Thermoelectric-piezoelectric single-channel two-parameter sensor based on Te nanotube and manufacturing method of thermoelectric-piezoelectric single-channel two-parameter sensor

Abstract

The invention relates to the technical field of sensors, in particular to a Te nanotube-based thermoelectric-piezoelectric single-channel two-parameter sensor and a manufacturing method thereof. The sensor comprises a multi-layer composite film structure which sequentially comprises a polyimide flexible substrate, a lower electrode indium tin oxide conductive layer, a SiO2 dielectric layer, a Te nanotube film sensing layer, a polydimethylsiloxane packaging protection layer and an upper electrode gold layer from bottom to top, and gold wires are led out from the upper electrode gold layer and the lower electrode indium tin oxide conductive layer through elargol to serve as unique output ends; the polyimide flexible substrate serves as a flexible support, and the upper electrode gold layer, the lower electrode indium tin oxide conductive layer and an external circuit form a loop to output signals. The thermoelectric-piezoelectric single-channel two-parameter sensor can simultaneously output thermoelectric-piezoelectric signals in a single channel, has excellent flexibility, is simple in preparation method and low in cost, can realize large-scale preparation and miniaturized application, and has great potential in the fields of medical health, human-computer interaction and the like.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes and a manufacturing method thereof. Background Art

[0002] As the energy crisis becomes increasingly serious, the exploration of green and renewable energy has become an important issue. At present, the mainstream green and renewable energy sources are concentrated on macro applications, such as solar energy, wind energy, hydropower, etc., which are widely used due to their low collection costs. However, in addition to these, there are some green and renewable energy sources that are difficult to collect and can be used at the micro scale, such as various forms of thermal energy and mechanical energy that exist in large quantities in the living environment. On the other hand, with the continuous development of electronic devices, the development of flexible wearable devices tends to be miniaturized, integrated, and multifunctional to monitor human health. However, the traditional battery-powered mode greatly limits the miniaturization of the device. Therefore, there is an urgent need for a self-powered multifunctional sensor that can use human thermal energy and mechanical energy for power supply.

[0003] Traditional flexible thermoelectric-piezoelectric dual sensors integrate a thermoelectric material and a piezoelectric material through a three-dimensional structural design to achieve composite dual-parameter sensing. Most of them have dual-channel output and obtain thermoelectric and piezoelectric signals separately. The structure is complex and has more than one set of electrodes, which affects stability. The preparation process is complicated, the cost is high, and it limits the miniaturization of the device. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes and a method for making the same, which can simultaneously output linearly superimposed thermoelectric-piezoelectric signals in a single channel, that is, it has the ability to monitor temperature and pressure simultaneously, and does not require an external power supply. The preparation method is simple, low-cost, and has a single raw material. Nanotubes are prepared by thermal evaporation of the single element Te, which is used as a thermoelectric and piezoelectric material at the same time, and signal acquisition is completed through a simple multi-layer structure design. Only one set of electrodes outputs thermoelectric-piezoelectric signals in a single channel at the same time, and a stable thermoelectric-piezoelectric coupling signal can be measured by a multimeter without amplification.

[0005] The technical solution of the present invention is:

[0006] A thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, the sensor includes a multi-layer composite film structure, which includes, from bottom to top: a polyimide flexible substrate, a lower electrode indium tin oxide conductive layer, a SiO2 dielectric layer, a Te nanotube film sensing layer, a polydimethylsiloxane encapsulation protection layer, and an upper electrode gold layer. The upper electrode gold layer and the lower electrode indium tin oxide conductive layer are respectively led out with gold wires through silver glue as the only output end; the polyimide flexible substrate serves as a flexible support, and the upper electrode gold layer, the lower electrode indium tin oxide conductive layer and the external circuit form a loop to output signals.

[0007] The thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes is characterized in that a lower electrode indium tin oxide conductive layer, a SiO2 dielectric layer, and a Te nanotube thin film sensing layer are sequentially deposited on a polyimide flexible substrate, a polydimethylsiloxane encapsulation protective layer is spin-coated on the Te nanotube thin film sensing layer, and an upper electrode gold layer is deposited on the polydimethylsiloxane encapsulation protective layer. One end of a gold wire is fixed to the upper electrode gold layer by silver glue, and one end of the other gold wire is fixed to the lower electrode indium tin oxide conductive layer by silver glue. The free ends of the two gold wires are the output ends of the sensor. The gold wires on the upper electrode gold layer and the lower electrode indium tin oxide conductive layer are conveniently connected to the test equipment as the output ends.

[0008] The thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes has a polyimide flexible substrate with a thickness of 25 to 75 μm, a lower electrode indium tin oxide conductive layer with a thickness of 90 to 110 nm, a SiO2 dielectric layer with a thickness of 90 to 110 nm, a polydimethylsiloxane encapsulation protective layer with a thickness of 2 to 3 μm, and an upper electrode gold layer with a thickness of 80 to 120 nm.

[0009] The thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, the Te nanotube thin film sensing layer is made of Te nanotubes with a diameter of 200-400nm, a length of 4-6μm, and a wall thickness of 40-60nm prepared by a tube furnace thermal evaporation method, which are interwoven with each other, and the C axis of the Te nanotube forms an angle of 0-45° with the polyimide flexible substrate.

[0010] The method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes comprises the following steps:

[0011] Step 1: depositing a conductive layer and a dielectric layer in sequence through a mask on a polyimide flexible substrate using a magnetron sputtering technique;

[0012] Step 2: thermal evaporation in a tube furnace to deposit a Te nanotube thin film sensing layer;

[0013] Step 3: Spin-coat a polydimethylsiloxane encapsulation protection layer on the Te nanotube film sensing layer;

[0014] Step 4: Use a magnetron sputtering mask to deposit an 80-120 nm thick upper electrode gold layer, where the area of ​​the upper electrode gold layer is smaller than the area of ​​the lower electrode indium tin oxide conductive layer to prevent the upper and lower electrodes from contacting and conducting;

[0015] Step 5: Remove the mask, remove the polyimide flexible substrate from the fixed glass substrate, peel off the polyimide mask tape to expose the reserved lower electrode indium tin oxide, and use silver glue to fix one end of the gold wire to the upper and lower electrodes respectively. The free ends of the two gold wires are the output ends of the sensor.

[0016] The method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, step 1 specifically comprises:

[0017] Step 1.1: Cut a 25-75 μm thick polyimide flexible substrate into a 1 cm × 2 cm rectangle, clean it with acetone and alcohol ultrasonically for 20-40 min, and finally blow it clean with nitrogen for later use;

[0018] Step 1.2: Using magnetron sputtering technology, a lower electrode indium tin oxide conductive layer with a thickness of 90 to 110 nm and a SiO2 dielectric layer with a thickness of 90 to 110 nm are sequentially deposited on the polyimide flexible substrate through masking.

[0019] In the method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, the growth process of the Te nanotubes in step 2 is specifically as follows:

[0020] Step 2.1: Place the quartz boat containing Te powder in the heating zone of the tube furnace;

[0021] Step 2.2: The prepared polyimide flexible substrate is fixed on a glass sheet, that is, polyimide masking tape is pasted on the 2-4 mm wide area on both sides of the polyimide flexible substrate to reserve the lower electrode, and polyimide masking tape is pasted on the edges of the polyimide flexible substrate to prevent the Te nanotubes deposited on the edge of the film from being connected to the indium tin oxide of the lower electrode, and the substrate is placed in the insulating area of ​​the tube furnace, and the quartz boat is 20-25 cm away from the polyimide flexible substrate;

[0022] Step 2.3: Close the port of the tube furnace, start the mechanical pump to pump the pressure in the tube furnace to 1-3 Pa, and then start the molecular pump to pump the pressure in the tube furnace to 5×10 -4 Pa, turn off the molecular pump, introduce 30-50 sccm argon gas, and maintain the pressure in the tube furnace at 20-30 Pa;

[0023] Step 2.4: Start the heating program, heat up to 280-320°C at a heating rate of 10-20°C / min, then heat up to 340-360°C at 4-6°C / min, keep warm for 18-22 minutes, and then cool in the furnace to obtain a Te nanotube thin film sensing layer.

[0024] The method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, step 3 is specifically:

[0025] Step 3.1: After taking out the polyimide flexible substrate on which the Te nanotube thin film sensing layer is deposited, peel off the polyimide masking tape in step 2, and re-apply the polyimide masking tape on both sides of the polyimide flexible substrate at a width of 1 to 3 mm to avoid lifting the film when removing the masking tape later;

[0026] Step 3.2: Prepare polydimethylsiloxane solution, mix the main agent and curing agent in a weight ratio of 10:1, put it in a vacuum box for 20 to 40 minutes to degas, and pour it into a syringe for use;

[0027] Step 3.3: The center of the glass sheet with the polyimide flexible substrate attached in step 2 is adsorbed on the spin coater, and the polydimethylsiloxane solution is drop-coated on the Te nanotube thin film sensing layer, first rotating at a low speed of 3000-5000 r / min for 10-15 s, and then rotating at a high speed of 7000-9000 r / min for 20-40 s, until the polydimethylsiloxane solution is evenly coated on the Te nanotube thin film sensing layer;

[0028] Step 3.4: Remove the glass sheet and place it on a heating table at 140-160°C for 18-22 minutes. After curing, the thickness of the polydimethylsiloxane is 2-3 μm.

[0029] In the method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, in step 2, Te nanotubes with intrinsic thermoelectric and piezoelectric effects are used as thermoelectric-piezoelectric sensing units.

[0030] In the method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, in step 2, the Te nanotubes are prepared by low-temperature thermal evaporation of Te powder.

[0031] The design ideas of the present invention are as follows:

[0032] The piezoelectric signal comes from the asymmetric crystal structure of Te nanotubes. The separation of positive and negative charge centers under radial external force produces a potential difference. The thermoelectric signal comes from the temperature difference driving the carrier movement to produce a potential difference at both ends of the device. When the resistance of the upper and lower electrodes of the film is low, the carriers can pass through the dielectric layer. Benefiting from the multilayer structure and the special structure of Te nanotubes, it is easy to establish an out-of-plane temperature difference and the response speed is fast, but the charge is easy to leak and the piezoelectric signal cannot be generated. When the resistance increases to a certain level, the carriers cannot pass through the dielectric layer, and the out-of-plane thermoelectric performance is lost, but the piezoelectric signal is enhanced due to the increased ability to prevent charge leakage. When the resistance is between the two, the thermoelectric voltage and electrical signals appear at the same time, with the same magnitude and linear superposition. By adjusting the properties of each film layer such as the growth parameters of Te nanotubes, the thickness of the SiO2 dielectric layer, and the thickness of the polydimethylsiloxane (PDMS) encapsulation protective layer, the output type of the device can be adjusted by macroscopically showing a change in resistance value.

[0033] Based on the above design guiding ideology, the present invention successfully produced a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes and its production method, which can basically realize the thermoelectric-piezoelectric single-channel dual-parameter sensing function. The sensor includes a multi-layer composite film structure, from bottom to top: polyimide (PI) flexible substrate, lower electrode indium tin oxide (ITO) conductive layer, SiO2 dielectric layer, Te nanotube film sensing layer, polydimethylsiloxane encapsulation protection layer, upper electrode gold layer, and the upper and lower electrodes are respectively led out with gold wires as the only output end. The polyimide flexible substrate provides flexible support, and the upper and lower electrode layers form a loop with the external circuit to output signals; the SiO2 dielectric layer of a certain thickness can block the leakage of induced charges in the electrode while allowing some carriers to pass through to simultaneously output piezoelectric-thermoelectric signals; the Te nanotube thin film sensing layer is interwoven with Te nanotubes with a large aspect ratio, and has a high piezoelectric coefficient and Seebeck coefficient. The C axis of the Te nanotube forms an angle of 0 to 45° with the polyimide flexible substrate, which is conducive to the generation of piezoelectric signals under radial force and out-of-plane thermoelectric signals in the longitudinal direction; the polydimethylsiloxane encapsulation protective layer is spin-coated on the Te nanotube, which can not only play a role similar to SiO2 as a dielectric layer, but also fill the gap, play a fixing and protective role, and improve the stability of the device; the gold wires of the upper and lower electrodes serve as output ends for easy access to test equipment.

[0034] The present invention provides a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes and a preparation method thereof, which has at least the following advantages and beneficial effects:

[0035] 1. The Te nanotube film sensing layer of the dual-parameter sensor of the present invention has both high piezoelectric coefficient and Seebeck coefficient, and its high surface area is beneficial to the electrical transport performance.

[0036] 2. The C axis of the Te nanotube of the dual-parameter sensor of the present invention forms an angle of 0 to 45° with the polyimide flexible substrate, which is conducive to the generation of piezoelectric signals under radial force and out-of-plane thermoelectric signals along the longitudinal direction. The multi-layer structure design is conducive to the establishment of out-of-plane temperature difference of the Te nanotube while maintaining the piezoelectric performance, greatly improving the response time and recovery time of temperature sensing.

[0037] 3. The components used in the dual-parameter sensor of the present invention have good flexibility, so that they can completely fit on the curved surface and realize sensing on various special-shaped contact surfaces such as the human body surface.

[0038] 4. The dual-parameter sensor of the present invention reduces the design of electrodes, simplifies the structure, improves reliability, and provides a new idea for the integration and miniaturization of sensors, that is, realizing multifunctional self-driven sensing by a single material and a single channel.

[0039] 5. The preparation method adopted by the present invention is simple, green and environmentally friendly, and can be suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a structural decomposition diagram of a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes of the present invention.

[0041] Figure 2 This is a structural front view of a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes of the present invention.

[0042] Figure 1-Figure 2 In the figure, 1-polyimide flexible substrate, 2-lower electrode indium tin oxide conductive layer, 3-SiO2 dielectric layer, 4-Te nanotube thin film sensing layer, 5-polydimethylsiloxane encapsulation protection layer, 6-upper electrode gold layer, 7-silver glue, 8-gold wire, 9-Te nanotube.

[0043] Figure 3 The present invention is a flow chart of a method for manufacturing a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes.

[0044] Figure 4 This is an electron scanning image of the Te nanotube thin film sensing layer of a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes.

[0045] Figure 5 This is an electron scanning image of the Te nanotube thin film sensing layer after spin coating PDMS of a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes. DETAILED DESCRIPTION

[0046] Hereinafter, a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes and a manufacturing method thereof will be described in detail in conjunction with the accompanying drawings and embodiments of the present invention.

[0047] like Figure 1 and Figure 2 As shown, the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes of the present invention comprises: a polyimide flexible substrate 1, a lower electrode indium tin oxide conductive layer 2, a SiO2 dielectric layer 3, a Te nanotube thin film sensing layer 4, a polydimethylsiloxane encapsulation protective layer 5, an upper electrode gold layer 6, silver glue 7, and a gold wire 8. The sensor is a multi-layer composite film structure, which is sequentially from bottom to top: a polyimide flexible substrate 1, a lower electrode indium tin oxide conductive layer 2, a SiO2 dielectric layer 3, a Te nanotube thin film sensing layer 4, a polydimethylsiloxane encapsulation protective layer 5, and an upper electrode gold layer 6. The upper electrode gold layer 6 and the lower electrode indium tin oxide conductive layer 2 are respectively led out with a gold wire 8 as the only output end through the silver glue 7. The polyimide flexible substrate 1 provides flexible support, and the upper electrode gold layer 6 and the lower electrode indium tin oxide conductive layer 2 form a loop with an external circuit to output a signal.

[0048] On the polyimide flexible substrate 1, the lower electrode indium tin oxide conductive layer 2, the SiO2 dielectric layer 3, and the Te nanotube thin film sensing layer 4 are sequentially deposited, the polydimethylsiloxane encapsulation protective layer 5 is spin-coated on the Te nanotube thin film sensing layer 4, and the upper electrode gold layer 6 is deposited on the polydimethylsiloxane encapsulation protective layer 5. The area of ​​the upper electrode gold layer 6 is slightly smaller than the area of ​​the lower electrode indium tin oxide conductive layer 2 to avoid contact and conduction between the upper and lower electrodes. One end of a gold wire 8 is fixed on the upper electrode gold layer 6 through silver glue 7, and one end of another gold wire 8 is fixed on the lower electrode indium tin oxide conductive layer 2 through silver glue 7. The free ends of the two gold wires 8 are the output ends of the sensor. The gold wires on the upper electrode gold layer 6 and the lower electrode indium tin oxide conductive layer 2 are conveniently connected to the test equipment as output ends.

[0049] Among them, the thickness of the polyimide flexible substrate 1 is 40-60 μm, the thickness of the lower electrode indium tin oxide conductive layer 2 is 90-110 nm, and the thickness of the SiO2 dielectric layer 3 is 90-110 nm. The output mode of the device's thermoelectric-piezoelectric performance can be adjusted by adjusting the thickness of the SiO2 dielectric layer 3. The thickness of the polydimethylsiloxane encapsulation protection layer 5 is 2-3 μm, and the thickness of the upper electrode gold layer 6 is 80-120 nm. The Te nanotube thin film sensing layer 4 is formed by interweaving Te nanotubes 9 with a diameter of 200-400 nm, a length of 4-6 μm, and a wall thickness of 40-60 nm. It has a high piezoelectric coefficient and Seebeck coefficient. The C axis of the Te nanotube 9 forms an angle of 0-45° with the polyimide flexible substrate 1, which is conducive to generating piezoelectric signals under radial force and generating out-of-plane thermoelectric signals along the longitudinal direction.

[0050] like Figure 3 As shown, a method for preparing a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes of the present invention comprises the following steps:

[0051] Step 1: Using magnetron sputtering technology, a conductive layer and a dielectric layer are sequentially deposited on a polyimide flexible substrate using a mask.

[0052] Step 1.1: Cut a 50 μm thick polyimide (Kapton) film into a 1 cm × 2 cm rectangle, clean it with acetone and alcohol ultrasonically for 30 min, and finally blow it clean with nitrogen for later use.

[0053] Step 1.2: Use magnetron sputtering technology to mask and deposit a 100nm lower electrode indium tin oxide conductive layer and a 100nm SiO2 dielectric layer on the polyimide flexible substrate in sequence. The mask covers the side to prevent the side of the polyimide flexible substrate from being plated.

[0054] Step 2: Deposition of Te nanotube thin film sensing layer by thermal evaporation in a tube furnace.

[0055] Step 2.1: Place a quartz boat carrying 0.1 g of high-purity Te powder (purity of 99.999 wt%) in the heating zone of a tube furnace.

[0056] Step 2.2: The prepared polyimide flexible substrate is fixed on a glass sheet, that is, polyimide masking tape is pasted on the 3 mm wide area on both sides of the polyimide flexible substrate to reserve the lower electrode indium tin oxide conductive layer, and polyimide masking tape is pasted on the edges of the polyimide flexible substrate to prevent the Te nanotubes deposited on the edge of the polyimide flexible substrate from being conductive to the lower electrode indium tin oxide conductive layer. The substrate is placed in the insulating area of ​​the tube furnace, and the quartz boat is 22 cm away from the polyimide flexible substrate.

[0057] Step 2.3: Close the port of the tube furnace, start the mechanical pump to pump the pressure in the tube furnace to 2Pa, and then start the molecular pump to pump the pressure in the tube furnace to 3×10 -4 Pa, turn off the molecular pump, introduce 40 sccm of high-purity argon (purity: 99.999 vol%), and maintain the pressure in the tube furnace at 25 Pa.

[0058] Step 2.4: Start the heating program, heat up to 300°C at a heating rate of 15°C / min, and then heat up to 350°C at a heating rate of 5°C / min. After keeping warm for 20 minutes, cool it in the furnace. The obtained Te nanotube thin film sensing layer is composed of Te nanotubes with a diameter of 200-400nm, a length of 4-6μm, and a wall thickness of 40-60nm interwoven with each other. It has high piezoelectric coefficient and Seebeck coefficient. The C axis of the Te nanotube forms an angle of 0-45° with the polyimide flexible substrate, which is conducive to the generation of piezoelectric signals under radial force and out-of-plane thermoelectric signals along the longitudinal direction.

[0059] Step 3: Spin-coat a polydimethylsiloxane encapsulation protection layer on the Te nanotube film sensing layer.

[0060] Step 3.1: After taking out the polyimide flexible substrate on which the Te nanotube thin film sensing layer is deposited, peel off the polyimide masking tape in step 2, and re-attach the polyimide masking tape on both sides of the polyimide flexible substrate at a width of 2 mm to avoid lifting the film when removing the masking tape later.

[0061] Step 3.2: Prepare the polydimethylsiloxane solution, mix the main agent (polydimethylsiloxane) and the curing agent (conventional platinum catalyst) evenly in a weight ratio of 10:1, put it in a vacuum box for 30 minutes to degas, and pour it into a syringe for use.

[0062] Step 3.3: Place the center of the glass sheet with the polyimide flexible substrate attached in step 2 on the spin coater, and drop 0.1 mL of polydimethylsiloxane on the Te nanotube thin film sensing layer. First, rotate at a low speed of 4000 r / min for 12 s, and then rotate at a high speed of 8000 r / min for 30 s until the polydimethylsiloxane is evenly coated on the Te nanotube thin film sensing layer.

[0063] Step 3.4: Remove the glass slide and place it on a heating platform at 150°C for 20 minutes. After curing, the thickness of the polydimethylsiloxane is 2 to 3 μm.

[0064] Step 4: Use a mask to deposit a 100nm thick gold layer for the upper electrode. The area of ​​the gold layer for the upper electrode is slightly smaller than the indium tin oxide conductive layer for the lower electrode to prevent the upper and lower electrodes from contacting and conducting.

[0065] Step 5: Remove the mask, remove the polyimide flexible substrate from the fixed glass substrate, peel off the polyimide mask tape to expose the reserved lower electrode indium tin oxide conductive layer, and use silver glue to fix one end of the gold wire to the upper and lower electrodes respectively. The free ends of the two gold wires are the output ends of the sensor.

[0066] After the above steps, the required thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes can be prepared. The sensor prepared by this method has excellent flexibility and stability, and is suitable for large-scale and miniaturized preparation. Thanks to the intrinsic properties of Te nanotubes, linear superposition thermoelectric-piezoelectric signals can be output simultaneously in a single channel.

[0067] The present invention is further explained or illustrated below by way of examples.

[0068] Example 1: Perceiving the size and rate of deformation

[0069] The thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes of the present invention is placed on a 1 mm thick polyvinyl chloride (PVC) board, one end is fixed, and the free end of the PVC board is moved by a linear motor-driven limit rod, thereby applying tensile or compressive stress to the device. At this time, piezoelectric signals about the motor movement direction, speed, and movement amplitude can be obtained from the multimeter at the same time. The polarity of the signal is reversed with the form of stress, and the amplitude of the signal increases with the strain size and strain rate.

[0070] Example 2: Sensing the temperature of a specific area

[0071] The thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes of the present invention is placed on a 1 mm thick PVC board, one end is fixed, and a heat source is placed 1 to 2 mm above the device. There is an out-of-plane temperature difference between the upper surface of the device and the lower surface of the Te nanotubes in the sensing layer. At this time, thermoelectric signals related to the temperature of the heat source can be obtained from the multimeter at the same time. The greater the temperature difference, the greater the signal amplitude.

[0072] Example 3: Sensing deformation and local temperature

[0073] The thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes of the present invention is placed on a 1 mm thick PVC board, one end is fixed, and the free end of the PVC board is moved by a linear motor driving a limit rod, thereby applying tensile or compressive stress to the device. At the same time, a heat source is placed 1 to 2 mm above the device. There is an out-of-plane temperature difference between the upper surface of the device and the lower surface of the Te nanotubes of the sensing layer. At this time, thermoelectric-piezoelectric coupling signals related to the motor movement direction, speed, movement amplitude and heat source temperature can be obtained from the multimeter at the same time, which is manifested as linear superposition.

[0074] Example 4: Sensing the bending angle and temperature of human finger joints

[0075] The Te nanotube-based thermoelectric-piezoelectric single-channel dual-parameter sensor of the present invention is attached to the finger joints. Different degrees of finger bending will bring different strains, and different bending speeds will bring different strain rates. There is a temperature difference between the finger temperature and the air temperature. Therefore, when the finger is bent, the thermoelectric-piezoelectric coupling signals of the finger bending rate, bending angle and finger temperature (constant room temperature) can be obtained from the multimeter.

[0076] like Figure 4 As shown, an electron scanning image of the Te nanotube thin film sensing layer of a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, Figure 4 It can be seen that the Te nanotubes prepared by this method have good crystal quality, large aspect ratio, uniform size, and are interwoven into a thin film instead of being perpendicular to the substrate, which is conducive to the generation of piezoelectric signals.

[0077] like Figure 5As shown, an electron scanning image of a Te nanotube thin film sensing layer after spin coating PDMS based on a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, Figure 5 It can be seen that PDMS fills the gaps between the Te nanotubes, and one end of some Te nanotubes is exposed, providing a channel for the transmission of thermoelectric signals.

[0078] The implementation results show that the thermoelectric-piezoelectric single-channel dual-parameter sensor of the present invention can simultaneously output thermoelectric-piezoelectric signals in a single channel, has excellent flexibility, simple preparation method, low cost, can be prepared on a large scale and applied in miniaturized form, and has great potential in the fields of medical health, human-computer interaction, etc.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the concept of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes, characterized in that: The sensor includes a multi-layer composite film structure, which includes, from bottom to top: a polyimide flexible substrate, a lower electrode indium tin oxide conductive layer, a SiO2 dielectric layer, a Te nanotube film sensing layer, a polydimethylsiloxane encapsulation protection layer, and an upper electrode gold layer. The upper electrode gold layer and the lower electrode indium tin oxide conductive layer are respectively led out with gold wires through silver glue as the only output end. The polyimide flexible substrate serves as a flexible support, and the upper electrode gold layer, the lower electrode indium tin oxide conductive layer and the external circuit form a loop to output signals.

2. The thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes according to claim 1, characterized in that: A lower electrode indium tin oxide conductive layer, a SiO2 dielectric layer, and a Te nanotube thin film sensing layer are sequentially deposited on a polyimide flexible substrate, a polydimethylsiloxane encapsulation protective layer is spin-coated on the Te nanotube thin film sensing layer, and an upper electrode gold layer is deposited on the polydimethylsiloxane encapsulation protective layer. One end of a gold wire is fixed to the upper electrode gold layer by silver glue, and one end of another gold wire is fixed to the lower electrode indium tin oxide conductive layer by silver glue. The free ends of the two gold wires are the output ends of the sensor. The gold wires on the upper electrode gold layer and the lower electrode indium tin oxide conductive layer serve as output ends for easy access to test equipment.

3. The thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes according to claim 1, characterized in that: The thickness of the polyimide flexible substrate is 25-75 μm, the thickness of the lower electrode indium tin oxide conductive layer is 90-110 nm, the thickness of the SiO2 dielectric layer is 90-110 nm, the thickness of the polydimethylsiloxane encapsulation protection layer is 2-3 μm, and the thickness of the upper electrode gold layer is 80-120 nm.

4. The thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes according to claim 1, characterized in that: The Te nanotube film sensing layer is formed by interweaving Te nanotubes with a diameter of 200-400nm, a length of 4-6μm, and a wall thickness of 40-60nm prepared by a tube furnace thermal evaporation method, and the C axis of the Te nanotube forms an angle of 0-45 degrees with the polyimide flexible substrate.

5. A method for preparing a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes according to any one of claims 1 to 4, characterized in that: The steps include: Step 1: depositing a conductive layer and a dielectric layer in sequence through a mask on a polyimide flexible substrate using a magnetron sputtering technique; Step 2: thermal evaporation in a tube furnace to deposit a Te nanotube thin film sensing layer; Step 3: Spin-coat a polydimethylsiloxane encapsulation protection layer on the Te nanotube film sensing layer; Step 4: Use a magnetron sputtering mask to deposit an 80-120 nm thick upper electrode gold layer, where the area of ​​the upper electrode gold layer is smaller than the area of ​​the lower electrode indium tin oxide conductive layer to prevent the upper and lower electrodes from contacting and conducting; Step 5: Remove the mask, remove the polyimide flexible substrate from the fixed glass substrate, peel off the polyimide mask tape to expose the reserved lower electrode indium tin oxide, and use silver glue to fix one end of the gold wire to the upper and lower electrodes respectively. The free ends of the two gold wires are the output ends of the sensor.

6. The method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes according to claim 5, characterized in that: Step 1 is as follows: Step 1.1: Cut a 25-75 μm thick polyimide flexible substrate into a 1 cm × 2 cm rectangle, clean it with acetone and alcohol ultrasonically for 20-40 min, and finally blow it clean with nitrogen for later use; Step 1.2: Using magnetron sputtering technology, a lower electrode indium tin oxide conductive layer with a thickness of 90 to 110 nm and a SiO2 dielectric layer with a thickness of 90 to 110 nm are sequentially deposited on the polyimide flexible substrate through masking.

7. The method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes according to claim 5, characterized in that: The growth process of Te nanotubes in step 2 is specifically as follows: Step 2.1: Place the quartz boat containing Te powder in the heating zone of the tube furnace; Step 2.2: The prepared polyimide flexible substrate is fixed on a glass sheet, that is, polyimide masking tape is pasted on the 2-4 mm wide area on both sides of the polyimide flexible substrate to reserve the lower electrode, and polyimide masking tape is pasted on the edges of the polyimide flexible substrate to prevent the Te nanotubes deposited on the edge of the film from being connected to the indium tin oxide of the lower electrode, and the substrate is placed in the insulating area of ​​the tube furnace, and the quartz boat is 20-25 cm away from the polyimide flexible substrate; Step 2.3: Close the port of the tube furnace, start the mechanical pump to pump the pressure in the tube furnace to 1-3 Pa, and then start the molecular pump to pump the pressure in the tube furnace to 5×10 -4 Pa, turn off the molecular pump, introduce 30-50 sccm argon gas, and maintain the pressure in the tube furnace at 20-30 Pa; Step 2.4: Start the heating program, heat up to 280-320°C at a heating rate of 10-20°C / min, then heat up to 340-360°C at 4-6°C / min, keep warm for 18-22 minutes, and then cool in the furnace to obtain a Te nanotube thin film sensing layer.

8. The method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes according to claim 5, characterized in that: Step 3 is as follows: Step 3.1: After taking out the polyimide flexible substrate on which the Te nanotube thin film sensing layer is deposited, peel off the polyimide masking tape in step 2, and re-apply the polyimide masking tape on both sides of the polyimide flexible substrate at a width of 1 to 3 mm to avoid lifting the film when removing the masking tape later; Step 3.2: Prepare polydimethylsiloxane solution, mix the main agent and curing agent in a weight ratio of 10:1, put it in a vacuum box for 20 to 40 minutes to degas, and pour it into a syringe for use; Step 3.3: The center of the glass sheet with the polyimide flexible substrate attached in step 2 is adsorbed on the spin coater, and the polydimethylsiloxane solution is drop-coated on the Te nanotube thin film sensing layer, first rotating at a low speed of 3000-5000 r / min for 10-15 s, and then rotating at a high speed of 7000-9000 r / min for 20-40 s, until the polydimethylsiloxane solution is evenly coated on the Te nanotube thin film sensing layer; Step 3.4: Remove the glass sheet and place it on a heating table at 140-160°C for 18-22 minutes. After curing, the thickness of the polydimethylsiloxane is 2-3 μm.

9. The method for preparing a thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes according to claim 5, characterized in that: In step 2, Te nanotubes with intrinsic pyroelectric and piezoelectric effects are used as pyroelectric-piezoelectric sensing units.

10. The method for preparing the thermoelectric-piezoelectric single-channel dual-parameter sensor based on Te nanotubes according to claim 5, characterized in that: In step 2, Te nanotubes are prepared by low-temperature thermal evaporation of Te powder.

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