Sensitive unit preparation method, sensitive unit and tactile sensor

Abstract

The invention provides a preparation method of a sensitive unit, the sensitive unit and a touch sensor, and the preparation method comprises the following steps: preparing a PDMS film, and carrying out plasma treatment on the PDMS film; conducting silver paste is subjected to silk-screen printing on the PDMS film to form upper and lower flexible electrodes; a PDMS / pedot: PSS composite solution is subjected to in-situ screen printing on the flexible electrode to form a PDMS / pedot: PSS electrode; a PDMS / MWCNT nano composite solution is coated on a mask on the PDMS / pedot: PSS electrode so as to form a sensitive layer; soaking the cured upper layer and the cured lower layer in a mixed solution of chloroform and PDMS, so that an uncured PDMS network is formed at the joint of the upper layer and the lower layer; and applying pressure so that the PDMS network in the sensitive layer and the electrode and the PDMS network in the chloroform are intertwined together to form a cross-linked network structure. By adopting the scheme, the problem of mechanical mismatch between layers of the sensitive units is solved.

Description

Technical Field

[0001] The present application belongs to the field of sensor technology, and in particular relates to a method for preparing a sensitive unit, a sensitive unit and a tactile sensor. Background Art

[0002] Tactile perception is an important function for biological beings to sense changes in external information. Robots also need tactile sensing functions to achieve anthropomorphic perception capabilities. Robot tactile perception refers to the process of detecting and identifying various physical information of objects or objects in contact through tactile sensing elements. In modern robotics technology, the development of tactile sensors has become the key to promoting the realization of more advanced functions of robot dexterous hands. Dexterous hands directly contact objects through tactile sensors to sense the contact state between the hand and the target object and the characteristic information of the object, such as contact position, force, slip, vibration, temperature and softness. This information is converted into electrical signals for object recognition, manipulation stability evaluation and precise force control.

[0003] The material and structural design of the sensitive unit is the basis of the performance of the tactile sensor. Existing sensitive units usually adopt a multi-layer structure, in which each layer uses different materials. Although this design can enable the sensor to meet performance requirements, it also brings about the problem of mechanical mismatch between layers. Mechanical mismatch between layers refers to the difference in physical properties such as thermal expansion coefficient and elastic modulus between different materials, which leads to interface detachment or structural damage during use. As the number of uses increases, this mechanical mismatch between layers will cause the working stability of the tactile sensor to drop sharply, affecting its long-term performance. Summary of the invention

[0004] The present application provides a method for preparing a sensitive unit, a sensitive unit and a tactile sensor to solve the problem of mechanical mismatch between layers of the existing sensitive unit.

[0005] In a first aspect, the present application provides a method for preparing a sensitive unit, comprising:

[0006] preparing a first PDMS film and a second PDMS film, and performing plasma treatment on the first PDMS film and the second PDMS film to obtain a third PDMS film and a fourth PDMS film;

[0007] Screen printing a conductive silver paste on a surface of the third PDMS film close to the fourth PDMS film to form a first flexible electrode; screen printing a conductive silver paste on a surface of the fourth PDMS film close to the third PDMS film to form a second flexible electrode;

[0008] In-situ screen printing a PDMS / pedot:PSS composite solution on the first flexible electrode and the second flexible electrode to form a first PDMS / pedot:PSS electrode and a second PDMS / pedot:PSS electrode, respectively;

[0009] Applying a PDMS / MWCNT nanocomposite solution to the surface of the first PDMS / pedot:PSS electrode close to the second PDMS / pedot:PSS electrode through a mask to obtain a first sensitive layer; applying a PDMS / MWCNT nanocomposite solution to the surface of the second PDMS / pedot:PSS electrode close to the first PDMS / pedot:PSS electrode through a mask to obtain a second sensitive layer;

[0010] placing the first sensitive layer and the second sensitive layer in a mixed solution of chloroform and PDMS to form an uncured PDMS network between the first sensitive layer and the second sensitive layer;

[0011] Under the action of external force, the PDMS network in each PDMS film, each electrode and each sensitive layer is entangled with the uncured PDMS network to obtain a cross-linked network structure as a sensitive unit.

[0012] Optionally, the thickness of the first PDMS film and the second PDMS film is greater than or equal to 80 microns and less than or equal to 300 microns.

[0013] Optionally, the plasma treatment time is greater than or equal to 15 minutes and less than or equal to 45 minutes.

[0014] Optionally, after printing the conductive silver paste on the surface of the third PDMS film and the fourth PDMS film as flexible electrodes, the silver paste is naturally air-dried, and a layer of PDMS / pedot:PSS electrode is in situ printed on each flexible electrode using a PDMS / pedot:PSS composite solution, and then heated and dried in a vacuum drying oven at a temperature greater than or equal to 80°C and less than or equal to 100°C.

[0015] Optionally, the heating and drying time is greater than or equal to 0.5 hours and less than or equal to 1.5 hours.

[0016] Optionally, the first aspect further comprises dissolving the multi-walled carbon nanotubes in a chloroform solution and performing ultrasonic dispersion, then adding polydimethylsiloxane to mix, and then adding a polydimethylsiloxane crosslinking agent to obtain a PDMS / MWCNT nanocomposite solution.

[0017] Optionally, the ratio of the multi-walled carbon nanotubes is greater than or equal to 10 mg / mL and less than or equal to 30 mg / mL; the ratio of the PDMS cross-linker to PDMS is greater than or equal to 8:1 and less than or equal to 10:1; the ratio of PDMS to pedot:PSS in the PDMS / pedot:PSS composite solution is greater than or equal to 5:1 and less than or equal to 8:1.

[0018] Optionally, the pressure for entanglement of the PDMS network and the uncured PDMS network in each PDMS membrane, each electrode and each sensitive layer is greater than or equal to 0.1 MPa and less than or equal to 1 MPa.

[0019] In a second aspect, the present application provides a sensitive unit, which is prepared by the preparation method described in the first aspect.

[0020] In a third aspect, the present application provides a tactile sensor, characterized in that it includes the sensitive unit as described in the second aspect.

[0021] The present application provides a preparation method of a sensitive unit, a sensitive unit and a tactile sensor. In the preparation method, a PDMS film is treated with plasma to improve electrode adhesion; the electrode is prepared by screen printing to improve the uniformity and consistency of the electrode; the introduction of a PDMS / pedot:PSS composite electrode enhances the flexibility and durability of the electrode, so that the sensitive unit can adapt to deformation requirements in complex operations; the drying process of the sensitive layer ensures its uniform curing and good mechanical properties; the formation process of a quasi-homogeneous cross-linked network structure, through the steps of immersion, stacking and pressurization, enables the functional layers to be firmly cross-linked, greatly enhancing the toughness and strength of the sensitive unit, and ensuring that the sensitive unit can work stably and for a long time under complex conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 A schematic diagram of a process for preparing a sensitive unit provided in an embodiment of the present application;

[0024] Figure 2 A schematic diagram of the structure of generating a quasi-homogeneous cross-linked network provided in an embodiment of the present application;

[0025] Figure 3 A schematic diagram of the structure of the method for preparing a sensitive unit provided in an embodiment of the present application;

[0026] Figure 4 A schematic diagram of the principle of a tactile sensor provided in an embodiment of the present application;

[0027] Figure 5 A schematic diagram of the structure of a sensitive unit provided in an embodiment of the present application.

[0028] Among them, 110, the third PDMS film; 120, the fourth PDMS film; 130, the first flexible electrode; 140, the second flexible electrode; 150, the first PDMS / pedot:PSS electrode; 160, the second PDMS / pedot:PSS electrode; 170, the first sensitive layer; 180, the second sensitive layer. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] As described in the background technology of this application, existing sensitive units usually adopt a multi-layer structure, in which each layer uses different materials. Although this design can enable the sensor to meet performance requirements, it also brings about the problem of mechanical mismatch between layers. Mechanical mismatch between layers refers to the difference in physical properties such as thermal expansion coefficient and elastic modulus between different materials, which leads to interface shedding or structural damage during use. As the number of uses increases, this mechanical mismatch between layers will cause the working stability of the tactile sensor to drop sharply, affecting its long-term performance.

[0031] Therefore, in order to solve the above problems, Figure 1 and Figure 3 As shown, the embodiment of the present application provides a method for preparing a sensitive unit, comprising:

[0032] Step 101 , preparing a first PDMS film and a second PDMS film, and performing plasma treatment on the first PDMS film and the second PDMS film to obtain a third PDMS film 110 and a fourth PDMS film 120 .

[0033] PDMS (polydimethylsiloxane) is a flexible material with excellent elasticity and chemical resistance. As a substrate, it not only provides structural support, but also effectively absorbs external impacts and protects internal sensitive components from damage. In addition, the transparency of PDMS allows optical detection in certain applications, increasing the application flexibility of the sensor. In this step, a first PDMS film and a second PDMS film with a thickness greater than or equal to 80 microns and less than or equal to 300 microns are prepared using a wet film preparation device with modulatable thickness; the first PDMS film and the second PDMS film are plasma treated to reduce the surface energy of the first PDMS film and the second PDMS film, so that the flexible electrode printed in step 102 has good adhesion; the plasma treatment time is greater than or equal to 15 minutes and less than or equal to 45 minutes.

[0034] Step 102, screen-print conductive silver paste on the surface of the third PDMS film 110 close to the fourth PDMS film 120 to form the first flexible electrode 130; screen-print conductive silver paste on the surface of the fourth PDMS film 120 close to the third PDMS film 110 to form the second flexible electrode 140.

[0035] In this step, the first flexible electrode 130 is used as the upper-layer flexible electrode, and the second flexible electrode 140 is used as the lower-layer flexible electrode. Exemplarily, upper and lower layer electrode screen-printing plates are respectively used to screen-print conductive silver paste on the third PDMS film 110 and the fourth PDMS film 120 as the upper and lower layer flexible electrodes. At this time, the upper and lower layer flexible electrodes are not removed from the PDMS film, and the silver paste is waited to air-dry naturally.

[0036] The upper and lower layer flexible electrodes (the first flexible electrode 130 and the second flexible electrode 140) are composed of silver particles and a polymer matrix, and have extremely high conductivity and good adhesion. Its advantage is that it can form a uniform electrode layer on the flexible substrate to ensure stable conduction of current. The use of flexible electrodes enables the sensitive unit to work effectively even at low voltages, realizes the detection of tiny forces, and its good conductivity helps to improve the sensitivity and response speed of signals. In this embodiment, a 200-mesh screen-printing stencil is used, and the pattern designed in the stencil can be printed onto the specified substrate through a screen printer.

[0037] Step 103, screen-print PDMS / pedot:PSS composite solution in situ on the first flexible electrode 130 and the second flexible electrode 140 to respectively form the first PDMS / pedot:PSS electrode 150 and the second PDMS / pedot:PSS electrode 160.

[0038] In this step, the preparation of the PDMS / pedot:PSS composite solution: Mix PDMS and pedot:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) in a ratio of 5:1 to 8:1 (ratio range), preferably 5:1, put it into a planetary mixer for mixing. The rotation speed of the planetary mixer is greater than 1000 rpm / min, and the mixing time should be greater than 10 minutes to ensure sufficient mixing.

[0039] After the silver paste of step 102 is naturally air-dried, the PDMS / pedot:PSS composite solution is in-situ screen-printed on the first flexible electrode 130 and the second flexible electrode 140 to form the first PDMS / pedot:PSS electrode 150 and the second PDMS / pedot:PSS electrode 160 respectively. After the first PDMS / pedot:PSS electrode 150 and the second PDMS / pedot:PSS electrode 160 are formed, the first PDMS / pedot:PSS electrode 150 and the second PDMS / pedot:PSS electrode 160 are removed and heated and dried at a temperature greater than or equal to 80° C. and less than or equal to 100° C. in a vacuum environment (in a vacuum drying oven) for a time greater than or equal to 0.5 hours and less than or equal to 1.5 hours. The prepared first PDMS / pedot:PSS electrode 150 and the second PDMS / pedot:PSS electrode 160 have excellent flexibility and certain stretchability, which can effectively compensate for the mechanical tearing of the silver electrodes (the first flexible electrode 130 and the second flexible electrode 140) when performing complex and difficult tasks.

[0040] The first PDMS / pedot:PSS electrode 150 and the second PDMS / pedot:PSS electrode 160 combine the flexibility of PDMS and the conductivity of pedot:PSS to form a material with excellent conductivity and mechanical properties. Pedot:PSS is a conductive polymer that is less conductive than silver paste electrodes but can provide higher flexibility. This composite material can effectively disperse stress when subjected to external forces, maintain the integrity of the electrode, avoid electrode breakage caused by stretching and torsion, and ensure the reliability of the sensitive unit in a dynamic environment.

[0041] Step 104, mask-brush the PDMS / MWCNT nanocomposite solution on the surface of the first PDMS / pedot:PSS electrode 150 close to the second PDMS / pedot:PSS electrode 160 to obtain a first sensitive layer 170; mask-brush the PDMS / MWCNT nanocomposite solution on the surface of the second PDMS / pedot:PSS electrode 160 close to the first PDMS / pedot:PSS electrode 150 to obtain a second sensitive layer 180.

[0042] In this step, the preparation of PDMS / MWCNT nanocomposite solution: First, MWCNT is dissolved in chloroform solution according to 10-30 mg / mL (concentration range) and dispersed in an ultrasonic crusher. The content of MWCNT will directly affect the sensitivity and range of the sensitive unit. If there is no special requirement, 15 mg / mL can be used, which can achieve a considerable balance between sensitivity and range. Then, PDMS is added to the mixed solution of chloroform and MWCNT at a ratio of 190 mg / mL and placed in a magnetic stirrer for mixing. Then, the nanocomposite solution is placed in an ultrasonic bath for dispersion again. Finally, the PDMS crosslinker is added to the mixed solution of chloroform, MWCNT and PDMS at a ratio of 8:1 to 10:1 (ratio range), and mixed by magnetic stirring. To ensure the complete dispersion of MWCNT and PDMS in the solution, the speed of the magnetic stirrer should be greater than 1000 rpm / min, and the mixing time should be greater than 10 minutes, which can be beneficial to the curing of the nanocomposite solution and improve the stability of the performance of the sensitive layer.

[0043] The PDMS / MWCNT sensitive layer (the first sensitive layer 170 and the second sensitive layer 180) is the core part of the sensitive unit. The high conductivity and excellent mechanical properties of multi-walled carbon nanotubes (MWCNTs) are used to enhance the piezoresistive effect of the sensitive unit. When an external force is applied, the arrangement and contact state of the MWCNTs will change, resulting in a significant change in resistance, thereby achieving accurate perception of force. The use of this sensitive layer material enables the sensitive unit to operate within a variety of pressure ranges to meet different application requirements.

[0044] Step 105 , placing the first sensitive layer 170 and the second sensitive layer 180 in a vacuum environment, heating and drying them, and then placing them in a mixed solution of chloroform and PDMS to form an uncured PDMS network between the first sensitive layer 170 and the second sensitive layer 180 .

[0045] In this step, the first sensitive layer 170 and the second sensitive layer 180 are placed in a vacuum environment at 80-100° C. and heated and dried for 0.5 to 1.5 hours.

[0046] Step 106, under the action of external force, the PDMS network in each PDMS film, each electrode and each sensitive layer is entangled with the uncured PDMS network to obtain a cross-linked network structure as a sensitive unit.

[0047] In this step, the cross-linked network structure is a quasi-homogeneous cross-linked network structure. Quasi-homogeneous means that different functional layers of the sensitive unit are made of the same material. Taking PDMS as an example, Figure 2As shown, the electrode and sensitive layer based on the PDMS composite material are first immersed in a solvent mixed with PDMS and chloroform. After it expands, the functional layers are stacked in order and a certain pressure is applied. During this process, the uncured PDMS monomer and curing agent in the chloroform will gradually penetrate from the junction of the electrode and the sensitive layer into the pre-formed PDMS network inside the functional layer. After the PDMS in the chloroform is cured, a new PDMS network will be formed, and it will be entangled with the pre-formed PDMS network to form a cross-linked network structure. This process makes the functional layers firmly cross-linked together, and finally achieves seamless connection, thereby enhancing the toughness and strength of the sensitive unit, so that it can still maintain high stability under complex conditions.

[0048] Exemplarily, the pressure for intertwining the PDMS network in each PDMS membrane, each electrode and each sensitive layer with the uncured PDMS network is greater than or equal to 0.1 MPa and less than or equal to 1 MPa, ensuring that the upper and lower layers can be effectively intertwined to form a strong cross-linked network.

[0049] In the process of forming a cross-linked network structure, the upper and lower layers are positioned and assembled using a fixture or mold, and the positioning accuracy of the fixture or mold ranges from ±0.1mm to ±1mm, ensuring the accuracy of the upper and lower layer assembly and avoiding the impact of assembly deviation on the performance of sensitive units.

[0050] In order to make the solution of the present application clearer, the embodiments of the present application further disclose specific examples.

[0051] Example 1

[0052] 1) Dissolve MWCNT in chloroform solution at a concentration of 10 mg / mL and disperse in an ultrasonic crusher for 30 minutes; then add PDMS to the solution at a concentration of 190 mg / mL and mix in a magnetic stirrer at a speed of 1000 rpm / min for 10 minutes; disperse the nanocomposite solution in an ultrasonic bath again; finally, add PDMS crosslinker to the solution at a ratio of 8:1 and mix by magnetic stirring.

[0053] 2) PDMS and pedot:PSS were mixed in a ratio of 5:1 and placed in a planetary mixer for mixing at a speed of 1000 rpm / min for 10 minutes.

[0054] 3) A first PDMS film and a second PDMS film with a thickness of 80 μm were prepared using a wet film preparation device with adjustable thickness, and the first PDMS film and the second PDMS film were plasma treated for 15 minutes to obtain a third PDMS film and a fourth PDMS film.

[0055] 4) Using the upper and lower electrode screen printing plates respectively, screen-print the conductive silver paste on the third PDMS film and the fourth PDMS film as the first flexible electrode and the second flexible electrode, after the silver paste is naturally air-dried, in-situ screen-print the PDMS / pedot:PSS composite solution on the first flexible electrode and the second flexible electrode to obtain the first PDMS / pedot:PSS electrode and the second PDMS / pedot:PSS electrode, and then remove the first PDMS / pedot:PSS electrode and the second PDMS / pedot:PSS electrode and heat dry them in a vacuum drying oven at 80°C for 30 minutes.

[0056] 5) Mask-brush the PDMS / MWCNT nanocomposite solution on the surface of the first PDMS / pedot:PSS electrode close to the second PDMS / pedot:PSS electrode to obtain a first sensitive layer; mask-brush the PDMS / MWCNT nanocomposite solution on the surface of the second PDMS / pedot:PSS electrode close to the first PDMS / pedot:PSS electrode to obtain a second sensitive layer, and then dry the first sensitive layer and the second sensitive layer in a vacuum drying oven at 80°C for 30 minutes.

[0057] 6) Immerse the cured first sensitive layer and the second sensitive layer in a mixed solution of chloroform and PDMS.

[0058] 7) Use a fixture or mold for positioning and assembly, and apply a pressure of 0.5 MPa to entangle the PDMS networks of the third PDMS membrane, the fourth PDMS membrane, the first flexible electrode, the second flexible electrode, the first PDMS / pedot:PSS electrode, the second PDMS / pedot:PSS electrode, the first sensitive layer and the second sensitive layer with the PDMS network in chloroform to form a cross-linked network structure.

[0059] Example 2

[0060] 1) Dissolve MWCNT in chloroform solution at a concentration of 25 mg / mL and disperse in an ultrasonic crusher for 40 minutes; then add PDMS to the solution at a concentration of 190 mg / mL and mix in a magnetic stirrer at a speed of 1000 rpm / min for 30 minutes; disperse the nanocomposite solution in an ultrasonic bath again; finally, add PDMS crosslinker to the solution at a ratio of 9:1 and mix by magnetic stirring.

[0061] 2) PDMS and pedot:PSS were mixed in a ratio of 7:1 and placed in a planetary mixer for mixing at a speed of 1000 rpm / min for 30 minutes.

[0062] 3) A first PDMS film and a second PDMS film with a thickness of 150 μm were prepared using a wet film preparation device with adjustable thickness, and the first PDMS film and the second PDMS film were plasma treated for 30 minutes to obtain a third PDMS film and a fourth PDMS film.

[0063] 4) Using the upper and lower electrode screen printing plates respectively, the conductive silver paste is screen-printed on the third PDMS film and the fourth PDMS film as the first flexible electrode and the second flexible electrode. After the silver paste is naturally air-dried, the PDMS / pedot:PSS composite solution is in situ screen-printed on the first flexible electrode and the second flexible electrode to obtain the first PDMS / pedot:PSS electrode and the second PDMS / pedot:PSS electrode. Subsequently, the first PDMS / pedot:PSS electrode and the second PDMS / pedot:PSS electrode are removed and heated and dried at 90°C in a vacuum drying oven for 60 minutes.

[0064] 5) Mask-brush the PDMS / MWCNT nanocomposite solution on the surface of the first PDMS / pedot:PSS electrode close to the second PDMS / pedot:PSS electrode to obtain a first sensitive layer; mask-brush the PDMS / MWCNT nanocomposite solution on the surface of the second PDMS / pedot:PSS electrode close to the first PDMS / pedot:PSS electrode to obtain a second sensitive layer, and then dry the first sensitive layer and the second sensitive layer in a vacuum drying oven at 90°C for 60 minutes.

[0065] 6) Immerse the cured first sensitive layer and the second sensitive layer in a mixed solution of chloroform and PDMS.

[0066] 7) Use a fixture or mold for positioning and assembly, and apply a pressure of 1 MPa to entangle the PDMS networks of the third PDMS membrane, the fourth PDMS membrane, the first flexible electrode, the second flexible electrode, the first PDMS / pedot:PSS electrode, the second PDMS / pedot:PSS electrode, the first sensitive layer and the second sensitive layer with the PDMS network in chloroform to form a cross-linked network structure.

[0067] Example 3

[0068] 1) Dissolve MWCNT in chloroform solution at a concentration of 30 mg / mL and disperse in an ultrasonic crusher for 45 minutes; then add PDMS to the solution at a concentration of 190 mg / mL and mix in a magnetic stirrer at a speed of 1000 rpm / min for 45 minutes; disperse the nanocomposite solution in an ultrasonic bath again; finally, add PDMS crosslinker to the solution at a ratio of 10:1 and mix by magnetic stirring.

[0069] 2) PDMS and pedot:PSS were mixed in a ratio of 8:1 and placed in a planetary mixer for mixing at a speed of 1000 rpm / min for 45 minutes.

[0070] 3) A first PDMS film and a second PDMS film with a thickness of 250 μm were prepared using a wet film preparation device with adjustable thickness, and the first PDMS film and the second PDMS film were plasma treated for 45 minutes to obtain a third PDMS film and a fourth PDMS film.

[0071] 4) Using the upper and lower electrode screen printing plates respectively, the conductive silver paste is screen-printed on the third PDMS film and the fourth PDMS film as the first flexible electrode and the second flexible electrode. After the silver paste is naturally air-dried, the PDMS / pedot:PSS composite solution is in situ screen-printed on the first flexible electrode and the second flexible electrode to obtain the first PDMS / pedot:PSS electrode and the second PDMS / pedot:PSS electrode. Subsequently, the first PDMS / pedot:PSS electrode and the second PDMS / pedot:PSS electrode are removed and heated and dried at 100° C. in a vacuum drying oven for 30 minutes.

[0072] 5) Mask-brush the PDMS / MWCNT nanocomposite solution on the surface of the first PDMS / pedot:PSS electrode close to the second PDMS / pedot:PSS electrode to obtain a first sensitive layer; mask-brush the PDMS / MWCNT nanocomposite solution on the surface of the second PDMS / pedot:PSS electrode close to the first PDMS / pedot:PSS electrode to obtain a second sensitive layer, and then dry the first sensitive layer and the second sensitive layer in a vacuum drying oven at 100°C for 30 minutes.

[0073] 6) Immerse the cured first sensitive layer and the second sensitive layer in a mixed solution of chloroform and PDMS.

[0074] 7) Use a fixture or mold for positioning and assembly, and apply a pressure of 1 MPa to entangle the PDMS networks of the third PDMS membrane, the fourth PDMS membrane, the first flexible electrode, the second flexible electrode, the first PDMS / pedot:PSS electrode, the second PDMS / pedot:PSS electrode, the first sensitive layer and the second sensitive layer with the PDMS network in chloroform to form a cross-linked network structure.

[0075] In addition, based on the above embodiments, other embodiments may be derived. For example, based on each embodiment, other process parameters in the embodiments may remain unchanged or may be changed as needed. In other words, those skilled in the art may combine and replace process parameters according to the above embodiments, and this application does not make any specific limitations.

[0076] The embodiment of the present application provides a method for preparing a sensitive unit, which improves the electrode adhesion by plasma treating the PDMS film; uses screen printing to prepare the electrode to improve the uniformity and consistency of the electrode, and the introduction of the PDMS / pedot:PSS composite electrode enhances the flexibility and durability of the electrode, so that the sensitive unit can adapt to the deformation requirements in complex operations; the drying process of the sensitive layer ensures its uniform curing and good mechanical properties, and the formation process of the quasi-homogeneous cross-linked network structure, through the steps of immersion, stacking and pressurization, makes the functional layers firmly cross-linked, greatly enhances the toughness and strength of the sensitive unit, and ensures that the sensitive unit can work stably for a long time under complex conditions.

[0077] Based on the preparation method of the sensitive unit disclosed above, the examples of this application also disclose a sensitive unit prepared by the above preparation method, such as Figure 5 As shown, the sensitive unit includes, from bottom to top, a fourth PDMS film 120, a second flexible electrode 140, a second PDMS / pedot:PSS electrode 160, a second sensitive layer 180, a first sensitive layer 170, a first PDMS / pedot:PSS electrode 150, a first flexible electrode 130 and a third PDMS film 110. Figure 5 It only indicates the positional relationship of each layer in the sensitive unit, and does not represent the final state of the sensitive unit.

[0078] The force is sensed through the combination of upper and lower electrodes and the sensitive layer. It is based on the piezoresistive effect. When external force acts on the sensitive unit, the pressure-sensitive material of the sensitive layer will deform, causing its internal conductive network to become different, thereby causing its resistance value to change, such as Figure 4 The sensitive layer is connected to the peripheral resistance scanning detection circuit via the flexible flat cable (FFC) interface of the row and column electrodes to form a closed loop, thereby realizing the rapid scanning detection of the array resistance of the sensitive layer.

[0079] Based on the sensitive unit provided in the foregoing embodiments of the present application, the embodiments of the present application partially provide a tactile sensor, including the sensitive unit as described in the foregoing embodiments.

[0080] The sensitive unit provided in the embodiment of the present application is applied to a tactile sensor, which overcomes the problem of mechanical mismatch between layers. The flexible material used as the electrode improves the stability and durability of the tactile sensor, ensures the reliability of high-intensity use, and can be widely used.

[0081] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a sensitive unit, characterized in that: include: preparing a first PDMS film and a second PDMS film, and performing plasma treatment on the first PDMS film and the second PDMS film to obtain a third PDMS film and a fourth PDMS film; Screen printing a conductive silver paste on a surface of the third PDMS film close to the fourth PDMS film to form a first flexible electrode; Screen printing a conductive silver paste on a surface of the fourth PDMS film close to the third PDMS film to form a second flexible electrode; In-situ screen printing a PDMS / pedot:PSS composite solution on the first flexible electrode and the second flexible electrode to form a first PDMS / pedot:PSS electrode and a second PDMS / pedot:PSS electrode, respectively; Applying a PDMS / MWCNT nanocomposite solution through a mask on the surface of the first PDMS / pedot:PSS electrode close to the second PDMS / pedot:PSS electrode to obtain a first sensitive layer; Applying a PDMS / MWCNT nanocomposite solution through a mask on the surface of the second PDMS / pedot:PSS electrode close to the first PDMS / pedot:PSS electrode to obtain a second sensitive layer; The first sensitive layer and the second sensitive layer are placed in a vacuum environment, heated and dried, and then placed in a mixed solution of chloroform and PDMS to form an uncured PDMS network between the first sensitive layer and the second sensitive layer; Under the action of external force, the PDMS network in each PDMS film, each electrode and each sensitive layer is entangled with the uncured PDMS network to obtain a cross-linked network structure as a sensitive unit.

2. The method for preparing a sensitive unit according to claim 1, characterized in that: The thickness of the first PDMS film and the second PDMS film is greater than or equal to 80 micrometers and less than or equal to 300 micrometers.

3. The method for preparing a sensitive unit according to claim 1, characterized in that: The plasma treatment time is greater than or equal to 15 minutes and less than or equal to 45 minutes.

4. The method for preparing a sensitive unit according to claim 1, characterized in that: After printing the conductive silver paste on the surface of the third PDMS film and the fourth PDMS film as flexible electrodes, the silver paste is naturally air-dried, and a layer of PDMS / pedot:PSS electrode is in situ printed on each flexible electrode using a PDMS / pedot:PSS composite solution, and then heated and dried at a temperature greater than or equal to 80°C and less than or equal to 100°C in a vacuum environment.

5. The method for preparing the sensitive unit according to claim 4, characterized in that: The heating drying time is greater than or equal to 0.5 hours and less than or equal to 1.5 hours.

6. The method for preparing a sensitive unit according to claim 4, characterized in that: The method also includes dissolving the multi-walled carbon nanotubes in a chloroform solution, performing ultrasonic dispersion, adding polydimethylsiloxane to mix, and then adding a polydimethylsiloxane crosslinking agent to obtain a PDMS / MWCNT nanocomposite solution.

7. The method for preparing a sensitive unit according to claim 6, characterized in that: The concentration of the multi-walled carbon nanotubes is greater than or equal to 10 mg / mL and less than or equal to 30 mg / mL; the ratio of the PDMS crosslinker to PDMS is greater than or equal to 8:1 and less than or equal to 10:1; the ratio of PDMS to pedot:PSS in the PDMS / pedot:PSS composite solution is greater than or equal to 5:1 and less than or equal to 8:

1.

8. The method for preparing a sensitive unit according to claim 1, characterized in that: The pressure for entanglement of the PDMS network and the uncured PDMS network in each PDMS film, each electrode and each sensitive layer is greater than or equal to 0.1 MPa and less than or equal to 1 MPa.

9. A sensitive unit, characterized in that: The sensitive unit is prepared by the preparation method according to any one of claims 1-8.

10. A tactile sensor, characterized in that: Comprising the sensitive unit as claimed in claim 9.

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