Method for manufacturing a three-dimensional flexible stress sensor and applications

Abstract

The present application relates to the technical field of force sensors and textile wearable measurement, and particularly relates to a preparation method and application of a three-dimensional flexible stress sensor, the three-dimensional flexible stress sensor is a five-layer structure, from top to bottom, the flexible microstructure layer, the upper electrode layer, the sensitive unit layer, the lower electrode layer and the protective layer, comprising the following steps: step one, preparing the flexible microstructure layer; step two, preparing the sensitive unit, four sensitive units constitute the sensitive unit layer; step three, selecting the conductive material as the upper electrode layer and the lower electrode layer; step four, selecting the soft insulating material as the protective layer; step five, packaging the flexible microstructure layer, the upper electrode layer, the sensitive unit layer, the lower electrode layer and the protective layer; the processing technology is simple, the compression characteristics are good, the sensitivity is high, three-dimensional force detection can be realized, and the three-dimensional flexible stress sensor has application potential in the fields of medical treatment, sports, health protection and the like.

Description

Technical Field

[0001] This invention relates to the technical field of force sensors and wearable measurement in textiles, and in particular to the fabrication method and application of a three-dimensional flexible stress sensor. Background Technology

[0002] In recent years, with the development of science and technology, intelligent robots, wearable devices and human-computer interaction technologies have developed rapidly. As the foundation of these fields, tactile sensors are becoming the focus of researchers' attention. Tactile sensors can detect various information about the external environment, such as pressure, displacement, temperature, humidity, hardness and shear force.

[0003] The primary sensing function of tactile sensors is force sensing. Traditional normal force sensing sensor technology is now mature. However, in most applications, in addition to one-dimensional force sensors, three-dimensional force sensors are also required. Current commercially available three-dimensional tactile force sensors are not flexible enough and cannot work in complex unstructured environments, such as the joints of robotic hands. Therefore, flexible three-dimensional tactile force sensors have broad application prospects in many fields such as biomedicine, wearable devices, and intelligent robots.

[0004] Currently, commercially available 3D tactile force sensors are not flexible and flexible enough to work in complex unstructured environments, such as the joints of robot hands. Most commonly used 3D force sensors are piezoresistive force sensors, which have advantages such as good linearity, strong anti-interference, and simple arraying. However, the sensitive materials of traditional piezoresistive force sensors have problems such as low sensitivity, long response time, and inability to accurately detect normal and shear forces during the force process, which affects the further application of flexible 3D force sensors. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for fabricating and applying a three-dimensional flexible stress sensor.

[0006] The present invention discloses a method for fabricating a three-dimensional flexible stress sensor, wherein the three-dimensional flexible stress sensor has a five-layer structure, consisting of a flexible microstructure layer, an upper electrode layer, a sensitive unit layer, a lower electrode layer, and a protective layer from top to bottom, and includes the following steps:

[0007] Step 1: Fabrication of the flexible microstructure layer;

[0008] Step 2: Prepare the sensitive units; four sensitive units constitute a sensitive unit layer.

[0009] Step 3: Select conductive materials as the upper and lower electrode layers;

[0010] Step 4: Select a soft insulating material as the protective layer;

[0011] Step 5: Encapsulate the flexible microstructure layer, upper electrode layer, sensitive unit layer, lower electrode layer, and protective layer.

[0012] Preferably, the following steps are included in step one:

[0013] (1) Select sandpaper as a template, clean and dry it, and then fix it with tape;

[0014] (2) PDMS is coated on the side of sandpaper with a rough microstructure. After drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS film with a groove structure opposite to that of the sandpaper.

[0015] (3) PDMS is coated on the surface of a PDMS film with a groove structure. After drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS film with the same microstructure as sandpaper, i.e., a flexible microstructure layer.

[0016] Preferably, step two includes the following steps:

[0017] (1) Using cashmere fabric as a carrier, ultrasonically cleaned with anhydrous ethanol, then cleaned again with deionized water to remove impurities from the fabric surface, and finally dried in an oven.

[0018] (2) Surface modification treatment is applied to clean cashmere fabrics to roughen their surface;

[0019] (3) The fabric is sequentially immersed in Mxene solution and silver nanowires to obtain Mxene / silver nanowire composite cashmere sensitive layer.

[0020] Preferably, in step four, the flexible insulating material is PDMS or resin.

[0021] Preferably, both the upper electrode layer and the lower electrode layer are connected by a common electrode and four patterned electrodes.

[0022] Preferably, in step three, the conductive material is copper foil or silver foil.

[0023] Preferably, the silver nanowires are prepared by chemical reduction, electrochemical method or microwave method.

[0024] Preferably, the preparation method of the Mxene (two-dimensional nanosheet) solution includes fluorine-containing etching, fluorine-free etching, or organic solvent-assisted intercalation collection.

[0025] Preferably, the sensitive units are arranged in an array.

[0026] The three-dimensional flexible stress sensor of the present invention can be used to detect stress in three dimensions.

[0027] Compared with the prior art, the advantages of the present invention are: simple processing technology, good compression characteristics, high sensitivity, and the ability to detect three-dimensional forces, which has great application potential in the fields of medical treatment, sports, and health protection. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the three-dimensional flexible stress sensor of the present invention;

[0029] Figure 2 This is a schematic diagram of the deformation of the three-dimensional flexible stress sensor of the present invention under the action of force in different directions;

[0030] Figure 3 This is a schematic diagram of the force decomposition of the shear force on the three-dimensional flexible stress sensor of the present invention. Detailed Implementation

[0031] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0032] Example 1

[0033] The present invention discloses a method for fabricating a three-dimensional flexible stress sensor, wherein the three-dimensional flexible stress sensor has a five-layer structure, consisting of a flexible microstructure layer, an upper electrode layer, a sensitive unit layer, a lower electrode layer, and a protective layer from top to bottom, and includes the following steps:

[0034] Step 1: Fabrication of the flexible microstructure layer;

[0035] Step 2: Prepare the sensitive units; four sensitive units constitute a sensitive unit layer.

[0036] Step 3: Select conductive materials as the upper and lower electrode layers;

[0037] Step 4: Select a soft insulating material as the protective layer;

[0038] Step 5: Encapsulate the flexible microstructure layer, upper electrode layer, sensitive unit layer, lower electrode layer, and protective layer;

[0039] The following steps in step one:

[0040] (1) Select sandpaper as a template, clean and dry it, and then fix it with tape;

[0041] (2) PDMS is coated on the side of sandpaper with a rough microstructure. After drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS film with a groove structure opposite to that of the sandpaper.

[0042] (3) PDMS is coated on the surface of a PDMS film with a groove structure, dried in an oven, and carefully peeled off with tweezers to obtain a PDMS film with the same microstructure as sandpaper, i.e., a flexible microstructure layer;

[0043] Step two includes the following steps:

[0044] (1) Using cashmere fabric as a carrier, ultrasonically cleaned with anhydrous ethanol, then cleaned again with deionized water to remove impurities from the fabric surface, and finally dried in an oven.

[0045] (2) Surface modification treatment is applied to clean cashmere fabrics to roughen their surface;

[0046] (3) The fabric was sequentially immersed in Mxene solution and silver nanowires to obtain Mxene / silver nanowire composite cashmere sensitive layer;

[0047] In step four, the flexible insulating material is PDMS or resin;

[0048] Both the upper and lower electrode layers consist of a common electrode and four patterned electrodes connected together.

[0049] In step three, the conductive material is copper foil or silver foil;

[0050] The silver nanowires are prepared by chemical reduction, electrochemical methods, or microwave methods.

[0051] The methods for preparing the Mxene two-dimensional nanosheets include fluorine-containing etching, fluorine-free etching, or organic solvent-assisted intercalation and collection.

[0052] Example 2

[0053] Applications of the three-dimensional flexible stress sensor of this invention, such as Figure 2 As shown, (a) is a top view of the sensitive unit layer, (b) is the free state without external force, (c) is the deformation under normal pressure Fz, (d) is the deformation under shear force Fx in the x direction, and (e) is the deformation under shear force Fy in the y direction. When the three-dimensional flexible stress sensor is subjected to three-dimensional forces, the sensitive unit deforms, thus changing the resistance value. When the sensor is subjected to normal pressure, all four sensitive units are subjected to the same force, resulting in the same compression. When the sensor is subjected to shear force in the x direction, the force on the right sensitive unit is greater than that on the left sensitive unit, and the compression deformation on the right is greater than that on the left. When the sensor is subjected to shear force in the y direction, the force on the rear sensitive unit is greater than that on the front sensitive unit, and the compression deformation on the rear is greater than that on the front. Figure 3As shown, a spatial rectangular coordinate system is established with the point of force application as the center. The three-dimensional shear force experienced by the sensor is decomposed. The angle between the direction of the shear force F and the z-axis is set as α, and the angle between the shear force F projected onto the xoy plane and the x-axis is set as β. Therefore, any shear force can be decomposed into x, y, and z axes. The specific decomposition is as follows:

[0054] Fz = Fcosα;

[0055] Fx = Fsinαcosβ;

[0056] Fy = Fsinαsinβ;

[0057] Based on this principle, three-dimensional force detection can be achieved.

[0058] The main functions achieved by this invention are:

[0059] (1) The protective layer of the three-dimensional flexible stress sensor is designed as a flexible microstructure layer. Its hemispherical structure can amplify the external pressure on the sensitive unit layer. Through structural innovation, the sensitivity of the flexible pressure sensor can be improved by using common materials.

[0060] (2) The three-dimensional flexible stress sensor detects three-dimensional force by arranging the sensitive units in an array and connecting them with four patterned electrodes, and by using the different resistance values ​​generated by different sensitive units.

[0061] (3) Three-dimensional flexible stress sensor structure. It has a five-layer structure, namely upper and lower electrode layers, sensitive unit layer, flexible microstructure layer and lower protective layer. The fabricated flexible three-dimensional force sensor has simple processing technology, good durability and strong compression characteristics, and can realize the detection of three-dimensional force.

[0062] (4) In this invention, the electrode layer can be prepared by simple processes such as laser direct writing, printing, and template method; the sensitive unit layer can be prepared by impregnation, coating and other methods. In industry, mature process flow can be used to process a high-sensitivity flexible three-dimensional force sensor.

[0063] The fabrication method and application of the three-dimensional flexible stress sensor of the present invention can be implemented using common mechanical methods in terms of installation, connection, or setting. Any method that achieves the desired beneficial effect is acceptable. The sensing mechanism of the three-dimensional flexible stress sensor in this invention is as follows: when the sensor is subjected to a three-dimensional force, the flexible microstructure layer amplifies and transmits the force to four sensitive units. These sensitive units deform accordingly, resulting in a change in resistance. When the sensor is subjected to normal pressure, the four sensitive units experience the same force, resulting in the same compression and a similar change in resistance. When the sensor is subjected to shear force in the X direction, the force on the right-hand sensitive unit is greater than that on the left-hand sensitive unit, leading to a greater compression deformation on the right and a greater change in resistance. Based on this principle, the detection of three-dimensional forces can be achieved.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a three-dimensional flexible stress sensor, characterized in that, The three-dimensional flexible stress sensor has a five-layer structure, consisting of a flexible microstructure layer, an upper electrode layer, a sensitive unit layer, a lower electrode layer, and a protective layer from top to bottom. The fabrication method of the three-dimensional flexible stress sensor includes the following steps: Step 1: Fabrication of the flexible microstructure layer; Step 2: Prepare the sensitive units; four sensitive units constitute a sensitive unit layer. Step 3: Select conductive materials as the upper and lower electrode layers; Step 4: Select a soft insulating material as the protective layer; Step 5: Encapsulate the flexible microstructure layer, upper electrode layer, sensitive unit layer, lower electrode layer, and protective layer; The following steps in step one: (1) Select sandpaper as a template, clean and dry it, and then fix it with tape; (2) PDMS is coated on the side of sandpaper with a rough microstructure. After drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS film with a groove structure opposite to that of the sandpaper. (3) PDMS is coated on the surface of a PDMS film with a groove structure, dried in an oven, and carefully peeled off with tweezers to obtain a PDMS film with the same microstructure as sandpaper, i.e., a flexible microstructure layer; Step two includes the following steps: (1) Using cashmere fabric as a carrier, ultrasonically cleaned with anhydrous ethanol, then cleaned again with deionized water to remove impurities from the fabric surface, and finally dried in an oven. (2) Surface modification treatment is applied to clean cashmere fabrics to roughen their surface; (3) The fabric is sequentially immersed in MXene solution and silver nanowires to obtain MXene / silver nanowire composite cashmere sensitive layer.

2. The method for fabricating a three-dimensional flexible stress sensor as described in claim 1, characterized in that, In step four, the flexible insulating material is PDMS.

3. The method for fabricating a three-dimensional flexible stress sensor as described in claim 1, characterized in that, Both the upper and lower electrode layers consist of a common electrode and four patterned electrodes connected together.

4. The method for fabricating a three-dimensional flexible stress sensor as described in claim 1, characterized in that, In step three, the conductive material is copper foil or silver foil.

5. The method for fabricating a three-dimensional flexible stress sensor as described in claim 1, characterized in that, The silver nanowires can be prepared by chemical reduction, electrochemical methods, or microwave methods.

6. The method for fabricating a three-dimensional flexible stress sensor as described in claim 1, characterized in that, The preparation methods of the MXene solution include fluorine-containing etching, fluorine-free etching, or organic solvent-assisted intercalation collection.

7. The method for fabricating a three-dimensional flexible stress sensor as described in claim 1, characterized in that, The sensitive units are arranged in an array.

8. The method for fabricating a three-dimensional flexible stress sensor as described in claim 1, characterized in that, In step four, the flexible insulating material is resin.

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