Force-temperature dual-mode wearable wireless sensing device and preparation method thereof

Abstract

The invention relates to a force-temperature dual-mode wearable wireless sensing device and a preparation method thereof, belongs to the technical field of sensors, and aims to provide a device which can be attached to the skin, can simultaneously monitor physiological activities such as pulse beat and environment temperature and can synchronously monitor the properties of objects including weight and temperature. The invention particularly relates to design, preparation and optimization of a wireless sensing system. And by selecting flexible materials such as the TPU film and the dust-free cloth, the sensor has good flexibility and air permeability, is comfortable to wear and is not easy to cause skin discomfort. Two functions of capacitive force sensing and resistive temperature sensing are integrated, pressure and temperature can be monitored at the same time, and more comprehensive health monitoring data are provided. And by adopting the flexible coil and the LC oscillation circuit, wireless transmission of signals is realized, the use of a traditional hard circuit board is avoided, and the flexibility and the wearable performance of the equipment are further improved.

Description

Technical Field

[0001] The present invention relates to a wearable wireless sensor device with dual force and temperature modes and a preparation method thereof, belonging to the field of sensor technology. The present invention aims to provide a device that can be attached to the skin and can simultaneously monitor physiological activities such as pulse beats and ambient temperature, and synchronously monitor the properties of an object including weight and temperature. The present invention specifically relates to the design, preparation and optimization of a wireless sensor system. Background Art

[0002] With the rapid development of science and technology, wearable devices have made significant progress in the fields of health monitoring, motion analysis and medical diagnosis. These devices can monitor the physiological parameters of the human body, such as heart rate, blood oxygen level, movement status, etc. in real time by embedding various sensors, which greatly improves people's understanding and management of their own health conditions. However, the wearable sensors currently on the market mainly use rigid silicon-based or metal materials. Although they have high detection accuracy, they lack sufficient flexibility and are difficult to fit well with the surface of human skin, resulting in poor wearing comfort. In addition, the breathability of these sensors is also poor, and wearing them for a long time can easily cause skin discomfort and even eczema. Another limiting factor is that existing wearable sensors can usually only monitor a single physiological parameter and cannot meet the needs of comprehensive monitoring of multiple parameters.

[0003] General pressure sensors and temperature sensors are usually separate individual devices that require independent power supplies and data processing modules, which increases the complexity and cost of the system. In addition, wireless transmission modules also have certain limitations in existing wearable devices. Traditional wireless transmission modules mostly use rigid circuit boards and fixed antennas, which increase the thickness and weight of the device and are not conducive to the lightness and flexibility of the device. Moreover, in actual application environments, such as moisture or sweat, the performance and stability of rigid sensors are often affected, making it difficult to ensure continuous and accurate monitoring results. Therefore, it is of great significance to develop a wearable device that is flexible, breathable, has multifunctional sensing capabilities, and can stably transmit wireless signals. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to propose a force-temperature dual-modal wearable wireless sensor device and a preparation method thereof, with the aim of providing a design scheme that is comfortable to wear and can simultaneously respond to different degrees of pressure and different ambient temperatures with high sensitivity and speed. In addition, by adjusting the coil specifications and parameters, the pressure and temperature signals can be stably transmitted to the receiving end through a coil coupling method based on Faraday's law of electromagnetic induction without power supply.

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

[0006] A wearable wireless sensor device with dual force and temperature modes comprises, in sequence, a copper coil 1, a silver nanowire electrode layer 2, a TPU sensitive layer 3, a CNT electrode layer 4, and a PEDOT:PSS / AgNWs resistor 5.

[0007] A method for preparing a wearable wireless sensor device with dual force and temperature modes, the method comprising the steps of:

[0008] Step 1, preparing a dielectric layer solution, wherein the solute of the dielectric layer solution is thermoplastic polyurethane elastomer (TPU), and the solvent of the dielectric layer solution is at least one of N,N-dimethylformamide (DMF), tetrahydrofuran (THF), methyl ethyl ketone (MEK), and cyclohexanone (CHN);

[0009] The mass concentration of the medium layer solution is 18%;

[0010] Step 2, electrospinning the medium layer solution obtained in step 1 on an electrospinning machine;

[0011] During electrospinning, the receiving roller of the electrospinning machine is covered with aluminum foil;

[0012] The medium layer solution is injected through a needle tube; the needle tube advances at a speed of 0.5-2mL / h, the voltage is 10-15kV, the speed of the receiving drum is 10-50rpm, the needle tube moves back and forth at a speed of 30-50mm / s, the needle tube specification is preferably 20mL, the ambient humidity is less than 20%, the ambient temperature is higher than 37°C, the spinning time is 4-7h, a TPU fiber membrane is formed on the aluminum foil, and then the TPU fiber membrane is peeled off from the receiving tube together with the aluminum foil, and preferably the TPU fiber membrane is peeled off from the aluminum foil;

[0013] Step 3, spraying a layer of ethanol-phase silver nanowire dispersion (AgNWs) on the surface of the TPU fiber membrane obtained in step 2 to form an electrode layer on the surface of the TPU fiber membrane. The temperature of the TPU fiber membrane during spraying is 60-80° C. to obtain a TPU fiber membrane with a silver nanowire electrode layer on the surface;

[0014] Step 4, dipping the non-woven fabric in the carbon nanotube solution (CNT), and drying the non-woven fabric in an oven after dipping to obtain a non-woven fabric dipped in the carbon nanotube solution (CNT);

[0015] Step 5, placing the TPU fiber membrane obtained in step 3 on the non-woven fabric obtained in step 4, and hot pressing them together through a hot pressing process, and the obtained product is called a capacitor module;

[0016] Step 6, dipping the doughnut-shaped dust-free cloth in a mixed solution of PEDOT:PSS and AgNWs, and baking the mixture after dipping to obtain a thermistor module; the inner diameter of the doughnut-shaped dust-free cloth is greater than the diameter of the capacitor module obtained in step 5, preferably greater than 0.1-0.2 mm;

[0017] Step 7, making a transmitting coil and a receiving coil. When making the transmitting coil, 60-80 turns of copper enameled wire are wound on the outer surface of the bracket to form a copper enameled coil A with an inner diameter of 1 cm. Then, the copper enameled coil A is removed from the bracket and a layer of PDMS is coated on the surface of the copper enameled coil A for packaging to obtain a transmitting coil, with both ends of the transmitting coil being exposed;

[0018] When making a receiving coil, 20-30 turns of copper enameled wire are wound on the outer surface of the bracket to form a copper enameled coil B with an inner diameter of 1 cm. Then, the copper enameled coil B is removed from the bracket and a layer of PDMS is coated on the surface of the copper enameled coil B for packaging to obtain a receiving coil, with both ends of the receiving coil exposed.

[0019] The bracket is made of two acrylic plates bonded by acrylic glue. The thickness of the two acrylic plates is 1-3mm. The diameter of one acrylic plate is 1cm, and the diameter of the other acrylic plate is greater than 1cm.

[0020] Step eight, device assembly, install the capacitor module obtained in step five in the middle hollow position of the thermistor module obtained in step six and connect it with copper enameled wire and apply silver paste on the contact end to ensure good conduction, and then connect them in series with the transmitting coil obtained in step seven. When connecting in series, use copper enameled wire to connect and apply silver paste on the contact end to ensure good conduction. The transmitting coil is located on the top to obtain a wearable wireless sensor device with force and temperature dual modes.

[0021] When conducting wireless transmission test on the obtained force-temperature dual-modal wearable wireless sensor device, a receiving coil is used to connect a vector network analyzer for testing.

[0022] Beneficial Effects

[0023] 1. Flexibility and breathability: By selecting flexible materials such as TPU film and dust-free cloth, the sensor has good flexibility and breathability, is comfortable to wear, and is not likely to cause skin discomfort.

[0024] 2. Multifunctional sensing: It integrates capacitive force sensing and resistive temperature sensing, and can monitor pressure and temperature at the same time, providing more comprehensive health monitoring data.

[0025] 3. Wireless transmission: The use of flexible coils and LC oscillation circuits realizes wireless transmission of signals, avoiding the use of traditional hard circuit boards and further improving the flexibility and wearability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of the force-temperature dual-modal wearable wireless sensor device of the present invention;

[0027] Figure 2 It is a schematic diagram of the method flow of the present invention;

[0028] 1-Preparation of TPU sensitive layer, 2-Preparation of resistance module, 3-Preparation of electrode layer by spraying, 4-Preparation of CNT electrode layer;

[0029] Figure 3 This is a schematic diagram of the receiving end's response to pressure and temperature in the embodiment;

[0030] Figure 4 The frequency shift response of the wireless receiving end under different pressures in the embodiment;

[0031] Figure 5 Response of the wireless receiving end to the reflection coefficient amplitude at different temperatures in the embodiment. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below through specific implementation methods, and examples of the implementation methods are shown in the accompanying drawings. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0033] 1. Structural design: The final form of this dual-mode wearable wireless sensor device is as follows: Figure 1 As shown, the circular multi-layer patch structure is an ideal wearable device that is both breathable and comfortable. In addition, the resistance module and the capacitance module are both on the bottom layer, which can monitor more accurately. The coil is placed on the upper layer to better resonate with the receiving end to realize wireless signal transmission.

[0034] 2. Sensor performance optimization strategy: In order to ensure the transmission of temperature signals, the coil quality factor comparison was carried out to optimize its coupling performance, thereby obtaining a high-resolution temperature response.

[0035] Example

[0036] like Figure 1 As shown, this product is a wearable wireless sensor device with dual force and temperature modes, which includes a copper coil 1, a silver nanowire electrode layer 2, a TPU sensitive layer 3, a CNT electrode layer 4, and a PEDOT:PSS / AgNWs resistor 5 in sequence.

[0037] like Figure 2 As shown, a method for preparing a wearable wireless sensor device with dual force and temperature modes comprises the following steps:

[0038] Step 1: prepare a medium layer solution, disperse 3.6 g of thermoplastic polyurethane elastomer (TPU) particles into a mixture of 10 mL of N,N-dimethylformamide (DMF) and 10 mL of tetrahydrofuran (THF), and stir magnetically at room temperature until dissolved to obtain a 18 wt% TPU spinning solution;

[0039] Step 2: Wrap a piece of aluminum foil on the receiving roller in the electrospinning machine, pour the TPU solution obtained in step 1 into a 20mL syringe, and spin for 6 hours at a voltage of 12kV, a syringe advancement speed of 1.5mL / h, a receiving roller speed of 30rpm, a needle reciprocating speed of 50mm / s, a humidity of less than 20%, and a temperature above 37°C. Finally, peel off the spun TPU fiber membrane from the receiving tube.

[0040] Step 3: Cut a small piece of 2*2cm2 from the TPU film obtained in step 2, place it on a heating table at 80℃, press and fix the two ends on the table with a glass sheet, and then use a spray gun to spray a layer of ethanol-phase silver nanowire dispersion (AgNWs) on the surface of the TPU film to form an electrode layer on the surface of the TPU. The purpose of heating is to accelerate the volatilization of ethanol in the silver nanowires and prevent the silver nanowires from penetrating the entire TPU film.

[0041] Step 4: Pour an appropriate amount of carbon nanotube solution (CNT) into a culture dish, cut a piece of non-woven fabric of 5*5cm2, soak it in the culture dish, and then put it into an oven for baking and drying to obtain a non-woven fabric impregnated with the carbon nanotube solution (CNT).

[0042] Step 5: Cut the two films obtained in step 3 and step 4 into circles of the same size (1 cm in diameter) by laser cutting, then stack and align the two circular films, place the TPU fiber film on the upper layer, and hot press them together by hot pressing to obtain a capacitor module.

[0043] Step 6: Prepare a piece of dust-free cloth and cut it into a ring shape (outer diameter 1.3 cm, inner diameter 1.1 cm) by laser cutting. At the same time, weigh 5g PEDOT:PSS and 2g AgNWs in a glass bottle and mix them. Stir magnetically until the mixture is uniform. Immerse the ring-shaped dust-free cloth in the solution and bake it on a hot plate at 120℃ for 30 minutes to obtain a thermistor module.

[0044] Step 7: Use laser cutting technology to cut a 2mm thick acrylic plate, cut out discs with diameters of 1cm and 3cm respectively, and then use acrylic glue to stick the two pieces together as a bracket. Wrap the copper enameled wire with a wire diameter of 50μm around the bracket for 60 turns and 30 turns respectively, peel it out with tweezers, and then apply a layer of PDMS on the surface for packaging to obtain the transmitting and receiving coils.

[0045] Step 8: Device assembly. Install the capacitor module obtained in step 5 in the middle hollow position of the thermistor module obtained in step 6 and connect it with copper enameled wire and apply silver paste on the contact end to ensure good conduction, and then connect it in series with the transmitting coil obtained in step 7. When connecting in series, use copper enameled wire to connect and apply silver paste on the contact end to ensure good conduction. The transmitting coil is located on the top to obtain a wearable wireless sensor device with dual force and temperature modes.

[0046] The prepared receiving coil is connected to a vector network analyzer to realize wireless monitoring of pressure and temperature. The change of pressure affects the movement of the resonant frequency, and the change of temperature causes the temperature sensitive resistor to change, thereby affecting the change of the resonant amplitude. The two changing factors do not affect each other, realizing the simultaneous monitoring of pressure and temperature. The wireless transmission process is as follows Figure 3 shown.

[0047] The obtained product was subjected to pressure performance test. The test conditions were as follows: a pressure of 0 to 30 KPa was applied to the capacitor module to test its resonance shift. The frequency decreased as the pressure increased. The results are as follows: Figure 4 shown.

[0048] The obtained product was tested for temperature performance. The test conditions were to raise the temperature of the device from room temperature to 40°C and test the change of its resonance amplitude. The temperature increase caused the temperature sensitive resistance to decrease, and the absolute value of the resonance amplitude S11 also increased with the decrease of resistance. The results are as follows: Figure 5 shown.

[0049] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A wearable wireless sensor device with dual force and temperature modes, characterized in that: The wireless sensor device includes a copper coil, a silver nanowire electrode layer, a TPU sensitive layer, a CNT electrode layer, and a PEDOT:PSS / AgNWs resistor in sequence.

2. A method for preparing a wearable wireless sensor device with dual force and temperature modes, characterized in that The steps of the method include: Step 1, preparing a dielectric layer solution; Step 2, electrospinning the medium layer solution obtained in step 1 on an electrospinning machine to obtain a TPU fiber membrane; Step 3, spraying a layer of ethanol-phase silver nanowire dispersion on the surface of the TPU fiber membrane obtained in step 2, the temperature of the TPU fiber membrane during spraying is 60-80° C., to obtain a TPU fiber membrane with a silver nanowire electrode layer on the surface; Step 4, dipping the non-woven fabric in the carbon nanotube solution, and drying the non-woven fabric in an oven after dipping to obtain a non-woven fabric dipped in the carbon nanotube solution; Step 5, placing the TPU fiber membrane obtained in step 3 on the non-woven fabric obtained in step 4, and then hot-pressing them together to obtain a capacitor module; Step 6, dipping the doughnut-shaped dust-free cloth in a mixed solution of PEDOT:PSS and AgNWs, and baking the mixture after dipping to obtain a thermistor module; the inner diameter of the doughnut-shaped dust-free cloth is greater than the outer diameter of the capacitor module obtained in step 5; Step 7: Make a transmitting coil; Step eight, install the capacitor module obtained in step five in the middle hollow position of the thermistor module obtained in step six and connect it with copper enameled wire and apply silver paste on the contact end to ensure good conduction, and then connect them in series with the transmitting coil obtained in step seven. When connecting in series, use copper enameled wire to connect and apply silver paste on the contact end to ensure good conduction. The transmitting coil is located on top to obtain a force-temperature dual-mode wearable wireless sensor device.

3. The method for preparing a wearable wireless sensor device with dual force and temperature modes according to claim 2, characterized in that: In the step 1, the solute of the dielectric layer solution is thermoplastic polyurethane elastomer, and the solvent of the dielectric layer solution is at least one of N,N-dimethylformamide, tetrahydrofuran, methyl ethyl ketone, and cyclohexanone; The mass concentration of the medium layer solution is 18%.

4. The method for preparing a wearable wireless sensor device with dual force and temperature modes according to claim 2, characterized in that: In the step 2, during electrospinning, the receiving roller of the electrospinning machine is coated with aluminum foil, and the medium layer solution is injected through a needle tube; the needle tube advancement speed is 0.5-2mL / h, the voltage is 10-15kV, the rotation speed of the receiving roller is 10-50rpm, the needle tube moves back and forth at a speed of 30-50mm / s, the needle tube specification is 20mL, the ambient humidity is less than 20%, the ambient temperature is higher than 37°C, the spinning time is 4-7h, a TPU fiber membrane is formed on the aluminum foil, and then the TPU fiber membrane is peeled off from the receiving tube together with the aluminum foil, and it is best to peel the TPU fiber membrane off the aluminum foil.

5. The method for preparing a wearable wireless sensor device with dual force and temperature modes according to claim 2, characterized in that: In the step five, the TPU fiber membrane and the non-woven fabric are hot pressed together through a hot pressing process.

6. The method for preparing a wearable wireless sensor device with dual force and temperature modes according to claim 2, characterized in that: In step six, the inner diameter of the annular dust-free cloth is 0.1-0.2 mm larger than the outer diameter of the capacitor module.

7. The method for preparing a wearable wireless sensor device with dual force and temperature modes according to claim 2, characterized in that: In the step seven, when making the transmitting coil, 60-80 turns of copper enameled wire are wound on the outer surface of the bracket to form a copper enameled coil A with an inner diameter of 1 cm, and then the copper enameled coil A is removed from the bracket and a layer of PDMS is coated on the surface of the copper enameled coil A for packaging to obtain the transmitting coil, and both ends of the transmitting coil are exposed.

8. The method for preparing a wearable wireless sensor device with dual force and temperature modes according to claim 7, characterized in that: The bracket is formed by bonding two acrylic plates by acrylic glue, the thickness of the two acrylic plates is 1-3mm, the diameter of one acrylic plate is 1cm, and the diameter of the other acrylic plate is greater than 1cm.

9. The method for preparing a wearable wireless sensor device with dual force and temperature modes according to claim 2, characterized in that: When conducting wireless transmission test on the obtained force-temperature dual-modal wearable wireless sensor device, a receiving coil is used to connect a vector network analyzer for testing.

10. The method for preparing a wearable wireless sensor device with dual force and temperature modes according to claim 9, characterized in that: The method for making the receiving coil is as follows: 20-30 turns of copper enameled wire are wound on the outer surface of the bracket to form a copper enameled coil B with an inner diameter of 1 cm, and then the copper enameled coil B is removed from the bracket and a layer of PDMS is coated on the surface of the copper enameled coil B for packaging to obtain the receiving coil, with both ends of the receiving coil being exposed.

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