Wearable composite sensor for strain and positioning

Abstract

The invention belongs to the field of sensors, and particularly relates to a wearable composite sensor for strain and positioning, which comprises a strain identification module and a position identification module, when the position identification module is not subjected to external force, the sensitive layer and the metal electrode layer are not in contact with each other, and a conductive path is not generated; when the sensitive layer is subjected to pressure of interphalangeal joints through the lantern ring, the sensitive layer at the pressed part penetrates through the inert gas spacing layer to be in contact with the metal electrode layer, the first electrode and the output electrode form a conductive path, and a position signal is generated through the microstructure substrate; when a finger is bent, the strain sensing module transmits bending stress to the sensitive layer through the lantern ring, and when the sensitive layer is subjected to the bending stress, the resistance value between the first electrode and the second electrode changes to generate a strain signal. The sensor disclosed by the invention is simple in structure, simple in preparation process, high in identification accuracy and high in strain sensing sensitivity.

Description

Technical Field

[0001] The present invention belongs to the field of sensors, and in particular relates to a wearable composite sensor for strain and positioning. Background Art

[0002] With the rapid development of intelligent technology, the performance of high-precision hand motion monitoring systems in complex operations and high-precision applications such as virtual reality (VR), augmented reality (AR), smart gloves and robotics makes it impossible to provide comprehensive and integrated motion feedback.

[0003] The demand in the field is increasing. Accurate hand motion capture can not only significantly improve the user experience, but also improve the efficiency and accuracy of operations. However, most existing hand motion monitoring sensors can only measure a single physical quantity, such as the bending angle of the finger. This limitation limits the sensor. The human skin contains a variety of sensing units, such as position receptors, pressure receptors, strain receptors, and temperature receptors. These sensing units work together to enable humans to respond accurately to external stimuli. Position receptors are responsible for sensing the vibration and displacement of the skin, pressure receptors detect changes in pressure on the skin, strain receptors monitor the stretching of the skin and tissues, and temperature receptors sense changes in temperature. The design goal of bionic sensors is to simulate these sensing units to achieve comprehensive monitoring of hand movements, thereby enhancing the comprehensive functions and responsiveness of the sensors.

[0004] However, existing bionic strain measurement technology usually relies on finger bending signals to infer the overall bending angle, which may have analytical errors. Since inverse kinematics calculations may not accurately reflect the angle of each joint, this error may lead to insufficient operation accuracy in practical applications. Although composite sensors try to integrate multiple functions to simultaneously obtain bending angle and position information, they still face many challenges, including complex circuit layout, cumbersome sensor structure, difficult preparation, low accuracy and signal interference. These problems make it difficult for existing composite sensors to meet the needs of high-precision monitoring in practical applications. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a wearable composite sensor for strain and positioning, comprising: a metal electrode layer, a sensitive layer, a non-conductive gasket (3), an inert gas spacer layer (4), a first electrode (5), a non-conductive pad (6), a second electrode (9), a lead (10), an insulating package (11) and a ring (12);

[0006] The metal electrode layer, the sensitive layer, the non-conductive gasket (3), the inert gas spacer layer (4), the first electrode (5), the non-conductive pad (6), and the second electrode (9) together constitute a position recognition module;

[0007] The metal electrode layer is composed of a metal coating (1) and a coating substrate (2), and the metal coating (1) is attached to the surface of the coating substrate (2);

[0008] The sensitive layer comprises a conductive sensitive material layer (7) and a microstructure substrate (8), wherein the conductive sensitive material layer (7) is attached to the surface of the microstructure substrate (8);

[0009] The metal film plating (1) is externally connected to the lead wire (10) as an output electrode;

[0010] The sensitive layer and the metal electrode layer are supported by a plurality of the non-conductive pads (6) and filled with inert gas to form the inert gas spacing layer (4);

[0011] The first electrode (5) and the second electrode (9) are respectively connected to two ends of the same side of the non-conductive gasket (3);

[0012] The non-conductive gasket (3) surrounds the periphery of the sensitive layer and the metal electrode layer, and one end with the first electrode (5) and the second electrode (9) is connected to the sensitive layer;

[0013] When the position identification module is not subjected to external force, the sensitive layer and the metal electrode layer do not contact each other and no conductive path is generated; when the sensitive layer is subjected to pressure from the interphalangeal joints of the fingers through the sleeve ring (13), the sensitive layer at the pressure point passes through the inert gas spacing layer (4) and contacts the metal electrode layer, the low resistance of the metal film plating (1) on the metal electrode layer contacts the high resistance of the conductive sensitive material layer (7) on the sensitive layer, the first electrode and the output electrode form a conductive path, and a position signal is generated through the microstructure substrate (8);

[0014] The sensitive layer, the first electrode (5), and the second electrode (9) together constitute a strain sensing module;

[0015] The first electrode (5) and the second electrode (9) are bonded to both sides of the sensitive layer;

[0016] The first electrode (5) and the second electrode (9) are respectively connected to the lead wire (10) to serve as an input electrode and the second electrode (9) as an output electrode;

[0017] When the finger is bent, the strain sensing module transmits bending stress to the sensitive layer through the ring (13); when the sensitive layer is subjected to the bending stress, the resistance between the first electrode (5) and the second electrode (9) changes, thereby generating a strain signal;

[0018] The outer side of the insulating package (11) is connected to the sleeve ring (12); the insulating package (11) wraps the position identification module and the strain sensing module inside.

[0019] Beneficial effects of the present invention:

[0020] 1) Compared with a single detection sensor, the composite sensor of the present invention utilizes a sensitive layer and three electrodes to simultaneously detect the measurement of two signals, bending strain and position positioning. The microstructure design of the sensitive layer improves the signal resolution of the sensor, and can more finely detect and distinguish different signal intensities or reduce coupling interference. The overall sensor mainly realizes sensing through the sensitive layer and the metal electrode layer, and the structure is stable and simple.

[0021] 2) The sensitive layer of the composite sensor of the present invention serves as both a high-resistance layer for positioning and a sensitive layer for bending stress sensing. By integrating the positioning and bending stress sensing functions into the same sensitive layer, the sensor structure is simplified, and the volume and complexity of the sensor are reduced. A single sensitive layer can be used to measure bending stress and can also be used in conjunction with a metal electrode layer for high-precision positioning, thereby improving the overall efficiency of the sensor.

[0022] 3) The sensitive layer of the composite sensor of the present invention adopts a microstructure design to optimize the stress response and acts as a high resistance layer in the positioning function to ensure precise positioning. The stress measurement and positioning functions are integrated into one sensitive layer, which greatly simplifies the structural design of the sensor. This integration not only reduces the number of required components and reduces production costs, but also simplifies the manufacturing and assembly process.

[0023] 4) The sensitive layer microstructure of the composite sensor of the present invention adopts a spiral structure imitating iron tree flowers. The microstructure is designed as a number of micro-scale spirally arranged units, which can distinguish between positional compression and bending stress. Its structural design produces compression when subjected to pressure. When vertical pressure is applied, the spiral microstructure will produce compressive deformation along its height direction (perpendicular to the substrate). This compression is mainly concentrated on the top. Due to the large aspect ratio of the structure (10:1), the compression causes a change in the contact area, resulting in a change in resistance; when the sensor is subjected to bending stress, the spiral scales will undergo lateral displacement or rotation at the bending point, resulting in a change in the relative position between the scales. This change is different from the compression caused by vertical pressure, but instead produces tensile deformation on the inside and outside of the bending point. Due to the design characteristics of the spiral structure, the resistance changes caused by the bending stress.

[0024] 5) The composite sensor of the present invention utilizes a strain sensing mechanism to measure the bending angle of the entire finger and a sliding rheostat-like principle to confirm the bending of the interphalangeal joints. Through collaborative sensing, the hand motion capture system is simplified and the workload of back-end processing is reduced.

[0025] 6) The composite sensor of the present invention adds pads on both sides of the interphalangeal joints of human fingers to ensure good support when the sensor is long, ensuring the stability and durability of the sensor structure. After experiencing tensile deformation, the supporting pads return to their original state in a short time to ensure the stable performance of the sensor during frequent use.

[0026] 7) The composite sensor of the present invention is filled with inert gas in the spacing layer, which effectively prevents oxidation of internal materials and circuits and prolongs the service life of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A front view of a wearable composite sensor structure for strain and positioning according to the present invention;

[0028] Figure 2 A top view of a wearable composite sensor structure for strain and positioning according to the present invention;

[0029] Figure 3 A side view of a wearable composite sensor structure for strain and positioning according to the present invention;

[0030] Figure 4 This is a schematic diagram of the spiral microstructure of the imitation cycad flower of the present invention;

[0031] Figure 5 A schematic diagram of the position positioning principle of a wearable composite sensor for strain and positioning according to the present invention;

[0032] Figure 6 A schematic diagram of bending stress of a wearable composite sensor for strain and positioning according to the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention 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.

[0034] In this embodiment, a wearable composite sensor for strain and positioning is provided, such as Figure 1 , 2 , 3, comprising: a metal electrode layer, a sensitive layer, a non-conductive gasket (3), an inert gas spacer (4), a first electrode (5), a non-conductive pad (6), a second electrode (9), a lead (10), an insulating package (11) and a sleeve (12);

[0035] The metal electrode layer, the sensitive layer, the non-conductive gasket (3), the inert gas spacer layer (4), the first electrode (5), the non-conductive pad (6), and the second electrode (9) together constitute a position recognition module;

[0036] The metal electrode layer is composed of a metal coating (1) and a coating substrate (2), and the metal coating (1) is attached to the surface of the coating substrate (2);

[0037] The sensitive layer comprises a conductive sensitive material layer (7) and a microstructure substrate (8), wherein the conductive sensitive material layer (7) is attached to the surface of the microstructure substrate (8);

[0038] The metal film plating (1) is externally connected to the lead wire (10) as an output electrode;

[0039] The sensitive layer and the metal electrode layer are supported by a plurality of the non-conductive pads (6) and filled with inert gas to form the inert gas spacing layer (4);

[0040] The first electrode (5) and the second electrode (9) are respectively connected to two ends of the same side of the non-conductive gasket (3);

[0041] The non-conductive gasket (3) surrounds the periphery of the sensitive layer and the metal electrode layer, and one end with the first electrode (5) and the second electrode (9) is connected to the sensitive layer;

[0042] When the position identification module is not subjected to external force, the sensitive layer and the metal electrode layer do not contact each other and no conductive path is generated; when the sensitive layer is subjected to pressure from the interphalangeal joints of the fingers through the sleeve ring (13), the sensitive layer at the pressure point passes through the inert gas spacing layer (4) and contacts the metal electrode layer, the low resistance of the metal film plating (1) on the metal electrode layer contacts the high resistance of the conductive sensitive material layer (7) on the sensitive layer, the first electrode and the output electrode form a conductive path, and a position signal is generated through the microstructure substrate (8);

[0043] The sensitive layer, the first electrode (5), and the second electrode (9) together constitute a strain sensing module;

[0044] The first electrode (5) and the second electrode (9) are bonded to both sides of the sensitive layer;

[0045] The first electrode (5) and the second electrode (9) are respectively connected to the lead wire (10) to serve as an input electrode and the second electrode (9) as an output electrode;

[0046] When the finger is bent, the strain sensing module transmits bending stress to the sensitive layer through the ring (13); when the sensitive layer is subjected to the bending stress, the resistance between the first electrode (5) and the second electrode (9) changes, thereby generating a strain signal;

[0047] The outer side of the insulating package (11) is connected to the sleeve ring (12); the insulating package (11) wraps the position identification module and the strain sensing module inside.

[0048] Preferably, the metal film plating (1) material is one of gold (Au), silver (Ag), and copper (Cu), preferably metal copper (Cu);

[0049] The coating substrate (2) material can be selected from one of the materials such as polyimide (PI), polyester (PET), silicone, etc., preferably silicone; the coating substrate (2) material is attached with a layer of conductive metal material by physical vapor deposition, chemical vapor deposition, spraying, electroplating, etc., preferably physical vapor deposition.

[0050] Preferably, the conductive sensitive material layer (7) can be made of one or more of metal nanowires, carbon nanotubes, graphene, and conductive rubber, preferably carbon nanotubes.

[0051] Preferably, Figure 4 As shown, the microstructure substrate (8) can be selected from one of polyimide (PI), polyester (PET), polyimide (PI), polyethylene (PE), silica gel, and paper substrate, preferably silica gel; its microstructure is one of a pine cone scale structure, a conch shell structure, a double helical spring structure, and an imitation cycad spiral microstructure, preferably an imitation cycad spiral microstructure;

[0052] The spiral angle of the imitation iron tree flower spiral microstructure is 20-45°; the diameter of the first layer is 50-100 microns, the diameter of the second layer is 100-150 microns, the diameter of the third layer is 100-150 microns, the diameter of the fourth layer is 200-250 microns, the layer height is 20-50 microns, and the pitch is 10-25 microns; the first layer is preferably 80 microns in diameter, 20 microns in height, and 15 microns in pitch; the second layer is preferably 120 microns in diameter, 25 microns in height, and 18 microns in pitch; the third layer is preferably 170 microns in diameter, 30 microns in height, and 20 microns in pitch; the fourth layer is preferably 220 microns in diameter, 35 microns in height, and 22 microns in pitch;

[0053] The arrangement of the imitation iron tree flower spiral microstructure can be a staggered arrangement, a gradient arrangement, or a honeycomb structure, and a staggered arrangement is preferred.

[0054] Preferably, the inert gas filled in the inert gas spacer layer (4) can be selected from one of nitrogen, helium and argon; the thickness of the inert gas spacer layer is 0.5 to 2 mm, preferably helium, and the filling gas spacer thickness is 2 mm.

[0055] Preferably, the non-conductive gasket (3) can be made of one of polytetrafluoroethylene, epoxy resin, polycarbonate, and polytetrafluoroethylene, preferably polytetrafluoroethylene.

[0056] Preferably, the non-conductive pad (6) can be made of one of polyurethane (PU), thermoplastic elastomer, rubber, and foam silicone, preferably foam silicone.

[0057] Preferably, the thickness of the non-conductive gasket (3) can be selected from 1.5 to 2.5 mm, preferably 2.5 mm.

[0058] Preferably, the non-conductive spacer (6) can be selected to be 1-2 mm, preferably 2 mm.

[0059] The sensitive layer is used as both a high resistance layer for positioning and a sensitive layer for bending stress sensing. The metal electrode layer is used as both a low resistance layer for positioning sensing and an output electrode for the third electrode.

[0060] In this embodiment, a method for preparing a wearable composite sensor for strain and positioning recognition is provided, comprising:

[0061] 1) Preparation of silver nanowire dispersion: Disperse the silver nanowires in deionized water (or ethanol, acetone, DMF, etc.) to a base concentration of 5 mg / mL (range 0.1-5 mg / mL). Use an ultrasonic oscillator at a frequency of 50 kHz for 10 minutes to ensure that the silver nanowires are evenly distributed.

[0062] 2) Preparation of sensitive layer silicone substrate: Use 3D printing technology to print the sensitive layer substrate mold with metal aluminum as the substrate. The upper surface of the substrate is designed to imitate the spiral microstructure of the iron tree flower. The inside of the mold needs to be coated with a silicone oil release agent to facilitate subsequent demolding. Use a high-precision sprayer to spray the silver nanowire dispersion, and then slowly pour the silicone into the mold, pouring it from one side and allowing the silicone to gradually flow to the other side to reduce the generation of bubbles. Place the mold containing silicone on a vibration table, and vibration helps to discharge bubbles. Subsequently, the mold can be cured at room temperature for 24 hours, or in an oven at 80°C for 2 hours. After curing, remove the substrate from the mold, smooth the surface of the substrate, and remove excess material.

[0063] 3) Sensitive layer electrode access: Use a dust-free cloth to clean the surface, use the metal copper film as the electrode, and evenly apply conductive glue on both sides of the sensitive layer. The thickness of the glue layer needs to be moderate to ensure good electrical contact. Align and place the electrode on the area where the glue is applied and wait for it to dry naturally. Subsequently, fix the lead in the bonding position and further fix it with conductive silver glue. Store the prepared sensitive layer in a clean storage box.

[0064] 4) Preparation of metal electrode layer:

[0065] 4-1) Preparation of silicone substrate: Use a laser cutting machine to cut the silicone substrate, set the power to 20W, the cutting speed to 10mm / s, and the gas flow rate to 3L / min. After cutting, remove the cutting residue on the silicone substrate.

[0066] 4-2) Metal film coating: Place the silicone substrate obtained in step 6-1 in a magnetron sputtering device, clean the metal copper target, and set the distance between it and the silicone substrate to 10 cm. Select argon as the sputtering gas, and set the parameters to vacuum chamber pressure 5x10^-6Torr, sputtering frequency 100W, argon flow rate 50sccm, and sputtering time 5 minutes. After sputtering, check the adhesion between the metal film and the silicone substrate to ensure that there is no peeling phenomenon.

[0067] 5) Wire bonding: Use conductive silver glue to bond a wire to a section of the metal electrode layer prepared in step

[44] .

[0068] 6) Bonding support pads: According to the experimental requirements, the prepared sensitive layer is bonded with support pads (size: 3 mm long, 3 mm wide, 2 mm thick) on both sides of each knuckle joint.

[0069] 7) Pre-fixation of insulation package: The lower surfaces of the sensitive layer and the metal electrode layer are respectively adhered to the PET film of the insulation package, the size of the PET film is 110mm long, 16mm wide and 0.5mm thick. Reserve appropriate size to prevent packaging failure, and then bond the non-conductive gasket to the PET film.

[0070] 8) Package sealing: Among the two reserved needles, one is the air inlet and the other is the air outlet. Connect the inert gas source to the air inlet, slowly open the gas flow valve, let the inert gas flow into the spacer layer, and gradually exhaust the air in the container. Maintain a certain gas flow rate and let the gas flow in the container for a period of time to ensure that the air is completely replaced. Then, pull out the two needles, seal the remaining holes with a clamp, and finally use a 100℃ hot air gun for sealing. After sealing, remove the clamp and cut off the excess packaging part.

[0071] When there is no external force, Figure 1 As shown, the sensor remains stationary. When a certain pressure is applied, such as Figure 5 As shown, the sensor will deform and the sensitive layer will form an electrical contact with the metal electrode layer. The current flows in from the input electrode and flows through the output electrode through the pressing point. The change of the pressing position causes the current connected to the circuit to change differently. When the pressing position is close to the metal electrode layer, the resistance of the loop will decrease; on the contrary, when the pressing position is far away from the lead position on the right side of the metal electrode layer, the resistance will increase. This proves that the sensor can sense and identify different pressing positions.

[0072] When the sensor is bent, Figure 6 As shown, when the sensitive layer is subjected to bending stress, it deforms, resulting in a change in its resistance value.

[0073] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A wearable composite sensor for strain and positioning, characterized in that: include: A metal electrode layer, a sensitive layer, a non-conductive gasket (3), an inert gas spacer layer (4), a first electrode (5), a non-conductive pad (6), a second electrode (9), a lead (10), an insulating package (11), and a sleeve ring (12); The metal electrode layer, the sensitive layer, the non-conductive gasket (3), the inert gas spacer layer (4), the first electrode (5), the non-conductive pad (6), and the second electrode (9) together constitute a position recognition module; The metal electrode layer is composed of a metal coating (1) and a coating substrate (2), and the metal coating (1) is attached to the surface of the coating substrate (2); The sensitive layer comprises a conductive sensitive material layer (7) and a microstructure substrate (8), wherein the conductive sensitive material layer (7) is attached to the surface of the microstructure substrate (8); The metal film plating (1) is externally connected to the lead wire (10) as an output electrode; The sensitive layer and the metal electrode layer are supported by a plurality of the non-conductive pads (6) and filled with inert gas to form the inert gas spacing layer (4); The first electrode (5) and the second electrode (9) are respectively connected to two ends of the same side of the non-conductive gasket (3); The non-conductive gasket (3) surrounds the periphery of the sensitive layer and the metal electrode layer, and one end with the first electrode (5) and the second electrode (9) is connected to the sensitive layer; When the position identification module is not subjected to external force, the sensitive layer and the metal electrode layer do not contact each other and no conductive path is generated; when the sensitive layer is subjected to pressure from the interphalangeal joints of the fingers through the sleeve ring (13), the sensitive layer at the pressure point passes through the inert gas spacing layer (4) and contacts the metal electrode layer, the low resistance of the metal film plating (1) on the metal electrode layer contacts the high resistance of the conductive sensitive material layer (7) on the sensitive layer, the first electrode and the output electrode form a conductive path, and a position signal is generated through the microstructure substrate (8); The sensitive layer, the first electrode (5), and the second electrode (9) together constitute a strain sensing module; The first electrode (5) and the second electrode (9) are bonded to both sides of the sensitive layer; The first electrode (5) and the second electrode (9) are respectively connected to the lead wire (10) to serve as an input electrode and the second electrode (9) as an output electrode; When the finger is bent, the strain sensing module transmits bending stress to the sensitive layer through the ring (13); when the sensitive layer is subjected to the bending stress, the resistance between the first electrode (5) and the second electrode (9) changes, thereby generating a strain signal; The outer side of the insulating package (11) is connected to the sleeve ring (12); the insulating package (11) wraps the position identification module and the strain sensing module inside.

2. A wearable composite sensor for strain and positioning according to claim 1, characterized in that: The metal film plating (1) material is one of gold (Au), silver (Ag), and copper (Cu), preferably metal copper (Cu); The coating substrate (2) material can be selected from one of the materials such as polyimide (PI), polyester (PET), silicone, etc., preferably silicone; the coating substrate (2) material is attached with a layer of conductive metal material by physical vapor deposition, chemical vapor deposition, spraying, electroplating, etc., preferably physical vapor deposition.

3. A wearable composite sensor for strain and positioning according to claim 1, characterized in that: The conductive sensitive material layer (7) may be made of one or more of metal nanowires, carbon nanotubes, graphene, and conductive rubber, preferably carbon nanotubes.

4. A wearable composite sensor for strain and positioning according to claim 1, characterized in that: The microstructure substrate (8) can be selected from one of polyimide (PI), polyester (PET), polyimide (PI), polyethylene (PE), silica gel, and paper substrate, preferably silica gel; its microstructure is one of a pine cone scale structure, a conch shell structure, a double helical spring structure, and an imitation cycad spiral microstructure, preferably an imitation cycad spiral microstructure; The spiral angle of the imitation iron tree flower spiral microstructure is 20-45°; the diameter of the first layer is 50-100 microns, the diameter of the second layer is 100-150 microns, the diameter of the third layer is 100-150 microns, the diameter of the fourth layer is 200-250 microns, the layer height is 20-50 microns, and the pitch is 10-25 microns; the first layer is preferably 80 microns in diameter, 20 microns in height, and 15 microns in pitch; the second layer is preferably 120 microns in diameter, 25 microns in height, and 18 microns in pitch; the third layer is preferably 170 microns in diameter, 30 microns in height, and 20 microns in pitch; the fourth layer is preferably 220 microns in diameter, 35 microns in height, and 22 microns in pitch; The arrangement of the imitation iron tree flower spiral microstructure can be a staggered arrangement, a gradient arrangement, or a honeycomb structure, and a staggered arrangement is preferred.

5. A wearable composite sensor for strain and positioning according to claim 1, characterized in that: The inert gas filled in the inert gas spacer layer (4) can be selected from nitrogen, helium and argon; the thickness of the inert gas spacer layer is 0.5 to 2 mm, preferably helium, and the filling gas spacer thickness is 2 mm.

6. A wearable composite sensor for strain and positioning according to claim 1, characterized in that: The non-conductive gasket (3) can be made of one of polytetrafluoroethylene, epoxy resin, polycarbonate, and polytetrafluoroethylene, preferably polytetrafluoroethylene.

7. A wearable composite sensor for strain and positioning according to claim 1, characterized in that: The non-conductive pad (6) may be made of one of polyurethane (PU), thermoplastic elastomer, rubber, and foam silicone, preferably foam silicone.

8. A wearable composite sensor for strain and positioning according to claim 1, characterized in that: The thickness of the non-conductive gasket (3) can be selected from 1.5 to 2.5 mm, preferably 2.5 mm.

9. A wearable composite sensor for strain and positioning according to claim 1, characterized in that: The non-conductive spacer (6) can be selected to be 1-2 mm, preferably 2 mm.

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