Decoupling design of high-sensitivity flexible temperature-pressure dual-function sensor and preparation method of high-sensitivity flexible temperature-pressure dual-function sensor

Abstract

The invention belongs to the technical field of flexible sensors, and relates to a decoupling design and a preparation method of a high-sensitivity flexible temperature-pressure dual-function sensor, in particular to a preparation method of a dual-function flexible sensor capable of detecting external temperature stimulation and pressure stimulation at the same time. The temperature sensor in the bifunctional sensor is a carbon nanofiber membrane obtained by an electrostatic spinning method, and has good response to temperature stimulation based on a thermal resistance working mechanism. A pressure sensing part of the bifunctional sensor is a flexible porous pressure sensor with PDMS silicone rubber as a skeleton, and responds to pressure stimulation based on a piezocapacitance working mechanism. The dual-function sensor realizes complete decoupling of a temperature signal and a pressure signal based on different sensing mechanisms. The manufacturing process of the dual-function sensor is simple, efficient, reliable and low in cost; and the manufactured flexible sensor is high in sensitivity and is applied to the fields of wearable equipment, man-machine interaction, electronic skin, bionic robots and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to a decoupling design of a high-sensitivity flexible temperature-pressure dual-function sensor and a preparation method thereof. Background Art

[0002] In recent years, flexible multifunctional sensors that can detect important physical stimuli such as pressure and temperature have become a research hotspot due to their application prospects in flexible electronics, prosthetic development, soft robotics and medical devices. In order to monitor more than one physical stimulus at the same time, multifunctional sensor devices should be able to detect and decouple multiple stimulus sources simultaneously without interfering with each other. At present, the most commonly used method is to integrate sensing components with different functions to realize the use of multifunctional devices. Each sensing part of this multifunctional sensor works through different sensing mechanisms and outputs different types of electrical signals, so that the signal interference between them is very small. The external stimuli such as temperature, pressure or deformation are identified by detecting different electrical signals, realizing multifunctional decoupling.

[0003] Based on the above, the present invention proposes a decoupling design of a highly sensitive flexible temperature-pressure dual-function sensor and a preparation method thereof. The temperature sensing part of the sensor is a carbon nanofiber membrane obtained by an electrospinning method, which generates a resistance signal response to an external temperature stimulus. The pressure sensing part is a flexible porous pressure sensor with a PDMS silicone rubber substrate to which carbon nanotube conductive fillers and barium titanate dielectric fillers are added. Under external pressure stimulation, the distance between the two electrode layers decreases, and the sensor generates different capacitance signal responses. The temperature sensor and the pressure sensor in the dual-function sensor adopt different working mechanisms. The resistance and capacitance signals output under temperature and pressure stimulation do not interfere with each other, realizing real-time detection and decoupling of temperature and pressure signals. The sensor manufacturing process is simple, efficient, reliable and low-cost. The device shows a high sensitivity response to temperature and pressure signals and can be applied to wearable devices, human-computer interaction, electronic skin, bionic robots and other fields. Summary of the invention

[0004] In view of this, the present invention aims to provide a decoupling design of a highly sensitive flexible temperature-pressure dual-function sensor and a preparation method thereof. The temperature sensor in the dual-function sensor provided by the present invention is based on a thermal resistor working mechanism, and the pressure sensor adopts a piezo-capacitor working mechanism. Under temperature and pressure stimulation, it outputs non-interfering resistance and capacitance signals to detect temperature and pressure signals in real time. The sensor exhibits a highly sensitive response to temperature and pressure signals, and the manufacturing process is simple, efficient, reliable and low-cost.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A decoupling design of a high-sensitivity flexible temperature-pressure dual-function sensor and a preparation method thereof specifically include the following steps:

[0007] S1. Prepare a PET encapsulation layer coated with silver electrodes: place a screen printing plate on a PET film, then place a certain amount of evenly stirred conductive silver paste in the screen frame of the screen printing plate, use a scraper to apply the conductive silver paste evenly on the PET film, and cure it at 120°C for 2 h to obtain a PET encapsulation layer coated with silver electrodes.

[0008] S2. Preparation of pressure sensor: Mix carbon nanotubes (2wt%), barium titanate powder (5-20wt%), and solid template pore-forming agent in a certain proportion, grind them thoroughly to make them uniform, add a certain amount of cyclohexane, stir magnetically for 2 h, and ultrasonically treat for 30 min. Add polydimethylsiloxane prepolymer and curing agent in a volume ratio of 10:1, stir magnetically for 2 h, and ultrasonically treat for 30 min. Let it stand to remove the foam to obtain a uniformly dispersed slurry. Pour the slurry into a mold, place a glass plate on top of the mold, and put it in an oven for curing to obtain a pressure-sensitive film; soak the pressure-sensitive film repeatedly in deionized water to remove the solid template pore-forming agent, and obtain a flexible porous pressure-sensitive film material containing carbon nanotubes / barium titanate fillers, and encapsulate it with a PET film coated with silver electrodes up and down to obtain a flexible porous pressure sensor with a pressure-capacitive response mechanism and a BaTiO3 / MwCNTs / PDMS film as a dielectric layer.

[0009] S3. Preparation of temperature sensor: PAN (10 wt%) was dissolved in DMF to obtain a precursor solution, which was magnetically stirred at 80 °C for 3 h to obtain a precursor polymer. The electrospinning machine was operated at 16 kV, and the distance between the spinning needle and the collector was kept constant. The flow rate was maintained at 0.2 mL h −1 , on the drum collector at 0.5 m min -1 The PAN nanofiber membrane was prepared at a rotation speed of 100 rpm. During the spinning process, the relative humidity was kept below 40%. The PAN nanofiber membrane was then stabilized in an oven at 230 °C for 3 h and then heated at 550 °C in an inert atmosphere at 2 °C min -1 The carbon nanofiber membrane was carbonized at a rate of 1 h to obtain a carbon nanofiber membrane. The obtained carbon nanofiber membrane was equipped with upper and lower electrodes to obtain a CNF flexible temperature sensor.

[0010] S4. Encapsulation of dual-function flexible sensor: The above devices are installed from top to bottom in the order of PET encapsulation layer, silver electrode, pressure sensor, silver electrode, temperature sensor, silver electrode, and PET encapsulation layer to obtain a temperature-pressure dual-function sensor. The upper and lower electrode layers are respectively connected to leads to read the output resistance and capacitance signals.

[0011] Furthermore, the PET packaging layer coated with the silver electrode in S1 is connected to a wire through two pins led out from the silver electrode to detect the sensor resistance and capacitance signals.

[0012] Furthermore, the size of the coated silver electrode in S1 is 1cm*1cm.

[0013] Furthermore, the solid template pore-forming agent described in S2 includes coffee sugar, sucrose, PS microspheres, citric acid, etc.

[0014] Furthermore, the depth of the mold in S2 is 0.5 mm to 2 mm.

[0015] Furthermore, the electrospinning precursor solution preparation process described in S3 is as follows: first, 1 g of PAN polyacrylonitrile is weighed, 10 ml of DMF solution is added thereto, and magnetic stirring is performed at 80° C. for 3 h to fully dissolve and mix the solution evenly, thereby obtaining a 10 wt % PAN DMF electrospinning precursor solution.

[0016] Furthermore, the distance between the spinning needle and the collector described in S3 is kept constant at 150 mm.

[0017] Furthermore, the inert atmosphere in S3 includes nitrogen atmosphere, argon atmosphere, etc.

[0018] The present invention also provides a wearable device comprising at least one dual-mode sensor disclosed above.

[0019] The decoupling design of a high-sensitivity flexible temperature-pressure dual-function sensor and its preparation method described in the present invention have the following excellent effects:

[0020] First, the carbon nanofiber membrane, PDMS flexible foam and other materials used in the sensor of the present invention have good biocompatibility and can be in direct contact with skin tissue. In addition, the prepared carbon nanofiber membrane and PDMS porous foam materials have good flexibility and bendability and can fit well with uneven surfaces.

[0021] Second, the temperature sensor in the dual-function sensor is based on the working mechanism of thermal resistors, and the pressure sensor adopts the working mechanism of piezo-capacitors. Therefore, under the stimulation of temperature and pressure, the sensor outputs non-interfering resistance and capacitance signals, and can detect temperature and pressure signals in real time. In addition, the sensor shows high sensitivity response to temperature and pressure signals, and the manufacturing process is simple, efficient, reliable and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 Schematic diagram of the preparation process of the dual-function sensor of the present invention.

[0024] Figure 2 This is a SEM image of the pressure sensor of the dual-function sensor of the present invention.

[0025] Figure 3 It is a schematic diagram of the pressure response performance test of the pressure sensor of the present invention.

[0026] Figure 4 This is a response performance diagram of the pressure sensor of the present invention when the temperature changes.

[0027] Figure 5 It is a schematic diagram of the temperature response performance test of the temperature sensor of the present invention.

[0028] Figure 6 This is a response performance diagram of the temperature sensor of the present invention when the pressure changes. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention and the drawings of the specification to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The embodiment of the invention discloses a method for preparing a dual-function flexible sensor.

[0031] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0032] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0033] Embodiment 1:

[0034] According to the method for preparing the dual-function flexible sensor of the present invention, this embodiment describes the specific preparation process thereof:

[0035] S1. Prepare a PET encapsulation layer coated with silver electrodes: place a screen printing plate on a PET film, then place a certain amount of evenly stirred conductive silver paste in the screen frame of the screen printing plate, use a scraper to apply the conductive silver paste evenly on the PET film, and cure it at 120°C for 2 h to obtain a PET encapsulation layer coated with silver electrodes.

[0036] S2. Preparation of pressure sensor: Mix carbon nanotubes (2wt%), barium titanate powder (5-20wt%), and solid template pore-forming agent in a certain proportion, grind them thoroughly to make them uniform, add a certain amount of cyclohexane, stir magnetically for 2 h, and ultrasonically treat for 30 min. Add polydimethylsiloxane prepolymer and curing agent in a volume ratio of 10:1, stir magnetically for 2 h, and ultrasonically treat for 30 min. Let it stand to remove the foam to obtain a uniformly dispersed slurry. Pour the slurry into a mold, place a glass plate on top of the mold, and put it in an oven for curing to obtain a pressure-sensitive film; soak the pressure-sensitive film repeatedly in deionized water to remove the solid template pore-forming agent, and obtain a flexible porous pressure-sensitive film material containing carbon nanotubes / barium titanate fillers, and encapsulate it with a PET film coated with silver electrodes up and down to obtain a flexible porous pressure sensor with a pressure-capacitive response mechanism and a BaTiO3 / MwCNTs / PDMS film as a dielectric layer.

[0037] S3. Preparation of temperature sensor: PAN (10 wt%) was dissolved in DMF to obtain a precursor solution, which was magnetically stirred at 80 °C for 3 h to obtain a precursor polymer. The electrospinning machine was operated at 16 kV, and the distance between the spinning needle and the collector was kept constant. The flow rate was maintained at 0.2 mL h −1 , on the drum collector at 0.5 m min -1 The PAN nanofiber membrane was prepared at a rotation speed of 100 rpm. During the spinning process, the relative humidity was kept below 40%. The PAN nanofiber membrane was then stabilized in an oven at 230 °C for 3 h and then heated at 550 °C in an inert atmosphere at 2 °C min -1 The carbon nanofiber membrane was carbonized at a rate of 1 h to obtain a carbon nanofiber membrane. The obtained carbon nanofiber membrane was equipped with upper and lower electrodes to obtain a CNF flexible temperature sensor.

[0038] S4. Encapsulation of dual-function flexible sensor: The above devices are installed from top to bottom in the order of PET encapsulation layer, silver electrode, pressure sensor, silver electrode, temperature sensor, silver electrode, and PET encapsulation layer to obtain a temperature-pressure dual-function sensor. The upper and lower electrode layers are respectively connected to leads to read the output resistance and capacitance signals.

[0039] Furthermore, the size of the temperature sensor and the pressure sensor described in the first embodiment of the present invention are both 1 cm*1 cm.

[0040] Furthermore, the pressure sensing layer of the dual-function flexible sensor described in the first embodiment of the present invention is a flexible porous pressure-sensitive film material containing carbon nanotubes / barium titanate fillers.

[0041] Furthermore, the temperature sensing layer of the dual-function flexible sensor described in the first embodiment of the present invention is made of a PAN precursor solution through an electrospinning process, and the specific configuration process is as follows:

[0042] First, 1 g of PAN was weighed, 10 ml of DMF solution was added, and magnetic stirring was performed at 80 °C for 3 h to fully dissolve and mix evenly to obtain a 10 wt % PAN DMF electrospinning precursor solution.

[0043] In addition, in order to further illustrate the superiority of the technology of the present invention, the inventors also conducted the following experiment, which demonstrated the key performance parameters of the dual-function flexible sensor prepared in Example 1.

[0044] Figure 2 The SEM image of the pressure sensor in the dual-function sensor of the present invention is shown. Figure 2 It can be seen that the prepared pressure sensor has a rich pore structure, and under applied pressure conditions, the sensor exhibits higher sensitivity.

[0045] Figure 3 The pressure sensing performance of the dual-function flexible sensor of the present invention is demonstrated, wherein the pressure sensitive unit used is a flexible porous pressure sensitive membrane material containing carbon nanotubes / barium titanate fillers. Figure 3 It can be seen that after applying different pressures to the sensor, the sensor exhibits different capacitive signal responses and the sensor exhibits high sensitivity to pressure stimulation. In practical applications, it can accurately capture subtle human activity signals, such as breathing and pulse.

[0046] Figure 4 The capacitance change response of the pressure sensor in the dual-function sensor of the present invention when the temperature changes (30~110℃) is demonstrated. Figure 4 It can be seen that under different temperature changes, the capacitance signal output by the dual-function sensor is close to zero, proving that temperature changes will not affect the capacitance signal output, and the capacitance signal change is only caused by pressure changes.

[0047] Figure 5 The temperature sensing performance of the dual-function flexible sensor of the present invention is demonstrated. Figure 5It can be seen that at different temperatures, the sensor exhibits different resistance signal responses. At a temperature of 30-80°C, the resistance change rate of the sensor shows a high linear relationship with temperature, proving that the dual-function flexible sensor can accurately capture the temperature changes of the human body in practical applications.

[0048] Figure 6 The resistance change response of the temperature sensor in the dual-function sensor of the present invention when the pressure changes (0~100KPa) is demonstrated. Figure 6 It can be seen that under different pressure changes, the resistance signal output by the dual-function sensor is close to zero, proving that pressure changes will not affect the resistance signal output, and the resistance signal change is only caused by temperature changes.

[0049] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A decoupling design of a high-sensitivity flexible temperature-pressure dual-function sensor and a preparation method thereof, characterized in that: The method specifically comprises the following steps: S1. Preparation of a PET encapsulation layer coated with a silver electrode: placing a screen printing plate on a PET film, then placing a certain amount of evenly stirred conductive silver paste in the screen frame of the screen printing plate, using a scraper to apply the conductive silver paste evenly on the PET film, and curing at 120°C for 2 h to obtain a PET encapsulation layer coated with a silver electrode; S2. Preparation of pressure sensor: Mix carbon nanotubes (2wt%), barium titanate powder (5-20wt%), and solid template pore-forming agent in a certain proportion, grind them thoroughly to make them evenly mixed, add a certain amount of cyclohexane, stir magnetically for 2 h, and ultrasonically treat for 30 min. Add polydimethylsiloxane prepolymer and curing agent in a volume ratio of 10:1, stir magnetically for 2 h, and ultrasonically treat for 30 min. Let it stand to remove the foam to obtain a uniformly dispersed slurry. Pour the slurry into a mold, place a glass plate on top of the mold, and put it in an oven for curing to obtain a pressure-sensitive film; repeatedly soak the pressure-sensitive film in deionized water to remove the solid template pore-forming agent to obtain a flexible porous pressure-sensitive film material containing carbon nanotubes / barium titanate fillers, and encapsulate it with a PET film coated with silver electrodes to obtain a flexible porous pressure sensor with a piezocaisture response mechanism and a BaTiO3 / MwCNTs / PDMS film as a dielectric layer; S3. Preparation of temperature sensor: PAN (10 wt%) was dissolved in DMF to obtain a precursor solution, which was magnetically stirred at 80 °C for 3 h to obtain a precursor polymer. The electrospinning machine was operated at 16 kV, and the distance between the spinning needle and the collector was kept constant. The flow rate was maintained at 0.2 mL h −1 , on the drum collector at 0.5 m min -1 The PAN nanofiber membrane was prepared at a rotation speed of 100 rpm. During the spinning process, the relative humidity was kept below 40%. The PAN nanofiber membrane was then stabilized in an oven at 230 °C for 3 h and then heated at 550 °C in an inert atmosphere at 2 °C min -1 The carbon nanofiber membrane was carbonized at a rate of 1 h to obtain a carbon nanofiber membrane. The obtained carbon nanofiber membrane was equipped with upper and lower electrodes to obtain a CNF flexible temperature sensor; S4. Encapsulation of dual-function flexible sensor: The above devices are installed from top to bottom in the order of PET encapsulation layer, silver electrode, pressure sensor, silver electrode, temperature sensor, silver electrode, and PET encapsulation layer to obtain a temperature-pressure dual-function sensor. The upper and lower electrode layers are respectively connected to leads to read the output resistance and capacitance signals.

2. According to claim 1, a decoupling design of a high-sensitivity flexible temperature-pressure dual-function sensor and a preparation method thereof are characterized in that: The temperature sensing part of the dual-function sensor is a carbon nanofiber membrane obtained by electrospinning, which generates a resistance signal response to external temperature stimulation. The pressure sensing part is a flexible porous pressure sensor with PDMS silicone rubber as the skeleton, with carbon nanotube conductive fillers and barium titanate dielectric fillers added. Under external pressure stimulation, the distance between the two electrode layers decreases, and the sensor generates different capacitance signal responses. The dual-function sensor realizes real-time detection and decoupling of temperature and pressure stimulation by outputting resistance and capacitance signals under different stimulations.

3. The decoupling design and preparation method of a high-sensitivity flexible temperature-pressure dual-function sensor according to claim 1 is characterized in that: The PET packaging layer coated with the silver electrode in S1 is connected to the wire through two pins led out from the silver electrode to detect the sensor resistance and capacitance signals.

4. The decoupling design and preparation method of a high-sensitivity flexible temperature-pressure dual-function sensor according to claim 1, characterized in that: The solid template pore-forming agent described in S2 includes NaCl particles, coffee sugar, sucrose, PS microspheres, citric acid, etc.

5. The decoupling design and preparation method of a high-sensitivity flexible temperature-pressure dual-function sensor according to claim 1, characterized in that: The depth of the mold described in S2 is 0.5 mm to 2 mm.

6. The decoupling design and preparation method of a high-sensitivity flexible temperature-pressure dual-function sensor according to claim 1, characterized in that: The electrospinning precursor solution preparation process of S3 is as follows: first, 1 g of PAN polyacrylonitrile is weighed, 10 ml of DMF solution is added thereto, and magnetic stirring is performed at 80°C for 3 h to fully dissolve and mix the solution evenly, thereby obtaining a 10 wt% PAN DMF electrospinning precursor solution.

7. The decoupling design and preparation method of a high-sensitivity flexible temperature-pressure dual-function sensor according to claim 1, characterized in that: The distance between the spinning needle and the collector described in S3 was kept constant at 150 mm.

8. The decoupling design and preparation method of a high-sensitivity flexible temperature-pressure dual-function sensor according to claim 1, characterized in that: The inert atmosphere described in S3 includes nitrogen atmosphere, argon atmosphere, etc.

9. Application of a dual-function flexible sensor prepared by the method according to any one of claims 1 to 8 in wearable devices, human-computer interaction, electronic skin and bionic robots.

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