Flexible Ferroelectric Polymer Pyroelectric Material Sensor and Its Preparation Method

Abstract

The present invention discloses a flexible ferroelectric polymer pyroelectric material sensor and a preparation method thereof. The present invention uses a ferroelectric polymer based on polyvinylidene fluoride (PVDF). The sensor sequentially includes an upper flexible layer, an upper copper foil current collector layer, a polyvinylidene fluoride pyroelectric layer, a lower copper foil current collector layer, and a lower flexible layer. The polyvinylidene fluoride pyroelectric layer is adhered to the upper copper foil current collector layer and the lower copper foil current collector layer. The upper and lower copper foil layers adhered to the polyvinylidene fluoride pyroelectric layer are connected to an external circuit through wires. The upper flexible layer is adhered to the lower flexible layer and the polyvinylidene fluoride pyroelectric layer adhered with the upper and lower copper foil layers. At the same time, the present invention also provides a preparation method of the pyroelectric sensor. The pyroelectric sensor of the present invention has fast heat dissipation, fast response, simple structure, and the function of real-time body temperature monitoring.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and particularly relates to a flexible ferroelectric polymer pyroelectric material sensor and a preparation method thereof. Background Art

[0002] The Seebeck effect refers to the fact that a temperature difference between two points of a conductor or semiconductor will cause a voltage difference; in other words, a temperature gradient in a conductor or semiconductor will generate an electric field. Analyzed microscopically, the reason for the formation of the Seebeck effect is as follows: Taking an N-type semiconductor material as an example, when a temperature gradient is applied to both ends of the material, there are more high-energy electrons at the high-temperature end and more low-energy electrons at the cold end. During the thermal diffusion process, high-energy electrons have higher kinetic energy, enabling them to reach the other end faster than low-energy electrons, thereby causing an asymmetry in the number of electrons at both ends of the material, and then forming an electric field. When the drift force of the reverse electric field acting on the electrons reaches a dynamic balance with the diffusion force generated by the thermal motion, a stable potential difference is formed at both ends. And polyvinylidene fluoride, as an organic flexible ferroelectric polymer, has excellent pyroelectric properties.

[0003] Most traditional temperature sensors are made of inorganic materials and do not have the characteristics of flexibility, comfort, and wearability. Given that temperature sensors can measure the temperature of an object, they are widely used in all aspects of human life. Common traditional temperature measurement methods include mercury thermometers and infrared thermometers. Mercury thermometers are accurate in temperature measurement, but the measurement time is too long, which is obviously not suitable in this fast-paced era. Moreover, mercury is toxic and poses a threat to human health; while the principle of an infrared thermometer is to obtain the measured temperature by using the infrared radiation on the surface of an object, but improper use methods and environmental factors will greatly reduce the accuracy of the infrared thermometer. With the progress of technology and the development of the Internet of Things, flexible temperature sensors are expected to obtain real-time human body temperature signals in a wearable manner and have important application potential in various aspects such as medical health monitoring, sports detection, portable electronic devices, and human-computer interaction. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of existing sensor technologies such as long temperature measurement time and inaccurate temperature measurement, and to provide a flexible ferroelectric polymer pyroelectric material sensor with excellent accuracy, fast response, flexibility, and simple structure, that is, a pyroelectric sensor based on polyvinylidene fluoride material and a preparation method thereof.

[0005] To achieve the above purpose, the technical solutions provided by the present invention are as follows:

[0006] In a first aspect, the present invention provides a flexible ferroelectric polymer pyroelectric material sensor, characterized in that: a ferroelectric polymer based on polyvinylidene fluoride, the pyroelectric sensor has a sandwich structure, and sequentially includes an upper flexible layer, an upper copper foil current collector layer, i.e., an upper current collector layer, a polyvinylidene fluoride pyroelectric layer, i.e., a pyroelectric layer, a lower copper foil current collector layer, i.e., a lower current collector layer, and a lower flexible layer from top to bottom. Lead terminals made of conductive silver paste are respectively attached to the upper copper foil current collector layer and the lower copper foil current collector layer, and are connected to the outside through wires;

[0007] The polyvinylidene fluoride pyroelectric layer is attached to the upper copper foil current collector layer and the lower copper foil current collector layer. The polyvinylidene fluoride pyroelectric layer has a thin film structure and is located in the middle layer of the pyroelectric sensor;

[0008] One side of the upper copper foil current collector layer and the lower copper foil current collector layer are respectively attached to the upper and lower surfaces of the pyroelectric layer. And a lead terminal is respectively drop - formed on the surfaces of the upper copper foil current collector layer and the lower copper foil current collector layer using conductive silver paste to connect wires. The upper copper foil current collector layer and the lower copper foil current collector layer are both made of pure copper thin sheets. The lead terminals made of conductive silver paste are respectively attached to the upper surfaces of the upper copper foil current collector layer and the lower copper foil current collector layer. The lead terminals are connected to an external circuit through wires;

[0009] The upper flexible layer and the lower flexible layer are located on the outermost layer of the entire pyroelectric sensor, covering the pyroelectric layer and the copper foil current collector layer;

[0010] The thin film structure of the polyvinylidene fluoride pyroelectric layer is evenly distributed between the upper copper foil current collector layer and the lower copper foil current collector layer. The two lead terminals are respectively located above the upper copper foil current collector layer and the lower copper foil current collector layer.

[0011] As a preferred solution, the materials of the upper flexible layer and the lower flexible layer are polyimide PI.

[0012] Furthermore, the thicknesses of the upper flexible layer and the lower flexible layer are both 100 μm;

[0013] The thicknesses of the upper copper foil current collector layer and the lower copper foil current collector layer are both 10 μm;

[0014] The thickness of the polyvinylidene fluoride layer is 50 - 200 μm;

[0015] The conductive terminal is made of conductive silver paste and has a thickness of 100 μm;

[0016] The wire is an enameled wire with a diameter of 10 μm.

[0017] In a second aspect, the present invention provides a preparation method for a flexible ferroelectric polymer pyroelectric material sensor, including the following steps:

[0018] S1: Dissolve a certain mass of polyvinylidene fluoride powder in DMF, acetone, or a mixed solution of both. Control the concentration of the polyvinylidene fluoride solution at 10%-22%. Ultrasonically mix and dissolve the solvent system DMF / acetone (7:3) for 30 min at a temperature of 40 °C. After all the polyvinylidene fluoride is dissolved, filter it under vacuum, seal it, and let it stand for 5 h to obtain a stable polyvinylidene fluoride solution. Place the prepared substrate wafer on the wafer holder and clean it by a three-step method, that is, first place the wafer in acetone, ethanol, and deionized water successively for ultrasonic cleaning. After cleaning the wafer, blow off the water droplets with nitrogen and place it in a vacuum drying oven for drying, which is reserved for spin coating.

[0019] S2: Prepare the polyvinylidene fluoride pyroelectric layer. Place the polyvinylidene fluoride solution on the wafer on the spin coater, and adjust the appropriate rotation speed and time of the spin coater to prepare a polyvinylidene fluoride thin film. After drying the prepared polyvinylidene fluoride thin film in a vacuum drying oven, peel it off and cut it into an appropriate size.

[0020] S3: Install the upper and lower copper foil current collectors. Cut the copper foil into an appropriate size, stick the sticky sides of the upper and lower parts on both sides of the polyvinylidene fluoride thin film respectively, then lead out a terminal on each of the upper and lower copper foils, and then connect the wire to the terminal.

[0021] S4: Install the upper and lower flexible layers. Cut the PI film into an appropriate size, and wrap the upper and lower flexible layers around the polyvinylidene fluoride pyroelectric layer with the upper and lower copper foil current collectors attached, then the pyroelectric sensor can be obtained.

[0022] In step S2, the selected spin coating conditions are 500 rmp / min for 10 s; the spin-off conditions are 2000 rmp / min for 15 s. After preparing the wet film, dry the wafer. The temperature is 100 °C and the time is 6 h; in step S2, place the prepared polyvinylidene fluoride thin film in a vacuum drying oven, set the temperature to 60 °C, and the drying time is 1 h; the prepared polyvinylidene fluoride thin film is cut into a size of 2×2 cm.

[0023] In step S3, the copper foil is cut into a size of 1.5×1.5 cm;

[0024] In step S4, the PI film is cut into a size of 2.5×2.5 cm.

[0025] In step S3, on the surface of the copper foil current collector, drop a drop of conductive silver paste as the lead-out terminal, use the enameled wire as the wire to connect to the conductive silver paste, and dry and fix it. Make the lead-out terminal with the conductive silver paste, and then place it in a vacuum drying oven, set the temperature to 100 °C, and the drying time is 1 h.

[0026] The advantages and beneficial effects of the present invention are as follows:

[0027] The technical solution of the present invention is based on the Seebeck effect, that is, when the temperatures at both ends of the material are different, an output voltage can be generated, and different temperature differences at both ends will generate different output voltages. Therefore, this sensor has the characteristics of high precision, fast response, and low energy consumption. At the same time, both the material itself and the entire pyroelectric sensor are flexible and bendable substrates, which have great application potential in the fields of medical and health, electronic devices, wearable devices, etc.

[0028] The present invention uses wireless Bluetooth technology to establish a human body temperature detection system to monitor the physical condition of the human body. The design purpose of this system is to monitor the body temperature of the human body, obtain the body surface temperature data of the human body, and perform initial processing, and then transmit the data to the mobile phone terminal through Bluetooth, and further process it through the mobile phone software to synthesize a curve graph. Using a sensor and other components, the temperature sensor is used to monitor the body temperature of volunteers.

[0029] The pyroelectric temperature sensor and the wireless Bluetooth system introduced in the present invention can form an overall human body signal monitoring system. PVDF has excellent pyroelectric performance, and its comprehensive performance is superior to other traditional pyroelectric materials. The mobile phone software platform is successfully connected to the temperature sensor, and can generate the vital signs and temperature data of patients or applications. Generally speaking, the performance of this system is effective in collecting human body data, which is a suitable solution for Internet of Things-based healthcare.

[0030] In summary, different from the principles and applications of traditional pyroelectric sensors, the present invention can obtain electrical energy from human body heat or environmental temperature gradients, and through external circuit connection, achieve the effect of real-time monitoring. The thermocouple for detecting temperature according to the Seebeck effect in the present invention is designed to be used as a flexible temperature sensor. The thermocouple is formed by a pair of different metals or alloys, such as copper and constantan. A pyroelectric temperature sensor designed by the present invention. A sensing area of 2.0 cm × 2.0 cm is designed on the sensor. Characterization shows that the output voltage of the sensor is proportional to the designed temperature. It is very important to ensure the performance of the sensor without being affected by driving. The present invention has important application prospects in the fields of flexible wearable physical sensors and personalized healthcare. Brief Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of the present invention.

[0032] Figure 2 It is a cross-sectional structural diagram of the present invention.

[0033] Figure 3 It is a top view of the polyvinylidene fluoride of the present invention.

[0034] Figure 4 It is a top view of a flexible ferroelectric polymer pyroelectric material sensor of the present invention.

[0035] Figure 5 Schematic diagram of the test of a flexible ferroelectric polymer pyroelectric material sensor of the present invention with ice-water mixture (0 °C) as the calibration temperature under different temperature heat sources, supplemented by an infrared thermal imager as a reference.

[0036] Figure 6 Temperature cycle change and corresponding output voltage curve of a flexible ferroelectric polymer pyroelectric material sensor of the present invention.

[0037] In the figure: 1. Upper flexible layer; 2. Upper copper foil current collecting layer; 3. Lead-out terminal; 4. Wire; 5. Polyvinylidene fluoride pyroelectric layer; 6. Lower copper foil current collecting layer; 7. Lower flexible layer. Detailed implementation manners

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The same reference numerals represent the same or functionally identical elements or components.

[0039] As Figure 1 and Figure 2 shown, it is a schematic structural diagram of a flexible ferroelectric polymer pyroelectric material sensor according to a preferred embodiment of the present invention, which includes an upper flexible layer 1, an upper copper foil current collecting layer 2, a polyvinylidene fluoride pyroelectric layer 5, a lower copper foil current collecting layer 6, and a lower flexible layer 7 from top to bottom.

[0040] The polyvinylidene fluoride pyroelectric layer 5 is attached to the upper copper foil current collecting layer 2 and the lower copper foil current collecting layer 6. The polyvinylidene fluoride pyroelectric layer 5 is a thin film structure, and the copper foil current collecting layer is made of a pure copper thin sheet, which is used to collect the surface charges of the polyvinylidene fluoride pyroelectric layer. Conductive silver paste connects the upper copper foil current collecting layer 2, the lower copper foil current collecting layer 6 and the wire 4 led out by the two lead-out terminals 3. The lead-out terminal 3 is connected to an external circuit through the wire 4. The upper flexible layer 1 and the lower flexible layer 7 cover the upper copper foil current collecting layer 2, the polyvinylidene fluoride pyroelectric layer 5 and the lower copper foil current collecting layer 6.

[0041] The polyvinylidene fluoride pyroelectric layer 5 has a thickness of 50 - 200 μm. The prepared polyvinylidene fluoride film is cut into a size of 2 × 2 cm. As the external environmental temperature changes, the material becomes polarized, so that the positive and negative charge centers in a certain direction inside the material no longer coincide. Due to this change, charges are generated on the surface of the material. The upper copper foil current collecting layer 2 and the lower copper foil current collecting layer 6 have a thickness of 10 μm, and the copper foil constituting them is cut into a size of 1.5 × 1.5 cm. Copper has excellent electrical conductivity and can timely conduct the charges generated on the polyvinylidene fluoride pyroelectric layer through the wire.

[0042] The lead-out terminal 3 is made of conductive silver paste with a thickness of 100 μm; the wire 4 is an enameled wire with a diameter of 50 μm. This facilitates the connection to the external circuit. The upper flexible layer 1 and the lower flexible layer 7, with a thickness of 100 μm, are made of PI film cut into a size of 2.5×2.5 cm. Such a thin film structure is conducive to heat conduction, and the PI film has good heat conduction performance.

[0043] The specific preparation process of the above flexible ferroelectric polymer pyroelectric material sensor is as follows:

[0044] S1: Dissolve a certain mass of polyvinylidene fluoride powder in DMF, acetone, or a mixed solution of both, ultrasonically mix and dissolve for 30 min at an ultrasonic temperature of 40 °C. After all the polyvinylidene fluoride is dissolved, filter it under vacuum, seal it, and let it stand for 5 h to obtain a stable polyvinylidene fluoride solution. Place the prepared substrate wafer on the wafer holder and clean it by a three-step method, that is, first put the wafer into acetone, ethanol, and deionized water in sequence for ultrasonic cleaning. After cleaning the wafer, blow off the water droplets with nitrogen and put it into a vacuum drying oven for drying, reserved for spin coating.

[0045] S2: Prepare the polyvinylidene fluoride pyroelectric layer 5. Place the polyvinylidene fluoride solution on the wafer on the spin coater. The selected spin coating conditions are 500 rmp / min for 10 s; the spin-off conditions are 2000 rmp / min for 15 s. After preparing the wet film, dry the wafer. The temperature is 100 °C and the time is 6 h; in step S2, put the prepared polyvinylidene fluoride thin film into a vacuum drying oven, set the temperature to 60 °C, and the drying time is 1 h. After drying the prepared polyvinylidene fluoride thin film in the vacuum drying oven, peel it off and cut it into a size of 2×2 cm.

[0046] S3: Install the upper copper foil current collector layer 2 and the lower copper foil current collector layer 6. Cut the copper foil into a suitable size, stick the upper and lower sticky sides on both sides of the polyvinylidene fluoride thin film respectively, then lead out a terminal on each of the upper and lower copper foils, and then connect the wire to the terminal. Drop a drop of conductive silver paste on the surface of the copper foil current collector layer as the lead-out terminal, use the enameled wire as the wire to connect to the conductive silver paste, and dry and fix it. Make the lead-out terminal with conductive silver paste, and then place it in a vacuum drying oven, set the temperature to 100 °C, and the drying time is 1 h.

[0047] S4: Install the upper flexible layer 1 and the lower flexible layer 7. Cut the PI film into a suitable size, wrap the upper flexible layer 1 and the lower flexible layer 7 around the polyvinylidene fluoride pyroelectric layer 5 with the upper copper foil current collector layer 2 and the lower copper foil current collector layer 6 attached, and then the pyroelectric sensor can be obtained.

[0048] In the above test process, a PDMS film can also be used instead of the PI film as the upper flexible layer 1 and the lower flexible layer 7. PDMS has high light transmittance. The PDMS material itself has high dielectric properties, and the material is very flexible and tough, making the flat PDMS film have good electrostatic adsorption and good fitting effect, and good wearable effect.

[0049] For those not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are all conventional products that can be obtained through commercial purchase. The following takes the preparation of the polyvinylidene fluoride pyroelectric layer of the flexible ferroelectric polymer pyroelectric sensor as an example for illustration.

[0050] Example 1

[0051] The preparation method of the polyvinylidene fluoride pyroelectric layer of the flexible ferroelectric polymer pyroelectric sensor is as follows:

[0052] Dissolve a certain mass of polyvinylidene fluoride powder in DMF, acetone, or a mixed solution of both, ultrasonically mix and dissolve for 30 min, and the ultrasonic temperature is 40 °C. After all the polyvinylidene fluoride is dissolved, vacuum filter it, seal it and let it stand for 5 h to obtain a stable polyvinylidene fluoride solution. Place the prepared substrate on the substrate holder and clean it by a three-step method, that is, first put the substrate into acetone, ethanol, and deionized water in sequence and perform ultrasonic cleaning. After cleaning the substrate, blow off the water droplets with nitrogen and put it into a vacuum drying oven for drying, reserved for spin coating. Prepare the polyvinylidene fluoride pyroelectric layer 5. Place the polyvinylidene fluoride solution on the substrate on the spin coater. The selected spin coating conditions are 500 rmp / min for 10 s; the spin-off conditions are 2000 rmp / min for 15 s. After preparing the wet film, dry the substrate. The temperature is 100 °C and the time is 6 h; in step S2, put the prepared polyvinylidene fluoride film into a vacuum drying oven, set the temperature to 60 °C, and the drying time is 1 h. Put the prepared polyvinylidene fluoride film into the vacuum drying oven for drying and then peel it off, control the thickness to 100 μm, and cut it into a size of 2×2 cm.

[0053] Example 2

[0054] The preparation method of the polyvinylidene fluoride pyroelectric layer of the flexible ferroelectric polymer pyroelectric sensor is as follows:

[0055] Dissolve a certain mass of polyvinylidene fluoride powder in DMF, acetone, or a mixed solution of both. Ultrasonically mix and dissolve for 30 min at a temperature of 40 °C. After all the polyvinylidene fluoride is dissolved, perform vacuum filtration, seal, and let stand for 5 h to obtain a stable polyvinylidene fluoride solution. Place the prepared substrate wafer on the wafer holder and clean it by a three-step method, that is, first put the wafer into acetone, ethanol, and deionized water successively and perform ultrasonic cleaning in turn. After cleaning the wafer, blow off the water droplets with nitrogen and place it in a vacuum drying oven for drying, reserved for spin coating. Prepare the polyvinylidene fluoride pyroelectric layer 5. Place the polyvinylidene fluoride solution on the wafer on the spin coater. The selected spin coating conditions are 500 rmp / min for 10 s; the spin-off conditions are 2000 rmp / min for 15 s. After preparing the wet film, dry the wafer. The temperature is 100 °C and the time is 6 h; in step S2, place the prepared polyvinylidene fluoride film in a vacuum drying oven, set the temperature to 60 °C, and the drying time is 1 h. After drying the prepared polyvinylidene fluoride film in a vacuum drying oven, peel it off, control the thickness to 200 μm, and cut it into a size of 2×2 cm.

[0056] Example 3

[0057] The preparation method of the polyvinylidene fluoride pyroelectric layer of the flexible ferroelectric polymer pyroelectric sensor is as follows:

[0058] Dissolve a certain mass of polyvinylidene fluoride powder in DMF, acetone, or a mixed solution of both. Ultrasonically mix and dissolve for 30 min at a temperature of 40 °C. After all the polyvinylidene fluoride is dissolved, perform vacuum filtration, seal, and let stand for 5 h to obtain a stable polyvinylidene fluoride solution. Place the prepared substrate wafer on the wafer holder and clean it by a three-step method, that is, first put the wafer into acetone, ethanol, and deionized water successively and perform ultrasonic cleaning in turn. After cleaning the wafer, blow off the water droplets with nitrogen and place it in a vacuum drying oven for drying, reserved for spin coating. Prepare the polyvinylidene fluoride pyroelectric layer 5. Place the polyvinylidene fluoride solution on the wafer on the spin coater. The selected spin coating conditions are 500 rmp / min for 10 s; the spin-off conditions are 2000 rmp / min for 15 s. After preparing the wet film, dry the wafer. The temperature is 100 °C and the time is 6 h; in step S2, place the prepared polyvinylidene fluoride film in a vacuum drying oven, set the temperature to 60 °C, and the drying time is 1 h. After drying the prepared polyvinylidene fluoride film in a vacuum drying oven, peel it off, control the thickness to 100 μm, and cut it into a size of 2×1 cm.

[0059] Example 4

[0060] The preparation method of the polyvinylidene fluoride pyroelectric layer of the flexible ferroelectric polymer pyroelectric sensor is as follows:

[0061] Dissolve a certain mass of polyvinylidene fluoride powder in DMF, acetone, or a mixed solution of both. Ultrasonically mix and dissolve for 30 min at an ultrasonic temperature of 40 °C. After all the polyvinylidene fluoride is dissolved, filter it under vacuum and seal it for static placement for 5 h to obtain a stable polyvinylidene fluoride solution. Place the prepared substrate wafer on the wafer holder and clean it by a three-step method, that is, first place the wafer successively into acetone, ethanol, and deionized water, and perform ultrasonic cleaning in sequence. After cleaning the wafer, blow off the water droplets with nitrogen and place it in a vacuum drying oven for drying, leaving it for spin coating. Prepare the polyvinylidene fluoride pyroelectric layer 5. Place the polyvinylidene fluoride solution on the wafer on the spin coater. The selected spin coating conditions are 500 rmp / min for 10 s; the spin-off conditions are 2000 rmp / min for 15 s. After preparing the wet film, dry the wafer. The temperature is 100 °C and the time is 6 h; in step S2, place the prepared polyvinylidene fluoride thin film in a vacuum drying oven, set the temperature to 60 °C, and the drying time is 1 h. Place the prepared polyvinylidene fluoride thin film in a vacuum drying oven for drying and then peel it off. Control the thickness to 200 μm and cut it into a size of 2×1 cm.

[0062] Example 5

[0063] The preparation method of the polyvinylidene fluoride pyroelectric layer of the flexible ferroelectric polymer pyroelectric sensor is as follows:

[0064] Dissolve a certain mass of polyvinylidene fluoride powder in DMF, acetone, or a mixed solution of both. Ultrasonically mix and dissolve for 30 min at an ultrasonic temperature of 40 °C. After all the polyvinylidene fluoride is dissolved, filter it under vacuum and seal it for static placement for 5 h to obtain a stable polyvinylidene fluoride solution. Place the prepared substrate wafer on the wafer holder and clean it by a three-step method, that is, first place the wafer successively into acetone, ethanol, and deionized water, and perform ultrasonic cleaning in sequence. After cleaning the wafer, blow off the water droplets with nitrogen and place it in a vacuum drying oven for drying, leaving it for spin coating. Prepare the polyvinylidene fluoride pyroelectric layer 5. Place the polyvinylidene fluoride solution on the wafer on the spin coater. The selected spin coating conditions are 500 rmp / min for 10 s; the spin-off conditions are 2000 rmp / min for 15 s. After preparing the wet film, dry the wafer. The temperature is 100 °C and the time is 6 h; in step S2, place the prepared polyvinylidene fluoride thin film in a vacuum drying oven, set the temperature to 60 °C, and the drying time is 1 h. Place the prepared polyvinylidene fluoride thin film in a vacuum drying oven for drying and then peel it off. Control the thickness to 100 μm and cut it into a size of 2×2 cm. Drop a certain amount of silver nanocubes (AgNCs) on the dried polyvinylidene fluoride thin film. After drying, cool it to room temperature.

[0065] The difference between Example 2 and Example 1 is that the thicknesses of the polyvinylidene fluoride thin films are 100 μm and 200 μm respectively.

[0066] Example 3 is different from Example 1 in that the sizes of the cut polyvinylidene fluoride films are 2×2 cm and 2×1 cm respectively.

[0067] Example 4 is different from Example 1 in that the thicknesses and the sizes of the cut polyvinylidene fluoride films are 100 μm, 2×2 cm and 200 μm, 2×1 cm respectively.

[0068] Example 5 is different from Example 1 in that the polyvinylidene fluoride film in Example 5 is doped with silver nanocubes.

[0069] Basic principle of the pyroelectric sensor: By applying an external heat source at both ends of the polyvinylidene fluoride pyroelectric layer, a temperature gradient is generated. The positive and negative charge centers of the material will undergo relative displacement, thereby driving the change of polarization, causing the surface of the material to generate induced charges, so an electric field appears. If it is connected to an external circuit, a current can be shown.

[0070] As Figure 5 shown, a heat source is provided by a hot stage, and the ice-water mixture (0 °C) is used as the calibration temperature. The sensor is tested under different temperature heat sources, and the electrical properties are measured with a Keithley digital multimeter (Agilent 34410A), supplemented by an infrared thermal imaging (infisense P2) instrument as a reference.

[0071] As Figure 6 shown, the temperature cyclic variation and the corresponding output voltage curve of the pyroelectric material sensor. With the ice-water mixture (0 °C) as the calibration temperature, the output voltages obtained from the tests of the sensor under different temperature heat sources are all different. Thus, the corresponding temperature can be calibrated through the output voltage.

Claims

1. A flexible ferroelectric polymer pyroelectric material sensor, characterized in that: a ferroelectric polymer based on polyvinylidene fluoride, the pyroelectric material sensor has a sandwich structure, and successively includes an upper flexible layer, an upper copper foil current collector layer, i.e., the upper current collector layer, a polyvinylidene fluoride pyroelectric layer, i.e., the pyroelectric layer, a lower copper foil current collector layer, i.e., the lower current collector layer, and a lower flexible layer from top to bottom. Lead terminals made of conductive silver paste are respectively attached to the upper copper foil current collector layer and the lower copper foil current collector layer, and are connected to the outside through wires; the polyvinylidene fluoride pyroelectric layer is attached to the upper copper foil current collector layer and the lower copper foil current collector layer, the polyvinylidene fluoride pyroelectric layer is in a thin film structure and is located in the middle layer of the pyroelectric sensor; one side of the upper copper foil current collector layer and the lower copper foil current collector layer are respectively attached to the upper and lower surfaces of the pyroelectric layer, and a lead terminal is titrated on the surface of the upper copper foil current collector layer and the lower copper foil current collector layer with conductive silver paste respectively to connect the wire; the upper copper foil current collector layer and the lower copper foil current collector layer are both made of pure copper thin sheets, the lead terminals made of conductive silver paste are respectively attached to the upper surfaces of the upper copper foil current collector layer and the lower copper foil current collector layer, and the lead terminals are connected to an external circuit through wires; the upper flexible layer and the lower flexible layer are located on the outermost layer of the entire pyroelectric sensor and cover the pyroelectric layer and the copper foil current collector layer; the thin film structure of the polyvinylidene fluoride pyroelectric layer is evenly distributed between the upper copper foil current collector layer and the lower copper foil current collector layer, and the two lead terminals are respectively located above the upper copper foil current collector layer and the lower copper foil current collector layer.

2. The flexible ferroelectric polymer pyroelectric material sensor according to claim 1, characterized in that: the materials of the upper flexible layer and the lower flexible layer are polyimide PI.

3. The flexible ferroelectric polymer pyroelectric material sensor according to claim 2, characterized in that: the thicknesses of the upper flexible layer and the lower flexible layer are both 100 μm; the thicknesses of the upper copper foil current collector layer and the lower copper foil current collector layer are both 10 μm; the thickness of the polyvinylidene fluoride layer is 50 - 200 μm; the lead terminals are made of conductive silver paste and have a thickness of 100 μm; the wire is an enameled wire with a diameter of 10 μm.

4. A method for preparing the flexible ferroelectric polymer pyroelectric material sensor according to any one of claims 1 to 3, characterized in that: comprises the following steps: S1: Dissolve polyvinylidene fluoride powder in N,N - dimethylformamide DMF, acetone, or a mixed solution of both, ultrasonically mix and dissolve for 30 min, the ultrasonic temperature is 40 °C. After all the polyvinylidene fluoride is dissolved, vacuum filter, seal and stand for 5 h to obtain a stable polyvinylidene fluoride solution; Place the prepared substrate wafer on the wafer holder and clean it by a three - step method, that is, first put the wafer into acetone, ethanol, and deionized water successively for ultrasonic cleaning; After cleaning the wafer, blow off the water droplets with nitrogen and put it into a vacuum drying oven for drying for use in spin - coating; S2: Prepare the polyvinylidene fluoride pyroelectric layer: Place the polyvinylidene fluoride solution on the wafer on the spin coater, adjust the appropriate rotation speed and time of the spin coater to prepare a polyvinylidene fluoride thin film; Put the prepared polyvinylidene fluoride thin film into a vacuum drying oven for drying and then peel it off, and cut it into an appropriate size; S3: Install the upper copper foil current collector and the lower copper foil current collector: Cut the copper foil into an appropriate size, attach the sticky sides of the upper and lower parts to both sides of the polyvinylidene fluoride film respectively, then lead out a terminal from each of the upper and lower copper foils, and then connect the wire to the terminal; S4: Install the upper flexible layer and the lower flexible layer: Cut the PI film into an appropriate size, and wrap the upper flexible layer and the lower flexible layer around the polyvinylidene fluoride pyroelectric layer with the upper copper foil current collector and the lower copper foil current collector attached, then the pyroelectric sensor can be obtained.

5. The preparation method of the flexible ferroelectric polymer pyroelectric material sensor according to claim 4, characterized in that: the In the step S2, the selected spin coating conditions are 500 rmp / min for 10 s; the spin drying conditions are 2000 rmp / min for 15 s; after the wet film is prepared, the substrate is dried; the temperature is 100 °C and the time is 6 h; the prepared polyvinylidene fluoride film is put into a vacuum drying oven, the temperature is set at 60 °C, and the drying time is 1 h; the prepared polyvinylidene fluoride film is cut into a size of 2×2 cm; In the step S3, the copper foil is cut into a size of 1.5×1.5 cm; In the step S4, the PI film is cut into a size of 2.5×2.5 cm.

6. The preparation method of the flexible ferroelectric polymer pyroelectric material sensor according to claim 4 or 5, characterized in that: In the step S3, on the surface of the copper foil current collector, drop a drop of conductive silver paste as the lead-out terminal, connect the enameled wire as the wire to the conductive silver paste, and dry and fix it; make the lead-out terminal with conductive silver paste, then place it in a vacuum drying oven, the temperature is set at 100 °C, and the drying time is 1 h.

Images