A liquid metal microchannel structure based on the CC origami configuration

Abstract

The present invention discloses a liquid metal microchannel structure based on a CC origami configuration. It includes a microchannel layer, a packaging layer, a liquid metal layer, lead-out electrodes, and crease grooves; on both sides of the upper surface of the microchannel layer, a first microchannel groove and a second microchannel groove are respectively opened. Lead-out electrodes are placed at both ends corresponding to the first microchannel groove and the second microchannel groove. The first microchannel groove and the second microchannel groove of the microchannel layer are filled with liquid metal, and the liquid metal is in contact electrical connection with the lead-out electrodes in the microchannel grooves; on both sides of the upper surface of the microchannel layer, a first packaging layer and a second packaging layer are respectively laid. A crease groove is also opened on the upper surface of the microchannel layer between the first microchannel groove and the second microchannel groove, and the crease groove is a dividing groove between the first packaging layer and the second packaging layer. The structure of the present invention has the advantages of good adaptability, compact structure, light weight, easy manufacturing, etc. while removing the bending interference signals of the electronic skin.

Description

Technical Field

[0001] The present invention belongs to a liquid metal microchannel structure in the technical field of sensors, and particularly relates to a liquid metal microchannel structure based on a CC origami configuration. Background Art

[0002] Currently, electronic skin has become a popular research direction in the field of sensors. Electronic skin is generally also called a flexible pressure sensor. Compared with traditional rigid sensors, electronic skin can be attached to irregular or changing surfaces to perceive external force stimuli. Since electronic skin is made of flexible materials (such as silicone rubber, etc.), its body has the characteristic of flexibility, is not easy to hinder the movement of the carrier, and is easier to achieve lightweight.

[0003] When planar electronic skin covers a humanoid robot or a wearable sensing device, bending strain will be generated, affecting the initial resistance value or capacitance value; and when the robot joint moves, the surface covered by the electronic skin will deform, generating bending strain that changes constantly. In flexible pressure sensors based on sensitive elements such as conductive liquid microchannels and flexible electrodes, this bending strain will generate coupled resistance or capacitance changes. Summary of the Invention

[0004] To solve the problems and requirements in the background art, the present invention provides a microchannel structure based on a CC origami configuration for electronic skin design. Existing electronic skins based on liquid metal sensing materials generally construct a hollow microchannel structure, encapsulate liquid metal in a flexible substrate constituting the microchannel structure, and establish a mapping relationship between force stimuli and resistance signals through the deformation of the microchannel generated when pressed; in terms of microchannel structure design, it is mainly based on accumulated experience; at the sensor preparation level, a high-precision mold is mainly printed by 3D printing, a silicone substrate is cast with the mold and vacuum-treated to obtain a flexible substrate with uniform material, and liquid metal is injected with a micro syringe. The related technology of the present invention is based on the above sensing mechanism, design experience and preparation technology. This structure enables the electronic skin not to be interfered by bending signals, thereby improving the measurement accuracy of the sensor; on the other hand, when the electronic skin is placed on a wearable device, the creases designed based on the CC origami configuration can also reduce the resistance generated by the force sensor during joint movement and improve the movement performance of the joint.

[0005] The technical solution adopted by the present invention is as follows:

[0006] I. A liquid metal microchannel structure based on a CC origami configuration

[0007] The liquid metal microchannel structure includes a microchannel layer, a first encapsulation layer, a first liquid metal layer, a second encapsulation layer, a second liquid metal layer, lead electrodes, and crease grooves;

[0008] On both sides of the upper surface of the microchannel layer, a first microchannel groove and a second microchannel groove are respectively opened. Lead electrodes are placed at both ends corresponding to the first microchannel groove and the second microchannel groove. The first microchannel groove and the second microchannel groove in the microchannel layer are both filled with liquid metal, and the liquid metal is in contact electrical connection with the lead electrodes in the microchannel grooves; on both sides of the upper surface of the microchannel layer, a first encapsulation layer and a second encapsulation layer are respectively laid. The first encapsulation layer is used to encapsulate the liquid metal in the first microchannel groove, thereby forming a first liquid metal layer, and the second encapsulation layer is used to encapsulate the liquid metal in the second microchannel groove, thereby forming a second liquid metal layer; a crease groove is also opened on the upper surface of the microchannel layer between the first microchannel groove and the second microchannel groove, and the crease groove is a dividing groove between the first encapsulation layer and the second encapsulation layer.

[0009] The microchannel layer, the first encapsulation layer and the second encapsulation layer are all made of flexible materials.

[0010] The tensile and shear strength of the microchannel layer is the tensile and shear strength of Dow Corning dragon skin30. The groove distance at the same height in the crease groove is the same, and the groove distance at the bottom of the crease groove is 2-3mm.

[0011] The self-groove distance of the first microchannel groove is the same, and the self-groove distance of the second microchannel groove is the same. The tensile and shear strength of the microchannel layer is the tensile and shear strength of Dow Corning dragon skin30. The self-groove distance of the first microchannel groove and the self-groove distance of the second microchannel groove are both 1-2mm.

[0012] The width value range of the first microchannel groove and the second microchannel groove is 100-1000μm, and the thickness of the microchannel layer is greater than 1mm.

[0013] The thicknesses of the first encapsulation layer and the second encapsulation layer are both 1-2mm.

[0014] The shape parameters of the crease groove are obtained through the following steps:

[0015] 1) When there is no crease groove on the upper surface of the microchannel layer, the microchannel layer adheres to the surface of the object. After the surface of the object is bent, the microchannel layer is folded. Analyze the stress nephogram of the folded microchannel layer to obtain the original stress peak point, denoted as vertex O. Taking the vertex as the center of the sphere, determine the radius r according to the actual pressure sensor layout range on the surface of the object, thereby establishing a spherical boundary equation. Solve the spherical boundary equation to obtain two boundary points, and the stresses at both boundary points are stress peaks. Denote the two boundary points as the first endpoint P 1 , the second P 2 ;

[0016] 2) The vertex O, the first endpoint P 1 , the second endpoint P 2The plane formed by three points is denoted as u j -v j For the plane, solve for the first endpoint P 1 , the second endpoint P 2 The equivalent stresses of are the first projection stress σ j -v j on the plane P1 , the second projection stress σ P2 ;

[0017] 3) Denote the straight-line distance between the first endpoint P 1 and the second endpoint P 2 as the surface span l j , denote the distance from the vertex to the line connecting the endpoints as the surface arch height h j , and denote the average of the angles between the first projection stress σ P1 , the second projection stress σ P2 and the line connecting the first endpoint P 1 and the second endpoint P 2 as the tangential angle Based on the surface span l j , the surface arch height h j and the surface tangential angle obtain the crease curve in the developable surface by fitting through the following formula:

[0018]

[0019]

[0020] The equation of the crease curve in the developable surface is as follows:

[0021]

[0022] where m j , n j , a j , b j are the first - fourth elliptic curve parameters of the crease curve in the developable surface, and represent the two coordinate values of the point i on the crease curve in the developable surface;

[0023] 4) After performing a projection transformation on the crease curve in the developable surface based on the surface span l j , the surface arch height h j and the surface tangential angle obtain the equation of the crease curve after the developable surface is flattened, thereby obtaining the shape parameters of the crease groove.

[0024] The specific content of 4) is as follows:

[0025] 4.1) Calculate the projection angle β, projection arch height h′, and projection central angle θ according to the surface span l j , surface arch height h j and surface tangential angle using the following formulas:

[0026] h′ = h j cosβ

[0027]

[0028]

[0029] 4.2) Calculate the flattened span l 0 , flattened arch height h 0 and flattened tangential angle

[0030] h 0 = h′tanβ

[0031]

[0032]

[0033] 4.3) Based on the relationship between the flattened span l 0 , flattened arch height h 0 and flattened tangential angle and the first - fourth elliptic curve parameters m 0 , n 0 , a 0 , b 0 of the crease curve after the developable surface is unfolded, obtain the equation of the crease curve after the developable surface is flattened:

[0034]

[0035] n 0 = l 0 / 2

[0036] a 0 = h 0 + m 0

[0037]

[0038]

[0039] where and represent the two coordinate values of point i on the crease curve after the developable surface is flattened.

[0040] The microchannel structure proposed by the present invention includes a microchannel layer, a packaging layer, a liquid metal layer, and lead electrodes. The microchannel layer and the packaging layer use Dow Corning dragon skin30 silicone rubber as the base material, and the silicone rubber is secondarily cured to encapsulate the microchannel layer and the packaging layer. The liquid metal layer is divided into two parts, namely the upper liquid metal layer and the lower liquid metal layer. This layer is located in the hollow space between the microchannel layer and the packaging layer and is filled with liquid metal. A pair of lead electrodes are led out from the edges of the two liquid metal layers respectively, and are connected to circuit modules such as amplifier circuits and Bluetooth according to needs.

[0041] One side of the microchannel layer has embedded microchannels, and the microchannels are arranged along the "crease". The "crease" is a structural feature that runs through the microchannel layer and the packaging layer, and its cross-section is "V"-shaped, which is the dividing line between the upper and lower parts of the liquid metal layer.

[0042] The working principle of the present invention is as follows: The microchannel structure of the present invention is used in a liquid metal flexible force sensor. When the force sensor is bent along the designed direction, the bending strain will be concentrated at the crease instead of being evenly distributed on the flexible substrate, or even an unpredictable deformation, thus avoiding the problem of extrusion or stretching of the embedded microchannels caused by the bending of the flexible substrate. Since the cross-sectional area and length of the microchannels determine the magnitude of the output resistance signal, the crease of this microchannel structure can be used to absorb the bending strain, so that the output resistance signal can be maintained at a relatively stable value when the force sensor is bent without load.

[0043] II. A preparation method of a liquid metal microchannel structure based on a CC origami configuration:

[0044] 1. According to the three-dimensional model of the designed microchannel structure, a casting mold for the base material is designed. The mold includes a microchannel layer mold and a packaging layer mold, and the mold is designed with a crease. The designed mold is exported as an STL format.

[0045] 2. Import the STL format file into slicing software, and select a suitable material and a 3D printer for printing. The 3D printer used in the present invention is an Ultimaker S5, the selected material is TPU95A, the nozzle type is AA0.4, and the base and rough edges are removed after printing.

[0046] 3. Mix the AB glue of Dow Corning dragon skin30 in a ratio of 1:1 and stir well for 1 - 2 minutes, then pour it into the microchannel layer mold. Place the mold in a vacuum drying dish, turn on the vacuum pump, adjust the air pressure in the vacuum dish to -0.7 bar, and set the bubble extraction time to 3 minutes. Take out the mold after extracting the bubbles and let it stand for 5 - 10 minutes, and then put it into an oven to heat for 2 hours to accelerate the curing of the silicone rubber. After the curing is completed, take out the mold and peel it off to obtain the microchannel layer without injecting liquid metal.

[0047] 4. First, use double-sided tape to paste two parallel bosses on the glass plate. The height of the bosses is determined by the number of layers of double-sided tape. Then, drop the uncured silicone after mixing onto the glass plate between the two parallel bosses, and use a squeegee to scrape the uncured silicone to obtain the encapsulation layer. Gently place the grooved surface of the microchannel layer without liquid metal injected on the encapsulation layer, and after standing and curing, obtain the bonded structure of the microchannel layer and the encapsulation layer. The surface of the bonded structure of the microchannel layer and the encapsulation layer is smooth, and there are no bubbles inside and it is uniform.

[0048] 5. First, use a syringe to inject deionized water into the microchannel to clean the microchannel, and then use a syringe to inject liquid metal into the microchannel.

[0049] 6. The microchannel structure of the present invention is used for electronic skin. When this structure is used for electronic skin, the liquid metal in the microchannel is connected to the lead-out electrode, and the junction of the lead-out electrode and the microchannel is encapsulated with Dow Corning 173 glue.

[0050] III. An electronic skin

[0051] The electronic skin includes the liquid metal microchannel structure based on the CC origami configuration described above.

[0052] The electronic skin applying this microchannel structure can be attached to various surfaces for force sensing, such as the surface of a soft robot continuum, the surface of a rigid robot structure, the surface of wearable fabric, etc. It is mainly placed on the force sensing surface with fixed bending motion.

[0053] The beneficial effects of the present invention are:

[0054] 1. The electronic skin applying the microchannel structure is minimally interfered by bending signals and can be directly placed on the surface of a complex sensing curved surface to sense force stimuli;

[0055] 2. The electronic skin applying the microchannel structure is minimally interfered by bending strain, and the bending signals generated when the placement surface moves and deforms can be better removed by noise reduction processing methods, thereby improving the measurement accuracy of the force sensor;

[0056] 3. When the force sensor is a wearable device, the creases designed based on the CC origami configuration can reduce the resistance generated by the force sensor during joint movement and improve the movement performance of the joint;

[0057] 4. The microchannel structure uses the "crease" as the rotation axis, which has the advantages of flexibility and good adaptability compared with a rigid hinge;

[0058] 5. The microchannel structure adopts a subtractive design and does not add new components to the electronic skin, enabling it to further have the advantages of a compact structure and light weight;

[0059] 6. The microchannel structure is a 2.5D structure, which can be formed by mold demolding and is easy to manufacture. Description of the Drawings

[0060] Figure 1 It is a schematic diagram of the unfolding of the foldable developable surface of the present invention;

[0061] Figure 2 It is a diagram for defining the relevant parameters of the movement mechanism of the present invention;

[0062] Figure 3 It is a diagram for defining the relevant parameters of the parametric design of the present invention;

[0063] Figure 4 It is a diagram for defining the relevant parameters after the complete unfolding of the developable surface of the present invention;

[0064] Figure 5 It is a schematic diagram of the structure of the liquid metal flexible force sensor of the present invention;

[0065] Figure 6 It is a cross-sectional view of the liquid metal flexible force sensor of the present invention.

[0066] In the figure: 1. Microchannel layer, 2. First encapsulation layer, 3. First liquid metal layer, 4. Second encapsulation layer, 5. Second liquid metal layer, 6. Lead-out electrode, 7. Fold groove. Detailed Embodiments

[0067] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0068] As Figure 5 and 6 shown, the liquid metal microchannel structure of the present invention includes a microchannel layer 1, a first encapsulation layer 2, a first liquid metal layer 3, a second encapsulation layer 4, a second liquid metal layer 5, a lead-out electrode 6 and a fold groove 7;

[0069] The lower surface of the microchannel layer 1 is attached to the palm. On the upper surface of the microchannel layer 1, a first microchannel groove and a second microchannel groove are respectively opened on both sides. In the middle of each microchannel groove, it is arranged in a ring, there is no intersection between the flow channel grooves, and both ends are led out from the edges of the corresponding sides of the upper surface of the microchannel layer 1. Lead electrodes 6 are placed in the corresponding two ends of the first microchannel groove and the second microchannel groove. The first microchannel groove and the second microchannel groove in the microchannel layer 1 are both filled with liquid metal, and the liquid metal is in contact electrical connection with the lead electrodes 6 in the microchannel grooves. The lead electrodes 6 are connected to circuit modules such as an amplifier circuit, Bluetooth, etc. as needed. In a specific implementation, the resistance signal is converted into a voltage signal and amplified 100 times through the amplifier circuit.; On both sides of the upper surface of the microchannel layer 1, a first encapsulation layer 2 and a second encapsulation layer 4 are respectively laid. The first encapsulation layer 2 is used to encapsulate the liquid metal in the first microchannel groove, thereby forming a first liquid metal layer 3, and the second encapsulation layer 4 is used to encapsulate the liquid metal in the second microchannel groove, thereby forming a second liquid metal layer 5; A crease groove 7 is also opened on the upper surface of the microchannel layer 1 between the first microchannel groove and the second microchannel groove, that is, the liquid metal layer actually used for sensing is divided into two regions. The crease groove 7 is a dividing groove between the first encapsulation layer 2 and the second encapsulation layer 4, that is, the first encapsulation layer 2 and the second encapsulation layer 4 are also divided by the crease groove. The crease groove 7 is facing the palm print. The crease groove 7 concentrates the bending strain of the sensor at the crease, reduces the bending strain of the sensing area, thereby reducing the bending interference signal received during the operation of the sensor, thereby improving the measurement accuracy of the force sensor, and thus meeting the surface force sensing requirements for surfaces with fixed bending motions..

[0070] The microchannel layer 1, the first encapsulation layer 2, and the second encapsulation layer 4 are all made of flexible materials.

[0071] The tensile and shear strength of the microchannel layer 1 is the same as that of Dow Corning dragon skin 30. The groove distance at the same height in the crease groove 7 is the same, and the groove distance at the bottom of the crease groove 7 is 2 - 3 mm.

[0072] The self-groove distance of the first microchannel groove is the same, the self-groove distance of the second microchannel groove is the same, the tensile and shear strength of the microchannel layer 1 is the same as that of Dow Corning dragon skin 30, and the self-groove distance of the first microchannel groove and the self-groove distance of the second microchannel groove are both 1 - 2 mm.

[0073] The widths of the first microchannel groove and the second microchannel groove depend on the accuracy of the base mold, and the value range is 100 - 1000 μm. Considering the fitting problem between the microchannel layer and the encapsulation layer, the thickness of the microchannel layer 1 is greater than 1 mm.

[0074] The thicknesses of the first encapsulation layer 2 and the second encapsulation layer 4 are both 1 - 2 mm.

[0075] The method for designing the shape parameters of the crease groove 7 proposed by the present invention first needs to analyze the possible bending deformation conditions of the sensor according to the usage environment of the sensor. In most cases, the bending deformation shows a form of combined action of equal-curvature bending and folding. By designing the crease curve, the coupled bending deformation can be transformed into a single folding deformation. The microchannel structure design of the present invention is applicable to joint pressure sensing where the unfolded state is a plane and the crease is a curve when bent. The curve-shaped crease is developed from the Miura crease pattern, and one of the common zigzag crease patterns is called the CC origami pattern. A common method for creating a CC origami geometry is to reverse the cross-section of a known developable surface, such as a cylinder or a cone.

[0076] In the design process of the present invention, reverse design is required. The crease curve in the folded state is fitted by the developable surface formed by the sensor attachment surface under the action of joint movement. According to the plane unfolded after projection transformation, the crease curve after unfolding is determined, as Figure 1 shown. The design method of the crease groove realizes the purpose of using the liquid metal microchannel structure based on the CC origami configuration for complex surface pressure sensing, and has guiding significance for the design and application of this microchannel structure.

[0077] Specifically, the shape parameters of the crease groove 7 are obtained by the following steps:

[0078] 1) When there is no crease groove 7 on the upper surface of the microchannel layer 1, the microchannel layer 1 is attached to the object surface. After the object surface is bent, the microchannel layer 1 is folded. The stress nephogram of the folded microchannel layer 1 is analyzed by using the finite element simulation software ANSYS to obtain the original stress peak point, denoted as vertex O, as Figure 2 shown. Taking the vertex coordinates (x o , y o , z o ) as the center of the sphere, the radius r is determined according to the actual pressure sensor layout range on the object surface, so as to establish the spherical boundary equation. Two boundary points are obtained by solving the spherical boundary equation, and the stresses at the two boundary points are both stress peaks. The two boundary points are denoted as the first end point P 1 , the second P 2 ; the formula of the spherical boundary equation is as follows:

[0079]

[0080] where x, y, z are the xyz-direction coordinate values of the point in the stress nephogram, x o , y o , z o are the xyz-direction coordinate values of vertex O, σ x , σ y , σ z are the xyz-direction stresses of the point in the stress nephogram.

[0081] 2) Denote the plane formed by the vertex O, the first endpoint P 1 , and the second endpoint P 2 as the u j -v j plane. The crease curve lies in the u j -v j plane. Solve for the equivalent stresses of the first endpoint P 1 , the second endpoint P 2 in the finite element software ANSYS, and their first projection stresses σ j -v j on the u P1 , second projection stresses σ P2 ;

[0082] 3) As shown Figure 3 , denote the straight-line distance between the first endpoint P 1 , the second endpoint P 2 as the surface span l j , denote the distance from the vertex to the connecting line of the endpoints as the surface arch height h j , and denote the average of the angles between the first projection stress σ P1 , the second projection stress σ P2 and the connecting line of the first endpoint P 1 and the second endpoint P 2 as the tangential angle Based on the surface span l j , the surface arch height h j , and the surface tangential angle Surface span l j , surface arch height h j , and surface tangential angle are three elliptical shape parameters, and the crease curve in the developable surface is obtained by fitting through the following formula:

[0083]

[0084] n j = l j / 2

[0085] a j = h j + m j

[0086]

[0087] The equation of the crease curve in the developable surface is as follows:

[0088]

[0089] where mj , n j , a j , b j are the first - fourth elliptic curve parameters of the crease curve in the developable surface and represent two coordinate values of point i on the crease curve in the developable surface; the starting point of the points on the crease curve in the developable surface is the first endpoint P 1 , the end point is the second endpoint P 2 , v is the vector pointing from endpoint P 1 to endpoint P 2 , u is the normal vector of v on the u j - v j plane ( Figure 3 ).

[0090] 4) After performing a projection transformation on the crease curve in the developable surface according to the surface span l j , the surface arch height h j and the surface tangential angle , the equation of the crease curve after the developable surface is flattened is obtained, thereby obtaining the shape parameters of the crease groove 7.

[0091] 4) Specifically:[[]]

[0092] 4.1) According to the surface span l j , the surface arch height h j and the surface tangential angle , the projection angle β, the projection arch height h′ and the projection central angle θ are calculated using the following formulas. As Figure 3 shown, the projection angle β is the angle between the plane where the crease curve lies and the projection plane, the projection arch height h′ is the arch height of the projection of the crease curve, and the projection central angle θ is the central angle of the projection of the crease curve:[[]]

[0093] h′ = h j cosβ

[0094]

[0095]

[0096] Define the folding angle α to quantify the folding state Figure 3 . When the developable surface is unfolded along the crease, the shape of the crease curve changes, and the folding angle α increases accordingly. Further solve the crease curve when the folding angle α increases. When α is 180°, the plane where the crease curve lies is completely unfolded. As Figure 4 shown, it can be obtained that there is a relationship between the projection parameters and the elliptical shape parameters under the fully unfolded condition:[[]]

[0097] 4.2) Calculate the flattened span \(l\), the flattened arch height \(h\), and the flattened tangential angle according to the projection angle \(\beta\), the projection arch height \(h'\), and the projection central angle \(\theta\) using the following formulas: 0 The flattened span \(l\), 0 the flattened arch height \(h\), and the flattened tangential angle 0 are three shape parameters of the crease curve when the developable surface is fully unfolded: 0 The flattened span \(l\), the flattened arch height \(h\),

[0098] h 0 = h'tanβ

[0099]

[0100]

[0101] 4.3) According to the relationship between the flattened span \(l\), the flattened arch height \(h\), and the flattened tangential angle and the first - fourth elliptic curve parameters \(m\), \(n\), \(a\), \(b\) of the crease curve after the developable surface is unfolded, obtain the equation of the crease curve after the developable surface is flattened: 0 The flattened span \(l\), 0 the flattened arch height \(h\), and the flattened tangential angle 0 n 0 a 0 b 0 where \(x_i\) and \(y_i\) represent the two coordinate values of the point \(i\) on the crease curve after the developable surface is flattened, and \((x_0, y_0)\) is the starting point of the crease curve after the developable surface is flattened.

[0102]

[0103] n o = l o / 2

[0104] a 0 = h 0 + m 0

[0105]

[0106]

[0107] where and represent the two coordinate values of the point \(i\) on the crease curve after the developable surface is flattened, is the starting point of the crease curve after the developable surface is flattened.

[0108] In specific implementation, each parameter is respectively:

[0109]

[0110]

[0111]

[0112]

[0113]

[0114] Draw a view of the cross-section of the "crease" in a 2D drawing software (CAXA), define its grooving angle as 30°, and the grooving depth as 1.5 mm;

[0115] Design a microchannel pattern in a 2D drawing software (CAXA) according to the fitted elliptical curve and the cross-sectional dimensions of the crease. The width of the microchannel is 0.5 mm, the depth is 0.5 mm, the spacing between microchannels is 2 mm, and the wall thickness of the encapsulation layer and the microchannel layer is 1 mm, and model it in a 3D drawing software (Solidworks);

[0116] Design a casting mold for the base material according to the 3D model of the designed microchannel structure. The mold includes a microchannel layer mold and an encapsulation layer mold, and the designed mold is in STL format;

[0117] Mix the AB glue of Dow Corning dragon skin30 in a ratio of 1:1 and stir it thoroughly for 1 - 2 minutes, then pour it into the microchannel layer mold; put the mold into a vacuum drying dish, turn on the vacuum pump, adjust the air pressure in the vacuum dish to -0.7 bar, and set the bubble extraction time to 3 minutes; take out the mold after extracting the bubbles and let it stand for 5 - 10 minutes, and then put it into an oven to heat for 2 h to accelerate the curing of the silicone rubber; after the curing is completed, take out the mold and peel it off to obtain the microchannel layer without injecting liquid metal;

[0118] First, paste two parallel bosses on a glass plate with single-sided adhesive. The height of the bosses is determined by the number of layers of the single-sided adhesive. Then, drop the uncured silicone rubber after mixing onto the glass plate between the two parallel bosses, and then use a squeegee to scrape the uncured silicone rubber to obtain the encapsulation layer. Gently buckle the grooved surface of the microchannel layer without injecting liquid metal onto the encapsulation layer, and let it stand for curing to obtain the bonded structure of the microchannel layer and the encapsulation layer. The surface of the bonded structure of the microchannel layer and the encapsulation layer is smooth, and there are no bubbles inside. In a specific implementation, the thickness of each layer of single-sided adhesive is 0.2 mm, and the height of the boss is 0.8 mm, that is, the thickness of the encapsulation layer is 0.8 mm. The film prepared by this process has controllable thickness, uniform thickness, and excellent forming quality, is suitable for precision devices such as sensors, and effectively solves problems such as easy blockage of the flow channel and uneven bonding during the bonding of the layered flexible substrate.

[0119] First, use a syringe to inject deionized water into the microchannel to clean the microchannel, and then use a syringe to inject liquid metal into the microchannel; the liquid metal in the microchannel is connected to the lead-out electrode, and the junction of the lead-out electrode and the microchannel is encapsulated with Dow Corning 173 glue. The prepared electronic skin is as Figure 6 shown;

[0120] Connect the lead electrode of the electronic skin to the amplifier circuit. The amplifier circuit includes a power supply module E0505S, a voltage stabilizing triode LM317, and an instrumentation amplifier AD620, which can convert the resistance signal into a voltage signal and amplify it by 100 times. The current signal is sent to the control terminal through the Bluetooth module for noise reduction processing to obtain the force signal waveform diagram sensed by the electronic skin.

[0121] Place the electronic skin on the mechanical palm so that the crease is aligned with the rotation axis on the surface when the palm opens and closes. When the palm opens and closes without load, the measured sensor data is relatively stable; when the palm grasps an object, the change in the sensor reading can be clearly seen.

Claims

1. A liquid metal microchannel structure based on a CC origami configuration, characterized in that, it includes a microchannel layer (1), a first encapsulation layer (2), a first liquid metal layer (3), a second encapsulation layer (4), a second liquid metal layer (5), lead-out electrodes (6) and crease grooves (7); On both sides of the upper surface of the microchannel layer (1), a first microchannel groove and a second microchannel groove are respectively opened. Lead-out electrodes (6) are placed at both ends corresponding to the first microchannel groove and the second microchannel groove. The first microchannel groove and the second microchannel groove of the microchannel layer (1) are both filled with liquid metal, and the liquid metal is in electrical contact connection with the lead-out electrodes (6) in the microchannel grooves; On both sides of the upper surface of the microchannel layer (1), a first encapsulation layer (2) and a second encapsulation layer (4) are respectively laid. The first encapsulation layer (2) is used to encapsulate the liquid metal in the first microchannel groove, thereby forming a first liquid metal layer (3), and the second encapsulation layer (4) is used to encapsulate the liquid metal in the second microchannel groove, thereby forming a second liquid metal layer (5); A crease groove (7) is also opened on the upper surface of the microchannel layer (1) between the first microchannel groove and the second microchannel groove, and the crease groove (7) is a dividing groove between the first encapsulation layer (2) and the second encapsulation layer (4).

2. The liquid metal microchannel structure based on a CC origami configuration according to claim 1, characterized in that, the microchannel layer (1), the first encapsulation layer (2) and the second encapsulation layer (4) are all made of flexible materials.

3. The liquid metal microchannel structure based on a CC origami configuration according to claim 1, characterized in that, the tensile and shear strengths of the microchannel layer (1) are the tensile and shear strengths of Dow Corning dragon skin30, the groove distances at the same height in the crease groove (7) are the same, and the groove distance at the bottom of the crease groove (7) is 2 - 3 mm.

4. The liquid metal microchannel structure based on a CC origami configuration according to claim 1, characterized in that, the self-groove distances of the first microchannel groove are the same, the self-groove distances of the second microchannel groove are the same, the tensile and shear strengths of the microchannel layer (1) are the tensile and shear strengths of Dow Corning dragon skin30, and the self-groove distances of the first microchannel groove and the second microchannel groove are both 1 - 2 mm.

5. The liquid metal microchannel structure based on a CC origami configuration according to claim 1, characterized in that, the width value ranges of the first microchannel groove and the second microchannel groove are 100 - 1000 μm, and the thickness of the microchannel layer (1) is greater than 1 mm.

6. The liquid metal microchannel structure based on a CC origami configuration according to claim 1, characterized in that, the thicknesses of the first encapsulation layer (2) and the second encapsulation layer (4) are both 1 - 2 mm.

7. The liquid metal microchannel structure based on a CC origami configuration according to claim 1, characterized in that, the shape parameters of the crease groove (7) are obtained by the following steps: 1) When there is no crease groove (7) on the upper surface of the microchannel layer (1), the microchannel layer (1) adheres to the object surface. After the object surface is bent, the microchannel layer (1) is folded. Analyze the stress nephogram of the folded microchannel layer (1) to obtain the original stress peak point, denoted as vertex O. Taking the vertex as the center of the sphere, determine the radius r according to the actual pressure sensor layout range on the object surface, so as to establish the spherical boundary equation. Solve the spherical boundary equation to obtain two boundary points, and the stresses at the two boundary points are both stress peaks. Denote the two boundary points as the first endpoint P 1 , the second P 2 ; 2) Denote the plane formed by the three points of vertex O, the first endpoint P 1 , and the second endpoint P 2 as the u j -v j plane, and solve for the first projection stress σ 1 of the first endpoint P 2 , and the second projection stress σ j of the second endpoint P j on the u P1 -v P2 plane; 3) Denote the straight-line distance between the first endpoint P 1 and the second endpoint P 2 as the surface span l j , denote the distance from the vertex to the connection line of the endpoints as the surface arch height h j , and denote the average of the angles between the first projected stress σ P1 , the second projected stress σ P2 and the connection line of the first endpoint P 1 and the second endpoint P 2 as the tangential angle According to the surface span l j , the surface arch height h j and the surface tangential angle Obtain the crease curve in the developable surface by fitting through the following formula: n j ＝l j / 2 a j = h j + m j The equation of the crease curve in the developable surface is as follows: where m j , n j , a j , b j are the first - fourth elliptic curve parameters of the crease curve in the developable surface, and represent two coordinate values of the point i on the crease curve in the developable surface; 4) According to the surface span l j , the surface arch height h j and the surface tangential angle After performing a projection transformation on the crease curve in the developable surface, the equation of the crease curve after the developable surface is flattened is obtained, thereby obtaining the shape parameters of the crease groove (7).

8. The liquid metal microchannel structure based on a CC origami configuration according to claim 7, characterized in that, The 4) specifically is as follows: 4.1) According to the surface span l j , the surface arch height h j and the surface tangential angle The projection angle β, the projection arch height h', and the projection central angle θ are calculated using the following formula: h′ = h j cosβ 4.2) Calculate and obtain the flattened span \(l\), the flattened arch height \(h\), and the flattened tangential angle according to the projection angle \(\beta\), the projection arch height \(h'\), and the projection central angle \(\theta\) using the following formulas 0 and the flattened arch height \(h\) 0 and the flattened tangential angle h 0 = h'tanβ 4.3) According to the flattened span l 0 , the flattened arch height h 0 and the flattened tangential angle and the first - fourth elliptic curve parameters m 0 , n 0 , a 0 , b 0 of the crease curve after the developable surface is developed, and then obtain the equation of the crease curve after the developable surface is flattened: n 0 ＝l 0 / 2 a 0 = h 0 + m 0 Among them, and represent two coordinate values of point i on the crease curve after the developable surface is flattened.

9. A liquid metal microchannel structure based on a CC origami configuration according to claim 1, characterized in that the first encapsulation layer (2) and the second encapsulation layer (4) are obtained by the following preparation method: Use single-sided tape to paste two parallel bosses on a glass plate, then drop the uncured silicone after mixing on the glass plate between the two parallel bosses, and then use a squeegee to scrape the uncured silicone to obtain the encapsulation layer.

10. An electronic skin, characterized in that the electronic skin includes a liquid metal microchannel structure based on a CC origami configuration according to any one of claims 1-8.

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