Integrated screen-printed ion-type flexible pressure sensor and preparation method thereof

Abstract

The present invention discloses a high-sensitivity ion-type flexible pressure sensor based on integrated screen printing and a preparation method thereof, wherein an electrode layer and a sensitive layer are sequentially printed on a top flexible substrate and a bottom flexible substrate respectively by screen printing, and then double-sided tape is used as a spacer layer for adhesion to form a symmetrical sandwich structure. The present invention utilizes a large-scale preparation method of integrated screen printing to prepare a flexible pressure sensor, utilizes a unique doping method to adapt to the screen printing requirements of different materials, meets the demand for measuring pressure distribution by printing an array, and realizes the flexibility requirement of the sensor by a flexible substrate, and finally realizes the digitization and visualization of pressure information by combining the electrical signal measurement method, which can greatly speed up the preparation efficiency of the flexible pressure sensor and effectively improve the consistency of the flexible pressure sensor.

Description

Technical Field

[0001] The present invention belongs to the technical field of pressure sensors, and in particular relates to a high-sensitivity ionization-type flexible pressure sensor based on integrated screen printing and a preparation method thereof. Background Art

[0002] Flexible pressure sensors are flexible electronic devices used to sense the force on the surface of an object. They can be attached to various irregular surfaces and have broad application prospects in the fields of medical health, robotics, biomechanics, etc. With the development of science and technology, flexible pressure sensors that have the functions of flexibility and accurate measurement of pressure distribution information have become the focus of attention. However, how to mass-produce and the repeatability of the produced sensors have become the difficulties that restrict the development and application of flexible pressure sensors. Summary of the invention

[0003] The purpose of the present invention is to solve the deficiencies in existing functional requirements and technologies, and propose a high-sensitivity ion-type flexible pressure sensor based on integrated screen printing and a preparation method thereof. The flexible pressure sensor is prepared by a large-scale preparation method of integrated screen printing, and a unique doping method is used to adapt to the screen printing requirements of different materials. The demand for measuring pressure distribution is met by printing arrays, and the flexibility requirements of the sensor are achieved by using a flexible substrate. Finally, the pressure information is digitized and visualized in combination with the electrical signal measurement method.

[0004] In order to achieve the above purpose, the technical solution of the present invention is:

[0005] A method for preparing an ionization pressure sensor based on integrated screen printing comprises the following steps:

[0006] S1. Making a bottom layer group and a top layer group, wherein the making of the bottom layer group and the top layer group respectively comprises the following sub-steps:

[0007] S11, printing an array-arranged electrode layer on a flexible substrate using a screen printing process, and heating and curing after printing.

[0008] S12, adding the TPU material to the solvent to dissolve it until the solution is clear, adding the ionic liquid material and mixing evenly, then adding the hexagonal boron nitride powder and mixing evenly to obtain a sensitive layer solution, printing the array-arranged sensitive layer on the electrode layer by screen printing, and drying and evaporating after printing;

[0009] S2. Use insulating double-sided tape as a spacer layer, and attach the sensitive layers of the bottom layer group and the top layer group to the two sides of the spacer layer opposite to each other;

[0010] S3. Pressing the edges of the flexible substrates of the bottom layer group and the top layer group together through a hot pressing process to form a packaging structure. No vacuum sealing is performed during the hot pressing process, leaving gaps to obtain an ion-type pressure sensor.

[0011] Optionally, the flexible substrate is a PET film, a PI film or a PDMS film with a thickness of 50um-500um.

[0012] Optionally, in step S11, oily slow-drying water is dropped into the conductive silver paste, the mixture is stirred at 1000-3000 r / min for 5-10 min, an electrode layer is printed on a flexible substrate using a screen printing process, and after printing, the mixture is heated at 80°C for 5-10 min for curing; wherein the ratio of the conductive silver paste to the oily slow-drying water is 1 mL: 1-2 drops.

[0013] Optionally, in step S11, the electrode layer is screen-printed using a circular array mask with a diameter of 0.1 mm to 1 mm to obtain a unit array, wherein connection directions of the unit arrays of the bottom layer group and the top layer group are perpendicular to each other.

[0014] Optionally, in step S12, the sensitive layer is screen-printed using a mask having the same circular array arrangement as the electrode layer, and the diameter of the circle of the sensitive layer is 0.1 mm to 1 mm larger than the diameter of the circle of the electrode layer.

[0015] Optionally, in step S12, according to the mass volume ratio, 2g to 5g of TPU material is added to 5ml to 50ml of solvent and stirred at 120°C to 180°C for 60min to 120min until completely dissolved, 1ml to 5ml of ionic liquid material is added, stirred at 100°C to 200°C for 30min to 60min, and then 2g to 5g of hexagonal boron nitride powder is added, and stirred at 100°C to 200°C for 60min to 120min to obtain the sensitive layer solution. The solvent can be DMF, PDMS solution, silica gel solution, etc.; the ionic liquid material is 1-ethyl-3-methylimidazole bistrifluoromethanesulfonyl imide salt or some other organic ionic liquids.

[0016] Optionally, in step S12, after printing is completed, the material is dried and evaporated at 60° C. to 100° C. for 1 hour to 3 hours.

[0017] Optionally, in step S11 and step S12, the mesh size of the screen printing is 100 to 300 meshes.

[0018] Optionally, the thickness of the insulating double-sided tape is 50um to 500um.

[0019] An ionization pressure sensor prepared by the above preparation method includes a bottom layer group, a spacer layer and a top layer group, the bottom layer group and the top layer group respectively include a flexible substrate, an electrode layer and a sensitive layer, the electrode layer and the sensitive layer are a unit array structure; wherein one of the bottom layer group and the top layer group is used to lead out row signals, and the other is used to lead out column signals.

[0020] Among them, PET is polyethylene terephthalate; TPU is thermoplastic polyurethane elastomer rubber, which has high elasticity and is soluble in various solvents such as dimethylformamide; DMF is N,N-dimethylformamide, which is often used as a non-protonic polar solvent.

[0021] The beneficial effects of the present invention are:

[0022] The present invention proposes a method for preparing a flexible pressure sensor based on integrated screen printing, which can be widely used in the preparation of flexible pressure sensors. By integrated screen printing, the size and shape of the mask can be controlled, which can greatly speed up the preparation efficiency of the flexible pressure sensor and effectively improve the consistency of the flexible pressure sensor.

[0023] The h-BN doping process proposed in the present invention can be widely used in the preparation of consumables for screen printing, which can effectively solve the problem that different materials are not suitable for screen printing, and improve the effect of screen printing and the performance of sensors to a certain extent. It also provides a new method for the next generation of integrated flexible pressure sensors to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a structural schematic diagram of a high-sensitivity ion-type flexible pressure sensor based on integrated screen printing in an embodiment;

[0025] Figure 2 is a process flow chart of a method for preparing a high-sensitivity ion-type flexible pressure sensor based on integrated screen printing in an embodiment;

[0026] Figure 3 yes Figure 1 Schematic diagram of the top-down structure of the middle sensitive layer. DETAILED DESCRIPTION

[0027] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. The various drawings of the present invention are only for illustration to make it easier to understand the present invention, and the specific proportions can be adjusted according to design requirements. The upper and lower relationships of the relative elements and the definitions of the front / back in the figures described in the text should be understood by those skilled in the art to refer to the relative positions of the components, so they can all be flipped to present the same components, which should all fall within the scope disclosed in this specification.

[0028] refer to Figure 1As shown, the high-sensitivity ionization flexible pressure sensor structure based on integrated screen printing provided by an embodiment of the present invention includes a top layer group 100, a spacer layer 200 and a bottom layer group 300, specifically including a top flexible substrate 110, a top electrode layer 120, a top sensitive layer 130, a spacer layer 200, a bottom sensitive layer 330, a bottom electrode layer 320, and a bottom flexible substrate 310 in order, wherein the top electrode layer 120 is printed on the top flexible substrate 110, the top sensitive layer 130 is printed on the top electrode layer 120, the bottom electrode layer 320 is printed on the bottom flexible substrate 310, the bottom sensitive layer 330 is printed on the bottom electrode layer 320, and the spacer layer 200 connects the top layer group 100 and the bottom layer group 300.

[0029] In this example, the electrodes are led out by row and column scanning, the top layer group 100 leads out the column signal, and the bottom layer group 300 leads out the row signal. The lead-out electrodes are arranged in parallel below the ion-type pressure sensor array and connected to the acquisition circuit. The flexible array includes 15×15 sensor units, and the row and column scanning method is used to lead out the electrodes below the sensor array. The acquisition card is connected externally. The main control MCU in the acquisition card controls the timing of capacitance acquisition, communicates with the host computer, and uploads the capacitance signal to the host computer in real time to realize the visualization and analysis of the pressure signal.

[0030] In this example, the top flexible substrate 110 and the bottom flexible substrate 310 are made of PET film material, and the good mechanical properties, bending resistance and corrosion resistance ensure the universality of its working environment. Conductive silver paste is selected as the screen printing consumables to print the top electrode layer 120 and the bottom electrode layer 320. 1-ethyl-3-methylimidazole bistrifluoromethanesulfonyl imide salt ionic liquid doped with h-BN material is selected as the material of the top sensitive layer 130 and the bottom sensitive layer 330; double-sided polyurethane tape with a thickness of 260um is selected as the material of the spacer layer 200.

[0031] refer to Figure 2 As shown, the detailed production steps of the present invention include a screen printing substrate 1, a flexible substrate 2, a screen 3, a silver electrode layer mask 4, a screen printing brush 5, a conductive silver paste 6, a printing process 7, a printed silver electrode layer 8, an ion sensitive layer mask 9, an ion sensitive material 10, an ion sensitive material printing process 11, and a result 12 of the ion sensitive layer after printing.

[0032] refer to Figures 1-2 In one embodiment, a high-sensitivity ion-type flexible pressure sensor based on integrated screen printing and a preparation method thereof include the following steps:

[0033] Step 1, flexible substrate preparation:

[0034] The top flexible substrate 110 and the bottom flexible substrate 310 are made of a transparent PET film with a thickness of about 260 um. A piece of the PET film is washed with alcohol and deionized water for 1 to 5 minutes respectively, and then dried with a hot air blower.

[0035] Step 2, electrode layer preparation:

[0036] Prepare the silver electrode layer screen printing material, add 1-2 drops of oily slow-drying water to 1 ml of conductive silver paste for dilution, and then stir and mix on a magnetic stirrer at 1000-3000 r / min for 5 minutes until the mixture is uniform;

[0037] Remove air bubbles by vacuum and use a sieve with appropriate mesh size to filter out impurities;

[0038] Use a screen printer to print the electrode shape designed in advance on the bottom flexible material. After printing, heat and cure it at 80°C for 5 minutes to obtain the top electrode layer 120 and the bottom electrode layer 320; for example, use a designed circular array mask with a diameter of 0.5mm for screen printing.

[0039] Step 3, preparation of ion sensitive layer:

[0040] Prepare TPU solution: add 2g TPU material into 5ml DMF for dissolution, and stir magnetically at 120℃ for 60min until it is completely dissolved and the solution is clear;

[0041] Prepare an ion mixed solution, add 1 ml of ionic liquid material to the prepared TPU solution, and stir magnetically at 150°C for 30 min to complete the preparation;

[0042] Prepare the screen printing solution for the sensitive layer, add 2 g h-BN powder to the prepared ion mixed solution, and stir it on a magnetic stirrer at 150 °C for 1 h;

[0043] The prepared screen printing sensitive layer solution is screen printed on the electrode layer, and dried and evaporated at 80°C in a fume hood for 3 hours to obtain a top sensitive layer 130 and a bottom sensitive layer 330; for example, a designed circular array mask with a diameter of 0.6 mm (0.1 mm larger than the electrode mask) is used for screen printing, and the sensitive layer pattern obtained after printing is as follows: Figure 3 shown.

[0044] Step 5, preparation of spacer layer:

[0045] Cut the double-sided polyurethane tape into 5×2×0.26m 3 The small blocks on the left and right allow the sensor to have a certain pressure stroke;

[0046] Step 6, sensor packaging:

[0047] After aligning the top flexible substrate 110 with the bottom flexible substrate 310, the sides printed with the electrode layer and the ion sensitive layer are pasted together through the spacer layer 200. In this process, the double-sided polyurethane tape of the spacer layer 200 plays an adhesion role;

[0048] After bonding, use a heat sealer to evenly heat seal the sensor around it to seal it. In addition, a certain gap must be left to prevent air pressure from affecting the sensor.

[0049] The preparation method of the present invention is further illustrated by specific examples below.

[0050] Example 1

[0051] S1, bottom flexible substrate:

[0052] The bottom flexible substrate is a commercial PET film. A piece of PET film is washed with alcohol and deionized water for 1 to 5 minutes respectively, and then dried with a hot air blower.

[0053] S2, silver electrode layer:

[0054] Prepare the silver electrode layer screen printing material, add 1-2 drops of oily slow-drying water to 1 ml of conductive silver paste to dilute it, and then stir it on a magnetic stirrer until it is evenly mixed;

[0055] Remove air bubbles by vacuum and use a 500-mesh sieve to filter out impurities;

[0056] Use a 200-mesh screen printer to print the electrode shape designed in advance on the bottom flexible material. After printing, heat and cure it at 80°C for 5 minutes.

[0057] S3, preparing the sensitive layer:

[0058] Prepare TPU solution, add 2g TPU material into 5ml DMF to dissolve, and stir magnetically at 120℃ for 60min until it is completely dissolved and the solution is clear.

[0059] Prepare an ion mixed solution, add 1 ml of ionic liquid material to the prepared TPU solution, and complete the preparation by magnetic stirring at 150° C. for 30 min.

[0060] Prepare the sensitive layer screen printing solution, add 2g h-BN powder to the prepared ion mixed solution, and stir on a magnetic stirrer at 150°C for 1h until the solution is mixed evenly.

[0061] The prepared screen-printed sensitive layer solution was printed on the electrode layer through a 200-mesh screen and dried in a fume hood at 80°C for 3 h;

[0062] S4, spacer layer:

[0063] Cut the double-sided polyurethane tape into 5×2×0.26m 3 Pasted on the two sides of the sensor unit, the sensor has a certain pressure stroke.

[0064] S5, sensor package;

[0065] Repeat steps S1, S2, and S3 on another PET film, then align the two PET films and stick the sides printed with the electrode layer and the ion-sensitive layer together. In this process, the double-sided polyurethane tape of the spacer layer plays an adhesion role.

[0066] After bonding, a heat sealer is used to evenly seal the sensor around the edges to seal it. In addition, a certain gap must be left to prevent air pressure from affecting the sensor. Finally, a complete sensor structure with a spacer layer as the symmetry is prepared. In addition, a heat press machine is used to heat press the two layers of flexible substrate material (PET film) together to form the final sensor packaging structure. Finally, an ion-type flexible pressure sensor is obtained.

[0067] Example 2

[0068] S1, bottom flexible substrate:

[0069] The bottom flexible substrate is a commercial PI (polyimide) film. A piece of PI film is cleaned with alcohol and deionized water for 1 to 5 min respectively, and then dried with a hot air blower;

[0070] S2, silver electrode layer:

[0071] Prepare the silver electrode layer screen printing material, add 3-4 drops of oily slow-drying water to 2 ml of conductive silver paste to dilute it, and then stir it on a magnetic stirrer until it is evenly mixed;

[0072] Remove air bubbles by vacuum and use a 500-mesh sieve to filter out impurities;

[0073] Use a 300-mesh screen printer to print the electrode shape designed in advance on the bottom flexible material. After printing, heat and cure it at 90°C for 10 minutes.

[0074] S3, preparing the sensitive layer:

[0075] Prepare TPU solution: add 1g TPU material into 10ml DMF for dissolution, and stir magnetically at 130℃ for 100min until it is completely dissolved and the solution is clear.

[0076] An ion mixed solution was prepared, 2 ml of ionic liquid material (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt) was added to the prepared TPU solution, and the preparation was completed by magnetic stirring at 120° C. for 40 min.

[0077] Prepare the sensitive layer screen printing solution, add 1g h-BN powder to the prepared ion mixed solution, and stir on a magnetic stirrer at 120°C for 1.5h until the solution is mixed evenly.

[0078] The prepared screen-printed sensitive layer solution was printed on the electrode layer through a 300-mesh screen and dried in a fume hood at 60°C for 3 h;

[0079] S4, spacer layer:

[0080] Cut the double-sided polyurethane tape into 5×2×0.26m 3 Pasted on the two sides of the sensor unit, the sensor has a certain pressure stroke.

[0081] S5, sensor package;

[0082] Repeat steps S1, S2, and S3 on another PI film, then align the two PI films and stick the sides printed with the electrode layer and ion sensitive layer together. In this process, the double-sided polyurethane tape of the spacer layer plays an adhesion role. After bonding, use a heat sealer to evenly heat seal the sensor all around to seal it. In addition, a certain gap must be left to prevent the air pressure from affecting the sensor. Finally, a complete sensor structure with a spacer layer as the symmetry is prepared. In addition, a hot pressing machine is used to heat press the two layers of flexible substrate material (PI film) together to form the final sensor packaging structure. Finally, an ion-type flexible pressure sensor is obtained.

[0083] Example 3

[0084] S1, bottom flexible substrate:

[0085] The bottom flexible substrate is a commercial TPU film. A piece of TPU film is cleaned with alcohol and deionized water for 1 to 5 minutes respectively, and then dried with a hot air blower;

[0086] S2, silver electrode layer:

[0087] Prepare the silver electrode layer screen printing material, add 3-4 drops of oily slow-drying water to 2 ml of conductive silver paste to dilute it, and then stir it on a magnetic stirrer until it is evenly mixed;

[0088] Remove air bubbles by vacuum and use a 500-mesh sieve to filter out impurities;

[0089] Use a 100-mesh screen printer to print the electrode shape designed in advance on the bottom flexible material. After printing, heat and cure it at 60°C for 30 minutes.

[0090] S3, preparing the sensitive layer:

[0091] Prepare TPU solution: add 1g TPU material into 5ml DMF for dissolution, and stir magnetically at 120℃ for 60min until it is completely dissolved and the solution is clear.

[0092] An ion mixed solution was prepared, 1 ml of ionic liquid material (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt) was added to the prepared TPU solution, and the preparation was completed by magnetic stirring at 150° C. for 30 min.

[0093] Prepare the sensitive layer screen printing solution, add 1.5g h-BN powder to the prepared ion mixed solution, and stir on a magnetic stirrer at 120°C for 1h until the solution is mixed evenly.

[0094] The prepared screen-printed sensitive layer solution was printed on the electrode layer through a 100-mesh screen and dried in a fume hood at 60°C for 3 h;

[0095] S4, spacer layer:

[0096] Cut the double-sided polyurethane tape into 5×2×0.26m 3 Pasted on the two sides of the sensor unit, the sensor has a certain pressure stroke.

[0097] S5, sensor package;

[0098] Repeat steps S1, S2, and S3 on another TPU film. Then align the two TPU films and stick the sides printed with the electrode layer and the ion-sensitive layer together. In this process, the double-sided polyurethane tape of the spacer layer plays an adhesion role.

[0099] After bonding, a heat sealer is used to evenly seal the sensor around the edges to seal it. In addition, a certain gap must be left to prevent air pressure from affecting the sensor. Finally, a complete sensor structure with a spacer layer as the symmetry is prepared. In addition, a hot pressing machine is used to heat press the two layers of flexible substrate material (TPU film) together to form the final sensor packaging structure. Finally, an ion-type flexible pressure sensor is obtained.

[0100] The working mode of the high-sensitivity flexible pressure sensor based on integrated screen printing of the present invention is as follows:

[0101] Flexible pressure sensors are prepared by large-scale integrated screen printing, and the unique doping method is used to meet the screen printing requirements of different materials. The printing array method meets the needs of measuring pressure distribution, and the flexible PET substrate method is used to achieve the flexibility requirements of the sensor. Finally, the pressure information is digitized and visualized by combining the electrical signal measurement method. This effectively solves the problem of large-scale preparation of flexible pressure sensors and screen printing of different sensitive materials.

[0102] The above embodiments are only used to further illustrate a high-sensitivity ion-type flexible pressure sensor based on integrated screen printing and a preparation method thereof of the present invention, but the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing an ionization pressure sensor based on integrated screen printing, characterized in that: The following steps are involved: S1. Making a bottom layer group and a top layer group, wherein the making of the bottom layer group and the top layer group respectively comprises the following sub-steps: S11, printing an array-arranged electrode layer on a flexible substrate using a screen printing process, and performing heating and curing after printing, wherein the connection directions of the unit arrays of the electrode layers of the bottom layer group and the top layer group are perpendicular to each other; S12. According to the mass-to-volume ratio, 2g-5g of TPU material is added to 5ml-50ml of solvent, and stirred at 120°C-180°C for 60min-120min until completely dissolved, 1ml-5ml of ionic liquid material is added, and stirred at 100°C-200°C for 30min-60min, and then 2g-5g of hexagonal boron nitride powder is added, and stirred at 100°C-200°C for 60min-120min to obtain a sensitive layer solution, and an array-arranged sensitive layer is printed on the electrode layer by a screen printing process, and dried and evaporated after printing; The ionic liquid material is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt; S2. Use insulating double-sided tape as a spacer layer, and attach the sensitive layers of the bottom layer group and the top layer group to the two sides of the spacer layer opposite to each other; S3. Pressing the edges of the flexible substrates of the bottom layer group and the top layer group together through a hot pressing process to form a packaging structure. No vacuum sealing is performed during the hot pressing process, leaving gaps to obtain an ion-type pressure sensor.

2. The method for preparing an ion-type pressure sensor based on integrated screen printing according to claim 1, characterized in that: The flexible substrate is a PET film, a PI film or a PDMS film with a thickness of 50um-500um.

3. The method for preparing an ion-type pressure sensor based on integrated screen printing according to claim 1, characterized in that: In step S11, oily slow-drying water is dropped into the conductive silver paste, and the mixture is stirred at 1000-3000 r / min for 5-10 min. The electrode layer is printed on the flexible substrate by screen printing. After printing, the mixture is heated at 80° C. for 5-10 min for curing. The ratio of the conductive silver paste to the oily slow-drying water is 1 mL: 1-2 drops.

4. The method for preparing an ion-type pressure sensor based on integrated screen printing according to claim 1, characterized in that: In step S11, the electrode layer is screen-printed using a circular array mask with a diameter of 0.1 mm to 1 mm to obtain the unit array.

5. The method for preparing an ion-type pressure sensor based on integrated screen printing according to claim 4, characterized in that: In step S12, the sensitive layer is screen-printed using a mask having the same circular array arrangement as the electrode layer, and the diameter of the circle of the sensitive layer is 0.1 mm to 1 mm larger than the diameter of the circle of the electrode layer.

6. The method for preparing an ion-type pressure sensor based on integrated screen printing according to claim 1, characterized in that: In step S12, after printing is completed, the film is dried and evaporated at 60°C to 100°C for 1h to 3h.

7. The method for preparing an ion-type pressure sensor based on integrated screen printing according to claim 1, characterized in that: In step S11 and step S12, the mesh size of the screen printing is 100-300 meshes.

8. The method for preparing an ion-type pressure sensor based on integrated screen printing according to claim 1, characterized in that: The thickness of the insulating double-sided tape is 50um~500um.

9. An ionization pressure sensor prepared by the preparation method according to any one of claims 1 to 8, characterized in that: It includes a bottom layer group, a spacer layer and a top layer group, wherein the bottom layer group and the top layer group respectively include a flexible substrate, an electrode layer and a sensitive layer, and the electrode layer and the sensitive layer are a unit array structure; One of the bottom layer group and the top layer group is used to lead out row signals, and the other is used to lead out column signals.

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