A sensor for measuring human tactile and temperature and a method of manufacturing the same

Abstract

This invention belongs to the field of sensor technology, specifically relating to a sensor for measuring human touch and temperature, and its fabrication method. The sensor for measuring human touch and temperature includes a sensitive layer, a bottom AB silicone layer, a top AB silicone layer, and at least one flexible circuit. The flexible circuit is attached to one side of the sensitive layer. The bottom AB silicone layer is formed by coating the sensitive layer with AB silicone on the side away from the flexible circuit, and the top AB silicone layer is formed by coating the sensitive layer with AB silicone on the side where the flexible circuit is attached. The top and bottom AB silicone layers work together to enclose the sensitive layer with the flexible circuit attached between them. The sensor fabricated by this invention has a flexible structure that can adapt to the curves of the human body. The entire sensor is simple and convenient to operate, has a fast response speed, good stability, and high sensitivity, thus enabling it to be used as a wearable electronic device to measure changes in human touch and temperature.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronic device manufacturing technology, specifically relating to a sensor for measuring human touch and temperature based on material extrusion technology and electro-inking technology, and its preparation method. Background Technology

[0002] A sensor is a detection device that can sense the information being measured and transform that information into an electrical signal or other required form of output according to a certain rule, in order to meet the requirements of information transmission, processing, storage, display, recording, and control. Traditional sensors used on the human body include tactile sensors and temperature sensors. Both tactile and temperature sensors are generally rigid structures, making them unable to accurately measure the tactile and temperature processes of the human body. For example, mercury thermometers, electronic thermometers, and forehead thermometers are all rigid structures. Mercury and electronic thermometers require placement under the armpit or in the mouth during use, making operation cumbersome, and these thermometers also have long response times. While forehead thermometers have short response times, like mercury and electronic thermometers, they only obtain a single temperature value during measurement and cannot display real-time temperature data and trends, resulting in limited practicality.

[0003] Existing tactile sensors are generally rigid structures, which makes them unable to adapt well to the curves of the human body when used, resulting in inconvenience and low accuracy. Summary of the Invention

[0004] To address the problems of complex operation, inconvenient use, and low accuracy of existing tactile and temperature sensors, this invention provides a sensor for measuring human touch and temperature, and a method for its fabrication.

[0005] This invention employs the following technical solution: a sensor for measuring human touch and temperature, comprising a sensitive layer, a bottom AB silicone layer, a top AB silicone layer, and at least one flexible circuit; the sensitive layer measures changes in human touch and temperature, and comprises carbon nanotubes, AB silicone, and a PEDOT:PSS solution, wherein the carbon nanotubes, AB silicone, and PEDOT:PSS solution are mixed in a ratio of 1:10:1; the flexible circuit is adhered to one side of the sensitive layer, and the flexible circuit is used to convert the changes in human touch and temperature measured by the sensitive layer into electrical signals; the bottom AB silicone layer is formed by coating the side of the sensitive layer away from the flexible circuit with AB silicone; the top AB silicone layer is formed by coating the side of the sensitive layer with the flexible circuit attached with AB silicone, and the bottom and top AB silicone layers work together to encapsulate the sensitive layer with the flexible circuit attached between them; the AB silicone comprises a main agent A and a curing agent B, wherein the main agent A is one of epoxy resin, silicone, or acrylic modified epoxy resin; the mixing ratio of the main agent A and the curing agent B is 1:1.

[0006] As a further improvement of the present invention, the carbon nanotubes are hexagonal carbon nanotubes with a purity greater than 98%, and their diameter is 10nm-15nm and their length is 15nm-30nm.

[0007] The present invention also includes a method for preparing a sensor for measuring human touch and temperature, comprising the following steps:

[0008] S1, Prepare the sensitive layer and AB silicone;

[0009] S2, use Solidworks to draw the casting mold model, and use FDM3D printing technology to make the mold;

[0010] S3, draw the fluid jet printing regular array flexible circuit, print the flexible circuit on the substrate using an electro-jet printing device, and then sinter at 150°C for 30 minutes to obtain the flexible circuit.

[0011] S4. A portion of AB silicone is coated into the mold prepared in step S2 to form a bottom AB silicone layer. The prepared sensitive layer is loaded into a 3D printer and the sensitive layer is printed on the cured bottom AB silicone layer by the 3D printer through material extrusion.

[0012] S5. After printing, apply conductive silicone evenly to both ends of each flexible circuit, ensuring that the conductive silicone covers the endpoints of the flexible circuit. At the same time, attach multiple flexible circuits to the same side of the sensitive layer, with the flexible circuits attached to the side of the sensitive layer away from the bottom AB silicone layer, thus obtaining the mold sample. Then, place the mold sample at 120℃ for 30 minutes to cure.

[0013] S6. Apply another portion of AB silicone evenly to one side of the cured sensitive layer with the flexible circuit attached, forming a top AB silicone layer. The sensitive layer with the flexible circuit attached is encapsulated by the bottom AB silicone layer and the top AB silicone layer. After encapsulation, heat at 80°C for 30 minutes to obtain a sensor for measuring human touch and temperature.

[0014] As a further improvement of the present invention, the bottom AB silicone layers are mixed in a 1:1 ratio and then evenly applied to the mold, with a thickness of 2mm.

[0015] As a further improvement of the present invention, the flexible circuit has an S-shaped structure.

[0016] As a further improvement of the present invention, the ink material used in the fabrication process of the flexible circuit is nano-silver ion conductive ink, and the substrate material is polyethylene terephthalate with a thickness of 125 μm and a length and width of 100 mm.

[0017] As a further improvement of the present invention, the glass printhead in the electro-ink printing equipment has a diameter of 40μm, a height of 150μm, a bias voltage of 700V, and a printing speed of 0.15mm / s.

[0018] As a further improvement of the present invention, the preparation method of the sensitive layer includes the following steps: weigh 1g of carbon nanotubes and place them in a beaker; then weigh 5g of main agent A and 5g of curing agent B respectively, pour main agent A and curing agent B into the beaker containing carbon nanotubes, and then pour in 1g of PEDOT:PSS solution, mix and stir the various raw materials in the beaker until no bubbles are generated, thus obtaining the sensitive layer.

[0019] As a further improvement of the present invention, the inner diameter of the dispensing nozzle in the material extrusion 3D printer is 0.4 dm and the air pressure is 0.2 MPa.

[0020] As a further improvement to the present invention, the FDM3D printing technology uses any one of PLA, ABS, and TPU as the material.

[0021] The technical solution provided by this invention has the following beneficial effects:

[0022] (1) The sensor prepared by this invention has a flexible structure that can adapt to the curves of the human body. The entire sensor is simple and convenient to operate, with fast response speed, good stability, and high sensitivity. The sensor of this invention can monitor changes in human touch and temperature in real time, so it can be worn as a wearable electronic device for a long time to measure changes in human touch and temperature.

[0023] (2) The method for preparing the sensor in this invention is simple to operate, and the process of preparing the sensor does not produce harmful substances, making it safer. In addition, it can be worn as a wearable electronic device for a long time, and it can also be closely attached to the skin to measure the temperature or tactile changes of the human body with a fast response speed.

[0024] (3) This invention uses carbon nanotubes, AB silica gel and PEDOT:PSS solution as raw materials for the sensitive layer, which makes the sensitive layer have good conductivity, thereby improving its measurement accuracy and sensitivity. At the same time, the prepared sensor is flexible and can be bent at will, and the resistance is almost unaffected after bending, thus proving that it has high stability and can be used in the human body.

[0025] (4) By setting up multiple flexible circuits, it is possible to fully cover the sensitive layer and measure all parts of the sensitive layer, thereby improving its practicality. At the same time, multiple flexible circuits can also effectively prevent the entire sensor from becoming unusable when one circuit is damaged, thus greatly improving the service life of the sensor. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the sensor provided by the present invention for measuring human touch and temperature.

[0027] Figure 2 A schematic diagram of the flexible circuit provided by the present invention.

[0028] Figure 3 This is a schematic diagram illustrating the fabrication process of the sensor for measuring human touch and temperature provided by the present invention.

[0029] Figure 4 A diagram showing the dimensional parameters of the casting mold provided by this invention.

[0030] Figure 5 The G-code provided for the printing sensitive layer in this invention.

[0031] Figure 6 A scatter plot showing the resistivity of the sensor provided by this invention as a function of bending angle.

[0032] Figure 7 A graph showing the relationship between the resistance and temperature of the sensor provided by this invention.

[0033] Figure 8 The resistance change diagram of the sensor provided by the present invention under tensile or springback conditions.

[0034] Figure 9 The sensitivity fitting curve of the sensor provided by the present invention.

[0035] Figure 10Temperature cycling stability test diagram of the sensor provided by the present invention.

[0036] The diagram is labeled as follows: 1. Bottom AB silicone layer; 2. Sensitive layer; 3. Flexible circuit; 4. Top AB silicone layer. Detailed Implementation

[0037] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0038] In the description of this invention, it should be noted that directional terms such as "center," "lateral," "longitudinal," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific scope of protection of this invention. The terms "first," "second," etc., in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "comprising" and "having," and any variations thereof, in the specification and claims of this invention, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0039] This embodiment provides a sensor for measuring human touch and temperature, such as... Figure 1 As shown, it includes a sensitive layer 2, a bottom AB silicone layer 1, a top AB silicone layer 4, and at least one flexible circuit 3. The flexible circuit 3 is attached to one side of the sensitive layer 2. The bottom AB silicone layer 1 is formed by coating the sensitive layer 2 with AB silicone on the side away from the flexible circuit 3. The top AB silicone layer 4 is formed by coating the sensitive layer 2 with AB silicone on the side where the flexible circuit 3 is attached. The top AB silicone layer 4 and the bottom AB silicone layer 1 work together to enclose the sensitive layer 2 with the flexible circuit 3 attached between the top AB silicone layer 4 and the bottom AB silicone layer 1. By wrapping the sensitive layer 2 with the flexible circuit 3 attached with the top AB silicone layer 4 on both sides, the sensitive layer 2 can be protected, preventing it from being worn during use and extending its service life.

[0040] Sensitive layer 2 is used to measure changes in human touch and temperature. These changes are converted into electrical signals by flexible circuit 3, so people can know the changes in human touch and temperature simply by observing the changes in resistance. Sensitive layer 2 includes carbon nanotubes, AB silica gel, and PEDOT:PSS solution, which are mixed in a ratio of 1:10:1.

[0041] In this embodiment, the addition of carbon nanotubes imparts conductivity to the mixed material. This is because the carbon atoms on the carbon nanotubes form covalent bonds through sp2 hybridization, creating a large-scale delocalized π bond. This structure causes the valence band and conduction band of the carbon nanotubes to partially overlap, essentially creating a half-filled band structure where electrons can move freely, thus endowing the carbon nanotubes with metallic conductivity. The addition of AB silicone makes the sensitive layer 2 flexible, allowing it to be stretched and folded without breaking, while also returning to its original shape. This enables the prepared sensitive layer 2 to conform to the curves of the human body, improving its practicality. The addition of PEDOT:PSS solution, which acts as a conductive polymer, possesses high conductivity and stability. Furthermore, this solution exhibits good temperature response, allowing for rapid temperature measurement and improving the sensor's temperature response speed. Additionally, this solution can be used to adjust the consistency of the mixed material, ensuring that the prepared sensitive layer 2 possesses both good flexibility and a good temperature response speed.

[0042] In this embodiment, the carbon nanotubes have a diameter of 10nm-15nm, a length of 15μm-30μm, a purity of >98%, and a hexagonal crystal system.

[0043] AB silicone uses Smooth-On platinum-cured silicone (ecofiex) TM (00-20), where Smooth-On is the brand of the material, ecofiex TM 00-20 is the material's code. This material itself contains no metal, but its name includes platinum because it is manufactured using a two-component molding and vulcanization process, using platinum as a catalyst. The advantage of using platinum as a catalyst is that it makes the resulting AB silicone more robust and elastic, capable of stretching many times its original size without tearing, and rebounding to its original shape without deformation, giving it excellent recoverable deformation properties. Furthermore, it uses Smooth-On platinum-cured silicone (ecofiex). TM(00-20) This allows it to withstand sudden temperature changes while maintaining chemical stability. In this embodiment, the two components of AB silicone can be a main agent A and a curing agent B, wherein the main agent A can be one of epoxy resin, silicone, or acrylic-modified epoxy resin. The curing agent B can be mixed in a 1:1 ratio to initiate a polymerization reaction, thereby achieving the purpose of curing the AB silicone.

[0044] AB silicone can be prepared by mixing the main agent A and the curing agent B in a certain proportion and stirring until homogeneous.

[0045] It is understood that in this embodiment, the AB silicone includes main agent A and curing agent B. Therefore, in the actual preparation of sensitive layer 2, the ratio of each component is as follows: carbon nanotube: main agent A: curing agent B: PEDOT: PSS solution is 1:5:5:1.

[0046] The above ratio was chosen because experiments with different ratios in the early stages showed that the sensor fabricated at this ratio had the best performance. The specific experimental results are shown in Table 1 below.

[0047]

[0048] The experiments with different proportions show that the sensitive layer 2 prepared in groups 1, 2, 3, and 4 either failed to form or was difficult to extrude, making it impossible to print. Groups 5 through 10 all successfully printed sensitive layer 2, but the sensitive layers printed in groups 5 and 6 had very high resistance, resulting in poor conductivity. The sensitive layers printed in groups 8, 9, and 10 had lower resistance, resulting in good conductivity. When the dispensing nozzle diameter was 0.8 dm, the printing precision of the sensitive layer was poor, resulting in rough lines. A dispensing nozzle diameter of 0.4 dm yielded good results. Therefore, in this embodiment, group 10 parameters were chosen to prepare sensitive layer 2, i.e., the ratio of the raw materials for preparing sensitive layer 2—carbon nanotubes: main agent A: curing agent B: PEDOT: PSS solution—was 1:5:5:1.

[0049] In this embodiment, the preparation of the sensitive layer 2 includes the following steps: 1g of carbon nanotubes is weighed using an electronic balance and placed in a beaker. Then, 5g each of the main agent A and curing agent B are weighed and placed in separate beakers. Next, 1g of PEDOT:PSS solution is poured into the beaker, and the raw materials in the beaker are stirred for at least 30 minutes to ensure uniform mixing and that the mixture is free of air bubbles and impurities. The prepared sensitive layer 2 is carefully loaded into the dispensing syringe of the material extrusion 3D printer using a glass rod or other suitable tool. During the loading process, attention is paid to the uniformity and fullness of the material to avoid air bubbles or uneven distribution of the sensitive layer 2 in the dispensing syringe.

[0050] Please refer to Figure 2 In this embodiment, the flexible circuit 3 can be designed using AutoCAD professional electronic design software. Its structure can consist of multiple curved S-shaped structures. There can be multiple flexible circuits 3, which can be arranged along the longitudinal direction of the sensitive layer 2. By arranging multiple flexible circuits 3 along the longitudinal direction of the sensitive layer 2, the flexible circuits 3 can cover all positions of the sensitive layer 2, improving the sensitivity and coverage of the fabricated sensor. By setting multiple circuits, the impact of resistor breakage in the circuit on the overall sensor detection performance can be reduced. The reason is as follows: if only one circuit is fabricated, if this circuit wears out or other conditions occur, it will lead to an open circuit, rendering the sensor unusable. However, with multiple circuits, the open circuit of one or two circuits will not affect the use of the sensor, and according to the principle of parallel resistance, the total resistance can be reduced.

[0051] It is understood that, in this embodiment, please refer to Figure 2 The two ends of the flexible circuit 3 can be uniformly coated with conductive silicone to ensure that the coated conductive silicone covers the endpoints of the flexible circuit 3. At the same time, the prepared flexible circuit 3 is attached to the sensitive layer 2, so that one end of the flexible circuit 3 has good contact with the sensitive layer 2, and the other end of the flexible circuit 3 can contact the external power source. In this way, the changes sensed by the sensitive layer 2 are converted into electrical signals, and the human body's touch and temperature are detected.

[0052] Please refer to Figure 3 This embodiment also provides a method for preparing a sensor for measuring human touch and temperature, which includes the following steps:

[0053] S1. Prepare sensitive layer 2 and AB silicone separately for later use.

[0054] S2, a 3D model of the casting mold is constructed using SolidWorks software, with the dimensions of the model as follows: Figure 4 As shown. After drawing, export it in STL format and import it into slicing software for slicing. Set the slice layer height to 0.3mm and the temperature to 210℃. After slicing, generate G-code. The G-code can be post-processed as needed (some parts of the code may need to be manually modified). Then import the G-code into the FDM3D printer. The FDM3D printer will print according to the program on the G-code, thus printing the mold.

[0055] S3. Using AutoCAD professional electronic design software, the geometric structure of the flexible circuit 3 is drawn. After completing the design of a single circuit, an array setting is adopted. Multiple circuits are fabricated simultaneously by setting them in the vertical direction. The designed circuit image is saved as a DXF format and imported into an electro-ink printing device. Then, the flexible circuit 3 is printed on the substrate using the electro-ink printing device, thereby realizing the simultaneous printing of multiple array-set flexible circuits 3.

[0056] S4. Apply AB silicone evenly to the mold, ensuring a smooth application and a thickness of 2mm. Place the coated casting sample in a constant temperature and humidity chamber and cure at 80℃ for 30 minutes to obtain the bottom AB silicone layer 1. Then, carefully load the prepared sensitive layer 2 into the dispensing syringe of the material extrusion 3D printer using a glass rod or other suitable tool, and place the G-code on the material extrusion 3D printer. Subsequently, print the sensitive layer 2 onto the sample cured in step S4. During the printing process, the inner diameter of the dispensing nozzle is 0.4dm, and the air pressure is 0.2MPa.

[0057] S5, after printing, evenly apply conductive silicone to both ends of each flexible circuit 3, ensuring that the conductive silicone covers the endpoints of the flexible circuit 3. Simultaneously, attach the prepared flexible circuit 3 to one side of the sensitive layer 2, achieving multiple flexible circuit 3 structures on the same side of the sensitive layer 2. The flexible circuit 3 is attached to the side of the sensitive layer 2 away from the bottom AB silicone layer 1, thus obtaining the mold sample. The mold sample is then cured at 120℃ for 30 minutes.

[0058] S6. Another portion of AB silicone is evenly applied to one side of the sensitive layer 2 with the flexible circuit 3 after curing, forming the top AB silicone layer 4. The sensitive layer 2 with the flexible circuit 3 is encapsulated by the bottom AB silicone layer 1 and the top AB silicone layer 4. After encapsulation, it is placed in a constant temperature and humidity chamber and heated at 80°C for 30 minutes to obtain a sensor for measuring human touch and temperature.

[0059] The G-code for printing sensitive layer 2 can be found by referring to... Figure 5 As shown.

[0060] For FDM 3D printers, PLA material can be used. Before printing, it's important to clean the nozzles. PLA is the most common material used in FDM 3D printers. These printers melt the PLA material at high temperatures and then print it into a fixed shape through the printhead. While PLA is a usable material, FDM 3D printers can typically use PLA, ABS, TPU, and other materials. In this embodiment, the temperature is set to 210 degrees Celsius based on the characteristics of the selected PLA material. PLA's melting temperature is 190℃-220℃. If the temperature is set too low, the PLA material will not melt, and the desired shape cannot be printed. If the temperature is too high, the PLA material will carbonize and turn black, potentially causing nozzle clogging. Therefore, in actual operation, the temperature of the FDM 3D printer should be set according to the material being printed.

[0061] In this embodiment, after the circuit design is completed, in order to ensure the physical implementation of the circuit, the flexible circuit 3 is saved as a DXF format and imported into the inkjet printing equipment.

[0062] In this embodiment, the conductive ink used in the electro-inkjet printing equipment is nano-silver ion ink. Before use, it is stirred evenly to ensure uniform dispersion of the nano-silver ions and improve printing results. The substrate is polyethylene terephthalate with a thickness of 125 mm and a length and width of 100 mm. Before printing, the adhesion between the conductive ink and the substrate is ensured, guaranteeing a wetting angle of 36° to improve the quality and accuracy of the printed flexible circuit 3. Simultaneously, the surface of the electro-inkjet printing equipment needs to be cleaned of dust before use to prevent any dust or impurities from affecting the adhesion and printing quality of the conductive pattern.

[0063] Understandably, this embodiment uses a combination of response surface methodology and genetic algorithms to obtain a set of optimized process parameters for the electro-ink printing equipment, ensuring stability and printing quality during the electro-ink printing process. Specifically, the glass printhead of the electro-ink printing equipment has a diameter of 40 μm, a bias voltage of 700 V, a printhead height of 150 μm, and a printing speed of 0.15 mm / s. Under these parameters, the flexible circuit 3 fabricated exhibits good resistance stability. A smaller glass printhead diameter typically allows for more detailed printing effects. An appropriate bias voltage can prevent excessive resistance in the printed wires and suppress the "coffee ring" effect. The printhead height affects the ink jet position and dispersion, thus influencing printing quality and progress.

[0064] Furthermore, after printing the flexible circuit 3, a sintering and curing process is employed to ensure the stability of the wire resistance. The purpose of this step is to cause surface changes in the printed silver ions by heating under specific temperature conditions, thereby stabilizing the wire resistance. In this embodiment, a constant temperature and humidity test chamber is used, with the sintering and curing temperature set at 150°C and the heating time at 30 minutes.

[0065] Electro-ink printing, a type of 3D printing technology, produces circuits with high resolution and precision, thus improving the measurement accuracy of the fabricated sensor. The purpose of fabricating this flexible circuit 3 can be understood as a wire, because the sensitive layer 2 in the sensor measuring touch and temperature is subsequently encapsulated in AB silicone, making it difficult to measure the sensor's resistance. Therefore, in this embodiment, electro-ink printing is used to print the circuit, with one end connected to the sensitive layer in the sensor and the other end connected to an external power source, thereby measuring the sensor's resistance and converting changes in human touch and temperature into electrical signals. In this embodiment, PET is chosen as the substrate. PET is a bendable material (not stretchable), possessing high strength, high rigidity, and good wear resistance. It is colorless, transparent, and chemically stable, resulting in a flexible circuit structure that meets the requirements of the human body's curves, enabling more accurate measurements. PDMS material can also be used as the substrate. PDMS is bendable and stretchable, but much more expensive than PET. It has excellent stretchability and resilience and is commonly used in artificial skin, flexible electronics, and other fields. Therefore, PET is preferred in this embodiment.

[0066] In step S4, the sensitive layer 2 is printed by using a material extrusion 3D printer. 3D printing is low-cost, convenient, fast, and efficient, and the printed sensitive layer 2 has high precision.

[0067] In this embodiment, three printing technologies are used: electro-inking, material extrusion 3D printing, and FDM 3D printing. Electro-inking is used to print the flexible circuit 3, material extrusion 3D printing is used to print the sensitive layer 2, and FDM 3D printing is used to print the mold.

[0068] The sensor prepared by this invention is lightweight and low-cost, making it applicable to various scenarios.

[0069] It is understandable that the sensor prepared through this embodiment can not only be used to detect changes in human touch and temperature, but also be applied in industry.

[0070] When applied to the human body, this sensor can be used in the following ways: 1. In the medical field, it can be used in surgical robots. Due to its flexible structure, it provides tactile feedback during surgery without causing harm to the human body. This allows doctors to remotely control the robot and sense the tissue's hardness, elasticity, and other characteristics, improving surgical precision. 2. In the medical field, this sensor can also be used to monitor the physical condition of patients in a vegetative state. By wearing the sensor, any movement in the patient's body can be detected through electrical signals, allowing doctors to understand the patient's condition. 3. In the medical field, this sensor can also monitor a patient's body temperature in real time. By wearing the sensor, doctors can help determine fluctuations in the patient's body temperature and develop better treatment plans.

[0071] In the industrial field, the sensor of this invention can be used in the following ways: 1. Because the sensor of this invention is made of flexible material, when installed on an industrial robot, it can function as a tactile sensor to perceive information such as the position, shape, hardness, and texture of the object being contacted, facilitating better judgment by the industrial robot. 2. In precision assembly operations, the sensor of this invention can function as a tactile sensor to help the robot accurately perceive the position, shape, and contact force of components, thereby achieving high-precision insertion, assembly, or fastening operations. 3. For grasping irregularly shaped or easily damaged items, the sensor of this invention can function as a tactile sensor, allowing the robot to adjust its grasping strategy based on the pressure distribution when contacting the object, achieving flexible grasping and reducing damage.

[0072] It is understood that the above-described uses are only some of the application scenarios of the sensor prepared by the present invention, and in actual practice, the sensor prepared by the present invention is not limited to the above-described application scenarios.

[0073] Performance testing

[0074] To verify the performance of the sensor provided in this embodiment for measuring human touch and temperature, technicians designed a test plan and built a corresponding experimental platform and test system.

[0075] (a) Stability test

[0076] Since the sensor prepared in this embodiment is mainly used to measure human touch and temperature, and there may be unevenness or complete joints on the surface of human joints or skin, if the resistance of the sensor prepared in this embodiment is relatively stable under different bending angles, it indicates that the performance of the sensor prepared in this embodiment is relatively stable.

[0077] The specific operation is as follows: The prepared sensor is used to detect resistance changes. Since digital multimeters cannot perform continuous monitoring, an Arduino platform is used to design a circuit to read the real-time resistance changes of the sensor. Utilizing the voltage divider characteristics of a series circuit, the sensor resistance R can be derived from the known resistance voltage division. The formula R = ... Where R0 is a known resistance, R is the output resistance, U is the total voltage, and U0 is the voltage divider of the known resistance. To ensure the stability of the bending angle, an FDM 3D printer was used in this experiment to print molds at 30°, 60°, and 90° respectively. The sensor was then attached tightly to the mold, and the resistance value was read after the resistance stabilized, as shown in the figure. Figure 6 The data shown.

[0078] Figure 6 This is a scatter plot showing the change of the sensor prepared in this embodiment with the bending angle. Stability testing was conducted by continuously changing the bending angle with angular gradients of 0°, 30°, 60°, and 90°. Figure 6 As can be seen, the resistance change rate of the sensor prepared in this embodiment remains basically unchanged with the change of bending angle, indicating that the sensor prepared in this embodiment has good stability and can adapt to changes in the curve of the human body.

[0079] (ii) Testing the relationship between the sensor's resistance and temperature

[0080] This performance test also uses an Arduino platform to design a circuit to read the sensor's resistance changes. However, in this test, we used a heating platform, placing the sensor in close contact with it. Once the platform reached a specified temperature, we waited 5 minutes to ensure the sensor also reached that temperature before reading its resistance data, obtaining the following results: Figure 7 The graph shown.

[0081] Figure 7 This is a fitted graph showing the relationship between different resistance values ​​and temperature. Figure 7 As can be seen, the sensor's resistance gradually decreases with increasing temperature, indicating that the sensor prepared in this embodiment exhibits a negative temperature coefficient (NTC) thermosensitive characteristic. A negative temperature coefficient means that the sensor's resistance decreases with increasing temperature; that is, each temperature corresponds to a specific resistance value. Therefore, by measuring the resistance, the corresponding temperature can be calculated, thus achieving the purpose of temperature measurement. Furthermore, the sensor prepared in this embodiment has a flexible structure, and its resistance remains relatively stable even when bent. Therefore, in practical operation, by wearing the sensor for an extended period and monitoring the resistance value in real time, human body temperature can also be monitored.

[0082] (III) Tensile and Rebound Performance Testing of Sensors

[0083] The test was conducted as follows: a circuit was designed using the Arduino platform to read the real-time resistance change of the sensor. Then, a stretching platform was used to stretch the sensor. After the sensor resistance stabilized, the resistance value was read. The data is shown in Table 2 below.

[0084]

[0085] Where L0 is the initial sensor length, L is the sensor length after stretching, |L-L0| is the stretching amount, R1 is the resistance during stretching and descent, R2 is the resistance during springback and ascent, and R3 is the initial resistance of the sensor. Based on the above data and combined with... Figure 8 The data shows that the resistance of the sensor changes very little within a stretch of 3.5 mm, proving that the sensor prepared in this embodiment can meet the stretching problem caused by skin viscoelasticity during use. Furthermore, the experimental data shows that the sensor's resistance changes very little under stretching conditions, indicating that the sensor prepared by this invention is not easily damaged by mechanical forces, making it suitable for various complex environments. For example, it can be used as a wearable device or placed in smart textile products.

[0086] (iv) Sensor sensitivity test

[0087] The operation is as follows: This performance test also uses an Arduino platform to design a circuit to read the sensor's resistance change. However, in this test, we use a heating platform, placing the sensor tightly against it. Once the platform reaches a specified temperature, we wait 5 minutes to ensure the sensor also reaches the specified temperature. Then, we read the sensor's resistance data to obtain the following results: Figure 9 The graph shown.

[0088] The sensitivity curve of the sensor can be obtained through the above operations, as shown in the figure. Figure 9 As shown, where Figure 9 The slope of the linear fit of the curve is -0.0068782, and the correlation coefficient R is... 2 The value is 0.9969, which proves that the sensor prepared in this embodiment has good sensitivity to human body temperature.

[0089] Furthermore, the sensor prepared in this embodiment utilizes the thermal properties of active materials. Therefore, the resistivity TCR is an important indicator of its sensitivity. The resistivity is defined as the relative change in resistance when the temperature changes by 1°C.

[0090] In this context, T0 refers to the initial temperature, T refers to the current temperature, R(T0) is the resistance at the initial temperature, R(T) is the resistance at the current temperature, and TCR is the "temperature coefficient of resistance". It is a parameter that describes the degree to which the resistance of a material changes with temperature, reflecting the sensitivity of the resistance to temperature changes. It is usually expressed as the change in resistance per degree Celsius. Figure 9 The figures shown are a graph depicting the change in resistance R(T) - R(T0) and a graph showing the relationship between the relative rate of change of resistance (R(T) - R(T0)) / R(T0) and temperature T. The purpose of these two graphs is to visually demonstrate the sensor's sensitivity characteristics, understand its performance in practical applications, and ensure its measurement accuracy and stability within a specific range. Figure 9 Calculations based on the data show that the TCR of the sensor prepared in this embodiment is approximately -0.768% / ℃, indicating that the resistance decreases by 0.768% for every 1℃ increase in temperature. This data demonstrates that the sensor prepared in this embodiment exhibits good sensitivity when used in wearable devices, meeting the sensitivity requirements of the wearable device field.

[0091] (v) Temperature Cyclic Stability Test of Sensor

[0092] The results were obtained by subjecting the sensor to temperature cycling tests. Figure 10 As shown.

[0093] Figure 10 This is a stable cycle stability test chart of the sensor prepared in this embodiment. (By...) Figure 10 It can be seen that under multiple temperature cycles, the relative change in the sensor's resistance shows a small deviation, indicating that the sensor prepared in this embodiment has good stability and repeatability. Furthermore, through... Figure 10 It can also be seen that the sensor can still exhibit its sensitivity characteristics after multiple temperature cycles, proving that the sensor can still be used normally after multiple cycles.

[0094] The basic principles, main features, and advantages of this invention have been described above. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection claimed by this invention is defined by the appended claims and their equivalents.

Claims

1. A sensor for measuring human touch and temperature, characterized in that, It includes: Sensitive layer (2), the sensitive layer (2) is used to measure changes in human touch and temperature, the sensitive layer (2) includes carbon nanotubes, AB silica gel and PEDOT:PSS solution, the carbon nanotubes, the AB silica gel and the PEDOT:PSS solution are mixed in a ratio of 1:10:1; At least one flexible circuit (3) is attached to one side of the sensitive layer (2), and the flexible circuit (3) is used to convert the changes in human touch and temperature measured by the sensitive layer (2) into electrical signals; Bottom AB silicone layer (1), the bottom AB silicone layer (1) is formed by coating the sensitive layer (2) on the side away from the flexible circuit (3) with the AB silicone; The top AB silicone layer (4) is formed by coating the side of the flexible circuit (3) attached to the sensitive layer (2) with the AB silicone. The bottom AB silicone layer (1) and the top AB silicone layer (4) work together to wrap the sensitive layer (2) with the flexible circuit (3) attached between them. The AB silicone comprises a main agent A and a curing agent B, wherein the main agent A is one of epoxy resin, silicone or acrylic modified epoxy resin; the mixing ratio of the main agent A and the curing agent B is 1:

1.

2. The sensor for measuring human touch and temperature as described in claim 1, characterized in that, The carbon nanotubes are hexagonal carbon nanotubes with a purity greater than 98%, and their diameter is 10nm-15nm and their length is 15nm-30nm.

3. A method for preparing a sensor for measuring human touch and temperature, characterized in that, It includes the following steps: S1, prepare the sensitive layer (2) and the AB silicone in the sensor for measuring human touch and temperature as described in any one of claims 1-2; S2, use Solidworks to draw the casting mold model, and use FDM3D printing technology to make the mold; S3, draw the fluid jet printing regular array flexible circuit (3), and print the flexible circuit (3) on the substrate using an electro-jet printing device, and then sinter at 150°C for 30 minutes to obtain the flexible circuit (3). S4, a portion of AB silicone is coated into the mold prepared in step S2 to form the bottom AB silicone layer (1), and the prepared sensitive layer (2) is loaded into the 3D printer and printed on the cured bottom AB silicone layer (1) by the material extrusion 3D printer. S5. After printing, apply conductive silicone evenly to both ends of each flexible circuit (3) to ensure that the conductive silicone covers the endpoints of the flexible circuit (3) when it is applied. At the same time, attach multiple flexible circuits (3) to the same side of the sensitive layer (2). The flexible circuit (3) is attached to the side of the sensitive layer (2) away from the bottom AB silicone layer (1) to obtain the mold sample. Then, place the mold sample at 120°C for 30 minutes to cure. S6, another portion of AB silicone is evenly applied to one side of the sensitive layer (2) with the flexible circuit (3) after curing, forming the top AB silicone layer (4). The sensitive layer (2) with the flexible circuit (3) is encapsulated by the bottom AB silicone layer (1) and the top AB silicone layer (4). After encapsulation, it is heated at 80°C for 30 minutes to obtain the sensor for measuring human touch and temperature.

4. The method for preparing a sensor for measuring human touch and temperature as described in claim 3, characterized in that, The bottom AB silicone layer (1) is mixed in a 1:1 ratio and then evenly applied to the mold, with a thickness of 2mm.

5. The method for preparing a sensor for measuring human touch and temperature as described in claim 3, characterized in that, The flexible circuit (3) has an S-shaped structure.

6. The method for preparing a sensor for measuring human touch and temperature as described in claim 3, characterized in that, The flexible circuit (3) uses nano-silver ion conductive ink as the ink material and polyethylene terephthalate as the substrate material during the preparation process. The thickness of the substrate material is 125 μm and the length and width are both 100 mm.

7. The method for preparing a sensor for measuring human touch and temperature as described in claim 3, characterized in that, The diameter of the glass printhead in the described electro-inking equipment is 40μm, the height of the glass printhead is 150μm, the bias voltage is 700V, and the printing speed is 0.15mm / s.

8. The method for preparing a sensor for measuring human touch and temperature as described in claim 3, characterized in that, The preparation method of the sensitive layer (2) includes the following steps: weigh 1g of carbon nanotubes and place them in a beaker; then weigh 5g of main agent A and 5g of curing agent B respectively, pour the main agent A and curing agent B into the beaker containing the carbon nanotubes, and then pour in 1g of PEDOT:PSS solution, mix and stir the various raw materials in the beaker until no bubbles are generated, and the sensitive layer (2) is obtained.

9. The method for preparing a sensor for measuring human touch and temperature as described in claim 3, characterized in that, The inner diameter of the dispensing nozzle in the material extrusion 3D printer is 0.4 dm, and the air pressure is 0.2 MPa.

10. The method for preparing a sensor for measuring human touch and temperature as described in claim 3, characterized in that, The FDM 3D printing technology uses any one of PLA, ABS, or TPU as the material.

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