CN209841246U - Flexible sensor of multi-functional sensing - Google Patents
Flexible sensor of multi-functional sensing Download PDFInfo
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- CN209841246U CN209841246U CN201920783470.8U CN201920783470U CN209841246U CN 209841246 U CN209841246 U CN 209841246U CN 201920783470 U CN201920783470 U CN 201920783470U CN 209841246 U CN209841246 U CN 209841246U
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Abstract
The utility model belongs to the field of flexible sensors and discloses a multifunctional sensing flexible sensor, which comprises an upper electrode layer, a middle dielectric layer and a lower electrode layer, wherein the upper electrode layer and the lower electrode layer have the same structure and both comprise flexible base materials and liquid metal embedded in the base materials; the middle medium layer is arranged between the upper electrode layer and the lower electrode layer, and a plurality of micron-sized holes are formed in the middle medium layer; when the sensor is stressed by pressure, tension or is approached by a conductor, the magnitude of the pressure, tension or distance between the conductor and the sensor, which is stressed by the sensor, is obtained by measuring the change of the capacitance of the sensor; when the object to be measured rubs with the upper electrode layer, the pressure applied by the object to be measured to the upper electrode layer is obtained by measuring the change of the voltage in the upper electrode layer. Through the utility model discloses, combine two kinds of sensing principles of electric capacity sensing and frictional power generation, realize flexible sensor's high sensitivity and multi-functional measurement.
Description
Technical Field
The utility model belongs to the flexible sensor field, more specifically relates to a flexible sensor of multi-functional sensing.
Background
With the development of science and technology and society, the application of robots is gradually expanding from the fields of scientific research and industrial automation to the fields of medical treatment, family service and the like. The premise of realizing the interaction between the robot and the external environment is that the robot can detect the information of the external environment and human beings through a sensor system carried by the robot. The array of large area, soft, tactile and data processing micro-sensors covering the surface of the robot is called electronic skin. The electronic skin is an important perception form next to the vision of the robot and is one of the necessary media for the machine to directly act with the external environment.
At present to flexible, the multi-functional flexible electron skin of robot many focus on the sense of touch perception, and the perception ability is close to in the law of collection, can't react when the effect object is close, and the utility model provides a can for the sensor of stretching of robot electron skin provides probably for solving above-mentioned problem, and this sensor sensing principle both can detect pressure based on electric capacity sensing and friction electricity generation, also can detect the space orientation distance, can also measure the strain simultaneously.
The flexible electronic technology takes off the child in the stereoplasm electronic technology, has consequently also adopted traditional semiconductor technology in a large number, but some flexible materials are not good to the adaptability of traditional handicraft, consequently improve the technology very necessary, the utility model provides a flexible sensor of multi-functional sensing and preparation method thereof.
SUMMERY OF THE UTILITY MODEL
To the above defect of prior art or improve the demand, the utility model provides a flexible sensor of multi-functional sensing, it utilizes frictional layer friction electricity generation through utilizing upper and lower electrode layer formation electric capacity sensing, combines two kinds of sensing principles of electric capacity sensing and friction electricity generation, realizes the await measuring object space orientation, and pressure sensing and tensile production strain measurement's function realize flexible sensor's high sensitivity and multi-functional measurement.
In order to achieve the above object, according to the utility model discloses, a flexible sensor of multi-functional sensing is provided, its characterized in that, this sensor includes electrode layer, middle dielectric layer and bottom electrode layer, wherein:
the upper electrode layer and the lower electrode layer have the same structure and both comprise a flexible base material and liquid metal embedded in the base material, and the surface area of the upper electrode layer is larger than that of the lower electrode layer, so that a capacitive edge effect is generated between the upper electrode layer and the lower electrode layer; the middle dielectric layer is arranged between the upper electrode layer and the lower electrode layer, is made of the same flexible base material as the upper electrode layer and the lower electrode layer, and is provided with a plurality of micron-sized holes to form a micron-sized hole structure;
when the sensor is stressed by pressure, tension or is approached by a conductor, the capacitance between the upper electrode layer and the lower electrode layer changes, and the magnitude of the pressure, the tension or the distance between the conductor and the sensor, which is stressed by the sensor, is obtained by measuring the change of the capacitance of the sensor;
when the object to be measured rubs with the upper electrode layer, the pressure applied by the object to be measured to the upper electrode layer is obtained by measuring the change of the voltage in the upper electrode layer.
Further preferably, a friction layer is further disposed on the upper electrode layer, the friction layer is made of a flexible base material the same as that of the upper electrode layer, the surface roughness Ra of the friction layer is 1.6 μm to 6.4 μm, and when an object to be measured is rubbed with the friction layer by using a force below 15KPa, the magnitude of a force applied by the object to be measured is obtained by detecting a change in voltage on the upper electrode layer, so that the sensitivity of the sensor is improved.
Further preferably, the distance between the upper and lower electrode layers is preferably 50 to 200 μm, the thickness of the upper and lower electrode layers is preferably 100 to 200 μm, and the diameter of the micropores is preferably 70 to 210 μm.
Further preferably, the flexible matrix material is preferably PDMS, ecoflex, PI, PTFE or PET.
Further preferably, the liquid metal is preferably a gallium alloy.
According to another aspect of the present invention, there is provided a method for manufacturing the above flexible sensor, the method comprising the steps of:
(a) preparing upper and lower electrode layers
(a1) Selecting a substrate and a sacrificial layer solution, spin-coating the sacrificial layer solution on the substrate, forming a sacrificial layer on the matrix after the sacrificial layer solution is solidified, spin-coating the solution of the flexible matrix material on the sacrificial layer, forming a flexible matrix layer on the sacrificial layer after the solidification,
(a2) attaching a mask plate to the flexible substrate layer, sputtering an adhesion layer on the mask plate, then sputtering liquid metal on the adhesion layer, and removing the mask plate, wherein the adhesion layer is used for bonding the flexible substrate layer and the liquid metal;
(a3) spin-coating the solution of the flexible matrix layer on the flexible matrix layer sputtered with the liquid metal again, embedding the liquid metal in the flexible matrix layer after solidification, putting the substrate into water, and dissolving the sacrificial layer in the water to separate the flexible matrix layer from the substrate so as to obtain an upper electrode or a lower electrode;
(b) preparing an intermediate dielectric layer
(b1) Preparing a mold provided with a microcolumn, selecting a substrate, spin-coating the solution of the flexible matrix layer on the substrate, forming a flexible matrix layer on the substrate after curing, attaching the mold to the surface of the flexible matrix layer, and heating to connect the mold and the substrate;
(b2) carrying out hydrophobic treatment on the surface of the substrate adhered with the die, then spin-coating the solution of the flexible matrix layer on the die, and peeling off the flexible matrix layer from the die after the flexible matrix layer is cured, so as to obtain the intermediate medium layer with micron holes;
(c) and bonding the upper electrode layer, the middle dielectric layer and the lower electrode layer together in sequence from top to bottom in a reactive ion etching mode to obtain the required flexible sensor.
Further preferably, in the step (a2), the adhesion layer preferably includes an upper layer and a lower layer, the lower layer is gold, and the upper layer is chromium, wherein the gold is used for connecting the flexible base material and the chromium, and the chromium is used for connecting the gold and the flexible base material.
Further preferably, the preparation method further comprises the steps of preparing the friction layer, spin-coating the solution of the flexible base material on the surface of the abrasive paper, peeling off the flexible base material layer after film formation after curing and film formation to obtain the required friction layer, and bonding the friction layer on the upper electrode layer in a reactive ion etching manner to obtain the flexible sensor with the friction layer.
Further preferably, in the step (b1), the mold provided with the microcolumn is prepared preferably according to the following steps:
(b11) selecting a substrate, spin-coating a photoresist on the substrate, attaching a mask plate on the surface of the photoresist after the photoresist is cured, and then forming a plurality of micron holes on the surface of the photoresist by using a laser photoetching mode;
(b12) removing the mask plate, carrying out hydrophobic treatment on the surface of the photoresist with the micron holes, then spin-coating the solution of the flexible matrix material on the surface of the photoresist after the hydrophobic treatment, and stripping the flexible matrix material from the surface of the photoresist after the solution is solidified into a film so as to obtain the flexible matrix material with the micron posts on the surface, namely the mold with the micron posts on the surface.
Generally, through the utility model discloses above technical scheme who conceives compares with prior art, can gain following beneficial effect:
1. the utility model provides a friction layer that sensor set up, at the good linearity of friction electricity generation at low-pressure area (<15KPa), compensatied the lower shortcoming of electric capacity sensing at low-pressure area linearity, and the electric capacity sensing that upper and lower electrode layer formed has compensatied the not enough of friction electricity generation at the lower sensitivity of high-pressure area (>15KPa) at the good linearity of high-pressure area, and the complementation of two kinds of sensing principles has greatly increased sensor pressure measurement scope;
2. the flexible sensor provided by the utility model can measure three parameters of pressure, strain and space positioning distance, based on the principles of capacitance sensing and friction power generation, when applied to the robot field, the robot can realize real-time monitoring and feedback from positioning to grabbing the whole process, and simultaneously can measure the strain rate of the robot when receiving stretching;
3. the utility model provides a flexible sensor has higher sensitivity, and when carrying out space positioning, this kind of sensor can utilize the fringe effect of electric capacity, effectively amplifies the electric field and so as to strengthen positioning sensitivity, when carrying out pressure and strain measurement, the design of middle dielectric layer micron hole, go up the electrode and the sand paper on lower electrode layer surface is modified, can effectively promote pressure measurement's sensitivity;
4. the utility model provides a flexible sensor and the close laminating in await measuring object surface can keep the commonality contact, furthest's reduction the space on sensor and robot surface, help improving the intensity and the measuring accuracy of sensor like this.
Drawings
FIG. 1 is a flow chart of a process for making a flexible sensor constructed in accordance with a preferred embodiment of the present invention;
fig. 2 is a flow chart for preparing an interlevel dielectric layer constructed in accordance with a preferred embodiment of the present invention.
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
1-sandpaper, 2-cured polydimethylsiloxane film, 3-silicon wafer, 4-polyvinyl alcohol sacrificial layer, 5-base layer, 6-gold, 7-chromium, 8-mask, 9-gold electrode, 10-base, 11-liquid metal, 12-polyvinyl alcohol sacrificial layer in solution, 13-deionized water, 14-high temperature resistant glassware, 15-middle dielectric layer with micron pores, 17-SU 82050 photoresist, 19-ultraviolet light, 20-developing solution, 21-SU 82050 photoresist in development, 22-hydrophobic solution, 23-polydimethylsiloxane film for copying micron columns, 24-polydimethylsiloxane film with micron column structure, 25-polydimethylsiloxane film for copying micron pores, and 26-polydimethylsiloxane with micron pore structure.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Furthermore, the technical features mentioned in the embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
Fig. 1 is a flow chart of a manufacturing process of a flexible sensor constructed according to a preferred embodiment of the present invention, as shown in fig. 1, a flexible sensor of a multi-functional sensing principle, which has a three-layer structure and can be divided into an upper electrode layer, a middle dielectric layer and a lower electrode layer, wherein the area of the upper electrode is larger than that of the lower electrode, and the edge effect of a capacitor is utilized to improve the sensitivity of capacitor positioning; the surface of the upper electrode layer is provided with a friction layer, and the surface roughness of the upper electrode layer is increased by adopting sand paper modification, so that the output performance of friction power generation is improved, and the sensitivity of the sensor for pressure sensing based on the friction power generation principle is increased; the middle dielectric layer adopts a micron pore structure, so that the rigidity of the dielectric material is effectively reduced, the middle dielectric is easier to deform under the same load, and the sensitivity of the sensor for pressure sensing and tensile strain measurement based on the capacitance sensing principle is enhanced.
The upper electrode layer, the lower electrode layer and the middle dielectric layer are made of flexible and stretchable high polymer materials such as PDMS, ecoflex, PI, PTFE or PET and serve as a supporting layer and a dielectric layer of the sensor. The material has good stretchability to ensure the effectiveness of the electrode in working in a stretchable state, and simultaneously has a higher relative dielectric constant as a dielectric layer, thereby ensuring a larger initial capacitance value of the sensor. The functional layers of the upper electrode and the lower electrode are used for collecting and transmitting voltage and capacitance signals, and a liquid metal material is adopted, and comprises the following components in percentage by mass: 68.5 percent of gallium, 21.5 percent of indium and 10 percent of tin, and the material has good conductive performance and tensile property. The upper electrode layer, the middle dielectric layer and the lower electrode layer of the sensor are made of stretchable materials, so that the sensor has good stretchable performance. By adjusting the process parameters, the overall thickness of the sensor can be reduced so that the sensor can be closely attached to the robot surface by van der waals forces and maintain good conformal contact.
In order to improve the success rate and the quality of the sensor, the preparation method of the flexible sensor based on the multifunctional sensing principle mainly comprises a micron column hole process, an electrode process, a sacrificial layer process and a reactive ion etching process. Wherein the micropillar hole process is used for preparing the middle dielectric layer, the electrode process is used for preparing the upper electrode layer and the lower electrode layer, the sacrificial layer process is used for releasing the sensor from the silicon wafer, and the reactive ion etching process is used for bonding and packaging the upper electrode layer, the middle dielectric layer and the lower electrode layer. In the micron pore process, micron column pores with different diameters are prepared on polydimethylsiloxane by adopting photoetching and secondary mould-reversing methods, and the stability and precision of the process are ensured by photoetching; the mould of secondary reverse mould can reuse, has simplified the experimental procedure, has also reduced the waste simultaneously. The electrode process directly injects liquid metal on the gold electrode pattern by utilizing the hydrophobicity of the liquid metal to polydimethylsiloxane and the hydrophilicity to gold, and the process method simplifies the experimental steps. The sacrificial layer process adopts polyvinyl alcohol as a material, which is an organic high polymer material dissolved in water, is colorless, transparent, nontoxic and harmless, and has good film forming property. The solvent for dissolving the polyvinyl alcohol sacrificial layer is water, so that the silicon crystal cell and the sensor cannot be damaged, and the environment cannot be polluted. The reactive ion etching process can well bond the upper electrode layer, the middle dielectric layer and the lower electrode layer, and has high packaging strength. The method comprises the following steps:
first, upper and lower electrodes are prepared
(1) Cleaning the polished surface of the 4-inch silicon wafer 3 by sequentially adopting acetone, isopropanol and deionized water 13, and then drying by using nitrogen;
(2) spin-coating a sacrificial layer solution, namely a 10% polyvinyl alcohol aqueous solution 4 on a polished surface of a silicon crystal unit 3 at a spin-coating speed of 500-1000 rpm for 1-10 minutes, then heating the silicon crystal unit on a hot plate at a heating temperature of 80-100 ℃ for 5-20 minutes to evaporate water by heating, and curing polyvinyl alcohol into a film 4;
(3) spin-coating polydimethylsiloxane on a silicon cell coated with a sacrificial layer 4 to serve as a base layer 5, wherein the spin-coating speed is 800-1000 rpm and the spin-coating time is 50-100 s, then placing the silicon cell on a hot plate to be heated, the heating temperature is 80-100 ℃, the heating time is 10-30 min, and the polydimethylsiloxane is cured into a film 2;
(4) attaching a mask plate 8 to the surface of polydimethylsiloxane 2, then placing the wafer 3 coated with the polydimethylsiloxane 2 and the sacrificial layer 4 in a magnetron cavity to sputter a layer of chromium and gold, wherein the thickness of the chromium 7 is 10-50 nm, the thickness of the gold 6 is 50-200 nm, when the thickness of the gold or the chromium is too thin, the surface quality of the gold or the chromium is poor, filling of liquid metal is influenced, and the chromium serves as an adhesion layer between the gold and the polydimethylsiloxane 2;
(5) filling liquid metal 11 on the electrode pattern 9 sputtered with gold 6 by using an injector in an oxygen-free glove box, wherein the thickness of the sputtered liquid metal is 20-50 mu m, and sucking away redundant liquid metal by using the injector;
(6) spin coating polydimethylsiloxane again on the wafer 3 subjected to the steps, wherein the spin coating speed is 800-1000 rpm and the spin coating time is 50-100 s, then placing the wafer on a hot plate for heating at the temperature of 80-100 ℃ for 10-30 min, solidifying the polydimethylsiloxane into a film 2, placing the wafer into a crystallization vessel 14 filled with deionized water for water bath heating after the thickness of the polydimethylsiloxane film is 20-50 microns, and dissolving a polyvinyl alcohol sacrificial layer 12 to finish the preparation of an electrode layer;
FIG. 2 is a flow chart for preparing an intermediate dielectric layer constructed in accordance with a preferred embodiment of the present invention, as shown in FIG. 2, wherein steps (7) - (16) are laser lithography
(7) Cleaning a clean 4-inch silicon wafer 3 for multiple times (3 times or more) by using acetone, and then drying by using nitrogen;
(8) inverting the SU82050 # photoresist 17 on the surface of the wafer 3 to ensure that the photoresist 17 is at the center of the wafer as much as possible, holding the edge of the wafer 3 with a hand to tilt the silicon wafer and slowly rotate the silicon wafer to enable the photoresist 17 to cover most of the area of the silicon wafer, and standing for 20 minutes to eliminate bubbles generated by the photoresist 17 in the inversion process;
(9) spin-coating the photoresist 17, namely firstly spin-coating at a speed of 300-600 rpm for 1-5 minutes, then spin-coating at 1000-2500 rpm for 1-10 minutes, wherein the thickness of the obtained photoresist is 70-80 microns, and then standing for about 20 minutes to eliminate ripples and internal stress generated by spin-coating the photoresist 17;
(10) prebaking, namely raising the temperature from room temperature to 45 ℃ to prevent the surface of the photoresist from generating wrinkles due to internal stress, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 95 ℃, respectively keeping the temperature at 65 ℃ and 95 ℃ for 3 minutes and 9 minutes, and then naturally cooling to room temperature;
(11) exposing by ultraviolet 19 under the prepared pattern of the mask plate 8 by using a contact photoetching technology, wherein the wavelength of a photoetching machine adopted by the process is 365nm, and the photoetching power is 15mW/m2The exposure time is 15 s;
(12) post-baking, namely heating the photoresist to 45 ℃ from room temperature, in order to prevent the surface of the photoresist from generating wrinkles due to internal stress, heating the photoresist by taking 10 ℃ as a gradient, heating the photoresist to 95 ℃ from 45 ℃, respectively keeping the photoresist at 65 ℃ and 95 ℃ for 2 minutes and 7 minutes, and then naturally cooling the photoresist to room temperature;
(13) developing for 6 minutes 21 in a developing solution 20 special for SU82050 photoresist, then fixing for 1 minute in isopropanol, washing with a large amount of deionized water after taking out, and drying by nitrogen;
(14) hard baking, namely raising the temperature from room temperature to 45 ℃, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 200 ℃, keeping the temperature at 200 ℃ for 30 minutes, and then naturally cooling to room temperature, thus finishing the photoetching process;
(15) preparing ethanol and trichlorosilane into a hydrophobic solution 22 according to a volume ratio of 1:1000, soaking the silicon wafer 3 subjected to photoetching in the hydrophobic solution for 1 hour, performing hydrophobic treatment, washing the silicon wafer 3 with ethanol and deionized water, and drying the silicon wafer with nitrogen;
(16) inverting polydimethylsiloxane on the surface of the silicon wafer to completely cover the surface of the silicon wafer, standing for 2 hours 23, then placing the silicon wafer on a hot plate to be heated at the temperature of 50-100 ℃ for 10-20 minutes, curing the polydimethylsiloxane into a film 2, and stripping the polydimethylsiloxane film from the surface of the photoresist to finish the manufacturing of the micron column pattern 24;
(17) spin-coating a layer of polydimethylsiloxane solution on the surface of the cleaned silicon wafer at the spin-coating speed of 800-1000 rpm for 40-90 seconds, attaching the solution to the back of a polydimethylsiloxane film 22 with a micron column pattern, then placing the silicon wafer 3 on a hot plate for heating at the heating temperature of 80-100 ℃ for 10-20 minutes, and completing the bonding of the polydimethylsiloxane film and the silicon wafer;
(18) performing reactive ion etching on the silicon wafer 3 adhered with the micron column with oxygen, wherein the oxygen flow is 20 ml/min, the pressure in a reaction chamber is 70 Pa, the radio frequency power is 90 watts, the reaction time is 90 seconds, and then performing hydrophobic treatment as in the step (15);
(19) spin-coating polydimethylsiloxane on the surface of the silicon wafer 25 at a spin-coating speed of 200-500 rpm for 100-150 seconds, standing for 2 hours to ensure that the polydimethylsiloxane solution is fully immersed between the micro-pillars, then heating the silicon wafer on a hot plate at a heating temperature of 60-90 ℃ for 10-20 minutes, curing the polydimethylsiloxane into a film 2, stripping the polydimethylsiloxane film from the surface of the silicon wafer with the micro-pillars to obtain a polydimethylsiloxane film 26 with micro-holes, and completing the preparation of the middle dielectric layer with the micro-holes 15;
furthermore, a friction layer is prepared
(20) Spin-coating polydimethylsiloxane on the surface of clean sand paper 1 at the spin-coating speed of 800-1000 rpm for 1-5 minutes, then placing the sand paper 1 on a hot plate to be heated at the heating temperature of 80-100 ℃ for 10-20 minutes, curing the polydimethylsiloxane into a film 2, and stripping the polydimethylsiloxane film from the surface of the sand paper, wherein the thickness of the film obtained under the condition is 80-100 micrometers;
finally, packaging the upper and lower electrode layers, the friction layer and the middle medium layer
(21) Adhering a polydimethylsiloxane film with a sand paper surface structure, an upper electrode layer, a polydimethylsiloxane film 25 with micropores and a lower electrode layer together by reactive ion etching, then placing on a hot plate for heating, wherein the heating temperature is 80 ℃, the heating time is 30 minutes, and the bonding and adhesion process is accelerated, and the reactive ion etching parameters are as follows: the flow rate of oxygen is 20 ml/min, the pressure in the reaction chamber is 70 Pa, the radio frequency power is 90W, and the reaction time is 90 seconds, thus completing the preparation of the sensor.
Preferably, the electrode material adopts gallium alloy, and the mass fractions of gallium, indium and tin are respectively 68.5%, 21.5% and 10%.
As optimization, the filling of the liquid metal is carried out in a glove box with the oxygen content less than or equal to 2 ppm.
As optimization, the mold for manufacturing the micron holes is prepared by using SU82050 photoresist, and the thickness of the photoresist is controlled to be 70 +/-1 micron.
As an optimization, the preparation of the micro holes is prepared by adopting a secondary reverse mold process, as described in the steps (7) - (19), firstly, the micro holes are manufactured by utilizing photoetching, then, polydimethylsiloxane is spin-coated on photoresist for reverse mold, a micro column pattern is copied, and finally, the polydimethylsiloxane is spin-coated on the micro columns to finish the preparation of the micro holes.
As optimization, before the polydimethylsiloxane film is subjected to hydrophobic treatment, the polydimethylsiloxane film and oxygen are subjected to reactive ion etching.
As optimization, three types of sand paper, namely P1000, P600 and P280, are selected as the sand paper.
Preferably, the surface roughness Ra of the friction layer is 1.6-6.4 μm.
Preferably, the distance between the upper electrode layer and the lower electrode layer is 50-200 μm, the thickness of the upper electrode layer and the lower electrode layer is 100-200 μm, the distance and the thickness of the upper electrode layer and the lower electrode layer are used for ensuring larger capacitance and improving the anti-interference capability of the sensor, and the diameter of the micro-hole is preferably 70-210 μm, so that the rigidity of a middle dielectric layer of the sensor is reduced, the sensitivity of the sensor is improved, and the stability of the sensor is ensured.
Preferably, the flexible matrix material is PDMS, ecoflex, PI, PTFE or PET, so as to ensure the stretchability of the sensor.
Preferably, the liquid metal is gallium alloy, so that the electrode is liquid at normal temperature, the stretchability of the sensor is guaranteed, and meanwhile, the liquid metal is non-toxic and relatively safe.
The invention will be further illustrated with reference to specific examples.
Example 1:
(1) cleaning the polished surface of the 4-inch silicon crystal element by sequentially adopting acetone, isopropanol and deionized water, and then drying by using nitrogen;
(2) spin-coating 10% polyvinyl alcohol aqueous solution on a polished surface of a silicon crystal cell at a spin-coating speed of 500 rpm for 10 minutes, then heating the silicon crystal cell on a hot plate at a heating temperature of 80 ℃ for 20 minutes, and curing the polyvinyl alcohol to form a film;
(3) spin-coating polydimethylsiloxane on a silicon cell coated with a sacrificial layer at the speed of 800 revolutions per minute for 100 seconds, then heating the silicon cell on a hot plate at the temperature of 80 ℃ for 30 minutes, and curing the polydimethylsiloxane into a film;
(4) attaching a mask plate to the surface of polydimethylsiloxane, and then placing the wafer coated with polydimethylsiloxane and a sacrificial layer in a magnetron cavity to sputter a layer of chromium and gold, wherein the thickness of the chromium sputtered is 10nm, the thickness of the gold sputtered is 200nm, and the chromium serves as an adhesion layer between the gold and the polydimethylsiloxane;
(5) filling liquid metal on the electrode pattern sputtered with gold by using an injector in an oxygen-free glove box, and sucking away redundant liquid metal by using the injector, wherein the thickness of the liquid metal is about 20 microns;
(6) spin-coating polydimethylsiloxane again on the wafer subjected to the steps, wherein the spin-coating speed is 800 revolutions per minute and the spin-coating time is 100 seconds, then placing the wafer on a hot plate to be heated, the heating temperature is 80 ℃, the heating time is 30 minutes, and the polydimethylsiloxane is cured into a film, wherein the thickness of the film obtained under the conditions is 50 micrometers;
next, preparing an intermediate dielectric, wherein the steps (7) to (16) are laser lithography
(7) Cleaning a clean 4-inch silicon wafer for multiple times (3 times or more) by using acetone, and then drying the cleaned silicon wafer by using nitrogen;
(8) inverting the photoresist SU82050 on the surface of the wafer to ensure that the photoresist is at the center of the wafer as much as possible, holding the edge of the wafer by hand to enable the silicon wafer to be poured and slowly rotate to enable the photoresist to cover most of the area of the silicon wafer, and standing for 20 minutes to eliminate bubbles generated in the inverting process of the photoresist;
(9) spin-coating a photoresist, namely spin-coating for 5 minutes at 300 revolutions per minute, then spin-coating for 10 minutes at 100 revolutions per minute, wherein the thickness of the photoresist obtained under the condition is 70 micrometers, and standing for 20 minutes after the spin-coating is finished to eliminate ripples of the photoresist generated by the spin-coating;
(10) prebaking, namely raising the temperature from room temperature to 45 ℃ to prevent the surface of the photoresist from generating wrinkles due to internal stress, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 95 ℃, respectively keeping the temperature at 65 ℃ and 95 ℃ for 3 minutes and 9 minutes, and then naturally cooling to room temperature;
(11) exposing by ultraviolet exposure under the prepared pattern of a mask plate by using a contact photoetching technology, wherein the wavelength of a photoetching machine adopted by the process is 365nm, and the photoetching power is 15mW/m2The exposure time is 15 s;
(12) post-baking, namely heating the photoresist to 45 ℃ from room temperature, in order to prevent the surface of the photoresist from generating wrinkles due to internal stress, heating the photoresist by taking 10 ℃ as a gradient, heating the photoresist to 95 ℃ from 45 ℃, respectively keeping the photoresist at 65 ℃ and 95 ℃ for 2 minutes and 7 minutes, and then naturally cooling the photoresist to room temperature;
(13) developing in a developing solution special for SU82050 photoresist for 6 minutes, fixing in isopropanol for 1 minute, taking out, washing with a large amount of deionized water, and drying by nitrogen;
(14) hard baking, namely raising the temperature from room temperature to 45 ℃, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 200 ℃, keeping the temperature at 200 ℃ for 30 minutes, and then naturally cooling to room temperature, thus finishing the photoetching process;
(15) preparing ethanol and trichlorosilane into a hydrophobic solution according to the volume ratio of 1:1000, stirring the solution for 5 minutes by using a magnetic stirrer, soaking the silicon wafer subjected to photoetching in the solution for 1 hour, performing hydrophobic treatment, then washing the silicon wafer by using ethanol and deionized water, and drying the silicon wafer by using nitrogen;
(16) inverting polydimethylsiloxane on the surface of the silicon wafer to completely cover the surface of the silicon wafer, standing for 2 hours, then placing the silicon wafer on a hot plate for heating at the temperature of 100 ℃ for 10 minutes, curing the polydimethylsiloxane into a film, and stripping the polydimethylsiloxane film from the surface of the photoresist to finish the manufacturing of the micron column pattern;
(17) spin-coating a layer of polydimethylsiloxane solution on the surface of the cleaned silicon wafer at the spin-coating speed of 1000 rpm for 90 seconds, attaching the solution to the back of a polydimethylsiloxane film with a micron column pattern, then heating the silicon wafer on a hot plate at the heating temperature of 80 ℃ for 20 minutes to complete the bonding of the polydimethylsiloxane film and the silicon wafer;
(18) performing reactive ion etching on the silicon wafer adhered with the micron column and oxygen, wherein the oxygen flow is 20 ml/min, the pressure in a reaction chamber is 70 Pa, the radio frequency power is 90 watts, the reaction time is 90 seconds, and then performing hydrophobic treatment as in the step (15);
(19) spin-coating polydimethylsiloxane on the surface of the silicon wafer at the spin-coating speed of 500 revolutions per minute for 150 seconds, standing for 2 hours to ensure that the polydimethylsiloxane solution is fully immersed between the micro-columns, heating at the temperature of 90 ℃ for 10 minutes, then heating the silicon wafer on a hot plate, curing the polydimethylsiloxane into a film, and stripping the polydimethylsiloxane film from the surface of the silicon wafer with the micro-columns to finish the preparation of the polydimethylsiloxane film with the micro-holes;
furthermore, a friction layer is prepared
(20) Spin-coating polydimethylsiloxane on the surface of clean sand paper, wherein the model of the sand paper is P1000, the spin-coating speed is 800 revolutions per minute, the spin-coating time is 5 minutes, then placing the sand paper on a hot plate to be heated, the heating temperature is 80 ℃, the time is 20 minutes, solidifying the polydimethylsiloxane into a film, and stripping the polydimethylsiloxane film from the surface of the sand paper;
finally, packaging the upper and lower electrode layers, the friction layer and the middle medium layer
(21) Adhering the polydimethylsiloxane film with the abrasive paper surface structure, the upper electrode layer, the polydimethylsiloxane film with the micropores and the lower electrode layer together by reactive ion etching, wherein the reactive ion etching parameters are as follows: the flow rate of oxygen is 20 ml/min, the pressure in the reaction chamber is 70 Pa, the radio frequency power is 90W, the reaction time is 90 seconds, then the reaction chamber is placed on a hot plate to be heated, the heating temperature is 80 ℃, the heating time is 30 minutes, the bonding and bonding process is accelerated, and the preparation of the sensor is completed.
Example 2:
(1) cleaning the polished surface of the 4-inch silicon crystal element by sequentially adopting acetone, isopropanol and deionized water, and then drying by using nitrogen;
(2) spin-coating 10% polyvinyl alcohol aqueous solution on a polished surface of a silicon crystal cell at the spin-coating speed of 1000 rpm for 1 minute, then heating the silicon crystal cell on a hot plate at the heating temperature of 100 ℃ for 5 minutes, and curing the polyvinyl alcohol to form a film;
(3) spin coating polydimethylsiloxane on a silicon cell coated with a sacrificial layer at the speed of 1000 rpm for 50 seconds, and then heating the silicon cell on a hot plate at the temperature of 100 ℃ for 10 minutes to solidify the polydimethylsiloxane into a film;
(4) attaching a mask plate to the surface of polydimethylsiloxane, and then placing the wafer coated with polydimethylsiloxane and a sacrificial layer in a magnetron cavity to sputter a layer of chromium and gold, wherein the thickness of the chromium sputtered is 50nm, the thickness of the gold sputtered is 50nm, and the chromium serves as an adhesion layer between the gold and the polydimethylsiloxane;
(5) filling liquid metal on the electrode pattern sputtered with gold by using an injector in an oxygen-free glove box, and sucking away redundant liquid metal by using the injector, wherein the thickness of the liquid metal is about 50 microns;
(6) spin-coating polydimethylsiloxane again on the wafer subjected to the steps, wherein the spin-coating speed is 1000 revolutions per minute and the spin-coating time is 80 seconds, then placing the wafer on a hot plate to be heated, the heating temperature is 100 ℃, the heating time is 10 minutes, and the polydimethylsiloxane is cured into a film, wherein the thickness of the film obtained under the conditions is 50 micrometers;
next, preparing an intermediate dielectric, wherein the steps (7) to (16) are laser lithography
(7) Cleaning a clean 4-inch silicon wafer for multiple times (3 times or more) by using acetone, and then drying the cleaned silicon wafer by using nitrogen;
(8) inverting the photoresist SU82050 on the surface of the wafer to ensure that the photoresist is at the center of the wafer as much as possible, holding the edge of the wafer by hand to enable the silicon wafer to be poured and slowly rotate to enable the photoresist to cover most of the area of the silicon wafer, and standing for 20 minutes to eliminate bubbles generated in the inverting process of the photoresist;
(9) spin-coating a photoresist, namely spin-coating for 1 minute at 600 revolutions per minute, then spin-coating for 1 minute at 2500 revolutions per minute, wherein the thickness of the photoresist obtained under the condition is 80 micrometers, and standing for 20 minutes after the spin-coating is finished to eliminate ripples of the photoresist generated by the spin-coating;
(10) prebaking, namely raising the temperature from room temperature to 45 ℃ to prevent the surface of the photoresist from generating wrinkles due to internal stress, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 95 ℃, respectively keeping the temperature at 65 ℃ and 95 ℃ for 3 minutes and 9 minutes, and then naturally cooling to room temperature;
(11) exposing by ultraviolet exposure under the prepared pattern of a mask plate by using a contact photoetching technology, wherein the wavelength of a photoetching machine adopted by the process is 365nm, and the photoetching power is 15mW/m2The exposure time is 15 s;
(12) post-baking, namely heating the photoresist to 45 ℃ from room temperature, in order to prevent the surface of the photoresist from generating wrinkles due to internal stress, heating the photoresist by taking 10 ℃ as a gradient, heating the photoresist to 95 ℃ from 45 ℃, respectively keeping the photoresist at 65 ℃ and 95 ℃ for 2 minutes and 7 minutes, and then naturally cooling the photoresist to room temperature;
(13) developing in a developing solution special for SU82050 photoresist for 6 minutes, fixing in isopropanol for 1 minute, taking out, washing with a large amount of deionized water, and drying by nitrogen;
(14) hard baking, namely raising the temperature from room temperature to 45 ℃, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 200 ℃, keeping the temperature at 200 ℃ for 30 minutes, and then naturally cooling to room temperature, thus finishing the photoetching process;
(15) preparing ethanol and trichlorosilane into a hydrophobic solution according to the volume ratio of 1:1000, stirring the solution for 5 minutes by using a magnetic stirrer, soaking the silicon wafer subjected to photoetching in the solution for 1 hour, performing hydrophobic treatment, then washing the silicon wafer by using ethanol and deionized water, and drying the silicon wafer by using nitrogen;
(16) inverting polydimethylsiloxane on the surface of the silicon wafer, wherein the spin coating speed is 500 revolutions per minute for 150 seconds, completely covering the surface of the silicon wafer, standing for 2 hours, then placing the silicon wafer on a hot plate for heating at 50 ℃ for 20 minutes, curing the polydimethylsiloxane into a film, stripping the polydimethylsiloxane film from the surface of the photoresist, and finishing the manufacturing of the micron column pattern;
(17) spin-coating a layer of polydimethylsiloxane solution on the surface of the cleaned silicon wafer at the speed of 800 revolutions per minute for 40 seconds, attaching the solution to the back of a polydimethylsiloxane film with a micron column pattern, then heating the silicon wafer on a hot plate at the temperature of 100 ℃ for 10 minutes to complete the bonding of the polydimethylsiloxane film and the silicon wafer;
(18) performing reactive ion etching on the silicon wafer adhered with the micron column and oxygen, wherein the oxygen flow is 20 ml/min, the pressure in a reaction chamber is 70 Pa, the radio frequency power is 90 watts, the reaction time is 90 seconds, and then performing hydrophobic treatment as in the step (15);
(19) spin-coating polydimethylsiloxane on the surface of the silicon wafer at the spin-coating speed of 200 revolutions per minute for 100 seconds, standing for 2 hours to ensure that the polydimethylsiloxane solution is fully immersed between the micro-columns, heating at the temperature of 60 ℃ for 20 minutes, then heating the silicon wafer on a hot plate, curing the polydimethylsiloxane into a film, and stripping the polydimethylsiloxane film from the surface of the silicon wafer with the micro-columns to finish the preparation of the polydimethylsiloxane film with the micro-holes;
furthermore, a friction layer is prepared
(20) Spin-coating polydimethylsiloxane on the surface of clean sand paper, wherein the model of the sand paper is P600, the spin-coating speed is 1000 revolutions per minute, the spin-coating time is 1 minute, then placing the sand paper on a hot plate to be heated, the heating temperature is 100 ℃, the time is 10 minutes, solidifying the polydimethylsiloxane into a film, stripping the polydimethylsiloxane film from the surface of the sand paper, and obtaining the film with the thickness of 80 micrometers under the condition;
finally, packaging the upper and lower electrode layers, the friction layer and the middle medium layer
(21) Adhering the polydimethylsiloxane film with the abrasive paper surface structure, the upper electrode layer, the polydimethylsiloxane film with the micropores and the lower electrode layer together by reactive ion etching, wherein the reactive ion etching parameters are as follows: the flow rate of oxygen is 20 ml/min, the pressure in the reaction chamber is 70 Pa, the radio frequency power is 90W, the reaction time is 90 seconds, then the reaction chamber is placed on a hot plate to be heated, the heating temperature is 80 ℃, the heating time is 30 minutes, the bonding and bonding process is accelerated, and the preparation of the sensor is completed.
Example 3:
(1) cleaning the polished surface of the 4-inch silicon crystal element by sequentially adopting acetone, isopropanol and deionized water, and then drying by using nitrogen;
(2) spin-coating 10% polyvinyl alcohol aqueous solution on a polished surface of a silicon crystal cell at a spin-coating speed of 800 rpm for 2 minutes, then heating the silicon crystal cell on a hot plate at a heating temperature of 90 ℃ for 10 minutes, and curing the polyvinyl alcohol to form a film;
(3) spin-coating polydimethylsiloxane on a silicon cell coated with a sacrificial layer at the speed of 900 revolutions per minute for 90 seconds, then heating the silicon cell on a hot plate at the temperature of 90 ℃ for 20 minutes, and curing the polydimethylsiloxane into a film;
(4) attaching a mask plate to the surface of polydimethylsiloxane, and then placing the wafer coated with polydimethylsiloxane and a sacrificial layer in a magnetron cavity to sputter a layer of chromium and gold, wherein the thickness of the chromium sputtered is 30nm, the thickness of the gold sputtered is 100nm, and the chromium serves as an adhesion layer between the gold and the polydimethylsiloxane;
(5) filling liquid metal on the electrode pattern sputtered with gold by using an injector in an oxygen-free glove box, and sucking away redundant liquid metal by using the injector, wherein the thickness of the liquid metal is about 30 micrometers;
(6) spin-coating polydimethylsiloxane again on the wafer subjected to the steps, wherein the spin-coating speed is 900 revolutions per minute and the spin-coating time is 90 seconds, then placing the wafer on a hot plate to be heated, the heating temperature is 90 ℃, the heating time is 20 minutes, and the polydimethylsiloxane is cured into a film, wherein the thickness of the film obtained under the condition is 40 micrometers;
next, preparing an intermediate dielectric, wherein the steps (7) to (16) are laser lithography
(7) Cleaning a clean 4-inch silicon wafer for multiple times (3 times or more) by using acetone, and then drying the cleaned silicon wafer by using nitrogen;
(8) inverting the photoresist SU82050 on the surface of the wafer to ensure that the photoresist is at the center of the wafer as much as possible, holding the edge of the wafer by hand to enable the silicon wafer to be poured and slowly rotate to enable the photoresist to cover most of the area of the silicon wafer, and standing for 20 minutes to eliminate bubbles generated in the inverting process of the photoresist;
(9) spin-coating a photoresist, namely spin-coating the photoresist for 1 minute at 500 revolutions per minute, then spin-coating the photoresist for 1 minute at 2500 revolutions per minute, wherein the thickness of the photoresist obtained under the condition is 75 micrometers, and standing the photoresist for 20 minutes after the spin-coating is finished to eliminate ripples of the photoresist generated by the spin-coating;
(10) prebaking, namely raising the temperature from room temperature to 45 ℃ to prevent the surface of the photoresist from generating wrinkles due to internal stress, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 95 ℃, respectively keeping the temperature at 65 ℃ and 95 ℃ for 3 minutes and 9 minutes, and then naturally cooling to room temperature;
(11) exposing by ultraviolet exposure under the prepared pattern of a mask plate by using a contact photoetching technology, wherein the wavelength of a photoetching machine adopted by the process is 365nm, and the photoetching power is 15mW/m2The exposure time is 15 s;
(12) post-baking, namely heating the photoresist to 45 ℃ from room temperature, in order to prevent the surface of the photoresist from generating wrinkles due to internal stress, heating the photoresist by taking 10 ℃ as a gradient, heating the photoresist to 95 ℃ from 45 ℃, respectively keeping the photoresist at 65 ℃ and 95 ℃ for 2 minutes and 7 minutes, and then naturally cooling the photoresist to room temperature;
(13) developing in a developing solution special for SU82050 photoresist for 6 minutes, fixing in isopropanol for 1 minute, taking out, washing with a large amount of deionized water, and drying by nitrogen;
(14) hard baking, namely raising the temperature from room temperature to 45 ℃, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 200 ℃, keeping the temperature at 200 ℃ for 30 minutes, and then naturally cooling to room temperature, thus finishing the photoetching process;
(15) preparing ethanol and trichlorosilane into a hydrophobic solution according to the volume ratio of 1:1000, stirring the solution for 5 minutes by using a magnetic stirrer, soaking the silicon wafer subjected to photoetching in the solution for 1 hour, performing hydrophobic treatment, then washing the silicon wafer by using ethanol and deionized water, and drying the silicon wafer by using nitrogen;
(16) inverting polydimethylsiloxane on the surface of the silicon wafer, wherein the spin coating speed is 500 revolutions per minute for 150 seconds, completely covering the surface of the silicon wafer, standing for 2 hours, then placing the silicon wafer on a hot plate for heating at 90 ℃ for 15 minutes, curing the polydimethylsiloxane into a film, stripping the polydimethylsiloxane film from the surface of the photoresist, and finishing the manufacturing of the micron column pattern;
(17) spin-coating a layer of polydimethylsiloxane solution on the surface of the cleaned silicon wafer at the speed of 900 revolutions per minute for 80 seconds, attaching the solution to the back of a polydimethylsiloxane film with a micron column pattern, then heating the silicon wafer on a hot plate at the temperature of 90 ℃ for 15 minutes to complete the bonding of the polydimethylsiloxane film and the silicon wafer;
(18) performing reactive ion etching on the silicon wafer adhered with the micron column and oxygen, wherein the oxygen flow is 20 ml/min, the pressure in a reaction chamber is 70 Pa, the radio frequency power is 90 watts, the reaction time is 90 seconds, and then performing hydrophobic treatment as in the step (15);
(19) spin-coating polydimethylsiloxane on the surface of the silicon wafer at the spin-coating speed of 400 revolutions per minute for 120 seconds, standing for 2 hours to ensure that the polydimethylsiloxane solution is fully immersed between the micro-columns, heating at the temperature of 80 ℃ for 15 minutes, then heating the silicon wafer on a hot plate, curing the polydimethylsiloxane into a film, and stripping the polydimethylsiloxane film from the surface of the silicon wafer with the micro-columns to finish the preparation of the polydimethylsiloxane film with the micro-holes;
furthermore, a friction layer is prepared
(20) Spin-coating polydimethylsiloxane on the surface of clean abrasive paper, wherein the model of the abrasive paper is P280, the coating speed is 900 revolutions per minute, the spin-coating time is 2 minutes, then placing the abrasive paper on a hot plate to be heated, the heating temperature is 90 ℃, the time is 15 minutes, solidifying the polydimethylsiloxane into a film, stripping the polydimethylsiloxane film from the surface of the abrasive paper, and obtaining the film with the thickness of 90 micrometers under the condition;
finally, packaging the upper and lower electrode layers, the friction layer and the middle medium layer
(21) Adhering the polydimethylsiloxane film with the abrasive paper surface structure, the upper electrode layer, the polydimethylsiloxane film with the micropores and the lower electrode layer together by reactive ion etching, wherein the reactive ion etching parameters are as follows: the flow rate of oxygen is 20 ml/min, the pressure in the reaction chamber is 70 Pa, the radio frequency power is 90W, the reaction time is 90 seconds, then the reaction chamber is placed on a hot plate to be heated, the heating temperature is 80 ℃, the heating time is 30 minutes, the bonding and bonding process is accelerated, and the preparation of the sensor is completed.
Example 4:
(1) cleaning the polished surface of the 4-inch silicon crystal element by sequentially adopting acetone, isopropanol and deionized water, and then drying by using nitrogen;
(2) spin-coating 10% polyvinyl alcohol aqueous solution on a polished surface of a silicon crystal cell at a spin-coating speed of 70 rpm for 3 minutes, then heating the silicon crystal cell on a hot plate at a heating temperature of 85 ℃ for 14 minutes, and curing the polyvinyl alcohol to form a film;
(3) spin-coating polydimethylsiloxane on a silicon cell coated with a sacrificial layer at the speed of 800 rpm for 80 seconds, curing the polydimethylsiloxane into a film, and then heating the silicon cell on a hot plate at the temperature of 850 ℃ for 15 minutes to obtain a film with the thickness of 50 micrometers;
(4) attaching a mask plate to the surface of polydimethylsiloxane, and then placing the wafer coated with polydimethylsiloxane and a sacrificial layer in a magnetron cavity to sputter a layer of chromium and gold, wherein the thickness of the chromium sputtered is 40nm, the thickness of the gold sputtered is 300nm, and the chromium serves as an adhesion layer between the gold and the polydimethylsiloxane;
(5) filling liquid metal on the electrode pattern sputtered with gold by using an injector in an oxygen-free glove box, and sucking away redundant liquid metal by using the injector, wherein the thickness of the liquid metal is about 40 micrometers;
(6) spin coating polydimethylsiloxane again on the wafer subjected to the steps, wherein the spin coating speed is 850 revolutions per minute and the spin coating time is 70 seconds, then placing the wafer on a hot plate for heating, the heating temperature is 90 ℃, the heating time is 20 minutes, and the polydimethylsiloxane is cured into a film, wherein the thickness of the film obtained under the condition is 30 micrometers;
next, preparing an intermediate dielectric, wherein the steps (7) to (16) are laser lithography
(7) Cleaning a clean 4-inch silicon wafer for multiple times (3 times or more) by using acetone, and then drying the cleaned silicon wafer by using nitrogen;
(8) inverting the photoresist SU82050 on the surface of the wafer to ensure that the photoresist is at the center of the wafer as much as possible, holding the edge of the wafer by hand to enable the silicon wafer to be poured and slowly rotate to enable the photoresist to cover most of the area of the silicon wafer, and standing for 20 minutes to eliminate bubbles generated in the inverting process of the photoresist;
(9) spin-coating a photoresist, namely spin-coating for 1 minute at 400 rpm, spin-coating for 4 minutes at 2500 rpm under the condition that the thickness of the obtained photoresist is 75 micrometers, and standing for 20 minutes after the spin-coating is finished to eliminate ripples of the photoresist generated by the spin-coating;
(10) prebaking, namely raising the temperature from room temperature to 45 ℃ to prevent the surface of the photoresist from generating wrinkles due to internal stress, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 95 ℃, respectively keeping the temperature at 65 ℃ and 95 ℃ for 3 minutes and 9 minutes, and then naturally cooling to room temperature;
(11) exposing by ultraviolet exposure under the prepared pattern of a mask plate by using a contact photoetching technology, wherein the wavelength of a photoetching machine adopted by the process is 365nm, and the photoetching power is 15mW/m2The exposure time is 15 s;
(12) post-baking, namely heating the photoresist to 45 ℃ from room temperature, in order to prevent the surface of the photoresist from generating wrinkles due to internal stress, heating the photoresist by taking 10 ℃ as a gradient, heating the photoresist to 95 ℃ from 45 ℃, respectively keeping the photoresist at 65 ℃ and 95 ℃ for 2 minutes and 7 minutes, and then naturally cooling the photoresist to room temperature;
(13) developing in a developing solution special for SU82050 photoresist for 6 minutes, fixing in isopropanol for 1 minute, taking out, washing with a large amount of deionized water, and drying by nitrogen;
(14) hard baking, namely raising the temperature from room temperature to 45 ℃, then raising the temperature by taking 10 ℃ as a gradient, raising the temperature from 45 ℃ to 200 ℃, keeping the temperature at 200 ℃ for 30 minutes, and then naturally cooling to room temperature, thus finishing the photoetching process;
(15) preparing ethanol and trichlorosilane into a hydrophobic solution according to the volume ratio of 1:1000, stirring the solution for 5 minutes by using a magnetic stirrer, soaking the silicon wafer subjected to photoetching in the solution for 1 hour, performing hydrophobic treatment, then washing the silicon wafer by using ethanol and deionized water, and drying the silicon wafer by using nitrogen;
(16) inverting polydimethylsiloxane on the surface of the silicon wafer to completely cover the surface of the silicon wafer, standing for 2 hours, then placing the silicon wafer on a hot plate for heating at the temperature of 80 ℃ for 15 minutes, curing the polydimethylsiloxane into a film, and stripping the polydimethylsiloxane film from the surface of the photoresist to finish the manufacturing of the micron column pattern;
(17) spin-coating a layer of polydimethylsiloxane solution on the surface of the cleaned silicon wafer at the spin-coating speed of 850 revolutions per minute for 70 seconds, attaching the solution to the back of the polydimethylsiloxane film with the micron column pattern, then heating the silicon wafer on a hot plate at the heating temperature of 90 ℃ for 15 minutes to complete the bonding of the polydimethylsiloxane film and the silicon wafer;
(18) performing reactive ion etching on the silicon wafer adhered with the micron column and oxygen, wherein the oxygen flow is 20 ml/min, the pressure in a reaction chamber is 70 Pa, the radio frequency power is 90 watts, the reaction time is 90 seconds, and then performing hydrophobic treatment as in the step (15);
(19) spin-coating polydimethylsiloxane on the surface of the silicon wafer at the spin-coating speed of 300 revolutions per minute for 120 seconds, standing for 2 hours to ensure that the polydimethylsiloxane solution is fully immersed between the micro-columns, heating at the temperature of 70 ℃ for 20 minutes, then heating the silicon wafer on a hot plate, curing the polydimethylsiloxane into a film, and stripping the polydimethylsiloxane film from the surface of the silicon wafer with the micro-columns to finish the preparation of the polydimethylsiloxane film with the micro-holes;
furthermore, a friction layer is prepared
(20) Spin-coating polydimethylsiloxane on the surface of clean abrasive paper, wherein the model of the abrasive paper is P280, the coating speed is 850 revolutions per minute, the spin-coating time is 4 minutes, then placing the abrasive paper on a hot plate for heating at 90 ℃ for 10 minutes, curing the polydimethylsiloxane into a film, and stripping the polydimethylsiloxane film from the surface of the abrasive paper, wherein the thickness of the film obtained under the condition is 85 micrometers;
finally, packaging the upper and lower electrode layers, the friction layer and the middle medium layer
(21) Adhering the polydimethylsiloxane film with the abrasive paper surface structure, the upper electrode layer, the polydimethylsiloxane film with the micropores and the lower electrode layer together by reactive ion etching, wherein the reactive ion etching parameters are as follows: the flow rate of oxygen is 20 ml/min, the pressure in the reaction chamber is 70 Pa, the radio frequency power is 90W, the reaction time is 90 seconds, then the reaction chamber is placed on a hot plate to be heated, the heating temperature is 80 ℃, the heating time is 30 minutes, the bonding and bonding process is accelerated, and the preparation of the sensor is completed.
It will be understood by those skilled in the art that the foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Claims (7)
1. A multifunctional sensing flexible sensor, comprising an upper electrode layer, an intermediate dielectric layer and a lower electrode layer, wherein:
the upper electrode layer and the lower electrode layer have the same structure and both comprise a flexible base material and liquid metal embedded in the base material, and the surface area of the upper electrode layer is larger than that of the lower electrode layer, so that a capacitive edge effect is generated between the upper electrode layer and the lower electrode layer; the middle dielectric layer is arranged between the upper electrode layer and the lower electrode layer, is made of the same flexible base material as the upper electrode layer and the lower electrode layer, and is provided with a plurality of micron-sized holes to form a micron-sized hole structure;
when the sensor is stressed by pressure, tension or is approached by a conductor, the capacitance between the upper electrode layer and the lower electrode layer changes, and the magnitude of the pressure, the tension or the distance between the conductor and the sensor, which is stressed by the sensor, is obtained by measuring the change of the capacitance of the sensor;
when the object to be measured rubs with the upper electrode layer, the pressure applied by the object to be measured to the upper electrode layer is obtained by measuring the change of the voltage in the upper electrode layer.
2. The multifunctional sensing flexible sensor according to claim 1, wherein a friction layer is further disposed on the upper electrode layer, the friction layer is made of the same flexible base material as the upper electrode layer, the surface roughness Ra of the friction layer is 1.6 μm to 6.4 μm, and when an object to be measured is rubbed with the friction layer with a force of 15KPa or less, the magnitude of a force applied to the object to be measured is obtained by detecting a change in voltage on the upper electrode layer, thereby improving the sensitivity of the sensor.
3. The multifunctional sensing flexible sensor according to claim 1 or 2, wherein the distance between said upper and lower electrode layers is 50 μm to 200 μm.
4. The multifunctional sensing flexible sensor according to claim 1 or 2, wherein the thickness of the upper and lower electrode layers is 100 μm to 200 μm.
5. A multi-functional, sensing, flexible sensor according to claim 1 or 2, wherein said micro-holes have a diameter of 70 μm to 210 μm.
6. The flexible sensor of claim 1, wherein the flexible substrate material is PDMS, ecoflex, PI, PTFE or PET.
7. The flexible sensor of claim 1, wherein said liquid metal is gallium alloy.
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| CN110132457A (en) * | 2019-05-28 | 2019-08-16 | 华中科技大学 | A kind of flexible sensor of multifunctional sensing and preparation method thereof |
| CN111839503A (en) * | 2020-06-29 | 2020-10-30 | 华中科技大学 | Skin-attached electrocardiogram acceleration detection system and preparation method thereof |
| CN113375847A (en) * | 2021-06-01 | 2021-09-10 | 西安交通大学 | Ionic polymer friction sensing type artificial skin |
| CN113776709A (en) * | 2021-08-09 | 2021-12-10 | 济南大学 | Dual-mode flexible touch sensor and preparation method and application thereof |
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