite dielectric layer is a composite of an organic dielectric and an inorganic dielectric. The floating gate electrode in the floating-gate carbon nanotube transistor is extended in length for integration with other components, and its channel is made of a high-purity semiconductor carbon nanotube film. The present invention has a relatively low operating voltage, high sensing performance, high design flexibility, and high electrical and mechanical stability, which is conducive to the miniaturization and scale-up of sensor devices.

Description

Technical Field

[0001] The present invention relates to the field of pressure sensors, and in particular to a flexible pressure sensor integrated with carbon nanotube transistors and a preparation method thereof. Background Art

[0002] Transistor-integrated flexible pressure sensors are a new type of mechanically compliant sensor device that integrates transistor electronic circuits with sensitive elements. They can convert pressure signals into electrical changes, such as current or voltage, to detect external pressure signals. Compared with other types of sensors, transistor-integrated pressure sensors have the advantages of low power consumption, small device size, and the ability to directly convert pressure signals into easily processable electrical signals such as current or voltage. They have broad application prospects in fields such as neural prostheses, intelligent robots, and wearable and implantable health electronics. However, existing typical transistor-integrated flexible pressure sensors suffer from relatively high operating voltages, relatively low sensing performance, and relatively poor mechanical and electrical stability.

[0003] Existing transistor-integrated flexible pressure sensor designs include a typical design that integrates a microstructured elastomeric dielectric mechanical sensor with an organic semiconductor thin-film transistor. This integrated design method, on the one hand, has a relatively weak electrostatic control capability due to the relatively thick and relatively low dielectric constant of the microstructured elastomeric dielectric, requiring a large gate voltage to make limited adjustments to the source-drain current, that is, the sensing performance is relatively limited; on the other hand, organic semiconductor thin-film transistors generally have relatively poor electrical properties, such as low carrier mobility, and also require the transistor to operate at a relatively large voltage to effectively convert the capacitance change caused by pressure. At the same time, the electrical performance of organic semiconductor transistor thin-film devices is prone to further deterioration over time, and the organic semiconductor transistor preparation process is difficult to match the existing photolithography process, and there are also many problems in the miniaturization and scale of the device. In addition, the integration method of transistors in existing design schemes is usually to directly laminate the microstructure of the mechanical sensor onto the semiconductor film, which easily causes the semiconductor film to be damaged by the mechanical action of the microstructure. Summary of the Invention

[0004] The present invention solves the problems of existing transistor-integrated flexible pressure sensors, such as high operating voltage, low sensing performance, difficulty in miniaturization and scale-up, and easy damage of semiconductor films by mechanical effects. It provides a flexible pressure sensor with integrated carbon nanotube transistors and a preparation method to solve the above problems.

[0005] The technical solutions of the present invention are as follows:

[0006] The present invention provides a flexible pressure sensor with an integrated carbon nanotube transistor, comprising an elastomer composite gate electrode, a layered composite dielectric layer, and a floating gate carbon nanotube transistor. The characteristics of the flexible pressure sensor are that the elastomer composite gate electrode is a composite of an elastomer electrode and a metal electrode, the elastomer electrode is an elastomer made of a composite material of polydimethylsiloxane and conductive carbon nanotubes, the elastomer electrode forms a multi-scale microstructure on the outer surface facing the layered composite dielectric, the metal electrode is a lower metal layer electrode evaporated on the outer surface of the elastomer electrode with the multi-scale microstructure and an upper metal layer electrode connected to the surface of the elastomer electrode without the multi-scale microstructure; the layered composite dielectric layer is composed of an organic dielectric and an inorganic metal. The oxide dielectric forms a composite structure of upper and lower layers, which is located between the outer surface of the elastomer composite gate electrode with a multi-scale microstructure and the floating gate in the floating gate carbon nanotube transistor; the floating gate electrode in the floating gate carbon nanotube transistor is extended in length for integration with the elastomer composite gate electrode and the layered composite dielectric layer, the length of the extended section is greater than the length of the elastomer composite gate electrode and the layered composite dielectric layer, the upper surface of the extended section is connected to the inorganic metal oxide dielectric in the layered composite dielectric layer, and the upper surface of the non-extended section is deposited with the following in order from bottom to top: a transistor dielectric layer, a channel, and a source electrode and a drain electrode located at both ends of the channel, wherein the channel is made of a high-purity semiconductor carbon nanotube film.

[0007] Preferably, the method for preparing the elastomeric electrode from the polydimethylsiloxane and conductive carbon nanocomposite material is: mixing polydimethylsiloxane with a n-hexane solution, dispersing the conductive carbon nanotubes in isopropanol by water bath ultrasound, and finally mixing the two mixed solutions.

[0008] Preferably, the ratio of polydimethylsiloxane to n-hexane solution is 1:5-1:10, the ratio of conductive carbon nanotubes to isopropyl alcohol is 1:200, and the ratio of polydimethylsiloxane to conductive carbon nanotubes is 100:1-100:5.

[0009] Preferably, the multi-scale microstructure is a plurality of irregular three-dimensional structures or a plurality of micro-pyramid structures of different sizes.

[0010] Preferably, the metal electrode is made of titanium-gold alloy or chromium-gold alloy by electron beam or thermal evaporation, the thickness of the titanium or chromium is 5 nm, and the thickness of the gold is 50 nm.

[0011] Preferably, the organic dielectric in the layered composite dielectric layer is parylene or polyimide, with a thickness of less than 200 nm, and the inorganic metal oxide dielectric is hafnium oxide, with a thickness of 10-20 nm.

[0012] Preferably, the transistor dielectric layer in the floating gate carbon nanotube transistor is hafnium oxide with a thickness of 10-20 nm.

[0013] The present invention also provides a method for preparing the flexible pressure sensor integrated with the carbon nanotube transistor, comprising the following steps:

[0014] S1: thermally depositing parylene or spin-coating polyimide on a low-resistance silicon wafer to obtain a flexible substrate, evaporating a titanium-gold alloy or a chromium-gold alloy on the flexible substrate and peeling it off from the low-resistance silicon wafer to obtain a flexible upper metal layer electrode; using a mixed solution of polydimethylsiloxane and conductive carbon nanotubes to prepare an elastomeric electrode; forming a multi-scale microstructure on the outer surface of the elastomeric electrode facing the layered composite dielectric, and electron beam or thermally evaporating a titanium-gold alloy or a chromium-gold alloy on the outer surface of the elastomeric electrode having the multi-scale microstructure to obtain a lower metal layer electrode, wherein the thickness of the titanium or chromium is 5 nm and the thickness of the gold is 50 nm, and finally obtaining an elastomeric composite gate electrode composed of the elastomeric electrode and the metal electrode;

[0015] S2: Thermally deposit parylene or spin-coat polyimide on a low-resistance silicon wafer to obtain a flexible substrate, and deposit 5nm thick hafnium oxide on the flexible substrate by electron beam evaporation to increase the adhesion between the floating gate and the flexible substrate; evaporate titanium-gold alloy on the surface of the hafnium oxide to obtain an extended floating gate; deposit 10-20nm thick hafnium oxide on the surface of the floating gate by electron beam, and separate the hafnium oxide into two parts by photolithography and dry etching, which serve as the inorganic metal oxide dielectric in the layered composite dielectric layer and the transistor dielectric layer in the carbon nanotube transistor; on the surface of the transistor dielectric layer, deposit titanium-gold alloy on the surface of the hafnium oxide to obtain an extended floating gate; on the surface of the floating gate, deposit 10-20nm thick hafnium oxide by electron beam, and separate the hafnium oxide into two parts by photolithography and dry etching, which serve as the inorganic metal oxide dielectric in the layered composite dielectric layer and the transistor dielectric layer in the carbon nanotube transistor; on the surface of the transistor dielectric layer, deposit titanium-gold alloy on the surface of the floating gate ... A high-purity semiconductor carbon nanotube film is obtained by pulling and photolithography, that is, a channel is obtained; a source electrode and a drain electrode are then obtained at both ends of the channel by electron beam or thermal evaporation; finally, parylene or polyimide is deposited or spin-coated on the surface of the inorganic metal oxide dielectric, the source electrode, and the drain electrode, wherein the parylene or polyimide on the inorganic metal oxide dielectric serves as an organic dielectric and forms a layered composite dielectric layer with the inorganic metal oxide dielectric; finally, the bottom silicon wafer is peeled off, thereby obtaining an integrated layered composite dielectric layer and a carbon nanotube floating gate transistor;

[0016] S3: Laminating the elastomer composite gate electrode obtained in S1, the layered composite dielectric layer obtained in S2, and the carbon nanotube floating gate transistor to obtain a flexible pressure sensor integrated with the carbon nanotube transistor.

[0017] Preferably, the forming of the multi-scale microstructure comprises drop-coating a mixed solution of polydimethylsilane and conductive carbon nanotubes onto a hydrophobic substrate, evacuating the substrate and then heating and curing the mixed solution, wherein irregular microstructures naturally appear on the surface of the mixed solution during the curing process; or etching a silicon wafer by photolithography to obtain a mold of micro-pyramid structures of different sizes, treating the mold hydrophobically, pouring the mixed solution of polydimethylsilane and conductive carbon nanotubes into the mold and evacuating the substrate, heating and curing the mixed solution, and then peeling off the mold to obtain micro-pyramid structures of different sizes.

[0018] Preferably, the source electrode and drain electrode in S2 are made of a metal alloy of titanium, palladium and gold by electron beam or thermal evaporation, the thickness of the titanium metal layer is 0.3 nm, the thickness of the palladium metal layer is 40 nm, and the thickness of the gold is 50 nm.

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention provides a flexible pressure sensor with an integrated carbon nanotube transistor, comprising an elastomer composite gate electrode, a layered composite dielectric layer, and a floating gate carbon nanotube transistor. The characteristics of the flexible pressure sensor are that the elastomer composite gate electrode is a composite of an elastomer electrode and a metal electrode, the elastomer electrode is an elastomer prepared from a composite material of polydimethylsiloxane and conductive carbon nanotubes, the elastomer electrode forms a multi-scale microstructure on the outer surface facing the layered composite dielectric, the metal electrode is a lower metal layer electrode evaporated on the outer surface of the elastomer electrode having the multi-scale microstructure and an upper metal layer electrode connected to the surface of the elastomer electrode not having the multi-scale microstructure; the layered composite dielectric layer is composed of an organic dielectric and an inorganic metal. The invention relates to a composite structure of upper and lower layers formed by an oxide dielectric, which is located between the outer surface of the elastomer composite gate electrode with a multi-scale microstructure and the floating gate in the floating gate carbon nanotube transistor; the floating gate electrode in the floating gate carbon nanotube transistor is extended in length for integration with the elastomer composite gate electrode and the layered composite dielectric layer, the length of the extended section is greater than the length of the elastomer composite gate electrode and the layered composite dielectric layer, the upper surface of the extended section is connected to the inorganic metal oxide dielectric in the layered composite dielectric layer, and the upper surface of the non-extended section is deposited with the following in order from bottom to top: a transistor dielectric layer, a channel, and a source electrode and a drain electrode located at both ends of the channel, wherein the channel is made of a high-purity semiconductor carbon nanotube film.

[0021] Because the present invention introduces the use of an elastomeric composite electrode as a mechanically sensitive element and as a transistor gate, it avoids the problem of a high operating voltage and limited sensing performance caused by the weak electrostatic control force of the gate electrode due to the thick thickness and low relative dielectric constant of the elastomeric dielectric layer when using a microstructured dielectric design. The microstructured electrode design adopted in this scheme allows the selection of materials with higher dielectric constants and thinner thicknesses as dielectric layers, that is, a thin film dielectric layer with a thickness of less than micrometers and a relatively high dielectric constant is obtained by atomic layer deposition, thermal deposition and / or spin coating methods. This can significantly enhance the electrostatic control ability of the gate voltage, thereby achieving the conversion of capacitance changes caused by pressure and signal amplification at a lower operating voltage, improving the sensor's sensing performance and reducing the transistor's operating voltage. On the other hand, since the present invention does not adopt a microstructured dielectric design, parameters such as the floating gate area and the relative dielectric constant and thickness of the layered composite dielectric above the floating gate can be adjusted, increasing the flexibility of the integrated sensor design and providing the possibility of high-performance transistor-integrated sensors.

[0022] The present invention introduces a carbon nanotube transistor with a floating gate structure, extends the floating gate length in the semiconductor carbon nanotube transistor, and realizes the integration of the elastomer composite electrode and the carbon nanotube transistor. The pressure change can be directly divided through the floating gate and then converted into a current between the source and the drain. The ultra-thin, integrated device structure realizes the conversion of the pressure signal into an easy-to-process electrical signal, and avoids the problem of damage to the semiconductor film caused by directly laminating the microstructure of the mechanical sensitive element on the semiconductor film in the existing design scheme, thereby increasing the mechanical stability of the device. At the same time, compared with organic semiconductor films, carbon nanotube semiconductor films have excellent electrical properties and stability, can be matched with standard photolithography processes, and are conducive to the miniaturization and scale of sensor devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 : Structural diagram of a flexible pressure sensor with integrated carbon nanotube transistors.

[0024] Figure 2 : Circuit diagram of flexible pressure sensor with integrated carbon nanotube transistors. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the flexible pressure sensor integrated with carbon nanotube transistors proposed in the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, please refer to the drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present invention, so they have no technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0026] The technical solution of the present invention is described in detail below with reference to the accompanying drawings. The present invention provides a flexible pressure sensor with integrated carbon nanotube transistors, such as Figure 1 As shown, it includes: an elastomer composite gate electrode 1: a flexible substrate 11, an upper metal layer electrode 12 connected to the surface of the elastomer electrode without a multi-scale microstructure, an elastomer electrode 13 composed of a composite material, a multi-scale microstructure 15 formed on the outer surface of the elastomer electrode facing the layered composite dielectric layer, a lower metal layer electrode 14 evaporated on the surface of the multi-scale microstructure, a layered composite dielectric layer 2: an organic dielectric 21, an inorganic metal oxide dielectric 22, a floating gate carbon nanotube transistor 3: a floating gate 31, a transistor dielectric layer 32, a channel 33, a drain electrode 34, a source electrode 35, a flexible substrate 36, and a hafnium oxide metal layer.

[0027] In some embodiments of the present invention, the elastomer composite gate electrode 1 is composed of an elastomer electrode 13 and metal electrodes 12 and 14. The elastomer electrode 13 is an elastomer made of a composite material of polydimethylsiloxane and conductive carbon nanotubes. The elastomer electrode 13 forms a multi-scale microstructure 15 on the outer surface facing the layered composite dielectric layer 2. The metal electrode is a metal layer 14 evaporated on the outer surface of the elastomer electrode with a multi-scale microstructure and an upper metal layer electrode 11 connected to the surface of the elastomer electrode without a multi-scale microstructure; the layered composite dielectric layer 2 is located on the inner surface of the elastomer composite gate electrode with a multi-scale microstructure 15 and the floating gate electrode in the carbon nanotube crystal 3. 31, an organic dielectric 21 and an inorganic metal oxide dielectric 22 form a composite upper and lower structure; the floating gate 31 in the floating gate carbon nanotube transistor 3 is extended in length for integration with the elastomer composite gate electrode 1 and the layered composite dielectric layer 2, the length of the extended section is greater than the length of the elastomer composite gate electrode 1 and the layered composite dielectric layer 2, the upper surface of the extended section is connected to the inorganic metal oxide dielectric 22 in the layered composite dielectric layer 2, and the upper surface of the non-extended section is deposited in sequence from bottom to top: a transistor dielectric layer 32, a channel 33, and a source electrode 35 and a drain electrode 34 located at both ends of the channel, and the channel 33 is made of a high-purity semiconductor carbon nanotube film.

[0028] In some embodiments of the present invention, the preparation method of the polydimethylsiloxane and conductive carbon nanocomposite material used to prepare the elastomeric electrode 13 is: mixing polydimethylsiloxane with a n-hexane solution, dispersing the conductive carbon nanotubes in isopropyl alcohol by water bath ultrasound, and finally mixing the two solutions; in some embodiments of the present invention, the ratio of the polydimethylsiloxane to the n-hexane solution is 1:5-1:10, the ratio of the conductive carbon nanotubes to isopropyl alcohol is 1:200, and the ratio of the polydimethylsiloxane to the conductive carbon nanotubes is 100:1-100:5.

[0029] In some embodiments of the present invention, the multi-scale microstructure 15 is a plurality of irregular three-dimensional structures; in other embodiments of the present invention, the multi-scale microstructure 5 is a plurality of micro-pyramid structures of different sizes.

[0030] In some embodiments of the present invention, the metal electrodes in the elastomeric composite gate electrode 1: the upper metal layer electrode 12 and the lower metal layer electrode 15 are obtained by electron beam evaporation of a titanium-gold alloy, the thickness of the titanium is 5 nm, and the thickness of the gold is 50 nm; in other embodiments of the present invention, the metal electrodes in the elastomeric composite gate electrode 1: the upper metal layer electrode 12 and the lower metal layer electrode 15 are obtained by thermal evaporation of a titanium-gold alloy, the thickness of the titanium is 5 nm, and the thickness of the gold is 50 nm; in some embodiments of the present invention, the metal electrodes in the elastomeric composite gate electrode 1: the upper metal layer electrode 12 and the lower metal layer electrode 15 are obtained by electron beam evaporation of a chromium-gold alloy, the thickness of the chromium is 5 nm, and the thickness of the gold is 50 nm; in other embodiments of the present invention, the metal electrodes in the elastomeric composite gate electrode 1: the upper metal layer electrode 12 and the lower metal layer electrode 15 are obtained by thermal evaporation of a chromium-gold alloy, the thickness of the chromium is 5 nm, and the thickness of the gold is 50 nm.

[0031] In some embodiments of the present invention, the organic dielectric 21 in the layered composite dielectric layer 2 is polyparaxylene with a thickness of 150 nm, and the inorganic metal oxide dielectric 22 is hafnium oxide with a thickness of 15 nm; in other embodiments of the present invention, the organic dielectric 21 in the layered composite dielectric layer 2 is polyimide with a thickness of 150 nm, and the inorganic metal oxide dielectric 22 is hafnium oxide with a thickness of 15 nm.

[0032] In some embodiments of the present invention, the transistor dielectric layer 32 is made of hafnium oxide and has a thickness of 15 nm.

[0033] In some embodiments of the present invention, a method for preparing a flexible pressure sensor integrated with a carbon nanotube transistor comprises the following steps:

[0034] S1: thermally depositing parylene or spin-coating polyimide on a low-resistance silicon wafer to obtain a flexible substrate 11, evaporating a titanium-gold alloy or a chromium-gold alloy on the flexible substrate and peeling it off from the low-resistance silicon wafer to obtain an upper metal layer flexible electrode 12; using a mixed solution of polydimethylsiloxane and conductive carbon nanotubes to prepare an elastomer electrode 13; forming a multi-scale microstructure 15 on the outer surface of the elastomer electrode 13 facing the layered composite dielectric 2, and electron beam or thermally evaporating a titanium-gold alloy or a chromium-gold alloy on the outer surface of the elastomer electrode 13 having the multi-scale microstructure 15 to obtain a metal electrode 14, wherein the thickness of the titanium or chromium is 5 nm and the thickness of the gold is 50 nm, and finally obtaining an elastomer composite gate electrode 1 composed of the elastomer electrode 13 and the metal electrodes 12 and 14;

[0035] S2: Thermally depositing parylene or spin-coating polyimide on a low-resistance silicon wafer to obtain a flexible substrate 36, and depositing 5nm thick hafnium oxide 37 on the flexible substrate 36 by electron beam evaporation to increase the adhesion between the floating gate 31 and the flexible substrate 36; then evaporating titanium-gold alloy on the surface of the hafnium oxide to obtain an extended floating gate 31; electron beam depositing 10-20nm thick hafnium oxide on the surface of the floating gate 31, and dividing the hafnium oxide into two parts by photolithography and dry etching, respectively, as the inorganic metal oxide dielectric 22 in the layered composite dielectric layer 2 and the crystal in the carbon nanotube transistor 3. A body transistor dielectric layer 32 is formed; a high-purity semiconductor carbon nanotube film is formed on the surface of the transistor dielectric layer 32 by pulling and photolithography methods, thereby obtaining a channel 33; a source electrode 35 and a drain electrode 34 are then formed at both ends of the channel 33 by electron beam or thermal evaporation methods; finally, parylene or polyimide is deposited or spin-coated on the surfaces of the inorganic metal oxide dielectric 22, the source electrode 35, and the drain electrode 34, which together with the inorganic metal oxide dielectric 22 form a layered composite dielectric layer 2; finally, the bottom silicon wafer is peeled off to obtain the integrated layered composite dielectric layer 2 and the carbon nanotube transistor 3;

[0036] S3: Laminating the elastomer composite gate electrode 1 obtained in S1, the layered composite dielectric 2 obtained in S2, and the carbon nanotube floating gate transistor 3 to obtain a flexible pressure sensor integrated with the carbon nanotube transistor.

[0037] In some embodiments of the present invention, the method for forming the multi-scale microstructure 15 is to drop-coat a mixed solution of polydimethylsiloxane and conductive carbon nanotubes onto a hydrophobic substrate, evacuate the solution, and heat and solidify it. During the curing process, irregular microstructures naturally appear on the surface of the mixed solution. In other embodiments of the present invention, the method for forming the multi-scale microstructure 15 is to etch a silicon wafer by photolithography to obtain a mold of micro-pyramid structures of different sizes. After the mold is hydrophobicized, the mixed solution of polydimethylsiloxane and conductive carbon nanotubes is poured into the mold and evacuated. After heating and solidification, the mold is peeled off to obtain micro-pyramid structures of different sizes.

[0038] In some embodiments of the present invention, the source electrode 35 and the drain electrode 34 are made of titanium, palladium, and gold alloy by electron beam or thermal evaporation. The thickness of the titanium metal layer is 0.3 nm, the thickness of the palladium metal layer is 40 nm, and the thickness of the gold is 50 nm.

[0039] Attachment Figure 2 This is a circuit diagram of the flexible pressure sensor with integrated carbon nanotube transistors provided by the present invention. Specifically, according to the circuit diagram, the equivalent gate voltage can be expressed as: Where C s is the capacitance of the mechanical sensitive element; C gis the gate capacitance of the transistor; V gs is the gate voltage. According to the above formula, the change in equivalent gate voltage can be expressed as: As can be seen from the above formula, an increase in the capacitance change of the mechanical sensitive element, i.e., the elastomer composite gate electrode, can increase the change of the equivalent gate, thereby improving the gate voltage's ability to regulate the source-drain current. That is, this design method allows the sensor to operate at a lower operating voltage.

[0040] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The above-described embodiment merely represents one embodiment of the present invention. While the description is relatively specific and detailed, it should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A flexible pressure sensor with integrated carbon nanotube transistor, comprising an elastomer composite gate electrode, a layered composite dielectric layer, and a floating gate carbon nanotube transistor, characterized in that The elastomer composite gate electrode is composed of an elastomer electrode and a metal electrode. The elastomer electrode is an elastomer prepared from a composite material of polydimethylsiloxane and conductive carbon nanotubes. The elastomer electrode forms a multi-scale microstructure on the outer surface facing the layered composite dielectric. The metal electrode is a lower metal layer electrode evaporated on the outer surface of the elastomer electrode with a multi-scale microstructure and an upper metal layer electrode connected to the surface of the elastomer electrode without a multi-scale microstructure. The layered composite dielectric layer is composed of an organic dielectric and an inorganic metal oxide dielectric to form an upper and lower layer structure. It is located on the elastomer composite gate electrode. Between the outer surface with multi-scale microstructure and the floating gate in the floating gate carbon nanotube transistor; the floating gate electrode in the floating gate carbon nanotube transistor is extended in length for integration with the elastomer composite gate electrode and the layered composite dielectric layer, the length of the extended section is greater than the length of the elastomer composite gate electrode and the layered composite dielectric layer, the upper surface of the extended section is connected to the inorganic metal oxide dielectric in the layered composite dielectric layer, and the upper surface of the non-extended section is deposited with the following in order from bottom to top: a transistor dielectric layer, a channel, and a source electrode and a drain electrode located at both ends of the channel, wherein the channel is made of a high-purity semiconductor carbon nanotube film.

2. The flexible pressure sensor with integrated carbon nanotube transistor according to claim 1, characterized in that The method for preparing the elastomer electrode of the polydimethylsiloxane and conductive carbon nanocomposite material is as follows: polydimethylsiloxane is mixed with a n-hexane solution, conductive carbon nanotubes are dispersed in isopropyl alcohol by water bath ultrasound, and finally the two mixed solutions are mixed.

3. The flexible pressure sensor with integrated carbon nanotube transistor according to claim 2, characterized in that The ratio of the polydimethylsiloxane to the n-hexane solution is 1:5-1:10, the ratio of the conductive carbon nanotubes to the isopropyl alcohol is 1:200, and the ratio of the polydimethylsiloxane to the conductive carbon nanotubes is 100:1-100:

5.

4. The flexible pressure sensor with integrated carbon nanotube transistor according to claim 1, characterized in that The multi-scale microstructure is a plurality of irregular three-dimensional structures or a plurality of micro-pyramid structures of different sizes.

5. The flexible pressure sensor with integrated carbon nanotube transistor according to claim 1, characterized in that The metal electrode is made of titanium-gold alloy or chromium-gold alloy by electron beam or thermal evaporation. The thickness of the titanium or chromium is 5 nm, and the thickness of the gold is 50 nm.

6. The flexible pressure sensor with integrated carbon nanotube transistors according to claim 1, characterized in that: The organic dielectric in the layered composite dielectric layer is polyparaxylene or polyimide, with a thickness of less than 200 nm, and the inorganic metal oxide dielectric is hafnium oxide, with a thickness of 10-20 nm.

7. The flexible pressure sensor with integrated carbon nanotube transistor according to any one of claims 1 to 6, characterized in that: The transistor dielectric layer in the floating gate carbon nanotube transistor is hafnium oxide with a thickness of 10-20 nm.

8. A method for preparing a flexible pressure sensor integrated with a carbon nanotube transistor according to any one of claims 1 to 7, comprising the following steps: S1: thermally depositing parylene or spin-coating polyimide on a low-resistance silicon wafer to obtain a flexible substrate, evaporating a titanium-gold alloy or a chromium-gold alloy on the flexible substrate and peeling it off from the low-resistance silicon wafer to obtain a flexible upper metal layer electrode; using a mixed solution of polydimethylsiloxane and conductive carbon nanotubes to prepare an elastomeric electrode; forming a multi-scale microstructure on the outer surface of the elastomeric electrode facing the layered composite dielectric, and electron beam or thermally evaporating a titanium-gold alloy or a chromium-gold alloy on the outer surface of the elastomeric electrode having the multi-scale microstructure to obtain a lower metal layer electrode, wherein the thickness of the titanium or chromium is 5 nm and the thickness of the gold is 50 nm, and finally obtaining an elastomeric composite gate electrode composed of the elastomeric electrode and the metal electrode; S2: Thermally deposit parylene or spin-coat polyimide on a low-resistance silicon wafer to obtain a flexible substrate, and deposit 5nm thick hafnium oxide on the flexible substrate by electron beam evaporation to increase the adhesion between the floating gate and the flexible substrate; evaporate titanium-gold alloy on the surface of the hafnium oxide to obtain an extended floating gate; deposit 10-20nm thick hafnium oxide on the surface of the floating gate by electron beam, and separate the hafnium oxide into two parts by photolithography and dry etching, which serve as the inorganic metal oxide dielectric in the layered composite dielectric layer and the transistor dielectric layer in the carbon nanotube transistor; on the surface of the transistor dielectric layer, deposit titanium-gold alloy on the surface of the hafnium oxide to obtain an extended floating gate; on the surface of the floating gate, deposit 10-20nm thick hafnium oxide by electron beam, and separate the hafnium oxide into two parts by photolithography and dry etching, which serve as the inorganic metal oxide dielectric in the layered composite dielectric layer and the transistor dielectric layer in the carbon nanotube transistor; on the surface of the transistor dielectric layer, deposit titanium-gold alloy on the surface of the floating gate ... A high-purity semiconductor carbon nanotube film is obtained by pulling and photolithography, that is, a channel is obtained; a source electrode and a drain electrode are then obtained at both ends of the channel by electron beam or thermal evaporation; finally, parylene or polyimide is deposited or spin-coated on the surface of the inorganic metal oxide dielectric, the source electrode, and the drain electrode, wherein the parylene or polyimide on the inorganic metal oxide dielectric serves as an organic dielectric and forms a layered composite dielectric layer with the inorganic metal oxide dielectric; finally, the bottom silicon wafer is peeled off, thereby obtaining an integrated layered composite dielectric layer and a carbon nanotube floating gate transistor; S3: Laminating the elastomer composite gate electrode obtained in S1, the layered composite dielectric layer obtained in S2, and the carbon nanotube floating gate transistor to obtain a flexible pressure sensor integrated with the carbon nanotube transistor.

9. The preparation method according to claim 8, characterized in that The multi-scale microstructure formation method comprises the following steps: drop-coating a mixed solution of polydimethylsilane and conductive carbon nanotubes onto a hydrophobic substrate, evacuating the substrate, and then heating and curing the mixed solution. During the curing process, irregular microstructures naturally appear on the surface of the mixed solution. Alternatively, a silicon wafer is etched by photolithography to obtain a mold with micro-pyramid structures of different sizes. After the mold is hydrophobicized, the mixed solution of polydimethylsilane and conductive carbon nanotubes is poured into the mold and evacuated. After heating and curing, the mold is peeled off to obtain micro-pyramid structures of different sizes.

10. The preparation method according to claim 8 or 9, characterized in that The source electrode and drain electrode in S2 are made of a metal alloy of titanium, palladium and gold by electron beam or thermal evaporation. The thickness of the titanium metal layer is 0.3 nm, the thickness of the palladium metal layer is 40 nm, and the thickness of the gold is 50 nm.

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