A pressure-sensitive touch-sensitive UHF RFID electronic yarn and its preparation method

Abstract

The application belongs to the technical field of electronic yarn and discloses a pressure-sensitive touch type UHF RFID electronic yarn and a preparation method thereof. The electronic yarn comprises a bearing yarn and an interconnection body spirally wrapped on the surface of the bearing yarn. The interconnection body is composed of one UHF RFID chip and a hybrid antenna. The hybrid antenna comprises spiral conductive fibers and a pressure switch. All the spiral conductive fibers are distributed on both sides of the UHF RFID chip. The pressure switch comprises an insulating base, an insulating pressing block, a spring, a liftable conductive block, a balancing block and a pair of conductive touch pads. The method comprises the following steps: interconnecting the UHF RFID chip and the conductive fibers, spirally wrapping the UHF RFID intermediate part on the bearing yarn after the UHF RFID intermediate part is prepared, cutting the spiral conductive fibers, interconnecting the two ends formed by cutting the spiral conductive fibers with the two conductive touch pads respectively, and finally packaging all the interconnection points to form the electronic yarn. The electronic yarn has the characteristics of good accuracy and strong signal anti-interference ability, and the preparation method is simple.

Description

Technical Field

[0001] This invention belongs to the field of electronic yarn technology, and relates to a pressure-sensitive touch-controlled UHF RFID electronic yarn and its preparation method. Background Technology

[0002] Smart textiles, as a key carrier of human-computer interaction devices, are a hot research topic in today's society. Taking pressure-sensitive sensors as an example, they can capture subtle pressure changes and have significant application value in various scenarios such as motion tracking and health monitoring.

[0003] Traditional pressure sensors require external power supply and signal acquisition modules to be connected via wires, resulting in complex wiring. Ultra-high frequency radio frequency identification (UHF RFID) technology is characterized by being wireless, passive, low-power, and fast-response. Combining RFID technology with pressure sensors is expected to reduce wiring complexity and improve user-friendliness.

[0004] Among known UHF RFID sensors, yarn-based sensors, namely UHF RFID electronic yarn, are gradually gaining attention due to their excellent weavability. Patent application CN116999055A discloses a wireless passive strain sensing yarn for monitoring limb movement and its preparation method. This method involves integrating an interconnect consisting of a helical conductor and a chip into the yarn to create a strain electronic yarn. When the strain electronic yarn is integrated into the fabric, it deforms under pressure along with the fabric as the human body moves. This changes the gain of the helical conductor, altering the spatial distribution of the transmitted electromagnetic wave energy and ultimately affecting the energy received by the receiver. Based on the one-to-one correspondence between energy changes and pressure deformation, the human movement state can be deduced. However, besides pressure deformation, the energy received by the receiver also depends on the distance between the receiver and the electronic yarn, as well as external interference such as metallic devices. Therefore, the monitoring accuracy needs improvement.

[0005] One patent application discloses a gravity-sensing UHF RFID step sensing yarn and its fabrication method. This yarn is fabricated by introducing a gravity-sensing tilt switch into the antenna. During tilting, the instantaneous closure of the gravity-sensing tilt switch causes a sudden change in the yarn's structural dimensions, leading to a sudden change in the RSSI (Resonance, Signal, and Indication) signal. Similarly, another patent application discloses a strain-type UHF RFID step sensing yarn and its fabrication method. This yarn is fabricated by introducing a miniature tension switch into the antenna. During stretching, the instantaneous closure of the tension switch causes a sudden change in the yarn's structural dimensions, leading to a sudden change in the RSSI signal. However, the magnitude of the RSSI change is related not only to human physiological state but also to the monitoring distance. Therefore, calibration is required before each test, making the testing process complex and user-unfriendly.

[0006] Therefore, developing a pressure-sensitive touch-sensitive UHF RFID electronic yarn that does not require signal calibration to solve the above-mentioned problems is of great significance. Summary of the Invention

[0007] The purpose of this invention is to solve the problems existing in the prior art and to provide a pressure-sensitive touch-controlled UHF RFID electronic yarn and its preparation method.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A pressure-sensitive touch-sensitive UHF RFID electronic yarn includes a carrier yarn and an interconnect body spirally wrapped around the surface of the carrier yarn. The interconnect body consists of a UHF RFID chip and a hybrid antenna, which includes a spiral conductive fiber and a pressure switch.

[0010] The UHF RFID chip consists of one unit, with all spiral conductive fibers distributed on both sides of the chip; the number of spiral conductive fibers can be three or four, two more than the number of pressure switches, meaning the pressure switches consist of one or two units.

[0011] When there is only one spiral conductive fiber on either side of the UHF RFID chip, no pressure switch connection is required;

[0012] When there are at least two spiral conductive fibers on either side of the UHF RFID chip, a pressure switch is connected between each pair of adjacent spiral conductive fibers.

[0013] The pressure switch includes an insulating base, an insulating block, a spring, a liftable conductive block, a balance block, and a pair of conductive pads; the two ends of the spring are connected to the insulating base and the insulating block respectively, the liftable conductive block and the balance block are distributed on both sides of the spring, and a pair of conductive pads are set on the insulating base, each connected to a spiral conductive fiber;

[0014] By applying pressure to the insulating block, the spring is deformed, allowing the movable conductive block to contact the conductive pad and thus activate the pressure switch. When the pressure is released, the movable conductive block separates from the conductive pad again due to the spring force.

[0015] When the spring is compressed and deformed by less than x, the pressure switch is in the open state; when the spring is compressed and deformed by more than or equal to x, the pressure switch is in the closed state; x is the distance between the liftable conductive block and the conductive pad in the pressure switch.

[0016] As a preferred technical solution:

[0017] In the pressure-sensitive touch-sensitive UHF RFID electronic yarn described above, the UHF RFID chip is located at the center of the interconnect.

[0018] As described above, a pressure-sensitive touch-controlled UHF RFID electronic yarn uses the interconnection point between the spring and the insulating pressure block as a fulcrum, allowing the conductive block and the balance block to be raised and lowered with the same torque.

[0019] As described above, in a pressure-sensitive touch-controlled UHF RFID electronic yarn, when the pressure switch is not pressed or the spring deformation is less than x, the pressure-sensitive touch-controlled UHF RFID electronic yarn is in an inactive state, with no sensing signal output and a binary value of 0. At this time, there is no conductivity between the conductive pad and the liftable conductive block, poor impedance matching between the UHF RFID chip and the effective antenna, the sensing yarn does not transmit sensing signals to the outside, the reader cannot receive the sensing signal, and the Received Signal Strength Indicator (RSSI) has no data. The effective antenna is a spiral conductive fiber that forms a reliable electrical connection with the UHF RFID chip, i.e., a spiral conductive fiber that is conductive to the UHF RFID chip; when the conductive pad is disconnected from the liftable conductive block, the spiral conductor not connected to the chip is not included in the effective antenna range.

[0020] As described above, in a pressure-sensitive touch-controlled UHF RFID electronic yarn, when the spring of the pressure switch is deformed by a force greater than or equal to x, the pressure-sensitive touch-controlled UHF RFID electronic yarn is activated and outputs a sensing signal with a binary value of 1. At this time, there is conduction between the conductive pad and the liftable conductive block, the resistance is less than 1 ohm, the effective antenna structure size undergoes a sudden change, the impedance matching between the chip and the hybrid antenna is good, the electronic yarn emits sensing signals to the outside world, the reader can receive the sensing signals, and RSSI data is available. When the conductive pad and the liftable conductive block are connected, the spiral conductive fibers on both sides of the conductive pad are included in the effective antenna range.

[0021] As described above, in a pressure-sensitive touch-controlled UHF RFID electronic yarn, when there are two pressure switches, the insulating blocks of the two pressure switches are connected by a rigid rod. When the deformation exceeds the threshold, both pressure switches close, the electronic yarn is activated, and it emits a sensing signal. Slight pressure at a single point or localized friction can only compress one side of the switch, and cannot simultaneously compress both springs to reach the deformation threshold. This prevents individual antenna activation, effectively suppressing false triggering caused by slight disturbances and providing stronger anti-interference capabilities.

[0022] This invention also provides a method for preparing a pressure-sensitive touch-type UHF RFID electronic yarn as described above. The method involves three spiral conductive fibers and one pressure switch. First, the UHF RFID chip and conductive fibers are interconnected to form a UHF RFID intermediate component. Then, the UHF RFID intermediate component is spirally wound onto a carrier yarn, transforming the conductive fibers into spiral conductive fibers. Next, the spiral conductive fiber on one side of the UHF RFID chip is cut, and the two ends are interconnected with the two conductive pads of the pressure switch. Finally, all interconnections are encapsulated to form the pressure-sensitive touch-type UHF RFID electronic yarn. The cutting position needs to be selected according to actual needs, ensuring that when the pressure switch is on, the UHF RFID chip in the electronic yarn is activated, and the monitoring terminal can receive the sensing signal; when the pressure switch is off, the UHF RFID chip in the electronic yarn is not activated, and the monitoring terminal cannot receive the sensing signal.

[0023] This invention also provides a method for preparing a pressure-sensitive touch-type UHF RFID electronic yarn as described above. The method involves four spiral conductive fibers and two pressure switches distributed on both sides of an RFID chip. First, the UHF RFID chip and conductive fibers are interconnected to form a UHF RFID intermediate component. Then, the UHF RFID intermediate component is spirally wound onto a carrier yarn, transforming the conductive fibers into spiral conductive fibers. Subsequently, the spiral conductive fibers on one side of the UHF RFID chip are cut, and the resulting two ends are interconnected with the two conductive pads of the pressure switches. Simultaneously, the spiral conductive fibers on the other side of the UHF RFID chip are cut, and the resulting two ends are interconnected with the two conductive pads of another pressure switch. Finally, all interconnections are encapsulated to form the pressure-sensitive touch-type UHF RFID electronic yarn.

[0024] This invention also provides a method for preparing a pressure-sensitive touch-type UHF RFID electronic yarn as described above. The method involves four spiral conductive fibers and two pressure switches distributed on the same side of the RFID chip. First, the UHF RFID chip and conductive fibers are interconnected to form a UHF RFID intermediate component. Then, the UHF RFID intermediate component is spirally wound onto a carrier yarn, transforming the conductive fibers into spiral conductive fibers. Next, the spiral conductive fibers on one side of the UHF RFID chip are cut, and the resulting two ends are interconnected with the two conductive pads of the pressure switches. Then, the spiral conductive fibers connected to the pressure switches but not directly connected to the RFID chip are further cut, and the resulting two ends are interconnected with the two conductive pads of another pressure switch. Finally, all interconnections are encapsulated to form the pressure-sensitive touch-type UHF RFID electronic yarn.

[0025] As a preferred technical solution:

[0026] The method for preparing a pressure-sensitive touch-sensitive UHF RFID electronic yarn as described above involves encapsulating all interconnect points with flexible insulating adhesive.

[0027] Invention principle:

[0028] This invention enables binary switch-type detection, and its principle is significantly different from existing technologies (such as CN116999055A), as well as from the prior patent applications for a gravity-sensing UHF RFID step sensing yarn and its preparation method, and a strain-sensing UHF RFID step sensing yarn and its preparation method.

[0029] The sensing principle of the pressure-sensitive touch-controlled UHF RFID electronic yarn of this invention is as follows: the spiral conductor (in this invention, a spiral conductive fiber) connected to the UHF RFID chip is called the effective antenna. When the pressure switch in the electronic yarn is not under pressure, or under very little pressure, the spring deformation is less than the distance between the liftable conductive block and the conductive pad. At this time, the physical structure of the effective antenna is too short, resulting in poor impedance matching with the RFID chip. The pressure-sensitive touch-controlled UHF RFID electronic yarn is in an inactive state and does not transmit sensing signals to the outside world, so the reader cannot obtain sensing information. When the pressure switch in the electronic yarn is under pressure, and the spring deformation is greater than or equal to the distance between the liftable conductive block and the conductive pad, the liftable conductive block and the conductive pad become conductive, causing a sudden change in the physical structure size and impedance of the effective antenna. The effective antenna achieves excellent impedance matching with the RFID chip, and the pressure-sensitive touch-controlled UHF RFID electronic yarn switches to the active state, transmitting sensing signals to the outside world. The reader can then read the corresponding sensing information. This invention's sensing and monitoring only determines whether the electronic yarn radiates radio frequency signals outwards, without needing to analyze the signal strength. It implements a binary switch-type detection logic: no pressure, weak pressure, and no signal output indicate an off state with no sensing signal; pressure-induced conduction and the generation of radio frequency signals indicate an on state with a sensing signal.

[0030] Existing technologies collect continuous quantitative data throughout the entire process and use different values ​​to characterize the movement state. For example, CN116999055A discloses a wireless passive strain sensing yarn for monitoring limb movement state and its preparation method. Limb movement causes deformation of the sensing yarn, thereby changing the antenna gain of the sensing yarn and consequently changing the RSSI received by the monitoring end. During this process, the RFID chip is active throughout. When only the deformation is changed, there is a one-to-one mapping relationship between the RSSI and the degree of deformation of the sensing yarn, and the limb movement state can be deduced from the received RSSI. However, RSSI is also related to the presence of metal in the test environment and the distance between the reader and the sensing yarn, so the signal needs to be calibrated and standardized before each operation, making the operation complex. In the electronic yarn of this invention, the RFID chip is not active throughout the monitoring process. When the pressure switch is closed, the chip is active and transmits sensing signals; when it is open, it is inactive and does not transmit sensing signals. Throughout the monitoring process, this invention discards amplitude information and uses only the presence or absence of a signal as the criterion, which can avoid the influence of environmental factors on the monitoring data results. It is simple to operate and highly accurate.

[0031] Beneficial effects:

[0032] (1) The pressure-sensitive touch-controlled UHF RFID electronic yarn of the present invention can effectively improve monitoring accuracy and reduce noise interference, and has broad application prospects in motion monitoring and human-computer interaction.

[0033] (2) The pressure-sensitive touch-controlled UHF RFID electronic yarn of the present invention realizes binary switch detection. Compared with existing RFID sensors, it avoids signal calibration and has good accuracy and stronger anti-interference ability.

[0034] (3) The method for preparing a pressure-sensitive touch-sensitive UHF RFID electronic yarn of the present invention can be configured with a rigid rod linkage dual pressure switch structure. Only when both switches are pressed simultaneously can the sensing be activated. Everyday fabric wrinkles, slight friction and other weak external forces cannot trigger the two switches at the same time, effectively suppressing false triggering. It is suitable for long-term human movement and flexible wearable continuous monitoring scenarios. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a pressure-sensitive touch-controlled UHF RFID electronic yarn with a miniature pressure switch on one side.

[0036] Figure 2 This is a schematic diagram of a hybrid antenna structure for a pressure-sensitive touch-sensitive UHF RFID electronic yarn with a miniature pressure switch on one side; l is the single-arm axis length; r is the helix radius; a is the conductor radius; S is the pitch; l1 is the distance from the pressure switch to the UHF RFID chip;

[0037] Figure 3 Here are schematic diagrams of a pressure switch: (a) showing the switch with and without the carrier yarn and spiral conductor; (b) showing the switch without the carrier yarn and spiral conductor.

[0038] Figure 4 This is a schematic diagram of the structure of a pressure-sensitive touch-controlled UHF RFID electronic yarn with pressure switches on both sides.

[0039] Among them, 1 is a spiral conductive fiber; 2 is a carrier yarn; 3 is a UHF RFID chip; 4 is a pressure switch; 4-1 is a spring; 4-2 is an insulating pressure block; 4-3 is a balance block; 4-4 is a liftable conductive block; 4-5 is an insulating base; 4-6 is a conductive contact pad; and 4-7 is a rigid rod. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0041] The manufacturers and brands mentioned in the following embodiments are merely examples. The core of this invention lies in the technical solution itself, and it is not intended to limit specific manufacturers or brands. Products from other manufacturers and brands that meet the technical requirements and performance indicators specified in this invention can also meet the application requirements of this invention and are all feasible choices.

[0042] The polyurethane acrylate (PUA) adhesive used in each embodiment was prepared as follows: 55 wt% of polyurethane acrylate resin R96 (manufacturer: Chengdu Guangju Materials Technology Co., Ltd.), 17.5 wt% of tripropylene glycol diacrylate, 17.5 wt% of ethoxylated trimethylolpropane triacrylate, 8 wt% of 2-hydroxy-2-methyl-1-phenylpropanone, 1 wt% of propyltrimethoxysilane, 0.5 wt% of leveling agent BYK-333 (manufacturer: BYK Chemical Co., Ltd.), and 0.5 wt% of defoamer BYK-065 (manufacturer: BYK Chemical Co., Ltd.) were stirred in a magnetic stirrer at 50°C for 30 min to obtain UV-curable polyurethane acrylate.

[0043] A pressure-sensitive touch-sensitive UHF RFID electronic yarn, such as Figures 1-2 As shown, it includes a carrier yarn 2 and an interconnection body spirally wrapped around the surface of the carrier yarn 2. The interconnection body consists of a UHF RFID chip 3 and a hybrid antenna. The hybrid antenna includes a spiral conductive fiber 1 and a pressure switch 4.

[0044] There is one UHF RFID chip 3, which is located at the center of the interconnect. All spiral conductive fibers 1 are distributed on both sides of the UHF RFID chip 3. There are three or four spiral conductive fibers 1, which is two more than the pressure switch 4, that is, there is one or two pressure switches 4.

[0045] When there is only one spiral conductive fiber 1 on either side of the UHF RFID chip 3, there is no need for pressure switch 4 to connect;

[0046] When there are at least two spiral conductive fibers 1 on either side of the UHF RFID chip 3, a pressure switch 4 is connected between each pair of adjacent spiral conductive fibers 1.

[0047] like Figure 3 As shown, the pressure switch 4 includes an insulating base 4-5, an insulating pressure block 4-2, a spring 4-1, a liftable conductive block 4-4, a balance block 4-3, and a pair of conductive pads 4-6; the two ends of the spring 4-1 are connected to the insulating base 4-5 and the insulating pressure block 4-2 respectively, the liftable conductive block 4-4 and the balance block 4-3 are distributed on both sides of the spring 4-1, and a pair of conductive pads 4-6 are set on the insulating base 4-5, each connected to a spiral conductive fiber 1;

[0048] With the connection point between spring 4-1 and insulating pressure block 4-2 as the fulcrum, the conductive block 4-4 and the balance block 4-3 can be raised and lowered with the same torque;

[0049] By applying pressure to the insulating block 4-2, the spring 4-1 is deformed, thereby allowing the liftable conductive block 4-4 to contact the conductive pad 4-6, thus enabling the pressure switch 4 to conduct; the distance between the liftable conductive block 4-4 and the conductive pad 4-6 is x.

[0050] like Figure 4 As shown, when there are two pressure switches 4, the insulating blocks 4-2 of the two pressure switches 4 are connected by rigid rod contact pads 4-7;

[0051] When pressure switch 4 is not pressed or the spring is deformed by less than x, pressure switch 4 is in the open state, that is, the pressure-sensitive touch type UHF RFID electronic yarn is in the inactive state, there is no sensing signal output, and the output binary value is 0.

[0052] When the spring of pressure switch 4 is compressed and deformed by a factor greater than or equal to x, pressure switch 4 is in the conducting state, that is, the pressure-sensitive touch-controlled UHF RFID electronic yarn is in the activated state, and there is a sensing signal output, which outputs a binary value of 1.

[0053] Example 1

[0054] A method for preparing pressure-sensitive touch-type UHF RFID electronic yarn, comprising three spiral conductive fibers and one pressure switch, wherein the specific steps are as follows:

[0055] (1) Material preparation;

[0056] Conductive fiber: composed of slender copper conductors with a diameter of 0.09 mm and a conductivity of 5.8 × 10⁻⁶. 7 S / m;

[0057] UHF RFID chip: Alien Higgs 3 radio frequency chip;

[0058] Soldering material: solder wire;

[0059] Flexible insulating adhesive: PUA;

[0060] Carrying yarn: polyester yarn, dielectric constant α=3.2;

[0061] Pressure switch: It consists of an insulating base, a PV insulating pressure block, a stainless steel spring, a copper liftable conductive block, a balance block, and a pair of copper conductive pads; the distance between the liftable conductive block and the conductive pads is x=3mm, and the spring stiffness coefficient is 0.5N / mm;

[0062] (2) Preparation of UHF RFID middleware;

[0063] The ends of two conductive fibers are connected to the RF pin and GND pin of the UHF RFID chip by soldering, respectively. The connection area is coated with 0.06mL of flexible insulating adhesive and then cured in a UV curing oven (Baoding Zhonghe Machinery Company, HWUV0133X-18) at 1700W power for 8s to obtain the UHF RFID intermediate component.

[0064] (3) Fabrication of interconnects;

[0065] The UHF RFID intermediate is spirally wrapped onto the carrier yarn using a wrapping device, turning the conductive fiber into a spiral conductive fiber, forming an interconnect composed of the spiral conductive fiber and the UHF RFID chip;

[0066] Among them, the pitch S of the spiral conductive fiber is 1mm, the spiral radius r is 0.62mm, the single arm shaft length l is 30mm, and the conductor radius a is 0.045mm;

[0067] (4) Preparation of electronic yarn;

[0068] The spiral conductive fiber on one side of the UHF RFID chip is cut off, and the two ends are interconnected with the two conductive pads of the pressure switch to obtain a pressure-sensitive touch-sensitive UHF RFID electronic yarn; wherein, the distance l1 from the pressure switch to the UHF RFID chip is 5mm.

[0069] In an open area, the distance between the pressure-sensitive touch-sensitive UHF RFID electronic screen and the reader is 0.3m. The reader's antenna transmit power is 30dBm, the gain is 12dBi, and the test frequency band is 902~928MHz. When the pressure switch is not pressed, the reader cannot receive a sensor signal and outputs a binary value of 0. When the pressure switch is pressed and the spring compression exceeds 3mm, the reader receives a sensor signal and outputs a binary value of 1. This embodiment achieves sensor monitoring by monitoring the presence or absence of a signal, and there are no requirements for the specific RSSI value of the sensor signal.

[0070] To verify the accuracy of the monitoring in this embodiment, five cycles of testing were performed. Each time, the conductive fiber, which was disconnected due to the pressure switch, was turned on for 3 seconds, followed by a 3-second disconnection. The test results showed that a sensing signal was received only when the conductive fiber was on; no sensing signal was received when the conductive fiber was off, indicating 100% monitoring accuracy.

[0071] Comparative Example 1

[0072] A method for preparing a gravity-sensing UHF RFID electronic yarn is basically the same as in Example 1, except that: referring to the patent application (A gravity-sensing UHF RFID step sensing yarn and its preparation method), the pressure switch is replaced with a gravity-sensing tilt switch I, the pitch S of the prepared spiral conductive fiber is 1 mm, the spiral radius r is 0.62 mm, the single arm shaft length l is 30 mm, the conductor radius a is 0.045 mm, and the distance l3 from the gravity-sensing tilt switch to the RFID chip is 20 mm; wherein the gravity-sensing tilt switch I includes a movable conductor and a terminal block, and the tilt threshold is 10°.

[0073] In open areas, when the distance between the gravity-sensing UHF RFID electronic yarn and the reader is 0.3m and 0.6m, the RSSI jump values ​​before and after closing the conductive fiber disconnected by the gravity-sensing tilt switch are 6dBi and 4dBi, respectively. This means that the RSSI step amplitude generated by the switch switching varies with the sensing distance; to ensure accurate monitoring results, the step amplitude corresponding to physiological activity must be calibrated before each test, making the testing process cumbersome.

[0074] Comparative Example 2

[0075] A method for preparing strain-type UHF RFID electronic yarn is basically the same as in Example 1, except that: referring to the patent application (a strain-type UHF RFID step sensing yarn and its preparation method), the pressure switch is replaced with a miniature tension switch, the pitch S of the prepared helical conductive fiber is 1 mm, the helical radius r is 0.62 mm, the single arm shaft length l is 30 mm, the conductor radius a is 0.045 mm, and the distance l3 from the miniature tension switch to the RFID chip is 20 mm; wherein the miniature tension switch has a length of 5 mm and a stiffness coefficient of 0.5 N / mm.

[0076] In open areas, when the distance between the strain gauge UHF RFID electronic yarn and the reader is 0.3m and 0.6m, the RSSI jump values ​​before and after closing the conductive fiber disconnected by the miniature tension switch are 6dBi and 4dBi, respectively. This means that the RSSI step amplitude generated by the switch switching varies with the sensing distance; to ensure accurate monitoring results, the step amplitude corresponding to physiological activity must be calibrated before each test, making the testing process cumbersome.

[0077] Example 2

[0078] A method for preparing a pressure-sensitive touch-sensitive UHF RFID electronic yarn, comprising four spiral conductive fibers and two pressure switches distributed on both sides of the RFID chip, the specific steps of which are as follows:

[0079] (1) Material preparation;

[0080] Conductive fiber: composed of slender copper conductors with a diameter of 0.09 mm and a conductivity of 5.8 × 10⁻⁶. 7 S / m;

[0081] UHF RFID chip: Alien Higgs 3 radio frequency chip;

[0082] Soldering material: solder wire;

[0083] Flexible insulating adhesive: PUA;

[0084] Carrying yarn: polyester yarn, dielectric constant α=3.2;

[0085] Pressure switch: It consists of an insulating base, PV insulating blocks, stainless steel springs, copper liftable conductive blocks, balance blocks, and a pair of copper conductive pads; the insulating blocks of the two pressure switches are connected by a rigid rod; the distance between the liftable conductive blocks and the conductive pads is x=3mm, and the spring stiffness coefficient is 0.5N / mm;

[0086] (2) Preparation of UHF RFID middleware;

[0087] The ends of two conductive fibers are connected to the RF and GND pins of the UHF RFID chip by soldering, respectively. The connection area is coated with 0.06 mL of flexible insulating adhesive and then cured in an ultraviolet curing oven at 1700W for 8 seconds to obtain the UHF RFID intermediate component.

[0088] (3) Fabrication of interconnects;

[0089] The UHF RFID intermediate is spirally wrapped onto the carrier yarn using a wrapping device, turning the conductive fiber into a spiral conductive fiber, forming an interconnect composed of the spiral conductive fiber and the UHF RFID chip;

[0090] Among them, the pitch S of the spiral conductive fiber is 1mm, the spiral radius r is 0.62mm, the single arm shaft length l is 30mm, and the conductor radius a is 0.045mm;

[0091] (4) Preparation of electronic yarn;

[0092] The spiral conductive fiber on one side of the UHF RFID chip is cut, and the two ends are interconnected with the two conductive pads of the pressure switch, respectively. At the same time, the spiral conductive fiber on the other side of the UHF RFID chip is cut, and the two ends are interconnected with the two conductive pads of another pressure switch, respectively. Finally, all interconnection points are encapsulated with flexible insulating glue to obtain a pressure-sensitive touch-sensitive UHF RFID electronic yarn. The distance l1 from the pressure switch to the UHF RFID chip is 5mm.

[0093] In an open area, the distance between the pressure-sensitive touch-sensitive UHF RFID electronic screen and the reader is 0.6m. The reader antenna's transmit power is 30dBm, the gain is 12dBi, and the test frequency band is 902~928MHz. When the pressure switch is not pressed, the reader cannot receive a sensor signal and outputs a binary value of 0. When the pressure switch is pressed and the spring compression exceeds 3mm, the reader receives a sensor signal and outputs a binary value of 1. This embodiment achieves sensor monitoring by monitoring the presence or absence of a signal, and there are no requirements for the specific RSSI value of the sensor signal.

Claims

1. A pressure-sensitive touch-sensitive UHF RFID electronic yarn, comprising a carrier yarn and an interconnect spirally wound on the surface of the carrier yarn, the interconnect consisting of a UHF RFID chip and a hybrid antenna, characterized in that: The hybrid antenna comprises a helical conductive fiber and a pressure switch; The UHF RFID chip consists of one unit, with all spiral conductive fibers distributed on both sides of the chip; the number of spiral conductive fibers can be three or four, two more than that of a pressure switch. When there is only one spiral conductive fiber on either side of the UHF RFID chip, no pressure switch connection is required; When there are at least two spiral conductive fibers on either side of the UHF RFID chip, a pressure switch is connected between each pair of adjacent spiral conductive fibers. The pressure switch includes an insulating base, an insulating block, a spring, a liftable conductive block, a balance block, and a pair of conductive pads; the two ends of the spring are connected to the insulating base and the insulating block respectively, the liftable conductive block and the balance block are distributed on both sides of the spring, and a pair of conductive pads are set on the insulating base, each connected to a spiral conductive fiber; By applying pressure to the insulating block, the spring is deformed, which allows the conductive block to rise and fall to contact the conductive pad, thus enabling the pressure switch to be turned on. When the spring is compressed and deformed by less than x, the pressure switch is in the open state; when the spring is compressed and deformed by more than or equal to x, the pressure switch is in the closed state; x is the distance between the liftable conductive block and the conductive pad in the pressure switch.

2. The pressure-sensitive touch-controlled UHF RFID electronic yarn according to claim 1, characterized in that, The UHF RFID chip is located at the center of the interconnect.

3. The pressure-sensitive touch-sensitive UHF RFID electronic yarn according to claim 1, characterized in that, Using the connection point between the spring and the insulating pressure block as the fulcrum, the conductive block and the balance block can be raised and lowered with the same torque.

4. The pressure-sensitive touch-controlled UHF RFID electronic yarn according to claim 1, characterized in that, When the pressure switch is not pressed or the spring is deformed by less than x, the pressure-sensitive touch-type UHF RFID electronic switch is inactive, with no sensor signal output and a binary value of 0.

5. The pressure-sensitive touch-controlled UHF RFID electronic yarn according to claim 1, characterized in that, When the spring of the pressure switch is compressed and deformed by a factor greater than or equal to x, the pressure-sensitive touch-controlled UHF RFID electronic switch is activated and outputs a sensing signal with a binary value of 1.

6. The pressure-sensitive touch-sensitive UHF RFID electronic yarn according to claim 1, characterized in that, When there are two pressure switches, the insulating blocks of the two pressure switches are connected by a rigid rod.

7. A method for preparing a pressure-sensitive touch-sensitive UHF RFID electronic yarn as described in any one of claims 1 to 6, wherein the number of spiral conductive fibers is 3 and the number of pressure switches is 1, characterized in that: First, the UHF RFID chip and conductive fibers are interconnected to create a UHF RFID middleware. Then, the UHF RFID middleware is spirally wound onto the carrier yarn, turning the conductive fibers into spiral conductive fibers. Next, the spiral conductive fibers on one side of the UHF RFID chip are cut off, and the two ends are interconnected with the two conductive pads of the pressure switch. Finally, all interconnection points are encapsulated to form a pressure-sensitive touch-sensitive UHF RFID electronic yarn.

8. The method for preparing a pressure-sensitive touch-sensitive UHF RFID electronic yarn according to claim 7, characterized in that, All interconnect points are encapsulated with flexible insulating adhesive.

9. A method for preparing a pressure-sensitive touch-sensitive UHF RFID electronic yarn as described in any one of claims 1 to 6, wherein the number of spiral conductive fibers is 4, and the number of pressure switches is 2 and distributed on both sides of the RFID chip, characterized in that: First, a UHF RFID chip and conductive fibers are interconnected to create a UHF RFID middleware. Then, the UHF RFID middleware is spirally wound onto a carrier yarn, turning the conductive fibers into spiral conductive fibers. Next, the spiral conductive fibers on one side of the UHF RFID chip are cut, and the two ends are interconnected with the two conductive pads of a pressure switch. At the same time, the spiral conductive fibers on the other side of the UHF RFID chip are cut, and the two ends are interconnected with the two conductive pads of another pressure switch. Finally, all interconnections are encapsulated to form a pressure-sensitive touch-sensitive UHF RFID electronic yarn.

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