Bending motion sensor and preparation method of full-flexible motion capture glove

Abstract

The invention relates to the technical field of robot development, and mainly discloses a preparation method of a bending action sensor and a full-flexible action capture glove, which comprises the following steps: printing liquid metal on a base layer formed by curing an elastomer solution to form a liquid metal film, and engraving the liquid metal film through laser; in the laser engraving process, the liquid metal on a laser engraving path is oxidized to form an oxidation boundary, and a pattern drawn by the liquid metal in the oxidation boundary is an electrode loop; a layer of elastomer solution is dropped on the upper layer of the electrode loop for curing to form a protective layer, before the protective layer is cured, the electrode loop rubs in the protective layer to form a liquid flow channel, and after the protective layer is completely cured, the electrode loop can flow in the liquid flow channel; the problems that an existing motion capture glove is heavy in size and poor in wearing comfort are solved.

Description

Technical Field

[0001] The present invention relates to the field of robot development, and in particular to a bending motion sensor and a preparation method of a fully flexible motion capture glove. Background Art

[0002] With the rapid development of virtual reality (VR), augmented reality (AR) and robotics, high-precision and low-latency human motion capture systems have become the core technologies in the fields of human-computer interaction, medical rehabilitation, sports training and education. Especially in finger motion capture, accurately measuring the joint bending angle is the key to realizing virtual environment control, robot remote control, surgical simulation training and motion posture analysis.

[0003] Currently, most mainstream motion capture gloves adopt magnetic sensors, optical linear encoders (OLE) or traditional flexible sensor technologies. However, these solutions have significant drawbacks: magnetic sensors are vulnerable to electromagnetic interference and are bulky; optical systems rely on complex external devices, restricting mobility; although traditional flexible sensors have a certain degree of ductility, their rigid circuits or brittle substrate materials are prone to fatigue fracture under frequent bending, resulting in a decline in signal stability. In addition, existing sensors are mostly fixed on the glove surface through tapes or rigid connectors, which not only affects the wearing comfort, but also causes data drift due to insufficient fit, making it difficult to meet the reliability requirements for long-term monitoring in the medical and health fields or the requirement for unobtrusive capture of natural movements in sports training. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is that existing motion capture gloves are bulky and have poor wearing comfort.

[0005] The above technical problem is solved by the following technical solution: A preparation method of a bending motion sensor includes the following steps: printing liquid metal on a base layer formed by curing an elastomer solution to form a liquid metal film, and laser engraving the liquid metal film; during the laser engraving process, the liquid metal on the laser engraving path is oxidized to form an oxidation boundary, and the pattern drawn by the liquid metal within the oxidation boundary is an electrode circuit; dropping another layer of elastomer solution on the upper layer of the electrode circuit and curing it to form a protective layer. Before the protective layer is cured, the electrode circuit is imprinted inside the protective layer to form a liquid flow channel. After the protective layer is completely cured, the electrode circuit can flow within the liquid flow channel.

[0006] In a preferred embodiment of the preparation method of the bending motion sensor of the present invention: A collection part is further connected to the electrode circuit. The collection part includes a collection unit and several groups of flexible flat cables. One end of each flexible flat cable is simultaneously connected to the electrode circuits at the same collection point in different groups, and the other end is connected to the collection unit.

[0007] In a preferred embodiment of the method for preparing the bending motion sensor of the present invention: the electrode circuit is a zigzag strip pattern, and first and second pins are formed at both ends thereof; the flexible flat cable includes a plurality of groups of same-end collecting lines arranged in a row, and each group of same-end collecting lines includes a first lead and a second lead arranged in parallel. The first leads are respectively connected to the first pin and the collecting unit, and the second leads are respectively connected to the second pin and the collecting unit.

[0008] In a preferred embodiment of the method for preparing the bending motion sensor of the present invention: at least one group of electrode circuits is provided on the base layer, and the number and shape of the liquid flow channels correspond to the electrode circuits; if a plurality of groups of liquid flow channels are provided, each group of liquid flow channels is relatively independent.

[0009] In a preferred embodiment of the method for preparing the bending motion sensor of the present invention: the base layer and the protective layer are made of Ecoflex elastomeric silicone solution. Ecoflex reagents M and N are uniformly mixed in a mass ratio of 1:1, subjected to vacuum degassing treatment with a vacuum degree of -0.1 MPa and a time of 5 min, and then left to stand until the bubbles completely disappear to complete the preparation.

[0010] In a preferred embodiment of the method for preparing the bending motion sensor of the present invention: the elastomeric solution for forming the base layer is uniformly dripped on a glass slide. Before dripping, a hydrophobic layer needs to be coated on the surface of the glass slide, and the hydrophobic layer is polytetrafluoroethylene.

[0011] In a preferred embodiment of the method for preparing the bending motion sensor of the present invention: the electrode circuit uses a low-melting-point gallium-based room-temperature liquid alloy as the electrode material, including but not limited to gallium-indium alloy and gallium-indium-tin alloy, and the thickness of the electrode circuit is 50 μm.

[0012] To solve the above problems, the present invention also proposes the following technical solutions to solve: a flexible bending strain sensor is prepared by using the method for preparing the bending motion sensor described above. It includes a contact part, and a plurality of groups are provided. Each group of the contact parts includes a base layer and a protective layer arranged in layers, and at least one group of electrode circuits is covered in each group of the base layer and the protective layer; wherein, if the number of electrode circuits provided in each group of the base layer and the protective layer is greater than one group, the electrode circuits in this group are relatively independent; a collecting part, including a collecting unit and a plurality of groups of flexible flat cables. One end of the flexible flat cable is simultaneously connected to the electrode circuits at the same collecting point in different groups, and the other end is connected to the collecting unit.

[0013] To solve the above problems, the present invention also proposes the following technical solutions: A method for preparing a fully flexible liquid metal-based motion capture glove, which includes the above-mentioned method for preparing a bending motion sensor, and further includes connecting the flexible flat cable to the electrode circuit before encapsulating the protective layer. After all electrode circuits are connected to the flexible flat cable, the protective layer is encapsulated; a layer of elastomer solution is brushed on the base layer, and at the same time, the electrode circuits are aligned with the bending points of each joint of the finger part in the glove; the elastomer solution on the base layer is heated to fix the base layer at the outer joint of the finger part; after the base layer is fixed on the finger part, the other end of the flexible flat cable is connected and fixed to the acquisition unit.

[0014] To solve the above problems, the present invention also proposes the following technical solutions: A fully flexible liquid metal-based motion capture glove, which includes a glove, including a palm part and a finger part, and the contact part is arranged on the back of each finger part; if each group of contact parts only includes a group of electrode circuits, then a group of such electrode circuits is arranged on each joint bending point; if each group of contact parts includes more than one group of electrode circuits, then all electrode circuits in this group are fixed on the joint bending point of the same finger part; the joint bending points from the fingertip to the palm part are the first node, the second node, and the third node respectively; the same bending point of different fingers corresponds to the same group of flexible flat cables.

[0015] In a preferred embodiment of the method for preparing a fully flexible liquid metal-based motion capture glove according to the present invention: if each group of base layers only includes a group of electrode circuits, then a group of such electrode circuits is arranged on each joint bending point; if each group of base layers includes more than one group of electrode circuits, then all electrode circuits in this group are fixed on the joint bending point of the same finger part.

[0016] In a preferred embodiment of the method for preparing a fully flexible liquid metal-based motion capture glove according to the present invention: when the first lead wire is connected to the first pin, an additional liquid metal is covered at the connection to firmly connect, and then an elastomer solution is dropped at the connection and heated and fixed to complete the fixation of the connection point and the base layer.

[0017] The beneficial effects of the present invention are as follows:

[0018] The motion capture glove system prepared by the present invention is composed of a glove body and a flexible strain sensor assembly. The glove body is prepared from a highly elastic woven material, having good hand fit and wearing comfort. The flexible strain sensor uses Ecoflex elastomer as a flexible substrate, combines gallium indium tin alloy conductive material and a flexible flat cable connection component to construct a fully flexible and highly sensitive sensing system. Among them, the Ecoflex elastomer provides excellent stretchability and mechanical stability, and the gallium indium tin alloy exhibits excellent conductivity and theoretically infinite stretchability due to its liquid metal characteristics.

[0019] The flexible cable ensures a reliable connection between the sensor and the rear-end circuit board. By optimizing the curing process of the Ecoflex elastomer solution, the sensor is precisely integrated into the knuckle area of the glove, achieving a reliable bond between the sensor and the glove interface. Since both the sensor and the fixing module are fully flexible designs, the interference with finger bending movements is extremely small, thus realizing a highly comfortable wearing experience and precise and stable data acquisition. In addition, the preparation process of this flexible strain sensor is simple and efficient, easy to mass-produce, which greatly improves the production efficiency of the motion capture glove and the required equipment cost is low. Therefore, this solution not only has high practical application value but also has broad promotion potential. Brief Description of the Drawings

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present invention and do not limit the present invention. Among them:

[0021] Figure 1 Shows the manufacturing schematic diagram of the bending motion sensor;

[0022] Figure 2 Shows the overall structure diagram of the bending motion sensor;

[0023] Figure 3 Shows the forming schematic diagram of the electrode circuit and the liquid flow channel of the bending motion sensor;

[0024] Figure 4 Shows the oxidation boundary schematic diagram of the bending motion sensor;

[0025] Figure 5 Shows the electrode circuit layout diagram of the bending motion sensor;

[0026] Figure 6 Shows the connection schematic diagram between the electrode circuit and the acquisition part of the bending motion sensor.

[0027] Figure 7 Shows the structure schematic diagram of the fully flexible liquid metal-based motion capture glove.

[0028] Figure 8 Shows the bending node distribution diagram on the fully flexible liquid metal-based motion capture glove.

[0029] Figure 9 Shows the physical diagram of the fully flexible liquid metal-based motion capture glove.

[0030] Figure 10 Shows the installation position diagram of the electrode circuit on the fully flexible liquid metal-based motion capture glove.

[0031] Figure 11 Shows a schematic diagram of the connection between the electrode circuit of a fully flexible liquid metal-based motion capture glove and a flexible flat cable.

[0032] Figure 12 Shows the 400% strain resistance change data graph of a certain type of bending motion sensor.

[0033] Figure 13 Shows bending motion sensors with different circuit sizes.

[0034] Figure 14 Shows the physical diagram of the first type of bending motion sensor and the test data graph of 100% stretching amplitude.

[0035] Figure 15 Shows the physical diagram of the second type of bending motion sensor and the test data graph of 100% stretching amplitude.

[0036] Figure 16 Shows the physical diagram of the third type of bending motion sensor and the test data graph of 100% stretching amplitude.

[0037] Figure 17 Shows the physical diagram of the fourth type of bending motion sensor and the test data graph of 100% stretching amplitude.

[0038] Figure 18 Shows the interdigital electrode circuit pattern of the bending motion sensor and the physical diagrams of multiple groups of line widths.

[0039] Figure 19 Shows the complex picture of the liquid metal circuit pattern of the bending motion sensor. Detailed implementation manners

[0040] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below in conjunction with the detailed implementation manners and the accompanying drawings.

[0041] The terms used in the present invention are those general terms that are currently widely used in the art in consideration of the functions of the present invention. However, these terms may change according to the intentions of those of ordinary skill in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in this case, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but based on the meanings of the terms and the overall description of the present invention.

[0042] Refer to Figures 1 to 6 、 Figure 18 and Figure 19 , this embodiment provides a preparation method for a bending motion sensor, which includes the following steps:

[0043] Print the liquid metal on the base layer 101 formed by curing the elastomer solution to form a liquid metal film, and laser engrave the liquid metal film.

[0044] Among them, the elastomer solution for forming the base layer 101 is evenly dripped on the glass slide. Before dripping, a hydrophobic layer D needs to be coated on the surface of the glass slide. The hydrophobic layer D is polytetrafluoroethylene. The flexible bending strain sensor first uses a commercially available glass slide as the supporting material for the base layer 101.

[0045] The base layer 101 and the protective layer 102 are made of Ecoflex elastomer silicone solution. Mix the Ecoflex reagents M and N evenly according to a mass ratio of 1:1, perform vacuum degassing treatment, with a vacuum degree of -0.1 MPa and a time of 5 min, and then let it stand until the bubbles completely disappear to complete the preparation.

[0046] Specifically, the base layer 101 is the installation carrier of the electrode circuit 103, and its shape can be any regular shape such as a rectangle or a circle, and it is a flexible flat structure. To ensure the stable installation of the electrode circuit 103, the protective layer 102 can adopt the same structure and shape as the base layer 101.

[0047] Furthermore, the unfolded area of the protective layer 102 can be slightly larger than that of the base layer 101, which can ensure that the circuit installation space formed between the base layer 101 and the protective layer 10 is completely covered to ensure its sealing performance.

[0048] Furthermore, among them, if the number of electrode circuits 103 provided in each group of the base layer 101 and the protective layer 102 is more than one group, the electrode circuits 103 in this group are relatively independent and are not connected to each other within the base layer 101 and the protective layer 102.

[0049] During the laser engraving process, the liquid metal on the laser engraving path is oxidized to form an oxidation boundary J, and the pattern drawn by the liquid metal within the oxidation boundary J is the electrode circuit 103. In this embodiment, the laser is preferably an infrared laser.

[0050] Furthermore, the electrode circuit 103 uses a low-melting-point gallium-based room-temperature liquid alloy as the electrode material, including but not limited to gallium-indium alloy and gallium-indium-tin alloy, and the thickness of the electrode circuit 103 is 50 μm. In this embodiment, gallium-indium-tin alloy is preferably used.

[0051] Specifically, for the preparation of the base layer 101: Mix the Ecoflex reagents M and N evenly according to a mass ratio of 1:1, perform vacuum degassing treatment, with a vacuum degree of -0.1 MPa and a time of 5 min, and then let it stand until the bubbles completely disappear to complete the preparation.

[0052] Further, the prepared Ecoflex solution was evenly dropped onto the surface of the glass slide. After it naturally leveled, it was placed on a heating stage and cured at 100 °C for 15 minutes to finally form an Ecoflex elastomer substrate with a thickness of approximately 0.5 mm. The Ecoflex elastomer substrate here is the base layer 101.

[0053] For the engraving of the electrode circuit 103, a liquid metal printing process was adopted. In this embodiment, a gallium indium tin alloy was used as the conductive material. After repeatedly dipping a flat brush until the liquid metal uniformly adhered to its surface, it was printed on the surface of the base layer 101 to form a uniform liquid metal thin film with a thickness of approximately 50 μm. Subsequently, a laser etching technology was used for circuit patterning. The specific process is as follows:

[0054] First, the preset electrode circuit 103 pattern was designed through drawing software and saved. Further, the saved file was imported into the laser etching machine supporting software and converted into a file that the laser etching machine could recognize. The laser etching system preferably adopted a desktop laser marking device equipped with a 1064 nm continuous wave laser with a maximum output power of 50 W. By adjusting parameters such as the laser etching speed and processing frequency, the etching line width could be precisely controlled, and at the same time, manual adjustment of the pattern ratio was supported.

[0055] During this process, the photon energy of the infrared laser could break the chemical bonds between atoms in the liquid gallium indium tin alloy, prompting it to undergo a chemical reaction. In an environment with the presence of oxygen, this effect would accelerate the oxidation of the alloy surface, forming an oxidation boundary J, which helped to fix the shape of the liquid metal and form a pattern boundary.

[0056] Further, the Ecoflex elastomer surface had a certain surface energy, and the liquid gallium indium tin alloy had a certain wettability to it. This meant that the liquid metal could naturally spread on the elastomer surface, and due to the van der Waals force between molecules, it would generate a certain adhesion force with the elastomer substrate, keeping the liquid metal in a relatively stable position on the substrate and facilitating the laser engraving operation.

[0057] In this embodiment, a visual positioning system could also be equipped for the desktop laser marking device, which could achieve automatic or manual positioning through the supporting software to ensure the etching accuracy. In this experiment, an etching speed of 2000 mm / s and a processing power of 3% were adopted, and four repeated etchings were carried out to ensure the complete removal of the liquid metal. Depending on the pattern complexity, the etching time was between 1 s and 5 min. Through the above process, the precise patterning preparation of the liquid metal circuit was finally achieved.

[0058] On top of the electrode circuit 103, a layer of elastomer solution is dropped and cured to form a protective layer 102. Before the protective layer 102 is cured, the electrode circuit 103 is imprinted inside the protective layer to form a liquid flow channel Y. After the protective layer 102 is completely cured, the electrode circuit 103 can flow within the liquid flow channel Y.

[0059] Specifically, referring to Figure 3 and Figure 4 , after the electrode circuit 103 is fixed and formed on the base layer 101 by etching, a layer of elastomer solution is continuously dropped on the topmost layer of the electrode circuit 103 and cured. At this time, the elastomer solution gradually covers the electrode circuit 103 and contacts and seals with the base layer 101.

[0060] Furthermore, when the elastomer solution completely covers the upper surface of the base layer 101, the liquid electrode circuit 103 will support the elastomer solution, and a liquid flow channel Y is formed inside the upper elastomer solution film. Subsequently, the upper elastomer solution film is heated and cured to form the final solid protective layer 102. At this time, the base layer 101 and the protective layer 102 jointly seal the liquid electrode circuit 103 in the liquid flow channel Y.

[0061] Furthermore, at this time, the base layer 101 and the protective layer 102 are bent, the liquid flow channel Y is deformed by extrusion, and the stored electrode circuit 103 inside flows within the liquid flow channel Y. When the base layer 101 and the protective layer 102 return to the horizontal and straight state, the liquid flow channel Y will also restore its original shape, and the electrode circuit 103 flows back and refills the liquid flow channel Y again.

[0062] Still further, after the base layer 101 and the protective layer 102 are both cured, they are peeled off from the glass slide, and the manufacturing of the bending motion sensor is completed.

[0063] Referring to Figures 6 to 13 , in summary, by using the above preparation method, a flexible bending strain sensor can be prepared. The specific structure of this flexible bending strain sensor is as follows: It includes a contact part 100, which is provided with several groups. Each group of the contact part 100 includes a base layer 101 and a protective layer 102 arranged in layers, and at least one group of electrode circuits 103 is covered and arranged inside each group of the base layer 101 and the protective layer 102.

[0064] Among them, if the number of electrode circuits 103 arranged inside each group of the base layer 101 and the protective layer 102 is more than one group, the electrode circuits 103 within this group are relatively independent.

[0065] A collection part 200, which includes a collection unit 201 and several groups of flexible flat cables 202. One end of the flexible flat cable 202 is simultaneously connected to the electrode circuits 103 at the same collection point in different groups, and the other end is connected to the collection unit 201.

[0066] Among them, the acquisition unit 201 includes electrical components such as a central processing unit and a data acquisition board, and is used to receive information feedback from the upstream bending motion sensor through the flexible flat cable 202.

[0067] Further, the flexible flat cable 202 is preferably a 10PinFPC flexible flat cable, which connects the bending motion sensor and the acquisition unit 201 for information acquisition.

[0068] The electrode circuit 103 is a zigzag strip pattern, and its two ends form a first pin B1 and a second pin B2.

[0069] The flexible flat cable 202 includes several groups of co-terminal acquisition lines C arranged in a row. Each group of co-terminal acquisition lines C includes a first lead C1 and a second lead C2 arranged in parallel. The first lead C1 is respectively connected to the first pin B1 and the acquisition unit 201, and the second lead C2 is respectively connected to the second pin B2 and the acquisition unit 201.

[0070] At least one group of electrode circuits 103 is provided on the base layer 101, and the number and shape of the liquid flow channels Y correspond to those of the electrode circuits 103.

[0071] If several groups of liquid flow channels Y are provided, each group of liquid flow channels Y is relatively independent.

[0072] Further, for the convenience of manufacturing the above-mentioned bending motion sensor and the fully flexible liquid metal-based motion capture glove, this embodiment also provides a method for manufacturing a fully flexible liquid metal-based motion capture glove, which includes the manufacturing method of the above-mentioned bending motion sensor, and further includes the following steps:

[0073] Before encapsulating the protective layer 102, first connect the flexible flat cable 202 to the electrode circuit 103. After all the electrode circuits 103 are connected to the flexible flat cable 202, then encapsulate the protective layer 102.

[0074] Brush an elastomer solution on the base layer 101, and at the same time align the electrode circuit 103 with each joint bending point of the finger part 302 in the glove 300.

[0075] Among them, the main body of the glove 300 can be made of materials such as rubber and leather. In this embodiment, it is preferably prepared by a highly elastic woven material, which has good hand fit and wearing comfort.

[0076] Heat the elastomer solution on the base layer 101 to fix the base layer 101 at the outer joint of the finger part 302.

[0077] After the base layer 101 is fixed on the finger part 302, connect and fix the other end of the flexible flat cable 202 to the acquisition unit 201.

[0078] By using the above glove preparation method, a fully flexible liquid metal-based motion capture glove can be prepared. The specific structure of this fully flexible liquid metal-based motion capture glove is as follows: The glove 300 includes a palm part 301 and finger parts 302, and the contact part 100 is arranged on the back of each finger part 302.

[0079] If each contact part 100 only includes a group of electrode circuits 103, then a group of such electrode circuits 103 is arranged at each joint bending point.

[0080] If each contact part 100 includes more than one group of electrode circuits 103, then all the electrode circuits 103 in this group are fixed at the joint bending points of the same finger part 302.

[0081] Further, the joint bending points from the fingertip to the palm part 301 are the first node A1, the second node A2, and the third node A3 respectively.

[0082] The same bending points of different fingers correspond to the same group of flexible flat cables 202.

[0083] If each base layer 101 only includes a group of electrode circuits 103, then a group of such electrode circuits 103 is arranged at each joint bending point.

[0084] If each base layer 101 includes more than one group of electrode circuits 103, then all the electrode circuits 103 in this group are fixed at the joint bending points of the same finger part 302.

[0085] In summary, specifically, the bending motion sensor preferably uses 15 electrode circuits 103 to be connected to the acquisition unit 201 through 3 10Pin flexible flat cables 202, and these electrode circuits 103 are respectively accurately bonded at 15 joints of 5 finger parts 302.

[0086] Further, each 10Pin interface flexible flat cable 202 is respectively connected to the same joint bending points of different fingers and is connected to the first pin B1 and the second pin B2 of the electrode circuit 103.

[0087] In the design of the flexible flat cable 202, one end of the flexible flat cable 202 is all cut open and dispersed into five groups of same-end acquisition lines C. Each group of same-end acquisition lines C includes a first lead C1 and a second lead C2 to facilitate connection to the first pin B1 and the second pin B2 of the bending motion sensor; the other end remains intact to facilitate plugging into the 10pin socket of the signal acquisition circuit board in the acquisition unit 201.

[0088] Further, the bending motion sensor in this embodiment includes two distribution methods. One is that there is only one set of electrode circuits 103 in the bending motion sensor. In this case, three independent bending motion sensors need to be set on each finger part 302 to meet the data acquisition of the joint bending points.

[0089] The other is that three sets of electrode circuits 103 are preferably arranged longitudinally along the finger part 302 in the bending motion sensor. In this case, only one set of bending motion sensors needs to be set on each finger part 302 to meet the data acquisition of the joint bending points.

[0090] The first setting method has the advantages of convenient problem troubleshooting and low cost of spare part replacement; the second setting method has the advantages of convenient manufacturing and simple installation.

[0091] When the first lead C1 is connected to the first pin B1, an additional liquid metal is covered at the connection to make a stable connection. Subsequently, an elastomer solution is dropped at the connection and heated for fixation to complete the fixation of the connection point to the base layer 101.

[0092] Further, a 10Pin FPC flexible cable is selected to connect the acquisition unit 201 and the electrode circuit 103 in the bending motion sensor.

[0093] Among them, the pins of the flexible cable 202 are aligned parallel to the pins of the electrode circuit 103, and the widths of the pins of the flexible cable 202 and the etched electrode circuit 103 pattern pins are both 1.27 mm.

[0094] After the pins of the flexible cable 202 at the dispersion end are aligned parallel to the circuit pins, a fine brush is dipped into the liquid metal to make it evenly adhere to the liquid metal, and the circuit pins and the FPC pins are connected by using the fine brush, so that the liquid metal circuit extends to the first lead C1 and the second lead C2 of the flexible cable 202 to form a stable conductive path.

[0095] Subsequently, a drop of Ecoflex solution is dripped at the connection, and the dripping amount is about 0.1 mL. It is heated to 80 °C and cured for 10 min to complete the local encapsulation.

[0096] Repeat this step until all 5 sensor pins on a single glass slide are encapsulated. Finally, the Ecoflex solution is evenly covered on the surface of the whole device, and after it naturally levels, it is heated and cured to form the protective layer 102 to complete the overall encapsulation.

[0097] After the encapsulation is completed, the whole device is peeled off from the glass slide and cut into five independent sensor units. Repeat the preparation process three times to prepare a sensor that meets the requirements of 15 joint detections.

[0098] Refer to Figure 12, As an alternative embodiment, the liquid metal circuit device prepared by the above-mentioned preparation method of the bending motion sensor is fixed on a cyclic stretching table. Here, the liquid metal circuit device is a composite structure formed by a base layer 101, an electrode circuit 103, and a protective layer 102, and can also be regarded as the bending motion sensor body.

[0099] Further, clamp both ends of the bending motion sensor and perform loading and unloading stretching at a 400% amplitude. After the experiment is completed, draw a resistance data change graph according to the test results.

[0100] As can be seen from the reference Figure 12 , strain and ΔR / R 0 show a relatively regular linear relationship. The bending motion sensor fabricated by the above manufacturing method has a stable linear law of change in the relative resistance change rate under the action of strain, and it has a certain stability. Because a stable linear relationship means that within a certain range, the response of the bending motion sensor is predictable and regular, without random and large fluctuations.

[0101] Further, referring to Figure 12 , the slope of the straight line in 0 reflects the sensitivity. The larger the slope, the greater the change in ΔR / R

[0102] for the same strain change, which also means that the bending motion sensor is more sensitive to strain. Figure 13 Referring to

[0103] , as an alternative embodiment, the width and period of the circuit also affect the sensitivity of the sensor and its loading and unloading performance. In this embodiment, four different circuit patterns are designed and tested to select the most suitable circuit pattern for application on gloves. Figure 14 The first circuit pattern: 1 mm line width, 0.5 mm pitch, 6 periods.

[0104] Referring to Figure 15 The second circuit pattern: 0.8 mm line width, 0.5 mm pitch, 8 periods.

[0105] Referring to Figure 16 The third circuit pattern: 0.8 mm line width, 0.4 mm pitch, 8 periods.

[0106] Referring to Figure 17 The fourth circuit pattern: 0.6 mm line width, 0.4 mm pitch, 10 periods.

[0107] Further, the first circuit pattern: 1 mm line width, 0.5 mm pitch, 6 periods.

[0108] Analysis of the trend of the "Load" line: Starting from the origin, as the strain increases, ΔR / R0 rises slowly, and the overall upward trend is relatively gentle.

[0109] Physical meaning: The relatively wide line width makes the path for the current to pass through the liquid metal relatively broad. During the process of applying strain, the deformation of the liquid metal has a relatively small impact on the electron conduction path, resulting in a slow change in resistance and a slow increase in ΔR / R0. The relatively small number of cycles means that the amplification effect of the circuit structure on this strain-resistance change is limited.

[0110] Analysis of the trend of the "Unload" line: When unloading the strain, the "Unload" line follows the "Load" line downwards closely, and the area of the hysteresis loop formed with the "Load" line is relatively small.

[0111] Physical meaning: It indicates that during the unloading process, when the liquid electrode loop 103 returns to its initial state, the relative change rate of resistance can also recover relatively stably, the elastic recovery performance of the material is relatively good, and the energy loss is relatively small; however, due to the small overall change amplitude, the ability to capture subtle strain changes is relatively weak.

[0112] In the fully flexible liquid metal-based motion capture glove, as a bending motion sensor, this circuit pattern can provide a relatively stable resistance change signal for large-amplitude hand bending motions. However, due to its low sensitivity, it is difficult to accurately capture subtle motions such as slight finger bending and joint micro-flexion. For example, in the hand interaction scenario of virtual reality, it may not be able to accurately simulate the fine operations of the fingers, resulting in an inaccurate interaction experience.

[0113] Furthermore, the second circuit pattern: line width 0.8mm, spacing 0.5mm, 8 cycles.

[0114] Analysis of the trend of the "Load" line: Also starting from the origin, the upward trend is slightly steeper than that of the "Load" line of the first circuit pattern, and ΔR / R 0 rises slightly faster as the strain increases, and the maximum value reaches approximately 1.2.

[0115] Physical meaning: When the line width is reduced to 0.8mm, the current conduction path becomes narrower. When applying strain, the deformation of the liquid metal has a greater impact on the electron conduction path, resulting in a relatively more obvious change in resistance. At the same time, the structure with 8 cycles enhances the amplification effect of this change, making ΔR / R 0 increase faster.

[0116] Analysis of the trend of the "Unload" line: When unloading, the area of the hysteresis loop formed by the "Unload" line and the "Load" line is slightly larger than that of the first one.

[0117] Physical meaning: This means that during the unloading process, the elastic recovery process of the material has a relatively large energy loss, which may be due to the structural changes that cause a certain lag when the liquid metal returns to its initial state. But overall, the circuit's response sensitivity to the action has been improved.

[0118] In motion capture glove applications, this circuit style can generate more obvious resistance change signals for common hand bending movements, and can capture some slightly more subtle movement changes than the first circuit. However, in scenarios where high-precision capture of complex hand movements is required, such as the assessment of fine hand movements in medical rehabilitation training, its sensitivity is still insufficient and some key movement details may be missed.

[0119] Going further, the third circuit style: 0.8mm line width, 0.4mm spacing, 8 cycles.

[0120] “Load” line analysis trend: Starting from the origin, the upward trend is obviously steeper, ΔR / R 0 It rises rapidly with increasing strain and reaches a maximum value of about 2.0.

[0121] Physical significance: The line width is maintained at 0.8 mm, and the spacing is reduced to 0.4 mm. When the liquid metal is strained, the interaction between adjacent conduction paths is enhanced, the electronic conduction path is more affected by the strain, and the resistance change is more significant. The 8-period structure further amplifies this change effect, resulting in ΔR / R 0 Rapid growth.

[0122] “Unload” line analysis trend: During the unloading process, the “Unload” line and the “Load” line form a large hysteresis loop.

[0123] Physical significance: This indicates that the energy loss of the material is large during unloading, and the process of liquid metal returning to its initial state is more complicated, which may be due to the more complex stress changes in the structure caused by the reduction in spacing. Nevertheless, the circuit's ability to respond to small strains during loading is greatly improved.

[0124] Furthermore, in fully flexible liquid metal-based motion capture gloves, this circuit pattern can be used as a bending motion sensor to generate obvious resistance change signals for a variety of hand movements, and performs well in motion capture scenarios with general precision requirements, such as hand motion capture in ordinary games. However, in scenarios that require extremely high precision, such as professional animation production, the capture accuracy of motion changes caused by subtle contractions of hand muscles still needs to be improved.

[0125] Going further, the fourth circuit style: 0.6mm line width, 0.4mm spacing, 10 cycles.

[0126] "Load" line analysis trend: Starting from the origin, the upward trend is the steepest, with ΔR / R 0 rising sharply as the strain increases, and the maximum value approaching 2.5.

[0127] Physical meaning: The extremely narrow line width and small spacing make the electron conduction path of the liquid metal extremely vulnerable to influence when loading strain, resulting in a very significant change in resistance. The structure of 10 cycles further strengthens this amplification effect of strain-resistance change, leading to a rapid and large increase in ΔR / R 0 rapidly and significantly.

[0128] "Unload" line analysis trend: During unloading, the "Unload" line forms a large hysteresis loop with the "Load" line, but the correlation with the "Load" line is still close, indicating that although there is energy loss during unloading, the overall response characteristics of the material can still relatively stably reflect the strain change.

[0129] Physical meaning: It shows that although there is a certain amount of energy loss in this circuit during loading and unloading, it can maintain an effective response to the change in resistance under different strain states, providing a guarantee for accurately capturing actions.

[0130] Furthermore, when the fully flexible liquid metal-based motion capture glove is used as a bending motion sensor, this circuit style shows excellent performance. Its high sensitivity can accurately capture various complex motions of the hand from slight bending to a large fist, and can provide accurate motion data whether it is for immersive interaction in virtual reality and augmented reality scenarios or for the fine evaluation of the patient's hand motions in medical rehabilitation training. For example, in the application of virtual reality art creation, users can precisely control the strokes of a virtual paintbrush through the subtle motions of their hands to achieve a highly realistic creation experience.

[0131] By comprehensive comparison, the circuit style with a line width of 0.6 mm, a spacing of 0.4 mm, and 10 cycles performs best in terms of the sensitivity and accuracy of capturing hand bending motions, so it is most suitable as the bending motion sensor in the fully flexible liquid metal-based motion capture glove.

[0132] Finally, it should be pointed out that the methods and devices described in detail above are only examples, and those skilled in the art can modify these examples in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A method for preparing a bending motion sensor, characterized in that: include, Printing liquid metal on a base layer (101) formed by curing an elastomer solution to form a liquid metal film, and engraving the liquid metal film by laser; During the laser engraving process, the liquid metal on the laser engraving path is oxidized to form an oxidation boundary (J), and the pattern drawn by the liquid metal in the oxidation boundary (J) is an electrode loop (103); A layer of elastomer solution is dripped onto the upper layer of the electrode loop (103) and solidified to form a protective layer (102). Before the protective layer (102) is solidified, the electrode loop (103) is printed inside the protective layer to form a liquid flow channel (Y). After the protective layer (102) is completely solidified, the electrode loop (103) can flow in the liquid flow channel (Y).

2. The method for preparing the bending motion sensor according to claim 1, characterized in that: The electrode loop (103) is also connected to a collection unit (200), the collection unit (200) comprising a collection unit (201) and a plurality of groups of flexible flat cables (202), one end of the flexible flat cable (202) being simultaneously connected to electrode loops (103) at the same collection point in different groups, and the other end being connected to the collection unit (201).

3. The method for preparing the bending motion sensor according to claim 2, characterized in that: The electrode loop (103) is a zigzag strip pattern, with two ends forming a first pin (B1) and a second pin (B2); The flexible flat cable (202) comprises a plurality of groups of same-end collection lines (C) arranged in an arranged manner, each group of same-end collection lines (C) comprising a first lead (C1) and a second lead (C2) arranged in parallel, the first lead (C1) being respectively connected to a first pin (B1) and a collection unit (201), and the second lead (C2) being respectively connected to a second pin (B2) and a collection unit (201).

4. The method for preparing a bending motion sensor according to any one of claims 1 to 3, characterized in that: At least one group of electrode loops (103) is provided on the base layer (101), and the number and shape of the liquid flow channels (Y) correspond to those of the electrode loops (103); If the liquid flow channels (Y) are provided in several groups, each group of liquid flow channels (Y) is relatively independent.

5. The method for preparing the bending motion sensor according to claim 4, characterized in that: The base layer (101) and the protective layer (102) are made of Ecoflex elastomer silicone solution. Ecoflex reagent M and N are uniformly mixed in a mass ratio of 1:1, and subjected to vacuum degassing treatment with a vacuum degree of -0.1 MPa for 5 minutes. The preparation is completed after the bubbles are completely eliminated.

6. The method for preparing the bending motion sensor according to claim 1 to 3 or 5, characterized in that: The elastomer solution forming the base layer (101) is evenly dripped onto a glass slide. Before dripping, a hydrophobic layer (D) needs to be coated on the surface of the glass slide. The hydrophobic layer (D) is polytetrafluoroethylene.

7. The method for preparing the bending motion sensor according to claim 1 to 3 or 5, characterized in that: The electrode loop (103) uses a low-melting-point gallium-based room-temperature liquid alloy as an electrode material, including but not limited to a gallium-indium alloy and a gallium-indium-tin alloy, and the electrode loop (103) has a thickness of 50 μm.

8. A flexible bending strain sensor, prepared by the method for preparing a bending motion sensor according to any one of claims 1 to 7, characterized in that: include, A contact portion (100) is provided in a plurality of groups, each group of the contact portions (100) comprises a base layer (101) and a protective layer (102) arranged in layers, and each group of the base layer (101) and the protective layer (102) is provided with at least one group of electrode loops (103) enclosed therein; If the number of electrode loops (103) disposed in each group of the base layer (101) and the protective layer (102) is greater than one group, the electrode loops (103) in this group are relatively independent. The collection section (200) comprises a collection unit (201) and a plurality of groups of flexible flat cables (202), one end of the flexible flat cables (202) being simultaneously connected to electrode loops (103) at the same collection point in different groups, and the other end being connected to the collection unit (201).

9. A method for preparing a fully flexible liquid metal-based motion capture glove, characterized in that: The method for preparing the bending motion sensor further comprises: Before encapsulating the protective layer (102), the flexible flat cable (202) is first connected to the electrode loop (103), and after all the electrode loops (103) are connected to the flexible flat cable (202), the protective layer (102) is encapsulated; A layer of elastomer solution is brushed on the base layer (101), and at the same time, the electrode loop (103) is aligned with the bending points of each joint of the finger portion (302) in the glove (300); Heating the elastomer solution on the base layer (101) to fix the base layer (101) on the outer joint of the finger part (302); After the base layer (101) is fixed on the finger portion (302), the other end of the flexible flat cable (202) is connected and fixed to the collection unit (201).

10. A fully flexible liquid metal-based motion capture glove, characterized in that: include, The glove (300) comprises a palm portion (301) and finger portions (302), wherein the contact portion (100) is arranged on the back of each finger portion (302); If each set of contact parts (100) includes only one set of electrode loops (103), then each joint bending point is provided with one set of such electrode loops (103); If each group of contact parts (100) includes more than one group of electrode loops (103), all electrode loops (103) in this group are fixed on the joint bending point of the same finger part (302); The joint bending points in the direction from the fingertips to the palm (301) are respectively the first node (A1), the second node (A2) and the third node (A3); The same bending point of different fingers corresponds to the same set of flexible flat cables (202).

11. The method for preparing the fully flexible liquid metal-based motion capture gloves according to claim 10, characterized in that: If each set of base layers (101) includes only one set of electrode loops (103), then each joint bending point is provided with one set of such electrode loops (103); If each group of base layers (101) includes more than one group of electrode loops (103), all electrode loops (103) in this group are fixed on the joint bending point of the same finger (302).

12. The method for preparing the fully flexible liquid metal-based motion capture gloves according to claim 10 or 11, characterized in that: When the first lead (C1) is connected to the first pin (B1), additional liquid metal is covered on the connection to stabilize the connection, and then an elastomer solution is dripped on the connection, heated and fixed, thereby completing the fixation of the connection point and the base layer (101).

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