Flexible pressure sensor and preparation method and application thereof

Abstract

The invention discloses a flexible pressure sensor and a preparation method and application thereof. The preparation method of the flexible pressure sensor comprises the following steps: 1) uniformly mixing low-viscosity vinyl silicone oil, a conductive material and a catalyst to prepare conductive ink, and uniformly mixing high-viscosity vinyl silicone oil, hydrogen-containing silicone oil and fumed silica to prepare a functional material matrix; and 2) filling the conductive ink into a printing device, extending a printing head of the printing device into the functional material matrix, carrying out embedded 3D printing along a set printing path, carrying out cross-linking curing, taking out an obtained workpiece, and cleaning to obtain the flexible pressure sensor. The flexible pressure sensor has the advantages of being integrated in structure, excellent in performance, flexible in shape adjustment, high in flexible deformation capacity and the like, the preparation method of the flexible pressure sensor has the advantages of being easy to operate, low in equipment requirement, high in efficiency, low in cost and the like, and the flexible pressure sensor is suitable for large-scale industrial production and application.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure sensors, and in particular to a flexible pressure sensor and a preparation method and application thereof. Background Art

[0002] A pressure sensor is a device or apparatus that can sense a pressure signal and convert the pressure signal into an available output electrical signal according to a certain rule. It is widely used in water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace and other fields. At present, when preparing a pressure sensor, the electrode layer and the functional layer are usually prepared separately, and then bonded into a whole. However, due to the heterogeneity of the material, the interface bonding effect between the electrode layer and the functional layer is poor, which will directly affect the sensitivity and reliability of the pressure sensor, and may cause damage to the pressure sensor after long-term use. In addition, in order to increase the conductivity of the electrode layer, a rigid electrode material with good conductivity is usually used, which will cause the pressure sensor to have insufficient flexibility and poor flexible deformation ability. In addition, the current manufacturing method of most pressure sensors is to first prepare an integral sensor material, and then cut and process it according to actual needs to obtain the required shape. There are problems such as material waste, limited device shape and difficulty in integration, complex process, low preparation efficiency, high equipment requirements, high cost, etc., and it is easy to introduce errors and defects, increase the manufacturing cost of the pressure sensor and reduce the yield rate of the pressure sensor.

[0003] Therefore, it is of great significance to develop a method for preparing a pressure sensor with simple operation, low equipment requirements, high efficiency and low cost, and to prepare a pressure sensor with excellent performance, flexible shape and strong flexible deformation ability. Summary of the invention

[0004] The object of the present invention is to provide a flexible pressure sensor and a preparation method and application thereof.

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

[0006] A method for preparing a flexible pressure sensor comprises the following steps:

[0007] 1) low-viscosity vinyl silicone oil, conductive material and catalyst are mixed to form conductive ink, and high-viscosity vinyl silicone oil, hydrogen-containing silicone oil and fumed silica are mixed to form a functional material matrix;

[0008] 2) The conductive ink is loaded into a printing device, and then the print head of the printing device is inserted into the functional material matrix to perform embedded 3D printing along a set printing path, and then cross-linked and cured, and then the obtained part is taken out and cleaned to obtain a flexible pressure sensor.

[0009] Preferably, the viscosity of the low-viscosity vinyl silicone oil in step 1) is 300 mPa·s to 500 mPa·s, and the vinyl content is 0.16 mmol / g to 0.21 mmol / g.

[0010] Preferably, the conductive material in step 1) is at least one of a carbon-based material and a liquid metal.

[0011] Further preferably, the conductive material in step 1) is liquid metal. Liquid metal has both metallic conductivity and fluid properties, which can make the electrode layer have both high conductivity and high stretchability.

[0012] Preferably, the carbon-based material is at least one of carbon black, graphene, carbon nanotubes, and carbon fiber powder.

[0013] Preferably, the liquid metal is a gallium-indium-tin alloy having a melting point below 16°C.

[0014] Preferably, the catalyst in step 1) is a platinum catalyst.

[0015] Preferably, the conductive ink in step 1) comprises the following components in percentage by weight:

[0016] Low viscosity vinyl silicone oil: 10%~93%;

[0017] Conductive materials: 4% to 85%;

[0018] Catalyst: 3%~7%.

[0019] Further preferably, the conductive ink in step 1) comprises the following components in percentage by weight:

[0020] Low viscosity vinyl silicone oil: 10% to 30%;

[0021] Conductive materials: 65% to 85%;

[0022] Catalyst: 3%~7%.

[0023] Preferably, the high viscosity vinyl silicone oil in step 1) has a viscosity of 5000 mPa·s to 10000 mPa·s, and a vinyl content of 0.05 mmol / g to 0.06 mmol / g.

[0024] Preferably, the hydrogen content of the hydrogen-containing silicone oil in step 1) is 0.18 wt% to 0.25 wt%.

[0025] Preferably, the functional material matrix in step 1) comprises the following components in percentage by weight:

[0026] High viscosity vinyl silicone oil: 40%~90%;

[0027] Hydrogenated silicone oil: 5% to 12%;

[0028] Fumed silica: 2%~48%.

[0029] Further preferably, the functional material matrix in step 1) comprises the following components in percentage by weight:

[0030] High viscosity vinyl silicone oil: 75% to 90%;

[0031] Hydrogenated silicone oil: 5% to 12%;

[0032] Fumed silica: 2% to 15%.

[0033] Preferably, the components of the functional material matrix in step 1) further include functional fillers.

[0034] Preferably, the functional filler is at least one of barium titanate powder, polyacrylonitrile powder and nylon powder. The addition of the functional filler can improve the relative electron gain / loss capability of the functional layer in the flexible pressure sensor, thereby improving the electrical output performance of the flexible pressure sensor.

[0035] Preferably, the mass percentage of the functional filler in the functional material matrix is ​​0.1% to 53%.

[0036] Further preferably, the mass percentage of the functional filler in the functional material matrix is ​​3% to 18%.

[0037] Preferably, the spacing between any two adjacent printing paths in the set printing paths in step 2) is 1.5 mm to 2.5 mm.

[0038] Preferably, the product in step 2) is rectangular or circular.

[0039] Preferably, the cross-linking and curing in step 2) is carried out at a temperature of 60° C. to 90° C., and the cross-linking and curing time is 2 h to 5 h.

[0040] Preferably, in step 2), after the product is taken out and cleaned, it is further cross-linked and cured at a temperature of 60° C. to 90° C., and the cross-linking and curing time is 1.5 h to 2.5 h.

[0041] A flexible pressure sensor is made by the above-mentioned preparation method.

[0042] An electronic product comprises the above-mentioned flexible pressure sensor.

[0043] Principle of the present invention: The present invention mixes low-viscosity vinyl silicone oil, conductive material and catalyst to form a conductive ink with printing performance and catalyst diffusion effect, and mixes high-viscosity vinyl silicone oil, hydrogen-containing silicone oil and gas-phase silica to form a functional material matrix. After the conductive ink is loaded into a printing device, the print head of the printing device is inserted into the functional material matrix to perform embedded 3D printing along a set printing path. The printed conductive ink itself will undergo cross-linking and curing, and the catalyst in the conductive ink will diffuse outward in a small range along the printing path to cause the functional material matrix between adjacent printing paths to also undergo cross-linking and curing. The cured conductive ink becomes an electrode layer, and the cured functional material matrix becomes a functional layer. In this process, thanks to the fact that both the conductive ink and the functional material matrix contain a large amount of vinyl silicone oil, the electrode layer and the functional layer will be seamlessly connected to each other during the curing process, and the one-step preparation realizes the synchronous preparation and seamless integration of the electrode layer and the functional layer, constructs an integrally formed flexible pressure sensor, and increases the reliability of the pressure sensor. In addition, by flexibly designing different printing paths, the prepared flexible pressure sensors can exhibit different shapes, so that they can adapt to different application scenarios without the need for secondary processing. This has outstanding advantages in preparing customized, highly complex structured flexible pressure sensors.

[0044] The beneficial effects of the present invention are as follows: the flexible pressure sensor of the present invention has the advantages of structural integration, excellent performance, flexible shape adjustment, strong flexible deformation ability, etc., and its preparation method has the advantages of simple operation, low equipment requirements, high efficiency, low cost, etc., and is suitable for large-scale industrial production and application.

[0045] Specifically:

[0046] 1) The interface bonding effect between the electrode layer and the functional layer in the flexible pressure sensor of the present invention is good, and the two form an integrated structure, so that the flexible pressure sensor has good electrical performance, output performance and stability;

[0047] 2) The electrode layer and the functional layer in the flexible pressure sensor of the present invention are both made of silicone, so both are stretchable and have strong flexible deformation capability;

[0048] 3) The shape of the flexible pressure sensor of the present invention is flexible and changeable, and different sensor shapes can be designed according to different application scenarios. No special production equipment is required, and no subsequent secondary processing is required. It can meet the needs of personalization and customization, improve the manufacturing efficiency of the pressure sensor, and reduce the production cost of the pressure sensor;

[0049] 4) The electrode layer and the functional layer in the flexible pressure sensor of the present invention are prepared synchronously and seamlessly integrated, with simple operation, high production efficiency and low manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the preparation principle of the flexible pressure sensor in Example 1.

[0051] Figure 2 This is a schematic diagram of the printing path in Example 1.

[0052] Figure 3 This is a physical picture of the flexible pressure sensor in Example 1.

[0053] Figure 4 This is an optical microscope image of a cross section of the flexible pressure sensor in Example 1.

[0054] Figure 5 This is a graph showing the output electrical signal test results of the flexible pressure sensor in Example 1 at a frequency of 0.7 Hz and a pressure of 1.1 kPa.

[0055] Figure 6 This is a graph showing the output electrical signal results of the flexible pressure sensor in Example 1 at a frequency of 0.7 Hz and a pressure of 1.1 kPa to 112 kPa.

[0056] Figure 7 for Figure 6 Corresponding linear fitting analysis results.

[0057] Figure 8 This is a graph showing the test results of the output electrical signal of the flexible pressure sensor in Example 1 after 10,000 reciprocating contact-separation movements at a frequency of 0.7 Hz and a pressure of 1.1 kPa.

[0058] Fig. 9 This is a schematic diagram of the printing path in Example 2.

[0059] Fig.10 This is a physical picture of the flexible pressure sensor in Example 2.

[0060] Fig.11 This is a graph showing the test results of the output electrical signal of the flexible pressure sensor in Example 2 at a frequency of 0.7 Hz and a pressure of 1.1 kPa. DETAILED DESCRIPTION

[0061] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0062] Embodiment 1:

[0063] A flexible pressure sensor (preparation principle diagram as shown in Figure 1 The preparation method thereof is as follows:

[0064] 1) 1 g of low-viscosity vinyl silicone oil with a viscosity of 450 mPa·s and a vinyl content of 0.16 mmol / g, 6.6 g of a gallium-indium-tin alloy with a melting point of 11° C. (the mass percentages of gallium, indium and tin in the gallium-indium-tin alloy are 68.5%, 21.5% and 10%, respectively), and 0.3 g of a platinum catalyst ACS-PT-10 with a platinum content of 1000 ppm (Shanghai Sibao High-tech Materials Co., Ltd.) were added to a planetary mixer and the mixer was rotated at 1500 rpm. rpm for 5 min to obtain a conductive ink; 100 g of high-viscosity vinyl silicone oil with a viscosity of 5000 mPa·s and a vinyl content of 0.06 mmol / g, 14.13 g of hydrogenated silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 0.18 wt% and 4.2 g of fumed silica were added to a planetary mixer, stirred at a mixer speed of 2000 rpm for 6 min, and then vacuumed and degassed for 5 min to obtain a functional material matrix;

[0065] 2) The conductive ink is loaded into the printing device, and the print head of the printing device is inserted into the functional material matrix along the set printing path (the schematic diagram of the printing path is shown in FIG. Figure 2 As shown; reciprocating printing, the spacing between any two adjacent printing paths is 2mm) for embedded 3D printing, and then cross-linking and curing for 3h at a temperature of 70°C, and then taking out the obtained part and cleaning it with No. 120 solvent oil, and then cross-linking and curing for 2h at a temperature of 70°C to obtain a flexible pressure sensor (rectangular; the actual picture is as shown Figure 3 shown).

[0066] Performance Test:

[0067] 1) An optical microscope image of a cross section of the flexible pressure sensor in this embodiment is shown in FIG. Figure 4 shown.

[0068] Depend on Figure 4 It can be seen that in this embodiment, the simultaneous manufacturing and seamless integration of the electrode layer and the functional layer are indeed achieved through one-step printing.

[0069] 2) A contact-separation test device was built (composed of a linear motor and an acrylic plate with a conductive fabric attached to the surface, and the flexible pressure sensor and the acrylic plate with a conductive fabric attached to the surface were fixed to the fixed end and the movable end of the linear motor, respectively). The flexible pressure sensor in this embodiment was made to perform a reciprocating contact-separation motion, and an electrometer (6514, Keithley, USA) and a digital source meter (2611b, Keithley, USA) were used to measure and record the output electrical signals (voltage and current) of the flexible pressure sensor under the conditions of a frequency of 0.7 Hz and a pressure of 1.1 kPa. The test results are shown in FIG. Figure 5 (a is the voltage signal test result diagram, b is the current signal test result diagram) as shown.

[0070] Depend on Figure 5 It can be seen that the flexible pressure sensor has excellent force-to-electricity conversion capability and reproducibility.

[0071] 3) Referring to the above method, the output electrical signal (voltage and current) of the flexible pressure sensor in this embodiment is tested under the conditions of a frequency of 0.7 Hz and a pressure of 1.1 kPa to 112 kPa. The test results are as follows: Figure 6 (a is the voltage signal test result diagram, b is the current signal test result diagram), Figure 6 The corresponding linear fitting analysis results are as follows: Figure 7 (a is the linear fitting analysis result of voltage relative to pressure, b is the linear fitting analysis result of current relative to pressure; each point in the figure is the average value of 30 test results).

[0072] Depend on Figure 6 It can be seen that the output voltage and output current of the flexible pressure sensor perform well. As the applied pressure increases, the output voltage and current also increase almost linearly. The flexible pressure sensor can even sensitively detect a weak pressure of 1.1 kPa, indicating that its minimum detection limit (threshold stress) is less than 1.1 kPa.

[0073] Depend on Figure 7 It can be seen that the linear working range of the flexible pressure sensor is 1.1kPa~112kPa, the voltage sensitivity is about 0.308V / kPa, the current sensitivity is about 0.014μA / kPa, and the voltage and current linearities are 0.99247 and 0.99632 respectively, indicating that the flexible pressure sensor exhibits excellent sensitivity and linearity within the pressure range of 1.1kPa~112kPa, and has a good ability to perceive external stimuli.

[0074] 4) Referring to the above method, the flexible pressure sensor in this embodiment is subjected to 10,000 reciprocating contact-separation movements at a frequency of 0.7 Hz and a pressure of 1.1 kPa. The output electrical signals (voltage and current) obtained by the test are as follows: Figure 8 (a is the voltage signal test result diagram, b is the current signal test result diagram) as shown.

[0075] Depend on Figure 8 It can be seen that the flexible pressure sensor exhibits extremely stable performance. From the enlarged images of 10 cycles extracted from the 1000 and 10000 cycle data, it can be seen that there is no obvious attenuation of the signal at the beginning and end of the flexible pressure sensor (the reason is that the functional layer and the electrode layer have an excellent integrated structure, which can effectively avoid structural damage caused by multiple reciprocating contact-separation movements), indicating that the flexible pressure sensor exhibits extremely stable performance and has good durability.

[0076] Embodiment 2:

[0077] A flexible pressure sensor, the preparation method of which is as follows:

[0078] 1) 1 g of low-viscosity vinyl silicone oil with a viscosity of 450 mPa·s and a vinyl content of 0.16 mmol / g, 6.6 g of a gallium-indium-tin alloy with a melting point of 11° C. (the mass percentages of gallium, indium and tin in the gallium-indium-tin alloy are 68.5%, 21.5% and 10%, respectively), and 0.3 g of a platinum catalyst ACS-PT-10 with a platinum content of 1000 ppm (Shanghai Sibao High-tech Materials Co., Ltd.) were added to a planetary mixer and the mixer was rotated at 1500 rpm. rpm for 5 min to obtain a conductive ink; 100 g of high-viscosity vinyl silicone oil with a viscosity of 5000 mPa·s and a vinyl content of 0.06 mmol / g, 14.13 g of hydrogenated silicone oil with a viscosity of 50 mPa·s and a hydrogen content of 0.18 wt% and 4.2 g of fumed silica were added to a planetary mixer, stirred at a mixer speed of 2000 rpm for 6 min, and then vacuumed and degassed for 5 min to obtain a functional material matrix;

[0079] 2) The conductive ink is loaded into the printing device, and the print head of the printing device is inserted into the functional material matrix along the set printing path (the schematic diagram of the printing path is shown in FIG. Fig. 9 As shown; the diameter of the circular printing is gradually reduced, and the spacing between any two adjacent printing paths is 2mm) for embedded 3D printing, and then cross-linked and cured at a temperature of 70°C for 3h, and then the obtained part is taken out and cleaned with No. 120 solvent oil, and then cross-linked and cured at a temperature of 70°C for 2h to obtain a flexible pressure sensor (circular; the actual picture is as shown Fig.10 shown).

[0080] Performance Test:

[0081] The output electrical signals (voltage and current) of the flexible pressure sensor in this embodiment at a frequency of 0.7 Hz and a pressure of 1.1 kPa are as follows: Fig.11 (a is the voltage signal test result diagram, b is the current signal test result diagram) as shown.

[0082] Depend on Fig.11 It can be seen that the flexible pressure sensor has excellent force-to-electricity conversion capability and reproducibility.

[0083] Compared with the flexible pressure sensor in Example 1, the flexible pressure sensor in this embodiment has different shapes and sizes, but the working principles of both are friction electrification and electrostatic induction. Therefore, although the output signals of the two under the same pressure stimulation have different amplitudes, the change patterns are the same.

[0084] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a flexible pressure sensor, characterized in that: The following steps are involved: 1) low-viscosity vinyl silicone oil, conductive material and catalyst are mixed to form conductive ink, and high-viscosity vinyl silicone oil, hydrogen-containing silicone oil and fumed silica are mixed to form a functional material matrix; 2) The conductive ink is loaded into a printing device, and then the print head of the printing device is inserted into the functional material matrix to perform embedded 3D printing along a set printing path, and then cross-linked and cured, and then the obtained part is taken out and cleaned to obtain a flexible pressure sensor.

2. The preparation method according to claim 1, characterized in that: The viscosity of the low-viscosity vinyl silicone oil in step 1) is 300mPa·s to 500mPa·s, and the vinyl content is 0.16mmol / g to 0.21mmol / g; the viscosity of the high-viscosity vinyl silicone oil in step 1) is 5000mPa·s to 10000mPa·s, and the vinyl content is 0.05mmol / g to 0.06mmol / g; the hydrogen content of the hydrogen-containing silicone oil in step 1) is 0.18wt% to 0.25wt%.

3. The preparation method according to claim 1, characterized in that: The conductive material in step 1) is at least one of a carbon-based material and a liquid metal; the catalyst in step 1) is a platinum catalyst.

4. The preparation method according to claim 3, characterized in that: The carbon-based material is at least one of carbon black, graphene, carbon nanotubes, and carbon fiber powder; the liquid metal is a gallium-indium-tin alloy with a melting point lower than 16°C.

5. The preparation method according to any one of claims 1 to 4, characterized in that: Step 1) The conductive ink comprises the following components in percentage by weight: Low viscosity vinyl silicone oil: 10%~93%; Conductive materials: 4% to 85%; Catalyst: 3%~7%.

6. The preparation method according to any one of claims 1 to 4, characterized in that: Step 1) The functional material matrix includes the following components in percentage by weight: High viscosity vinyl silicone oil: 40%~90%; Hydrogenated silicone oil: 5% to 12%; Fumed silica: 2%~48%.

7. The preparation method according to any one of claims 1 to 4, characterized in that: Step 1) The components of the functional material matrix also include functional fillers; the functional fillers are at least one of barium titanate powder, polyacrylonitrile powder, and nylon powder.

8. The preparation method according to any one of claims 1 to 4, characterized in that: The spacing between any two adjacent printing paths in the set printing path in step 2) is 1.5 mm to 2.5 mm; the cross-linking and curing in step 2) is carried out at a temperature of 60° C. to 90° C., and the cross-linking and curing time is 2 h to 5 h.

9. A flexible pressure sensor, characterized in that: Prepared by the preparation method described in any one of claims 1 to 8.

10. An electronic product, characterized in that: The flexible pressure sensor comprises the flexible pressure sensor as claimed in claim 9.

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