Large-strain interdigital capacitive sensor based on liquid metal conductive paste

Abstract

The invention relates to the technical field of flexible electronic sensors, in particular to a large-strain interdigital capacitive sensor based on liquid metal conductive paste, which comprises a flexible substrate, and the flexible substrate comprises a bottom packaging layer and a top packaging layer integrally connected to the upper surface of the bottom packaging layer. A liquid metal interdigital electrode is embedded between the bottom packaging layer and the top packaging layer, the liquid metal interdigital electrode is formed after liquid metal conductive paste is subjected to laser ablation patterning, the end of the liquid metal interdigital electrode is connected with a flexible wire, and one end of the flexible wire extends to the outside of the flexible substrate; the liquid metal conductive slurry is paste conductive slurry which is rich in oxide and is formed by mechanically stirring and oxidizing liquid metal; the liquid metal is gallium-based liquid metal; the problems that an existing flexible strain sensor cannot meet the large strain measurement requirement and is poor in stability and complex in preparation process are solved.

Description

Technical Field

[0001] This invention relates to the field of flexible electronic sensor technology, specifically a large-strain interdigital capacitance sensor based on liquid metal conductive paste. Background Technology

[0002] With the rapid development of wearable devices, soft robots, and health monitoring, there is an increasingly urgent need for flexible sensors that can conformally fit the human body or complex curved surfaces and accurately monitor large deformations.

[0003] Traditional strain sensors are mostly based on metal foils or semiconductor materials, which have extremely poor flexibility and ductility, typically below 5%, making them unsuitable for measuring large strains greater than 100%. In recent years, while flexible sensors based on carbon nanomaterials (such as carbon nanotubes and graphene), conductive polymers, or metal nanowires have emerged, their ductility is limited by the intrinsic rigidity of the conductive substrate. Modulus mismatch between the rigid conductive material and the flexible elastomer substrate easily leads to interfacial delamination under repeated stretching, resulting in sensor signal drift and decreased durability. Furthermore, when nanomaterials are used as sensor sensing materials, they need to be combined with a flexible substrate through dispersion, coating, and patterning processes, which are complex, costly, and difficult to mass-produce.

[0004] Liquid metal possesses intrinsic flexibility and high conductivity, making it an ideal stretchable conductor. However, its extremely high surface tension makes it difficult to stably pattern on a substrate, and it easily aggregates into spheres. Existing technologies employ microchannel encapsulation of liquid metal, but this method involves complex mold design, and damage to the encapsulation can easily lead to liquid metal leakage.

[0005] Therefore, it is necessary to invent a large-strain interdigital capacitance sensor based on liquid metal conductive slurry to solve the above problems. Summary of the Invention

[0006] To address the problems of existing flexible strain sensors failing to meet the requirements of large strain measurement, having poor stability, and being complex in their fabrication process, this invention provides a large strain interdigital capacitive sensor based on liquid metal conductive slurry.

[0007] This invention is achieved using the following technical solution:

[0008] A large-strain interdigital capacitive sensor based on liquid metal conductive paste includes a flexible substrate. The flexible substrate includes a bottom encapsulation layer and a top encapsulation layer integrally connected to the upper surface of the bottom encapsulation layer. A liquid metal interdigital electrode is embedded between the bottom encapsulation layer and the top encapsulation layer. The liquid metal interdigital electrode is formed by patterning the liquid metal conductive paste through laser ablation. A flexible wire is connected to the end of the liquid metal interdigital electrode, and one end of the flexible wire extends to the outside of the flexible substrate.

[0009] Furthermore, the liquid metal conductive paste is a paste-like conductive paste rich in oxides formed by mechanical stirring and oxidation treatment of liquid metal.

[0010] Furthermore, the liquid metal is a gallium-based liquid metal.

[0011] Furthermore, the flexible substrate is a polymer elastomer, which is made of one of the following materials: polydimethylsiloxane, Smooth-On's Ecoflex series silicone, styrene-ethylene-butene-styrene block copolymer, Smooth-On's Dragon Skin series silicone, or polyurethane.

[0012] Furthermore, the flexible wire is made of conductive fabric, conductive tape or metal foil, and is connected to the liquid metal interdigitated electrode by a conductive adhesive.

[0013] A method for fabricating a large-strain interdigital capacitive sensor based on a liquid metal conductive paste, the method comprising the following steps:

[0014] S1: Preparation of liquid metal conductive paste;

[0015] S2: Fabricating a bottom encapsulation layer on a substrate to form a flexible substrate;

[0016] S3: The liquid metal conductive paste prepared in step S1 is coated onto the upper surface of the bottom encapsulation layer to form a conductive layer;

[0017] S4: The conductive layer is laser-ablated according to the preset interdigitated electrode pattern to remove excess slurry and form liquid metal interdigitated electrodes.

[0018] S5: Connect the flexible wire to the end of the liquid metal interdigitated electrode;

[0019] S6: A top encapsulation layer forming a flexible encapsulation layer is prepared on the liquid metal interdigitated electrode to obtain a large strain interdigitated capacitive sensor based on liquid metal conductive paste.

[0020] Furthermore, in step S1, the liquid metal conductive slurry is formed by mechanically centrifuging liquid metal in a centrifugal electric mixer for no less than 30 minutes.

[0021] Furthermore, in step S2, the method for forming the bottom encapsulation layer on the substrate is a blade coating method, a spin coating method, or a template method.

[0022] Furthermore, in step S4, the laser ablation is achieved using an ultraviolet laser.

[0023] Application of a large-strain interdigital capacitive sensor based on liquid metal conductive paste as described in this invention in the fabrication of wearable electronic devices, soft robot sensing systems, or electronic skin.

[0024] Compared with existing flexible strain sensors, the large strain interdigital capacitance sensor based on liquid metal conductive slurry provided by this invention has the following advantages:

[0025] 1. An innovative method is used to prepare a liquid metal slurry through mechanical stirring and oxidation as a conductive material. This slurry retains the high conductivity of liquid metal (…). Furthermore, due to its surface oxide layer, it possesses rheological properties similar to paste, thus solving the problem of high surface tension and difficulty in patterning of pure liquid metals.

[0026] 2. Applying selective laser ablation (SLA) technology to patterning liquid metal slurries. This method eliminates the need for complex photolithography and etching chemical processes, making it a maskless, digital, and non-contact green processing technology. It boasts advantages such as high efficiency, high precision, and high flexibility, allowing for on-the-spot modification of electrode pattern designs, greatly simplifying the process and reducing manufacturing costs.

[0027] 3. Due to the intrinsic fluidity of liquid metal and its perfect modulus matching (conformal contact) with the polymer substrate, the electrode can adapt to strain through deformation rather than fracture when stretched, enabling the sensor to achieve strain measurement of not less than 100% or even greater, which is far superior to sensors based on solid conductors.

[0028] 4. Liquid metal oxide slurry has a stable morphology and will not leak like pure liquid metal; it also has good wettability with the elastomer substrate and a strong interfacial bond. Under repeated stretching-rebound cycles, it has small signal drift and long fatigue life.

[0029] 5. Using interdigitated capacitors as the sensing element, the capacitance change is related to strain. Capacitive measurement is unaffected by changes in the conductor's own resistance. Compared to resistive sensors, its output signal is more stable, its anti-interference ability is stronger, and its measurement accuracy is higher.

[0030] 6. This invention, through its interdigitated structure design, enables decoupling of measurement modes. The sensor exhibits high sensitivity to in-surface strain but is extremely insensitive to normal pressure, enabling accurate and singular measurement of in-surface strain even under complex environments of contact pressure or pressing, thus solving the problem of multi-physics coupling crosstalk in existing sensors.

[0031] 7. The entire sensor structure is clearly layered and made entirely of flexible materials, with good biocompatibility. It is very suitable for wearable health monitoring (such as human joint movement, pulse, and respiration monitoring), soft robot posture perception, electronic skin and other fields, and has huge market application prospects. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the large strain interdigital capacitive sensor of the present invention.

[0033] Figure 2 This is a schematic diagram of the interdigital structure of the large strain interdigital capacitive sensor of the present invention.

[0034] Figure 3 This is a schematic diagram of the fabrication process of the large strain interdigital capacitive sensor of the present invention.

[0035] Figure 4 This is the equivalent circuit diagram of the large strain interdigital capacitive sensor of the present invention.

[0036] Figure 5 This is a schematic diagram of the in-plane stretching of the large strain interdigital capacitive sensor of the present invention.

[0037] Figure 6 This is a schematic diagram of the normal positive pressure of the large strain interdigital capacitive sensor of the present invention.

[0038] Figure 7 The tensile-strain curves of the large-strain interdigitated capacitive sensor of the present invention and a pure substrate material of the same size are shown.

[0039] Figure 8 The initial state capacitance value of the large strain interdigital capacitive sensor of the present invention is under different interdigital length, interdigital width and interdigital spacing conditions.

[0040] Figure 9 This is a graph showing the rate of change of capacitance of the large strain interdigital capacitive sensor of the present invention under different tensile strains.

[0041] Figure 10 This is a graph showing the rate of change of capacitance of the large strain interdigital capacitive sensor of the present invention under different positive pressures.

[0042] In the figure: 1. Flexible substrate; 2. Liquid metal interdigitated electrode; 3. Flexible wire; 11. Bottom encapsulation layer; 12. Top encapsulation layer. Detailed Implementation

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] A large-strain interdigital capacitive sensor based on liquid metal conductive slurry, such as Figure 1 As shown, the sensor includes a flexible substrate 1, which comprises a bottom encapsulation layer 11 and a top encapsulation layer 12 integrally connected to the upper surface of the bottom encapsulation layer 11, providing flexible and elastic support for the sensor. A liquid metal interdigitated electrode 2 is embedded between the bottom encapsulation layer 11 and the top encapsulation layer 12. The liquid metal interdigitated electrode 2 is fabricated by ultraviolet laser ablation and patterning of liquid metal conductive paste, serving as the sensing element of the sensor. A flexible wire 3 is connected to the end of the liquid metal interdigitated electrode 2, and one end of the flexible wire 3 extends to the outside of the flexible substrate 1. One end of the flexible wire 3 embedded inside the flexible substrate 1 is connected to the two electrode pads of the liquid metal interdigitated electrode 2, and the other end of the flexible wire 3 extending to the outside of the flexible substrate 1 is used to connect to an external measurement circuit.

[0046] The liquid metal conductive paste is a paste-like conductive paste rich in oxides formed by mechanical stirring and oxidation treatment of liquid metal.

[0047] The liquid metal is a eutectic gallium-indium alloy.

[0048] The flexible substrate 1 is a polymer elastomer with high elongation and high resilience, made of Ecoflex 00-30 silicone from Smooth-On.

[0049] The flexible wire 3 is made of silver fiber conductive fabric and is connected to the liquid metal interdigitated electrode 2 by a conductive adhesive.

[0050] like Figure 3 As shown, the sensor fabrication method in this embodiment includes the following steps:

[0051] S1: Preparation of liquid metal conductive paste: At room temperature, place the eutectic gallium-indium alloy in a centrifugal electric stirrer and mechanically stir at a speed of 3000 r / min for no less than 30 min, so that its surface undergoes an oxidation reaction with air to generate gallium oxide-rich material. Nanoparticles are coated on the surface of unoxidized eutectic gallium indium alloy droplets to form a liquid metal conductive paste with significantly increased viscosity. The paste is paste-like and has excellent printability, coatability and conformability.

[0052] S2: Mix the A and B components of Ecoflex 00-30 silicone at a mass ratio of 1:1 and stir for 3 minutes. Drop the mixture onto the center of the silicon wafer and spin coat it at 200 r / min for 2 minutes in a spin coater to form a uniform liquid film. After curing at 60°C for 2 hours, the bottom encapsulation layer 11 of the flexible substrate 1 is obtained.

[0053] S3: The liquid metal conductive paste prepared in step S1 is coated onto the upper surface of the bottom encapsulation layer 11 to form a conductive layer.

[0054] S4: The conductive layer is laser-ablated according to the preset interdigitated electrode pattern, and excess paste is selectively removed to form liquid metal interdigitated electrodes 2. This process eliminates the need for complex steps such as masking and development in traditional photolithography, and is fast, flexible, and environmentally friendly.

[0055] S5: Use a small amount of liquid metal oxide paste as a conductive adhesive to fix the flexible wire 3 to the electrodes at both ends of the liquid metal interdigitated electrode 2, as a lead wire.

[0056] S6: Pour the pre-mixed Ecoflex 00-30 mixture from step S1 onto the liquid metal interdigital electrode 2, ensuring complete coverage. After curing, it forms the top encapsulation layer 12 of the flexible encapsulation layer 1. Remove the silicon wafer to obtain a large strain interdigital capacitive sensor based on liquid metal conductive paste.

[0057] This invention provides a large-strain interdigital capacitance sensor based on a liquid metal conductive slurry. Through structural optimization, the sensor becomes insensitive to normal pressure, but specifically responds only to in-plane strain, achieving intrinsic decoupling measurement of normal pressure and in-plane strain. The principle of this decoupling design is that the initial capacitance value and its change mainly depend on the distribution of electric field lines between the interdigitates and the thickness of the dielectric layer. When the sensor is subjected to in-plane stretching, the flexible substrate 1 and the liquid metal interdigital electrodes 2 are elongated, resulting in an increase in the spacing between the interdigital electrodes. and effective overlapping area The situation changes; according to the principle of capacitance, the unit capacitor formed by two adjacent interdigitated fingers changes. It consists of three parallel capacitance components, which are two edge electric field capacitances originating from the opposite edges of the coplanar interdigital electrodes. , and a capacitance originating from the parallel plates between the sides of adjacent interdigitated electrodes. ,Right now The equivalent circuit diagram of the large strain interdigital capacitive sensor of the present invention is as follows: Figure 4 As shown. The total capacitance of the entire interdigital capacitive sensor. It is all the parallel unit capacitors The sum of these values ​​is proportional to the number of interdigitated pairs in the interdigitated capacitor, and is expressed as:

[0058] (1)

[0059] (2)

[0060] (3)

[0061] in, The exponents that constitute the interdigital capacitor. Let be the relative permittivity of flexible substrate 1. The vacuum permittivity, , , , These refer to the finger length, finger width, spacing, and thickness of the interdigitated capacitor, such as... Figure 2 As shown. When the interdigital capacitive sensor is subjected to in-plane tensile deformation, due to the Poisson effect of the material, the finger width of the interdigital electrode... and spacing Increase, refers to length and thickness The decrease in capacitance results in a change in the capacitance of the interdigital electrode units, leading to a change in the total capacitance of the sensor, thus enabling strain measurement. A schematic diagram of the in-plane tension of the interdigital capacitive sensor is shown below. Figure 5 As shown. When the sensor undergoes tensile deformation, the capacitance between the interdigitated fingers is... The two edge electric field capacitances generated between two coplanar opposing electrodes and Parallel plate capacitance between electrodes The total capacitance is , can be represented as:

[0062] (4)

[0063] (5)

[0064] (6)

[0065] in, The strain applied to the sensor, Let be the Poisson's ratio for the flexible substrate material. The rate of change of capacitance under in-plane tensile strain is expressed as:

[0066] (7)

[0067] (8)

[0068] It is evident that the capacitance change rate of the interdigital capacitive sensor under in-plane tensile strain is not only related to the applied strain. Related to this, it is also affected by the Poisson's ratio of the substrate material. The effect of the measured rate of change of capacitance is greater than the value predicted by the geometric change caused solely by the Poisson effect. This significant enhancement effect is mainly due to the extremely high sensitivity of the edge electric field capacitance to changes in the finger spacing.

[0069] However, when the interdigital capacitive sensor is subjected to normal force, due to the incompressibility (volume conservation) of liquid metal, the total thickness of the sensor must be considered. Considering the normal compressive strain of the sensor Thickness strain of interdigitated electrodes Modeling and analysis are performed, represented as follows:

[0070] (9)

[0071] (10)

[0072] A schematic diagram of the normal positive pressure of an interdigital capacitive sensor is shown below. Figure 6 As shown. When the sensor is subjected to positive pressure, the interdigital capacitance is... The two edge electric field capacitances generated between two coplanar opposing electrodes and Parallel plate capacitance between electrodes Total capacitance It can be represented as:

[0073] (11)

[0074] (12)

[0075] (13)

[0076] in, This represents the compressive deformation of the sensor under normal pressure. The rate of change of the total capacitance of the interdigital capacitive sensor under normal normal pressure is:

[0077] (14)

[0078] It is evident that the effect of normal pressure on the sensor capacitance value is negligible. The interdigital capacitance sensor provided by this invention can effectively suppress the interference of normal pressure, enabling accurate measurement of in-plane tensile strain.

[0079] Example 2

[0080] The difference between this embodiment and Embodiment 1 is that the flexible substrate 1 is made of polydimethylsiloxane (PDMS, Dow Corning Sylgard 184), and its base agent and curing agent are mixed at a mass ratio of 10:1 and cured at 80°C for 2 hours to form an encapsulation layer. The flexible wire 3 is made of copper cloth. The remaining preparation steps and parameters are the same as in Embodiment 1.

[0081] To systematically verify and elucidate the influence of interdigital electrode geometric parameters on sensor performance, based on the preparation method of Example 1, this invention designed and fabricated a series of sensors for testing, hereinafter collectively referred to as experimental examples, with only the length of the interdigital electrodes being varied. ),width( ) and spacing ( ).

[0082] Experimental Example Series A (corresponding to) Figure 8 (Left image): Fixed fork index N=100, spacing =200μm, interdigitated width Seven values ​​were selected within the range of 200μm to 500μm: 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, and 500μm. For each width, the interdigitated finger length was further specified. Five values ​​were selected within the range of 28mm to 36mm: 28mm, 30mm, 32mm, 34mm, and 36mm, resulting in 35 possible parameter combinations. Test results show that, at a certain spacing, when the electrode width is constant, the zero-strain capacitance increases with the increase of the interdigital length. At a certain spacing, increasing the interdigital width shifts the relationship curve between the interdigital length and the zero-strain capacitance upwards overall, and the slope of the curve remains essentially consistent.

[0083] Experimental Example Series B (corresponding to) Figure 8 (Middle diagram): Fixed fork index N=100, length =32mm, interdigital spacing and width Seven values ​​were selected within the range of 200μm to 500μm: 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, and 500μm, resulting in 49 possible parameter combinations. Test results show that, with a fixed interdigital length and interdigital spacing, the zero-strain capacitance increases with increasing interdigital width; increasing the interdigital spacing shifts the relationship curve between interdigital width and zero-strain capacitance downwards overall.

[0084] For experimental series C (corresponding to) Figure 8 (Right figure): The parameter combination is the same as in series B. The reorganized data shows that: when the interdigit width is constant, the zero-strain capacitance decreases as the interdigit spacing increases; increasing the interdigit width shifts the relationship curve between interdigit spacing and zero-strain capacitance upwards, meaning that for the same interdigit width, the zero-strain capacitance increases.

[0085] In summary, the above experimental examples combined Figure 8 It is demonstrated that the zero-strain capacitance value of the sensor of the present invention is directly related to the geometric parameters of the interdigital length, width, and spacing. The initial capacitance of the sensor can be controlled by adjusting the interdigital parameters, and the corresponding relationship conforms to the typical parallel plate and edge field capacitance theory.

[0086] The performance test results of the sensor prepared based on the above experimental examples further verify the excellent characteristics of the present invention:

[0087] like Figure 7 The figure shows a comparison of the tensile-strain curves of the sensor of this invention with those of a pure substrate material of the same size. It can be seen that within a large strain range of 20% to 80%, the tensile-strain curve of the sensor essentially overlaps with that of the pure flexible substrate, and exhibits a high degree of consistency over multiple cycles. This fully demonstrates that the liquid metal interdigitated electrode, benefiting from its intrinsic flexibility, can stretch and deform synchronously with the elastic substrate. There is no friction, sliding, or stress concentration between the electrode and the substrate, and its influence on the overall elastic modulus of the substrate is negligible. This characteristic ensures that the sensor possesses excellent flexibility, resilience, and structural stability during long-term operation when subjected to repeated large strains.

[0088] like Figure 9 As shown, all other parameters are fixed, namely the cross index N=100 and the cross length. =32mm, interdigital spacing =200μm, interdigitated width =200μm, only the total thickness Tensile tests were conducted on different sensors, and the results showed that when tensile strain was applied, the capacitance of the sensor decreased, the increment of the capacitance change rate increased, and the tensile strain-capacitance change rate curves of sensors with different total thicknesses completely overlapped. This indicates that the in-plane tensile strain response of the sensor is independent of the total thickness.

[0089] like Figure 10 As shown, for a cross index N=100 and a cross finger length =32mm, interdigital spacing =200μm, interdigitated width =200μm, total thickness When a normal force is applied to a sensor with a thickness of 0.1 mm, the rate of change of capacitance of the sensor is almost zero (e.g., at a total thickness of 0.1 mm, the rate of change at maximum pressure is only 0.001%). This experiment verifies that the sensor described in this invention is extremely insensitive to normal force, possesses excellent stress decoupling characteristics, and can achieve accurate measurement of in-plane tensile strain under complex environments.

[0090] In specific implementation, the materials of the flexible conductor 3 include, but are not limited to, silver fiber conductive fabric, copper braided tape, and copper cloth; the liquid metal includes, but is not limited to, gallium, eutectic gallium indium alloy, and gallium indium tin alloy; and the materials of the substrate include, but are not limited to, silicon wafers, acrylic sheets, and release paper.

[0091] In the description of this invention, it should be understood that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0092] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A large-strain interdigital capacitive sensor based on liquid metal conductive slurry, characterized in that: The flexible substrate (1) includes a bottom encapsulation layer (11) and a top encapsulation layer (12) integrally connected to the upper surface of the bottom encapsulation layer (11). A liquid metal interdigitated electrode (2) is embedded between the bottom encapsulation layer (11) and the top encapsulation layer (12). The liquid metal interdigitated electrode (2) is formed by patterning liquid metal conductive paste by laser ablation. A flexible wire (3) is connected to the end of the liquid metal interdigitated electrode (2), and one end of the flexible wire (3) extends to the outside of the flexible substrate (1).

2. The large strain interdigital capacitance sensor based on liquid metal conductive slurry according to claim 1, characterized in that: The liquid metal conductive paste is a paste-like conductive paste rich in oxides formed by mechanical stirring and oxidation treatment of liquid metal.

3. A large-strain interdigital capacitance sensor based on liquid metal conductive slurry according to claim 2, characterized in that: The liquid metal is a gallium-based liquid metal.

4. A large-strain interdigital capacitance sensor based on liquid metal conductive slurry according to claim 1, characterized in that: The flexible substrate (1) is a polymer elastomer, which is made of one of the following materials: polydimethylsiloxane, Smooth-On's Ecoflex series silicone, styrene-ethylene-butene-styrene block copolymer, Smooth-On's DragonSkin series silicone, or polyurethane.

5. A large-strain interdigital capacitance sensor based on liquid metal conductive slurry according to claim 1, characterized in that: The flexible wire (3) is made of conductive fabric, conductive tape or metal foil and is connected to the liquid metal interdigitated electrode (2) by conductive adhesive.

6. A method for fabricating a large-strain interdigital capacitive sensor based on a liquid metal conductive paste, the method being used to fabricate a large-strain interdigital capacitive sensor based on a liquid metal conductive paste as described in any one of claims 1-5, characterized in that: Includes the following steps: S1: Preparation of liquid metal conductive paste; S2: Prepare a bottom encapsulation layer (11) on a substrate to form a flexible substrate (1). S3: The liquid metal conductive paste prepared in step S1 is coated on the upper surface of the bottom encapsulation layer (11) to form a conductive layer; S4: The conductive layer is laser-ablated according to the preset interdigitated electrode pattern to remove excess slurry and form liquid metal interdigitated electrodes (2). S5: Connect the flexible wire (3) to the end of the liquid metal interdigitated electrode (2); S6: A top encapsulation layer (12) forming a flexible encapsulation layer (1) is prepared on the liquid metal interdigitated electrode (2) to obtain a large strain interdigitated capacitive sensor based on liquid metal conductive paste.

7. The method for fabricating a large-strain interdigital capacitance sensor based on liquid metal conductive paste according to claim 6, characterized in that: In step S1, the liquid metal conductive slurry is formed by placing liquid metal in a centrifugal electric mixer and mechanically centrifuging for no less than 30 minutes.

8. The method for fabricating a large-strain interdigital capacitance sensor based on liquid metal conductive paste according to claim 6, characterized in that: In step S2, the method for forming the bottom encapsulation layer (11) on the substrate is by scraping, spin coating or stencil coating.

9. The method for fabricating a large-strain interdigital capacitance sensor based on liquid metal conductive paste according to claim 6, characterized in that: In step S4, the laser ablation is achieved using an ultraviolet laser.

10. The application of a large-strain interdigital capacitive sensor based on liquid metal conductive paste as described in any one of claims 1-5 in the fabrication of wearable electronic devices, soft robot sensing systems, or electronic skin.

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