WO2021238042A1 - 液态金属薄膜电极的制造方法及柔性压力传感器 - Google Patents

液态金属薄膜电极的制造方法及柔性压力传感器 Download PDF

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WO2021238042A1
WO2021238042A1 PCT/CN2020/123605 CN2020123605W WO2021238042A1 WO 2021238042 A1 WO2021238042 A1 WO 2021238042A1 CN 2020123605 W CN2020123605 W CN 2020123605W WO 2021238042 A1 WO2021238042 A1 WO 2021238042A1
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liquid metal
electrode
elastomer composite
composite electrode
pressure sensor
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PCT/CN2020/123605
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English (en)
French (fr)
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刘坚
张忆秋
聂宝清
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苏州大学
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
    • G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors

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  • the invention relates to the technical field of flexible pressure sensors, in particular to a manufacturing method of liquid metal film electrodes and flexible pressure sensors.
  • the capacitive pressure sensor can be divided into capacitive, resistive, piezoelectric, etc. according to their working principles. Among them, the capacitive pressure sensor has the advantages of low detection limit, high sensitivity, low energy consumption, low heat generation, and compact structure.
  • the capacitive pressure sensor is composed of flexible electrodes and capacitive medium, and the output signal response is realized according to the change of the electrode facing area, the separation distance and the capacitive medium under the action of external force.
  • the preparation schemes of flexible electrodes can be roughly divided into two types: one is polydimethylsiloxane (PDMS), styrene-ethylene-butylene-styrene block copolymer (SEBS), polyurethane (PU) ) And other elastic polymer matrixes are mixed with conductive fillers such as graphene, carbon nanotubes (CNTs), metal nanoparticles or nanowires; the other is to use self-stretchable conductive materials, such as ionic liquids, ionic gels, Liquid metal, etc.
  • PDMS polydimethylsiloxane
  • SEBS styrene-ethylene-butylene-styrene block copolymer
  • PU polyurethane
  • conductive fillers such as graphene, carbon nanotubes (CNTs), metal nanoparticles or nanowires
  • self-stretchable conductive materials such as ionic liquids, ionic gels, Liquid metal, etc
  • the method of incorporating conductive fillers into the elastomer polymer will increase the overall Young's modulus of the material, reduce the mechanical strength and stretchability, and easily lead to a sharp increase in electrical resistance during the deformation process. Large, even irreversible damage; when liquid metal and other materials are used as flexible electrodes, its fluidity increases the difficulty of three-dimensional structure modification and packaging.
  • the technical problem to be solved by the present invention is to overcome the problems of poor stretchability of the pressure sensor in the prior art and the susceptibility of the pressure signal to stretching interference, so as to provide a highly sensitive and stretchable liquid metal film electrode manufacturing Method and flexible pressure sensor.
  • a method for manufacturing a liquid metal thin film electrode of the present invention includes: mixing two components of an elastomer dielectric layer in proportions, stirring and removing bubbles, and then adding them dropwise to the surface active agent.
  • the first carrier is processed and spin-coated; the first carrier is heated, and the conductive tape is attached when the elastomer dielectric layer is not completely cured; the liquid metal is sprayed on the elastomer dielectric layer
  • a liquid metal electrode is formed, and the liquid metal electrode is connected to the conductive tape; a shaped body is added on the elastomer dielectric layer with the liquid metal electrode to form a first liquid metal elastomer composite electrode, which is to be cured , Separating the first liquid metal elastomer composite electrode from the first carrier.
  • the material used for the elastomer dielectric layer and the shaped body is silicone rubber.
  • the present invention also provides a method for preparing a liquid metal film electrode. After the steps of the method for preparing a liquid metal film electrode are completed, the method further includes: placing the first liquid metal elastomer composite electrode on a second carrier, Orient the elastomer dielectric layer in the first liquid metal elastomer composite electrode toward the second carrier, and align the stripes with the liquid metal electrode with the pores of the second carrier; align the second carrier And the first liquid metal elastomer composite electrode are placed in a vacuum environment, negative pressure is first applied, and then pressurized, so that the first liquid metal elastomer composite electrode is recessed into the micropores; The shaped body forms a second liquid metal elastomer composite electrode, and after curing, the second liquid metal elastomer composite electrode is separated from the second carrier.
  • the degree of depression of the first liquid metal elastomer composite electrode into the micropores is adjusted by changing the magnitude of the negative pressure.
  • the present invention also provides a flexible pressure sensor, including a first liquid metal elastomer composite electrode and a second liquid metal elastomer composite electrode, wherein the first liquid metal elastomer composite electrode has a planar structure, and the second liquid metal elastomer composite electrode has a planar structure.
  • the metal elastomer composite electrode has an arched structure, and the second liquid metal elastomer composite electrode is located above the first liquid metal elastomer composite electrode.
  • the liquid metal stripes of the first liquid metal elastomer composite electrode and the liquid metal stripes of the second liquid metal elastomer composite electrode are perpendicular to each other, and the second liquid metal elastomer The arched protrusions of the composite electrode are aligned with the liquid metal stripes of the first liquid metal elastomer composite electrode.
  • the present invention also provides a flexible pressure sensor, including the above-mentioned flexible pressure sensor, and the plurality of first liquid metal elastomer composite electrodes are multiple in number and arranged in an array, and the second liquid metal elastomer composite electrodes The number is also multiple, and they are arranged in an array.
  • the present invention also provides a flexible pressure sensor, including two second liquid metal elastomer composite electrodes, one of which is used as a bottom electrode and the other is used as a top electrode, and the second liquid metal elastomer composite electrode has an arched structure .
  • the present invention also provides a flexible pressure sensor, which includes the above-mentioned flexible pressure sensor.
  • the number of metal elastomer composite electrodes is also multiple, and they are arranged in an array.
  • the present invention also provides a flexible pressure sensor, including any one of the above-mentioned array-type flexible pressure sensors, and as a basic unit, the flexible pressure sensor is assembled in multiple layers.
  • the manufacturing method of the liquid metal film electrode and the flexible pressure sensor of the present invention include a liquid metal film with an arched structure, an Ecoflex film for uniformly encapsulating liquid metal, and an Ecoflex substrate as a structural support.
  • the arched structure can be maintained in shape. It is realized by Ecoflex filling.
  • the size of the basic unit space, the thickness of the liquid metal film, and the thickness of the Ecoflex film can be adjusted. And after testing, it can be obtained that the pressure sensor can withstand 94% tensile strain without obvious damage; the pressure response of the pressure sensor under 45% tensile strain is almost the same as the normal state, that is, it is not easy to be stretched. Interference to pressure measurement signal; immune to temperature and humidity interference.
  • Figure 1 is a flow chart of the manufacturing method of the first liquid metal elastomer composite electrode of the present invention
  • Figure 2 is a specific preparation process of the first liquid metal elastomer composite electrode of the present invention
  • FIG. 3 is a flow chart of the manufacturing method of the second liquid metal elastomer composite electrode of the present invention.
  • Figure 4 is a specific preparation process of the second liquid metal elastomer composite electrode of the present invention.
  • Figure 5a is a schematic diagram of the state of the present invention when the pressure sensor is not subjected to external pressure
  • Figure 5b is a schematic diagram of the state of the present invention when the pressure sensor is subjected to external pressure
  • Fig. 6 is a change curve of capacitance increase when the pressure sensor of the present invention is subjected to constantly changing pressure
  • FIG. 7 is a schematic diagram of the mechanical and electrical response of each unit in the pressure sensor array of the present invention.
  • Figure 8a is a schematic diagram of different states of the pressure sensor array of the present invention.
  • Figure 8b is a schematic diagram of the stretched state of the top arch electrode of the present invention when the strain is different;
  • Figure 8c shows the mechanical and electrical properties of the pressure sensor of the present invention in normal and stretched states
  • 8d is a schematic diagram of the variation of the coefficient of variation of the initial capacitance value of the pressure sensor of the present invention after multiple stretches;
  • FIG. 9 is a schematic diagram of the application of the pressure sensor array of the present invention to measure two-dimensional pressure distribution
  • Fig. 10 is a schematic diagram of pressure changes when the pressure sensor of the present invention is applied to the neck.
  • this embodiment provides a method for manufacturing a liquid metal thin film electrode, which includes the following steps: Step S1: The two components of the elastomer dielectric layer 10 are proportioned After mixing, stirring and removing bubbles, it is added dropwise on the first carrier 20 treated with surfactant, and spin-coated; Step S2: heating the first carrier 20, the elastomer dielectric When the layer is not completely cured, paste the conductive tape 30; step S3: spray liquid metal on the elastomer dielectric layer 10 to form a liquid metal electrode 40, and the liquid metal electrode 40 is connected to the conductive tape 30; step S4: Add a shaped body to the elastomer dielectric layer 10 with the liquid metal electrode 40 to form a first liquid metal elastomer composite electrode 61. After curing, remove the first liquid metal elastomer composite electrode 61 from the The first carrier 20 is separated.
  • the two components of the elastomer dielectric layer 10 are mixed in proportions, and after stirring and removing bubbles, they are added dropwise to the surface active agent.
  • the first carrier 20 it is beneficial to peel off the film, prevent tearing, and perform spin coating treatment to make the spin coating more uniform;
  • the first carrier 20 is heated, and the elastomer When the dielectric layer is not completely cured, paste the conductive tape 30 so as to realize the connection between the external wire and the liquid metal after the flexible sensor is packaged; in the step S3, the liquid metal is sprayed on the elastomer dielectric layer 10 to form The liquid metal electrode 40, and the liquid metal electrode 40 is connected to the conductive tape 30, which is conducive to signal transmission; in the step S4, a shaped body is added to the elastomer dielectric layer 10 with the liquid metal electrode 40 , It is beneficial to play the role of supporting and encapsulating the liquid metal to form the first liquid metal
  • the material used for the elastomer dielectric layer and the shaped body is silicone rubber.
  • the materials used for the elastomer dielectric layer and the shaped body include Ecoflex elastomer materials, PDMS elastomer materials, or other rubber materials, and combinations of these three materials; the first carrier 20 may It's a silicon wafer.
  • the liquid metal includes gallium indium alloy (EGaIn) and gallium indium tin alloy (Galinstan).
  • the A and B components of Ecoflex 0030 are mixed in a ratio of 1:1 (which can be mixed according to the mass ratio or volume ratio), fully stirred and vacuum defoamed, and then added dropwise to the center of the silicon wafer treated with the surfactant , Use a homogenizing spin coater to spin coat at 500 rpm for 10 seconds, and spin coat at 1000 rpm for 1 min.
  • the silicon wafer is placed on a 50°C heating plate, and the copper-nickel conductive cloth tape is pasted when it is not completely cured, so as to realize the connection between the external wire and the liquid metal after the flexible sensor is packaged.
  • the first liquid metal elastomer composite electrode 61 Before the first liquid metal elastomer composite electrode 61 is separated from the first carrier 20, it further includes the steps of cleaning and drying the first liquid metal elastomer composite electrode 61. Specifically, the prepared liquid metal elastomer composite electrode was slowly uncovered from the silicon wafer, washed with ultrapure water and ethanol, and finally placed in an oven to dry.
  • this embodiment provides a method for preparing a liquid metal thin film electrode.
  • the method further includes: step 1: step 1 A liquid metal elastomer composite electrode 61 is placed on the second carrier 50 so that the elastomer dielectric layer 10 in the first liquid metal elastomer composite electrode 61 faces the second carrier 50 and will have liquid metal The stripes of the electrode are aligned with the pores 51 of the second carrier 50;
  • Step 2 Place the second carrier 50 and the first liquid metal elastomer composite electrode 61 in a vacuum environment, first apply negative pressure, and then increase Press to make the first liquid metal elastomer composite electrode 61 recess into the micropores 51;
  • step 3 adding a shaped body into the recess to form a second liquid metal elastomer composite electrode 62, after curing, The second liquid metal elastomer composite electrode 62 is separated from the second carrier.
  • This embodiment provides a method for preparing a liquid metal thin film electrode. After the steps of the method for preparing a liquid metal thin film electrode described in the first embodiment are completed, the method further includes step 1, placing the first liquid metal elastomer composite electrode 61 On the second carrier 50, the elastomer dielectric layer 10 in the first liquid metal elastomer composite electrode 61 faces the second carrier 50, and the stripes with the liquid metal electrode are combined with the second carrier 50 The pores 51 of the pores 51 are aligned to facilitate the deformation of the elastomer dielectric layer 10; in step 2, the second carrier 50 and the first liquid metal elastomer composite electrode 61 are placed in a vacuum environment , First apply negative pressure, and then pressurize, the resulting pressure difference will cause the first liquid metal elastomer composite electrode 61 to sag in the micropore 51; in step 3, add shaping in the sag Body, which helps to support and encapsulate the liquid metal to form a second liquid metal elastomer composite electrode 62.
  • the second liquid metal elastomer composite electrode 62 is separated from the second carrier 50 , thus forming a group of non-planar electrodes with a three-dimensional structure, specifically, forming an arched electrode, which can be used as the top electrode of a flexible sensor.
  • the second carrier 50 may be a 96-well plate.
  • first liquid metal elastomer composite electrode 61 formed in the first embodiment on a 96-well plate, with the Ecoflex dielectric layer film facing the 96-well plate, and combine the liquid metal electrode stripes with the 96-well plate.
  • the circular holes of the plate are aligned.
  • the 96-well plate and the first liquid metal elastomer composite electrode 61 are integrally moved into a vacuum box, and a negative pressure of -0.03 MPa is applied.
  • a negative pressure of -0.03 MPa is applied.
  • an elastomer film and a mold are used to form a closed cavity, the film structure is changed by the air pressure difference between the inside and outside of the cavity, and the polymer is finally cast to maintain the structure.
  • the three-dimensional structure of the film can be changed.
  • the method described in the present application has the advantage that other flexible materials can be embedded under a thin film of uniform thickness inside the polymer.
  • the degree of depression of the first liquid metal elastomer composite electrode 61 into the micropore 51 is adjusted by changing the magnitude of the negative pressure. For example, the degree of depression can be adjusted by appropriately changing the size of the negative pressure in the experiment.
  • This embodiment provides a first flexible pressure sensor, including a first liquid metal elastomer composite electrode 61 and a second liquid metal elastomer composite electrode 62, wherein the first liquid metal
  • the elastomer composite electrode 61 has a planar structure
  • the second liquid metal elastomer composite electrode 62 has an arched structure
  • the second liquid metal elastomer composite electrode 62 is located on the surface of the first liquid metal elastomer composite electrode 61.
  • the flexible pressure sensor of this embodiment includes a first liquid metal elastomer composite electrode 61 and a second liquid metal elastomer composite electrode 62, wherein the first liquid metal elastomer composite electrode 61 has a planar structure, and the first liquid metal elastomer composite electrode 61 has a planar structure.
  • the two liquid metal elastomer composite electrodes 62 have an arched structure, and the second liquid metal elastomer composite electrode 62 is located above the first liquid metal elastomer composite electrode 61, that is, the first liquid metal elastomer composite electrode
  • the electrode 61 is used as the bottom layer, and the second liquid metal elastomer composite electrode 62 is used as the top layer, which is beneficial to bear more tensile strain and increase the service life; in addition, the pressure sensor responds to pressure under a certain tensile strain Almost the same as the normal state, it is not easy to be interfered by stretching to the pressure measurement signal, and the sensitivity is high, avoiding the interference of the external environment such as temperature and humidity.
  • the liquid metal stripes of the first liquid metal elastomer composite electrode 61 and the liquid metal stripes of the second liquid metal elastomer composite electrode 62 are perpendicular to each other, and the arcuate convexity of the second liquid metal elastomer composite electrode 62 Since the liquid metal stripes of the first liquid metal elastomer composite electrode 61 are aligned with each other, it is beneficial to bear more tensile strain and improve the service life.
  • the bottom electrode is a planar structure
  • the top electrode is a liquid metal film with an arched structure.
  • the Ecoflex capacitor dielectrics of the two layers of composite electrodes are stacked inward so that the liquid metal stripes of the two layers of electrodes are perpendicular to each other, and the arched protrusions on the top electrode are aligned with the center of the stripes of the bottom electrode.
  • a very small amount of Ecoflex is used for bonding in the area outside the sensor unit.
  • the pressure sensor when the liquid metal in the top electrode is bent along the arch-shaped elastic body, the pressure sensor maintains the smallest contact area and the largest separation distance between the two electrodes in the initial state of zero external force.
  • the pressure sensor is subjected to external pressure, as shown in FIG. 5b, the liquid metal film electrode on the top layer is squeezed, the contact area between the electrodes is obviously increased, and the separation distance is reduced at the same time.
  • the pressure sensor can be equivalent to a circuit in which a variable capacitor and a resistor are connected in series.
  • the capacitance can be predicted by the classic equation of a parallel plate capacitor: Among them, A represents the facing area of the two electrodes, d represents the distance between the two electrodes, and ⁇ 0 and ⁇ r represent the absolute dielectric constant and the relative dielectric constant of the capacitive medium, respectively.
  • This embodiment provides a second type of flexible pressure sensor.
  • the fourth embodiment is an improvement on the basis of the third embodiment, so that the entire flexible pressure sensor is arranged in an array.
  • the plurality of first The number of the liquid metal elastomer composite electrodes 61 is multiple, and they are arranged in an array, and the number of the second liquid metal elastomer composite electrodes 62 is also multiple, and they are arranged in an array, thereby forming a flexible pressure
  • the sensors are also arranged in an array, which is conducive to measuring pressure distribution and improving service life.
  • the flexible pressure sensors arranged in an array can be arranged in parallel or in a vertical arrangement.
  • they can be arranged in pairs (mirror symmetry) and arranged vertically; they can also be arranged in series one by one. .
  • This embodiment provides a third type of flexible pressure sensor, which is different from the first type of flexible pressure sensor described in the third embodiment. Specifically: it includes two second liquid metal elastomer composite electrodes 62, one of which is used as a bottom electrode , The other one serves as the top electrode, and the second liquid metal elastomer composite electrode 62 has an arched structure.
  • the third type of flexible pressure sensor described in this embodiment includes two second liquid metal elastomer composite electrodes 62, one of which serves as the bottom electrode and the other as the top electrode, and the second liquid metal elastomer composite electrode 62
  • the arched structure not only helps to improve the pressure resistance, but also enhances the anti-interference ability.
  • the curved arc directions of the arch structure used respectively include the same direction setting and the reverse setting.
  • the number of the second liquid metal elastomer composite electrodes as the bottom electrode is multiple and they are arranged in an array
  • the number of the second liquid metal elastomer composite electrodes as the top electrode is multiple and they are arranged in an array. It is good for measuring pressure distribution and improving service life.
  • This embodiment provides a fourth type of flexible pressure sensor, which is an improvement made on the basis of the fourth and fifth embodiments, specifically: including the flexible pressure sensor described in the fourth embodiment or the flexible pressure described in the fifth embodiment Any one of the sensors, and as a basic unit, the flexible pressure sensor is assembled in multiple layers.
  • the fourth flexible pressure sensor described in this embodiment includes any one of the flexible pressure sensor described in the fourth embodiment or the flexible pressure sensor described in the fifth embodiment, and as a basic unit, the flexible pressure sensor Multi-layer assembly is not only conducive to improving the pressure resistance, but also enhances the anti-interference ability.
  • FIG. 6 it shows the change curve of capacitance increase when the pressure sensor receives a pressure from 0 to 25kPa and then returns to 0.
  • 50 capacitance output readings are selected for each data point, and the average value and standard deviation are calculated.
  • the pressure sensor has a sensitivity of 39% kPa -1 in the range of 0-1 kPa, 15% kPa -1 in the range of 1-6 kPa , 10% kPa -1 in the range of 6-25 kPa, and a maximum pressure of 25 kPa Below, the hysteresis error is 8.46%.
  • the pressure-capacitance increment curves of all sensing units are arranged in order according to their spatial serial numbers, and the consistency of the mechanical-electrical response of each unit in the 4 ⁇ 4 sensor array is studied.
  • the capacitance increments of all curves have the same changing trend, and the sensitivity deviation of each unit is only 0.48%kPa -1 .
  • the three photos respectively show different states of the sensor array (tensile strain: 0, 45%, 94%). Thanks to the fluidity of the liquid metal and the lower Young's modulus of the Ecoflex elastomer, no obvious cracks appeared on the electrode and the elastomer during the stretching process.
  • This application uses numerical simulation to analyze the tensile state of the sensor.
  • Figure 8b shows the tensile state of the top arched electrode when the strain is 0, 14%, 31%, and 45%, and the volumetric strain of the arched electrode in each state. Distribution.
  • Each sensing unit contains an arched protrusion and a surrounding flat membrane. The deformed part of the pressure sensor is mainly concentrated in the arched protrusion position.
  • FIG. 8c summarizes the mechanical-electrical performance of the pressure sensor in normal (0% strain) and tensile (45% strain) states. The same mechanical load is applied to the same sensing unit in the pressure range of 0-4kPa. Due to the unique arched structure of the top electrode of the sensor, there is no significant difference in the change curve of capacitance increase with pressure in the two states.
  • 4 ⁇ 4 sensor arrays were used to detect different types of pressure sources, including a cylindrical weight (mass of 20g, bottom diameter of 13mm, representing a relatively concentrated load) and a ring Shaped tape (mass of 16g, diameter of 52mm, representing a relatively dispersed load).
  • a cylindrical weight mass of 20g, bottom diameter of 13mm, representing a relatively concentrated load
  • a ring Shaped tape mass of 16g, diameter of 52mm, representing a relatively dispersed load.
  • place the weight and tape in the corresponding position of the same sensor array record the capacitance increment displayed by each sensor unit, and calculate the pressure of each sensor unit.
  • the sensor arrays are numbered as shown in Figure 9(a).
  • the contact area between the weight and the sensor is small, and its bottom is roughly located on the No. 7 sensor unit, and there is also a small contact with the neighboring sensor unit.
  • Figure 9(c) the No.
  • Figure 9(ef) is the pressure contour map in the above two cases, which more clearly shows the relative position and intensity of the pressure source on the sensor array, and even the basic shape of the pressure source can be roughly inferred from the contour. appearance.
  • this application explores the potential application of recognizing the posture of the neck.
  • the pressure sensor has sufficient elasticity, softness and biocompatibility, can fit human skin comfortably, and adapt to most neck postures.
  • the pressure sensor array is attached to the skin of the neck and fixed with a film. There is an initial pressure between the sensor and the skin at this time.
  • the pressure between the sensor and the neck of the volunteer in the posture of looking straight ahead is defined as the initial value, and the capacitance value of each sensing unit in this posture is set as the initial capacitance.
  • the capacitance increment of each sensing unit is calculated, and the corresponding pressure change of each sensing unit is calculated.
  • Figure 10(c-d) shows the neck posture and the corresponding pressure distribution when the experimenter raises his head.
  • the color of the signals measured by all the sensing units changes in the figure, indicating that the pressure detected by all the sensing units of the volunteers in the head-up posture has increased compared with the forward-looking posture.
  • the sensor array detects a lateral pressure gradient. Among them, the leftmost column of sensor units detected the highest pressure increase, and the rightmost column of sensor units detected a pressure lower than that in the direct-viewing posture, indicating that the pressure was mainly distributed on the side where the experimenter turned.
  • various neck postures of the user can be inferred, providing an effective reference for subsequent real-time neck posture recognition.
  • the sensor array can be applied to detect unhealthy neck postures for patients in rehabilitation training, etc., and promptly remind them.

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Abstract

一种液态金属薄膜电极的制造方法及柔性压力传感器，包括：将弹性体介电层（10）的两种组分按照比例混合，经过搅拌并除去气泡后，滴加在经表面活性剂处理的第一载体（20）上，并进行旋涂处理；对第一载体（20）进行加热，在弹性体介电层（10）未完全固化时粘贴导电胶带（30）；将液体金属喷涂在弹性体介电层（10）上，形成液态金属电极（40），且液态金属电极（40）与导电胶带（30）相连；在带有液态金属电极（40）的弹性体介电层（10）上加入定型体，形成第一液态金属弹性体复合电极（61），待固化后，将第一液态金属弹性体复合电极（61）从第一载体（20）上分离。该柔性压力传感器灵敏度高，不易受外界环境干扰。

Description

液态金属薄膜电极的制造方法及柔性压力传感器 技术领域
本发明涉及柔性压力传感器的技术领域，尤其是指一种液态金属薄膜电极的制造方法及柔性压力传感器。
背景技术
柔性压力传感器按照工作原理可以分为电容式、电阻式、压电式等。其中，电容式压力传感器具有检测极限低、灵敏度高、能耗小、发热程度低以及结构紧凑等优点。电容式压力传感器由柔性电极和电容介质组成，根据外力作用下电极正对面积、间隔距离以及电容介质的改变实现输出信号的响应。其中，柔性电极的制备方案大体可分为两种：一种是向聚二甲基硅氧烷(PDMS)、苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(SEBS)、聚氨酯(PU)等弹性聚合物基质中掺入石墨烯、碳纳米管(CNTs)、金属纳米颗粒或纳米线等导电填料；另一种是选用自身可拉伸的导电材料，比如离子液体、离子凝胶、液态金属等。
上述两种柔性电极制备方案中，向弹性体聚合物中掺入导电填料的方法会增大材料整体的杨氏模量，降低机械强度和可拉伸性，在形变过程中容易导致电阻急剧增大，甚至产生不可逆损坏；而以液态金属等材料作为柔性电极时，其流动性增加了三维结构修饰和封装的难度。
另外现有的柔性压力传感器中，“柔性”往往仅限于能够自由弯曲以及轻微的拉伸。虽然目前有很多可拉伸材料被用于研发应变传感器，即利用材料拉伸形变产生的电学信号来反馈传感器的拉伸程度，但拉伸这一变量对于大多数压力传感器来说，是一个影响压力检测准确性的干扰因素，因此，压力传感器的可拉伸性并没有得到充足的研究，如何在保证压力灵敏度的基础 上提升传感器的柔性和可拉伸性仍然是一个值得研究的问题。
发明内容
为此，本发明所要解决的技术问题在于克服现有技术中压力传感器可拉伸性差、压力信号易受拉伸干扰等问题，从而提供一种高灵敏度、可拉伸的液态金属薄膜电极的制造方法及柔性压力传感器。
为解决上述技术问题，本发明的一种液态金属薄膜电极的制造方法，包括：将弹性体介电层的两种组分按照比例混合，经过搅拌并除去气泡后，滴加在经表面活性剂处理的第一载体上，并进行旋涂处理；对所述第一载体进行加热，在所述弹性体介电层未完全固化时粘贴导电胶带；将液体金属喷涂在所述弹性体介电层上，形成液态金属电极，且所述液态金属电极与所述导电胶带相连；在带有液态金属电极的弹性体介电层上加入定型体，形成第一液态金属弹性体复合电极，待固化后，将所述第一液态金属弹性体复合电极从所述第一载体上分离。
在本发明的一个实施例中，所述弹性体介电层和定型体所使用的材料是硅橡胶。
本发明还提供了一种液态金属薄膜电极的制备方法，在完成上述的液态金属薄膜电极的制备方法的步骤后，还包括：将第一液态金属弹性体复合电极置放在第二载体上，使所述第一液态金属弹性体复合电极中的弹性体介电层朝向所述第二载体，并将具有液态金属电极的条纹与所述第二载体的微孔对齐；将所述第二载体及第一液态金属弹性体复合电极置放在真空环境中，先施加负压，然后增压，使所述第一液态金属弹性体复合电极向所述微孔内凹陷；在所述凹陷内加入定型体，形成第二液态金属弹性体复合电极，待固化后，将所述第二液态金属弹性体复合电极从所述第二载体上分离。
在本发明的一个实施例中，所述第一液态金属弹性体复合电极向所述微孔内凹陷的程度通过改变负压的大小进行调节。
本发明还提供了一种柔性压力传感器，包括第一液态金属弹性体复合电极以及第二液态金属弹性体复合电极，其中所述第一液态金属弹性体复合电 极为平面结构，所述第二液态金属弹性体复合电极为拱形结构，且所述第二液态金属弹性体复合电极位于所述第一液态金属弹性体复合电极的上方。
在本发明的一个实施例中，所述第一液态金属弹性体复合电极的液态金属条纹与所述第二液态金属弹性体复合电极的液态金属条纹相互垂直，且所述第二液态金属弹性体复合电极的拱形凸起与所述第一液态金属弹性体复合电极的液态金属条纹相互对齐。
本发明还提供了一种柔性压力传感器，包括上述的柔性压力传感器，且多个第一液态金属弹性体复合电极的数量为多个，且呈阵列式排布，第二液态金属弹性体复合电极的数量也为多个，且呈阵列式排布。
本发明还提供了一种柔性压力传感器，包括两个第二液态金属弹性体复合电极，其中一个作为底层电极，另一个作为顶层电极，且所述第二液态金属弹性体复合电极为拱形结构。
本发明还提供了一种柔性压力传感器，包括上述的柔性压力传感器，作为底层电极的第二液态金属弹性体复合电极的数量为多个，且呈阵列式排布，作为顶层电极的第二液态金属弹性体复合电极的数量也为多个，且呈阵列式排布。
本发明还提供了一种柔性压力传感器，包括上述阵列式的柔性压力传感器中的任意一种，且作为基本单元，将所述柔性压力传感器进行多层的组装。
本发明的上述技术方案相比现有技术具有以下优点：
本发明所述的液态金属薄膜电极的制造方法及柔性压力传感器，包括拱形结构的液态金属薄膜、均匀包封液态金属的Ecoflex薄膜、作为结构支撑的Ecoflex基底，其中拱形结构形状的保持可以由Ecoflex填充来实现。另外，基本单元空间尺寸大小、液体金属薄膜厚度、Ecoflex的薄膜厚度均可调控。且经过试验可以得到：所述压力传感器可以承受94％拉伸应变，而没有出现明显损坏；所述压力传感器在45％拉伸应变下对压力的响应与正常状态几乎相同，即不易受到拉伸对压力测量信号的干扰；免疫温度、湿度的干扰。
附图说明
为了使本发明的内容更容易被清楚的理解，下面根据本发明的具体实施例并结合附图，对本发明作进一步详细的说明，其中
图1是本发明第一液态金属弹性体复合电极的制造方法流程图；
图2是本发明第一液态金属弹性体复合电极的具体制备过程；
图3是本发明第二液态金属弹性体复合电极的制造方法流程图；
图4是本发明第二液态金属弹性体复合电极的具体制备过程；
图5a是本发明在压力传感器在没有受到外界压力时的状态示意图；
图5b是本发明在压力传感器在受到外界压力时的状态示意图；
图6是本发明压力传感器受到不断变化的压力时的电容增量变化曲线；
图7是本发明压力传感器阵列中各单元机械与电学响应的示意图；
图8a是本发明压力传感器阵列的不同状态的示意图；
图8b是本发明顶层拱形电极在应变为不同时的拉伸状态示意图；
图8c是本发明压力传感器在正常以及拉伸状态下的机械与电学性能；
图8d是本发明压力传感器在多次拉伸后，初始电容值的变异系数的变化示意图；
图9是本发明压力传感器阵列测量二维压力分布的应用示意图；
图10是本发明压力传感器应用在颈部时压力变化的示意图。
说明书附图标记说明：10-弹性体介电层，20-第一载体，30-导电胶带，40-液态金属电极，50-第二载体，51-微孔，61-第一液态金属弹性体复合电极，62-第二液态金属弹性体复合电极。
具体实施方式
实施例一
如图1和图2和图5a和图5b所示，本实施例提供一种液态金属薄膜电 极的制造方法，包括如下步骤：步骤S1:将弹性体介电层10的两种组分按照比例混合，经过搅拌并除去气泡后，滴加在经表面活性剂处理的第一载体20上，并进行旋涂处理；步骤S2：对所述第一载体20进行加热，在所述弹性体介电层未完全固化时粘贴导电胶带30；步骤S3：将液体金属喷涂在所述弹性体介电层10上，形成液态金属电极40，且所述液态金属电极40与所述导电胶带30相连；步骤S4：在带有液态金属电极40的弹性体介电层10上加入定型体，形成第一液态金属弹性体复合电极61，待固化后，将所述第一液态金属弹性体复合电极61从所述第一载体20上分离。
本实施例所述液态金属薄膜电极的制造方法，所述步骤S1中，将弹性体介电层10的两种组分按照比例混合，经过搅拌并除去气泡后，滴加在经表面活性剂处理的第一载体20上，从而有利于揭膜，防止撕坏，并进行旋涂处理，使旋涂更均匀；所述步骤S2中，对所述第一载体20进行加热，在所述弹性体介电层未完全固化时粘贴导电胶带30，以便在柔性传感器封装完成后实现外部导线与液态金属的连接；所述步骤S3中，将液体金属喷涂在所述弹性体介电层10上，形成液态金属电极40，且所述液态金属电极40与所述导电胶带30相连，有利于信号的传输；所述步骤S4中，在带有液态金属电极40的弹性体介电层10上加入定型体，有利于起到支撑和封装液态金属的作用，形成第一液态金属弹性体复合电极61，待固化后，将所述第一液态金属弹性体复合电极61从所述第一载体20上分离，从而形成一组没有特殊三维结构的平面电极，可以用作柔性传感器的底层电极。
本实施例中，所述弹性体介电层和定型体所使用的材料是硅橡胶。具体地，所述弹性体介电层和定型体所使用的材料包括Ecoflex弹性体材料、PDMS弹性体材料、或者其它橡胶材料、以及这三种材料之间的组合；所述第一载体20可以是硅片。所述液态金属包括镓铟合金(EGaIn)和镓铟锡合金(Galinstan)。
具体地，将Ecoflex 0030的A、B组分以1:1的比例混合(其中可以按照质量比或者体积比混合)，充分搅拌并真空除泡，滴加在经表面活性剂处理的硅片中心，使用匀胶旋涂仪以500rpm旋涂10s，1000rpm旋涂1min。
将所述硅片置于50℃加热板，在未完全固化时粘贴铜镍导电布胶带，以便在柔性传感器封装完成后实现外部导线与液态金属的连接。
将少量液态金属滴加到喷笔中，连接气泵，设置气压为40psi，通过定制的不锈钢掩膜板，用压缩空气将液态金属在Ecoflex薄膜上喷涂液态金属电极40。喷涂时间可以为5s，喷嘴与掩膜板保持20cm的距离；在带有液态金属电极40图案的Ecoflex薄膜上滴加3g Ecoflex预聚体，以低转速旋涂使其均匀摊开，60℃加热10min使其固化。其中这层的Ecoflex起到支撑整个结构和封装液态金属的作用。
所述第一液态金属弹性体复合电极61从所述第一载体20上分离前，还包括对所述第一液态金属弹性体复合电极61进行清洗、干燥的步骤。具体地，将制备的液态金属弹性体复合电极从硅片上缓慢揭开，并用超纯水和乙醇清洗，最后放入烘箱中干燥。
实施例二
如图3和图4所示，本实施例提供一种液态金属薄膜电极的制备方法，在完成实施例一所述的液态金属薄膜电极的制备方法的步骤后，还包括：步骤step1：将第一液态金属弹性体复合电极61置放在第二载体50上，使所述第一液态金属弹性体复合电极61中的弹性体介电层10朝向所述第二载体50，并将具有液态金属电极的条纹与所述第二载体50的微孔51对齐；步骤step2：将所述第二载体50及第一液态金属弹性体复合电极61置放在真空环境中，先施加负压，然后增压，使所述第一液态金属弹性体复合电极61向所述微孔51内凹陷；步骤step3：在所述凹陷内加入定型体，形成第二液态金属弹性体复合电极62，待固化后，将所述第二液态金属弹性体复合电极62从所述第二载体上分离。
本实施例提供一种液态金属薄膜电极的制备方法，在完成实施例一所述的液态金属薄膜电极的制备方法的步骤后，还包括步骤step1，将第一液态金属弹性体复合电极61置放在第二载体50上，使所述第一液态金属弹性体复合电极61中的弹性体介电层10朝向所述第二载体50，并将具有液态金 属电极的条纹与所述第二载体50的微孔51对齐，从而有利于对所述弹性体介电层10进行变形；所述步骤step2中，将所述第二载体50及第一液态金属弹性体复合电极61置放在真空环境中，先施加负压，然后增压，从而产生的压强差会促使所述第一液态金属弹性体复合电极61向所述微孔51内凹陷；所述步骤step3中，在所述凹陷内加入定型体，有利于起到支撑和封装液态金属的作用，形成第二液态金属弹性体复合电极62，待固化后，将所述第二液态金属弹性体复合电极62从所述第二载体50上分离，从而形成一组具有三维结构的非平面电极，具体地，形成拱形电极，可以用作柔性传感器的顶层电极。
本实施例中，所述第二载体50可以是96孔板。
将实施例一种形成的所述第一液态金属弹性体复合电极61平铺在96孔板上，使Ecoflex介电层薄膜朝向所述96孔板，并将液态金属电极条纹与所述96孔板的圆形微孔对齐。
将所述96孔板与第一液态金属弹性体复合电极61整体移入真空箱，施加-0.03MPa的负压。在具体操作过程中，使用弹性体薄膜与模具形成密闭腔室，利用腔室内外气压差改变薄膜结构，最后浇铸聚合物保持结构。通过设计模具的不同内部结构，可以改变薄膜的三维结构。相比于直接在模具上浇铸聚合物，本申请所述的方法的优点在于可以在聚合物内部，厚度均匀的薄膜下嵌入其它柔性材料。
经过设定时间如30秒后，向所述真空箱中通入空气，所述真空箱内气压瞬间增大，使第一液态金属弹性体复合电极61被吸附在所述96孔板上。随着外界空气持续进入所述真空箱，所述96孔板外气压继续上升，产生的压强差促使弹性优异的复合电极向所述96孔板的圆形微孔内凹陷。所述第一液态金属弹性体复合电极61向所述微孔51内凹陷的程度通过改变负压的大小进行调节。如凹陷的程度可以在实验中通过适当改变负压的大小进行调节。
向所述凹陷中加入Ecoflex预聚体进行填充，形成第二液态金属弹性体 复合电极，放入60℃烘箱中加热10min，待Ecoflex完全固化后，将第二液态金属弹性体复合电极从所述96孔板上取出。
实施例三
请参考附图5a和图5b所示，本实施例提供第一种柔性压力传感器，包括第一液态金属弹性体复合电极61以及第二液态金属弹性体复合电极62，其中所述第一液态金属弹性体复合电极61为平面结构，所述第二液态金属弹性体复合电极62为拱形结构，且所述第二液态金属弹性体复合电极62位于所述第一液态金属弹性体复合电极61的上方。
本实施例所述的柔性压力传感器，包括第一液态金属弹性体复合电极61以及第二液态金属弹性体复合电极62，其中所述第一液态金属弹性体复合电极61为平面结构，所述第二液态金属弹性体复合电极62为拱形结构，且所述第二液态金属弹性体复合电极62位于所述第一液态金属弹性体复合电极61的上方，即将所述第一液态金属弹性体复合电极61作为底层，所述第二液态金属弹性体复合电极62作为顶层，从而有利于承受更多的拉伸应变，提高使用寿命；另外，所述压力传感器在一定拉伸应变下对压力的响应与正常状态几乎相同，不易受到拉伸对压力测量信号的干扰，灵敏度高，避免外界环境如温度、湿度的干扰。
所述第一液态金属弹性体复合电极61的液态金属条纹与所述第二液态金属弹性体复合电极62的液态金属条纹相互垂直，且所述第二液态金属弹性体复合电极62的拱形凸起与所述第一液态金属弹性体复合电极61的液态金属条纹相互对齐，从而有利于承受更多的拉伸应变，提高使用寿命。
具体地，其中底层电极为平面结构，顶层电极为拱形结构液态金属薄膜。两层复合电极的Ecoflex电容介质朝内叠放，使两层电极的液态金属条纹相互垂直，顶层电极上的拱形凸起与底层电极的条纹中心相互对齐。为了固定两层复合电极的相对位置，在传感单元以外的区域使用极少量的Ecoflex进行键合。
如图5a所示，当顶部电极中的液态金属沿着拱形结构弹性体弯曲，使 得压力传感器在零外力的初始状态下，保持两个电极之间最小的接触面积以及最大的间隔距离。当所述压力传感器受到外界压力的作用，如图5b所示，顶层的液态金属薄膜电极受到挤压，电极之间的接触面积明显增大，同时间隔距离减小。该压力传感器可以等效为一个可变电容器和电阻串联的电路，电容可以通过平行板电容器的经典方程来预测：
Figure PCTCN2020123605-appb-000001
其中，A代表两个电极的正对面积，d代表两个电极之间的距离，ε 0和ε r分别代表绝对介电常数和电容介质的相对介电常数。
实施例四
本实施例提供第二种柔性压力传感器，本实施例四是在所述实施例三上的基础上进行的改进，使整个柔性压力传感器呈阵列式排布，具体地，所述多个第一液态金属弹性体复合电极61的数量为多个，且呈阵列式排布，所述第二液态金属弹性体复合电极62的数量也为多个，且呈阵列式排布，从而形成的柔性压力传感器也呈阵列式排列，有利于测量压力分布，提高使用寿命。
另外，呈阵列式排列的柔性压力传感器，其中的阵列可以是平行排布，也可以是垂直排布，如可以是两两成对(镜像对称)编组垂直排布；也可以逐一串联垂直排布。
实施例五
本实施例提供第三种柔性压力传感器，与实施例三所述的第一种柔性压力传感器的组成由差别，具体地：包括两个第二液态金属弹性体复合电极62，其中一个作为底层电极，另一个作为顶层电极，且所述第二液态金属弹性体复合电极62为拱形结构。
本实施例所述的第三种柔性压力传感器，包括两个第二液态金属弹性体复合电极62，其中一个作为底层电极，另一个作为顶层电极，且所述第二液态金属弹性体复合电极62为拱形结构，不但有利于提高抗压能力，而且增强抗干扰能力。
另外，在所述顶层电极和底层电极中，分别使用的拱形结构的弯曲弧方向包括同向设置以及反向设置。
作为底层电极的第二液态金属弹性体复合电极的数量为多个，且呈阵列式排布，作为顶层电极的第二液态金属弹性体复合电极的数量为多个，且呈阵列式排布，有利于测量压力分布，提高使用寿命。
实施例六
本实施例提供第四种柔性压力传感器，是在实施例四和实施例五所在的基础上作出的改进，具体地：包括实施例四所述的柔性压力传感器或者实施例五所述的柔性压力传感器中的任意一种，且作为基本单元，将所述柔性压力传感器进行多层的组装。
本实施例所述的第四种柔性压力传感器，包括实施例四所述的柔性压力传感器或者实施例五所述的柔性压力传感器中的任意一种，且作为基本单元，将所述柔性压力传感器进行多层的组装，不但有利于提高抗压能力，而且增强抗干扰能力。
下面结合试验详细证明上述的有益效果：
如图6所示，展示了压力传感器受到从0到25kPa的压力，再恢复到0的过程中电容增量变化曲线。其中每个数据点选取50个电容输出读数，并计算平均值和标准偏差。该压力传感器在0-1kPa范围内灵敏度为39％kPa -1，在1-6kPa范围内灵敏度为15％kPa -1，在6-25kPa范围内灵敏度为10％kPa -1，在25kPa的最大压强下，迟滞性误差为8.46％。
如图7所示，将所有传感单元的压强-电容增量曲线根据各自的空间序号依次排列，研究了4×4传感器阵列中各单元机械-电学响应的一致性。在0-25kPa的压强范围内，所有曲线的电容增量均有相同的变化趋势，各个单元的灵敏度偏差仅为0.48％kPa -1。
如图8a所示，三张照片分别显示了传感器阵列的不同状态(拉伸应变：0、45％、94％)。得益于液态金属的流动性和Ecoflex弹性体较低的杨氏模量，在拉伸过程中电极和弹性体上均没有出现明显的裂纹。本申请用数值模拟分析了传感器的拉伸状态，图8b为顶层拱形电极在应变为0、14％、31％、45％时的拉伸状态，以及每个状态下拱形电极的体积应变分布情况。每个传感单 元包含一个拱形的凸起和周围平面的薄膜，压力传感器在受到压力时发生形变的部分主要集中在拱形的凸起位置。这个位置受到较厚的Ecoflex弹性体的保护，因此，当压力传感器在拉伸状态下，这种厚度不均一性使拉伸应变主要分散在与电容信号无关的部位，很大程度上削弱了拉伸应力对拱形电极造成的应变，从而减小了对电容信号的影响。图8c总结了所述压力传感器在正常(0％应变)以及拉伸(45％应变)状态下的机械-电学性能。在0-4kPa的压强范围内对同一个传感单元施加了相同的机械荷载，由于传感器顶层电极独特的拱形结构，在两种状态下，电容增量随压强的变化曲线没有显著的差别，验证了数值模拟的结果。这意味着该传感器即使在45％应变的拉伸状态下，仍然可以输出准确的电学信号。除此之外，本申请还对传感器进行了约为94％应变的反复拉伸-恢复循环，并每隔30次循环，在初始长度状态下测量了传感单元的电容大小。如图8d所示，在180次拉伸的过程中，这些初始电容值的变异系数(CV)小于1.2％，表明该传感器可以承受反复的高强度机械拉伸，且仍保持正常的功能。
如图9所示，使用4×4传感器阵列分别对不同类型的压力源进行了检测，包括一个圆柱形砝码(质量为20g，底面直径为13mm，代表压力相对集中的荷载)和一个圆环形的胶带(质量为16g，直径为52mm，代表压力相对分散的荷载)。如图9(a-b)所示，把砝码和胶带先后放置在同一个传感器阵列的相应位置，记录每个传感单元显示的电容增量，并计算出各传感单元承受的压强。如图9(a)所示对传感器阵列进行了编号。砝码与传感器的接触面积较小，其底部大致位于7号传感单元上，与邻近的传感单元也有较小的接触。如图9(c)所示，7号单元承受了大部分的压力(相对压强为1.41kPa)，邻近的传感单元显示出较小的相对压强：450Pa(3号)、180Pa(8号)、100Pa(6号)、80Pa(11号)、40Pa(4号)。相比之下，胶带在接触传感器时产生的压力较为分散。由图9(d)可知，处于传感器阵列四个角位置的单元由于与胶带直接接触的面积最大，承担了大部分的压力(相对压强160-210Pa)，接下来是四条边上的8个传感单元(70-130Pa)。中间的4个传感单元虽然没有与胶带直接接触，但由于受到周围压力的干 扰，也显示出了较小的信号。图9(e-f)是上述两种情况下的压强等值线图，更清楚地显示出压力源在传感器阵列上的相对位置以及强度，甚至还可以通过等值线大致推断出压力源的基本形貌。
如图10所示，通过检测传感器各单元与颈部之间的压强，本申请对识别颈部姿势的潜在应用进行了探索。该压力传感器具有足够的弹性、柔软度和生物相容性，可以舒适地贴合人体皮肤，并适应绝大多数颈部姿势。本申请把压力传感器阵列贴合在颈部皮肤上，用薄膜加以固定。此时传感器和皮肤之间有一个初始的压力。如图10(a-b)所示，将志愿者在直视前方的姿势下传感器与颈部之间的压强定义为初始值，并把这个姿势下各传感单元的电容值设为初始电容。当实验者变换各种颈部姿势时，计算出各传感单元的电容增量，并推算出每个传感单元对应压强的变化。
如图10(c-d)显示了实验者仰头时的颈部姿势以及对应的压力分布。所有传感单元测得的信号在图中的颜色由变化，说明与向前直视的姿势相比，志愿者在仰头的姿势下所有传感单元检测到的压强都变大了。如图10(e-f)，当实验者向左旋转头部时，传感器阵列检测到一个横向的压力梯度。其中，最左边的一列传感单元检测到最高的压力增量，而最右边的一列传感单元检测到比直视姿势下减小的压强，表明压力主要分布在实验者转向的一侧。
通过分析颈部区域的压力分布，可以推断出使用者的各种颈部姿势，为后续的实时颈部姿势识别提供有效参考。进而，该传感器阵列可以被应用于为康复训练中的患者等检测不健康的颈部姿势，并及时进行提醒。
显然，上述实施例仅仅是为清楚地说明所作的举例，并非对实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式变化或变动。这里无需也无法对所有的实施方式予以穷举。而由此所引伸出的显而易见的变化或变动仍处于本发明创造的保护范围之中。

Claims (10)

  1. 一种液态金属薄膜电极的制备方法，其特征在于，包括如下步骤：
    步骤S1:将弹性体介电层的两种组分按照比例混合，经过搅拌并除去气泡后，滴加在经表面活性剂处理的第一载体上，并进行旋涂处理；
    步骤S2：对所述第一载体进行加热，在所述弹性体介电层未完全固化时粘贴导电胶带；
    步骤S3：将液体金属喷涂在所述弹性体介电层上，形成液态金属电极，且所述液态金属电极与所述导电胶带相连；
    步骤S4：在带有液态金属电极的弹性体介电层上加入定型体，形成第一液态金属弹性体复合电极，待固化后，将所述第一液态金属弹性体复合电极从所述第一载体上分离。
  2. 根据权利要求1所述的液态金属薄膜电极的制备方法，其特征在于：所述的弹性体介电层和定型体所使用的材料是硅橡胶。
  3. 一种液态金属薄膜电极的制备方法，其特征在于：在完成权利要求1或2所述的液态金属薄膜电极的制备方法的步骤后，还包括：
    步骤step1：将第一液态金属弹性体复合电极置放在第二载体上，使所述第一液态金属弹性体复合电极中的弹性体介电层朝向所述第二载体，并将具有液态金属电极的条纹与所述第二载体的微孔对齐；
    步骤step2：将所述第二载体及第一液态金属弹性体复合电极置放在真空环境中，先施加负压，然后增压，使所述第一液态金属弹性体复合电极向所述微孔内凹陷；
    步骤step3：在所述凹陷内加入定型体，形成第二液态金属弹性体复合电极，待固化后，将所述第二液态金属弹性体复合电极从所述第二载体上分离。
  4. 根据权利要求3所述的液态金属薄膜电极的制备方法，其特征在于：所述第一液态金属弹性体复合电极向所述微孔内凹陷的程度通过改变负压的大小进行调节。
  5. 一种柔性压力传感器，其特征在于：包括第一液态金属弹性体复合电极以及第二液态金属弹性体复合电极，其中所述第一液态金属弹性体复合电极为平面结构，所述第二液态金属弹性体复合电极为拱形结构，且所述第二液态金属弹性体复合电极位于所述第一液态金属弹性体复合电极的上方。
  6. 根据权利要求5所述的柔性压力传感器，其特征在于：所述第一液态金属弹性体复合电极的液态金属条纹与所述第二液态金属弹性体复合电极的液态金属条纹相互垂直，且所述第二液态金属弹性体复合电极的拱形凸起与所述第一液态金属弹性体复合电极的液态金属条纹相互对齐。
  7. 一种柔性压力传感器，其特征在于：包括权利要求5-6中任意一项所述的柔性压力传感器，且多个第一液态金属弹性体复合电极的数量为多个，且呈阵列式排布，第二液态金属弹性体复合电极的数量也为多个，且呈阵列式排布。
  8. 一种柔性压力传感器，其特征在于：包括两个第二液态金属弹性体复合电极，其中一个作为底层电极，另一个作为顶层电极，且所述第二液态金属弹性体复合电极为拱形结构。
  9. 一种柔性压力传感器，其特征在于：包括权利要求8所述的柔性压力传感器，作为底层电极的第二液态金属弹性体复合电极的数量为多个，且呈阵列式排布，作为顶层电极的第二液态金属弹性体复合电极的数量也为多个，且呈阵列式排布。
  10. 一种柔性压力传感器，其特征在于：包括权利要求7所述的柔性压力传感器或者权利要求9所述的柔性压力传感器中的任意一种，且作为基本单元，将所述柔性压力传感器进行多层的组装。
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