Fingerstall based on ionic gel pressure sensor array and preparation method

Abstract

The invention relates to a fingerstall based on an ionic gel pressure sensor array and a preparation method. The fingerstall comprises a flexible fingerstall body and a flexible pressure sensor array main body fixedly embedded in the inner side of the flexible fingerstall body. The flexible pressure sensor array main body comprises a top flexible electrode layer, an ionic gel layer and a bottom flexible electrode layer which are arranged in sequence; the ionic gel layer is located between the top flexible electrode layer and the bottom flexible electrode layer, the top flexible electrode layer and the bottom flexible electrode layer are each composed of a polyimide film layer and a copper electrode, and the polyimide film layers and the copper electrodes are tightly attached and fixedly connected; the copper electrodes of the top flexible electrode layer and the bottom flexible electrode layer are formed by arranging and connecting a plurality of copper electrode units in a matrix manner; the copper electrode units of the top flexible electrode layer are connected in rows, the copper electrode units of the bottom flexible electrode layer are connected in columns, and the copper electrode connection directions are vertical after the two layers are assembled; one side, close to the top flexible electrode layer, of the ionic gel layer is provided with a uniform pyramid microstructure. According to the invention, the force of the finger acting on the pricking needle can be accurately obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to a finger sleeve based on an ion gel pressure sensor array and a preparation method thereof. Background Art

[0002] Acupuncture is one of the important components of traditional Chinese medicine. Under the guidance of traditional Chinese medicine theory, acupuncture uses needles to insert into the human body with a certain force and angle, twists, lifts and inserts the needles in the human body, and stimulates specific parts of the human body through specific techniques, so as to achieve the purpose of alleviating and treating diseases. At present, there are two quantitative methods for acupuncture techniques in clinical treatment: one is for doctors and patients to form subjective evaluations through their own feelings and oral descriptions, and at the same time quantify the evaluation content; the other is to use instruments and equipment to achieve an objective quantification of the doctor's acupuncture strength, stimulation amount and other techniques. There is a lack of objective quantitative methods in the quantitative study of acupuncture techniques, which affects the application and development of acupuncture in practice. Therefore, the quantification of acupuncture techniques is particularly important.

[0003] The main difficulties in objectively quantifying acupuncture techniques are as follows: 1. The acupuncturist's technique cannot be accurately identified during acupuncture. 2. The objective quantitative parameters for acupuncture are unclear, and there is a lack of effective methods to describe the needle movement process. 3. There are problems with traditional acupuncture teaching methods, high teaching costs and low efficiency for students, which leads to a shortage of relevant talents and hinders the development of acupuncture. 4. At present, there is a lack of research on related equipment for detecting the micro-force of the acupuncturist's fingers, which has become an important reason restricting the quantitative research of acupuncture techniques in traditional Chinese medicine.

[0004] When performing acupuncture, the speed, force and angle of needle insertion are key factors affecting the effect of acupuncture. The force of needle insertion is directly related to the strength of needle gripping. The strength of needle gripping has a decisive influence on the strength of acupuncture. In the prior art, no effective method for detecting the strength of needle gripping has been found. Summary of the invention

[0005] In view of the above technical problems, the present invention proposes a finger sleeve based on an ion gel pressure sensor array and a preparation method thereof, which can accurately obtain the force exerted by a finger on a needle.

[0006] One of the above-mentioned purposes of the present invention is achieved by the following technical solution:

[0007] A finger sleeve based on an ion gel pressure sensor array, comprising a flexible finger sleeve body and a flexible pressure sensor array body embedded inside the flexible finger sleeve body;

[0008] The flexible pressure sensor array body includes a top flexible electrode layer, an ion gel layer, and a bottom flexible electrode layer which are arranged in sequence; the ion gel layer is formed by a mixture of polymer and ionic liquid; the ion gel layer is located between the top flexible electrode layer and the bottom flexible electrode layer, and the top and bottom flexible electrode layers are both composed of a polyimide film layer and a copper electrode, and the polyimide film layer and the copper electrode are tightly fitted and fixedly connected; the copper electrodes of the top and bottom flexible electrode layers are both composed of a plurality of copper electrode units arranged and connected in a matrix; the copper electrode units of the top flexible electrode layer are connected in rows, and the copper electrode units of the bottom flexible electrode layer are connected in columns, and the connection direction of the copper electrodes is vertical after the two are assembled; a uniform pyramid microstructure is arranged on one side of the ion gel layer close to the top flexible electrode layer.

[0009] Moreover, the polymer is polyvinylidene fluoride-hexafluoropropylene, the ionic liquid is 1-ethyl-3-methylimidazoline bistrifluoromethylsulfonyl imide salt, and the mass ratio of the ionic liquid to the polymer is 1:2.

[0010] Moreover, the pyramid microstructure has a height of 500 microns, a bottom that is a square with a side length of 700 microns, and a spacing between the pyramid microstructures of 200 microns.

[0011] Moreover, the flexible finger sleeve body is made of soft rubber material.

[0012] The second object of the present invention is achieved by the following technical solution:

[0013] A method for manufacturing a finger sleeve based on an ion gel pressure sensor array comprises the following steps:

[0014] Step 1: preparing an ion gel layer, comprising:

[0015] 1.1: Take a certain amount of polymer polyvinylidene fluoride-hexafluoropropylene and dimethyl sulfoxide and mix them in a beaker at a mass ratio of 1:10, add a magnetic stirring rotor and seal the beaker; place the sealed beaker on a magnetic stirrer and stir at a speed of 1000r / min for 2 hours;

[0016] 1.2: Add a certain amount of 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide salt [EMIM][TFSI] ionic liquid into the beaker, and add [EMIM][TFSI] to PVDF-HFP at a ratio of 30%, 50% or 70% by mass of PVDF-HFP to obtain three mixtures; continue to stir the mixed solution at a stirring speed of 1000 r / min for 2 hours.

[0017] 1.3: Use a 3D printer to print a micro-pyramid structure resin mold, drop the prepared PDMS solution on the printed resin mold, and cure it at 80°C for 1h, and then peel it off to obtain the PDMS mold;

[0018] 1.4: The ion gel layer solution obtained in step 1.2 is applied to the PDMS mold, and then dried at 80° C. for 1 hour to fully solidify the inside of the ion gel layer and form an ion gel layer film on the surface of the PDMS mold; then the ion gel layer is peeled off from the PDMS mold to obtain an ion gel layer solid;

[0019] Step 2: Use flexible printed circuit board technology to prepare the bottom flexible electrode layer and the top flexible electrode layer, stack the prepared bottom flexible electrode layer, ion gel layer, and top flexible electrode layer from bottom to top, lead out wires from the top and bottom electrodes respectively, and package them with 3M double-sided tape to complete the production of the flexible pressure sensor array body.

[0020] Step 3: Place the flexible pressure sensor array body in the finger sleeve mold, mix EcoflexA and B rubber in a weight ratio of 1:1, let it stand to remove bubbles in the liquid, evenly add Ecoflex to the finger sleeve mold, and cure it at 80°C to obtain a finger sleeve based on the ion gel pressure sensor array.

[0021] The present invention has the following advantages and positive effects:

[0022] 1. The ion gel prepared by the present invention has high stretchability, high mechanical strength, high flexibility, good chemical stability and thermal stability, can be recycled and is environmentally friendly. The conductive behavior of the ion gel is due to the movement of ions, and the change in conductivity is mainly caused by the change in the shape of the gel under external stimulation, which ensures the collection of capacitance signals during acupuncture manipulation.

[0023] 2. The ion gel of the present invention adopts a pyramid microstructure on one side close to the top copper electrode layer. After a small pressure is applied, the tip of the pyramid will be compressed more, resulting in higher mechanical deformation, thereby improving the sensitivity of the pressure sensor and realizing the detection of tiny pressures.

[0024] 3. The pressure sensor of the present invention adopts a "sandwich" structure, in which the middle layer is made of ion gel, the top and bottom layers are flexible electrode layers made of polyimide, and the electrodes are copper electrodes. Polyimide has excellent thermal stability, mechanical toughness and chemical resistance, long service life and can be reused. Polyimide has good flexibility, which is conducive to better fit between the pressure sensor and the finger.

[0025] 4. The pressure sensor array of the present invention is arranged in a matrix, and can collect signals from different positions at the same time, identify different types of actions, and improve the accuracy of the finger sleeve in identifying finger actions, so as to accurately obtain the force exerted by the finger on the needle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The flexible pressure sensor array of the present invention is a top view and a front view of the main body, 1a, top view; 1b, front view;

[0027] Figure 2 It is a top view and a front view of the pyramid microstructure of the ion gel layer of the present invention, 2a, top view; 2b, front view;

[0028] Figure 3 Schematic diagram of the top flexible electrode layer of the ion gel pressure sensor array of the present invention;

[0029] Figure 4 Schematic diagram of the bottom flexible electrode layer based on the ion gel pressure sensor array of the present invention;

[0030] Figure 5 is a comparison diagram of the stress-strain curves of gels with different ionic liquid concentrations of the present invention;

[0031] Figure 6 This is a comparison chart of the gel capacitance per unit area at different ionic liquid concentrations of the present invention;

[0032] Figure 7 The stress-strain curve of the uniaxial tensile test of the 50% ionic liquid concentration gel of the present invention until the break;

[0033] Figure 8 This is a finite element analysis diagram of the pyramid microstructure of the ion gel layer of the present invention;

[0034] Fig. 9 It is a sensitivity diagram of the ion gel layer pressure sensor of the present invention;

[0035] Fig.10 The present invention is based on the detection of micro pressure by the ion gel layer pressure sensor;

[0036] Fig.11 It is a schematic diagram of the structure of the finger sleeve based on the ion gel pressure sensor array of the present invention. DETAILED DESCRIPTION

[0037] The structure of the present invention is further described below with reference to the accompanying drawings and by way of examples. It should be noted that the present examples are descriptive rather than restrictive.

[0038] A finger sleeve based on an ion gel pressure sensor array, see Figure 1-Figure 11The invention point is: it comprises a flexible finger sleeve body 2 and a flexible pressure sensor array body 1 embedded in the inner side of the flexible finger sleeve body. The flexible finger sleeve body can be made of silicone material or soft rubber material.

[0039] The flexible pressure sensor array body includes a top flexible electrode layer 1.1, an ion gel layer 1.2, and a bottom flexible electrode layer 1.3, which are arranged in sequence. The ion gel layer is a mixture of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and 1-ethyl-3-methylimidazoline bistrifluoromethylsulfonyl imide salt ([EMIM][TFSI]), and the ion gel layer is located between the top flexible electrode layer and the bottom flexible electrode layer. The top and bottom flexible electrode layers are both composed of a polyimide film layer and a copper electrode, and the polyimide film layer is tightly fitted and fixedly connected to the copper electrode. The copper electrodes of the top and bottom flexible electrode layers are both composed of a plurality of copper electrode units arranged and connected in a matrix. The copper electrode units of the top flexible electrode layer are connected in rows, and the copper electrode units of the bottom flexible electrode layer are connected in columns. After the two are assembled, the connection direction of the copper electrodes is vertical.

[0040] A uniform pyramid microstructure is arranged on one side of the ion gel layer close to the top flexible electrode layer. In the present invention, the pyramid microstructure is 500 microns high, the bottom is a square (with a side length of 700 microns), and the spacing between the pyramid microstructures is 200 microns.

[0041] In the present invention, the copper electrodes of the top and bottom flexible electrode layers are preferably in the form of a square array, consisting of 3×3 copper electrode units. The top flexible electrode layer is rectangular as a whole, with a thickness of 25μm, a length of 24.8mm, and a width of 14mm. The size of each top copper electrode unit is 2.4mm×2.4mm, the spacing between the top copper electrode units is 0.8mm, and the width of the interconnection line between the top copper electrode units is 0.15mm. The ion gel layer is about 200μm thick, square, and 10mm wide. The bottom flexible electrode layer is rectangular as a whole, with a thickness of 25μm, a length of 24.8mm, and a width of 14mm. The size of each bottom copper electrode unit is 2.4mm×2.4mm, the spacing between the bottom copper electrode units is 0.8mm, and the width of the interconnection line between the bottom copper electrodes is 0.15mm. Among them, the ion gel is aligned with the geometric center of the top and bottom flexible electrodes.

[0042] The advantage of the ion gel pressure sensor array is that it can collect signals from different positions at the same time. The design of the ion gel layer pressure sensor array is based on the following considerations:

[0043] In the present invention, the ion gel layer is formed by mixing the polymer PVDF-HFP and the ionic liquid [EMIM][TFSI]. Before preparing the ion gel layer, it is necessary to determine the mass ratio of the ionic liquid to the polymer. By increasing the concentration of the ionic liquid in the ion gel layer (30wt%, 50wt% and 70wt%) to enhance the performance of the sensor, the modulation of the sensing performance can be easily achieved. The elastic properties of the ion gel layer are related to the response speed of the sensor to force stimulation. The better the elasticity, the faster the device senses the force, and the faster the device recovers. The smaller the mass fraction of the ionic liquid, the better the elasticity of the ion gel layer ( Figure 5 ). However, due to the decrease in ion concentration, the capacitance per unit area is smaller, that is, the lower the content of ionic liquid, the faster the sensor response speed and the lower the sensitivity. Increasing the ion concentration from 20wt% to 70wt%, at 20Hz, the surface capacitance increases from 370 to 16540pF·cm -2 ( Figure 6 ). Therefore, in order to ensure that the sensor has both a fast response speed and a high sensitivity, the present invention selects a mass ratio of ionic liquid to polymer of 1:2. Through the uniaxial tensile test, it can be seen that the 50% concentration of the ion gel layer ( Figure 7 ), with high stretchability (up to 323%) and high mechanical strength (breaking strength up to 8.64MPa).

[0044] The ion gel layer adopts a pyramid microstructure design. The pyramid microstructure is 500 microns high and 700 microns wide at the bottom. The deformation of the microstructure under pressure loading is studied by two-dimensional finite element analysis ( Figure 8 ). The stress distribution of the pyramid is non-uniform, and the stress is concentrated at the tip due to the smaller contact area at the top and higher stress. Compared with other structures, the tip of the pyramid is compressed more under the same pressure, resulting in higher mechanical deformation at the top. Therefore, the pyramid shape is more sensitive to small pressures.

[0045] Sensitivity (S) is a key performance parameter of pressure sensors. It refers to the ratio of external load to sensor output capacitance, reflecting the sensor's response accuracy to external force signals. For capacitive pressure sensors, the sensitivity is generally expressed as: It is defined as S = δ (ΔC / C0) / δP, where ΔC is the capacitance change, C0 is the initial capacitance when not loaded, and P is the applied external pressure. It can be clearly seen from the formula that the unit of measurement for pressure sensor sensitivity is kPa -1 The experiment verified the ultra-high sensitivity of the ion gel layer pressure sensor ( Fig. 9 ), in the range of 0-1kPa, 40.6kPa can be obtained -1 High sensitivity, the sensitivity is 13.8kPa in the range of 1-5kPa -1, sensitivity is 2.05kPa in the range of 5-50kPa -1 , the sensitivity is 0.44kPa in the range of 50-300kPa -1 When a small pressure of about 500Pa is applied to the sensor, the pressure sensor signal changes significantly, indicating that the sensor has the ability to recognize small pressures ( Fig.10 ).

[0046] The present invention provides a method for manufacturing a finger sleeve based on an ion gel pressure sensor array, comprising the following steps:

[0047] Step 1: Preparation of ion gel layer

[0048] 1.1: Take a certain amount of polymer polyvinylidene fluoride-hexafluoropropylene and dimethyl sulfoxide and mix them in a beaker at a mass ratio of 1:10, add a magnetic stirring rotor and seal the beaker; place the sealed beaker on a magnetic stirrer and stir at a speed of 1000r / min for 2 hours;

[0049] 1.2: Add a certain amount of 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide salt [EMIM][TFSI] ionic liquid into the beaker, and add [EMIM][TFSI] to PVDF-HFP at a ratio of 30%, 50% or 70% by mass of PVDF-HFP to obtain three mixtures; continue to stir the mixed solution at a stirring speed of 1000 r / min for 2 hours.

[0050] 1.3: Use a 3D printer to print a micro-pyramid structure resin mold, drop the prepared PDMS solution on the printed resin mold, and cure it at 80°C for 1h, and then peel it off to obtain the PDMS mold;

[0051] 1.4: The ion gel layer solution obtained in step 1.2 is applied to the PDMS mold, and then dried at 80° C. for 1 hour to fully solidify the inside of the ion gel layer and form an ion gel layer film on the surface of the PDMS mold; then the ion gel layer is peeled off from the PDMS mold to obtain an ion gel layer solid;

[0052] Step 2: Use flexible printed circuit board technology to prepare the bottom flexible electrode layer and the top flexible electrode layer, stack the prepared bottom flexible electrode layer, ion gel layer, and top flexible electrode layer from bottom to top, lead out wires from the top and bottom electrodes respectively, and package them with 3M double-sided tape to complete the production of the flexible pressure sensor array body.

[0053] Step 3: Place the flexible pressure sensor array body in the finger sleeve mold, mix EcoflexA and B rubber in a weight ratio of 1:1, let it stand to remove bubbles in the liquid, evenly add Ecoflex to the finger sleeve mold, and cure it at 80°C to obtain a finger sleeve based on the ion gel pressure sensor array.

[0054] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A finger sleeve based on an ion gel pressure sensor array, characterized in that: It includes a flexible finger sleeve body and a flexible pressure sensor array body embedded inside the flexible finger sleeve body; The flexible pressure sensor array body includes a top flexible electrode layer, an ion gel layer, and a bottom flexible electrode layer which are arranged in sequence; the ion gel layer is formed by a mixture of polymer and ionic liquid; the ion gel layer is located between the top flexible electrode layer and the bottom flexible electrode layer, and the top and bottom flexible electrode layers are both composed of a polyimide film layer and a copper electrode, and the polyimide film layer is tightly attached to and fixedly connected to the copper electrode; the copper electrodes of the top and bottom flexible electrode layers are both composed of a plurality of copper electrode units arranged and connected in a matrix; the copper electrode units of the top flexible electrode layer are connected in rows, and the copper electrode units of the bottom flexible electrode layer are connected in columns, and the connection direction of the copper electrodes is perpendicular after the two are assembled; a uniform pyramid microstructure is arranged on one side of the ion gel layer close to the top flexible electrode layer.

2. The finger sleeve based on the ion gel pressure sensor array according to claim 1, characterized in that: The polymer is polyvinylidene fluoride-hexafluoropropylene; the ionic liquid is 1-ethyl-3-methylimidazoline bistrifluoromethylsulfonyl imide salt, and the mass ratio of the ionic liquid to the polymer is 1:

2.

3. The finger sleeve based on the ion gel pressure sensor array according to claim 1, characterized in that: The pyramid microstructure has a height of 500 micrometers, a bottom that is a square with a side length of 700 micrometers, and a spacing between the pyramid microstructures of 200 micrometers.

4. The finger sleeve based on the ion gel pressure sensor array according to claim 1, characterized in that: The flexible finger sleeve body is made of soft rubber material.

5. A method for manufacturing a fingertip of an ion gel layer pressure sensor array as claimed in any one of claims 1 to 4, characterized in that: The steps include: Step 1: preparing an ion gel layer, comprising: 1.1: Take a certain amount of polymer polyvinylidene fluoride-hexafluoropropylene and dimethyl sulfoxide and mix them in a beaker at a mass ratio of 1:10, add a magnetic stirring rotor and seal the beaker; place the sealed beaker on a magnetic stirrer and stir for 2 hours; 1.2: Add a certain amount of 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide salt [EMIM][TFSI] ionic liquid to the beaker, and add [EMIM][TFSI] to PVDF-HFP at a ratio of 30%, 50% or 70% by mass of PVDF-HFP to obtain three mixtures; continue to stir the mixed solution at a stirring speed of 1000 r / min for 2 hours; 1.3: Use a 3D printer to print a micro-pyramid structure resin mold, drop the prepared PDMS solution on the printed resin mold, and cure it at 80°C for 1h, and then peel it off to obtain the PDMS mold; 1.4: The ion gel layer solution obtained in step 1.2 is applied to the PDMS mold, and then dried at 80° C. for 1 hour to fully solidify the inside of the ion gel layer and form an ion gel layer film on the surface of the PDMS mold; then the ion gel layer is peeled off from the PDMS mold to obtain an ion gel layer solid; Step 2: Use flexible printed circuit board technology to prepare the bottom flexible electrode layer and the top flexible electrode layer, stack the prepared bottom flexible electrode layer, ion gel layer, and top flexible electrode layer from bottom to top, lead out wires from the top and bottom electrodes respectively, and package them with 3M double-sided tape to complete the production of the flexible pressure sensor array body. Step 3: Place the flexible pressure sensor array body in the finger sleeve mold, mix EcoflexA and B rubber in a weight ratio of 1:1, let it stand to remove bubbles in the liquid, evenly add Ecoflex to the finger sleeve mold, and cure it at 80°C to obtain a finger sleeve based on the ion gel pressure sensor array.

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