CN113776709A - Dual-mode flexible touch sensor and preparation method and application thereof - Google Patents

Dual-mode flexible touch sensor and preparation method and application thereof Download PDF

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CN113776709A
CN113776709A CN202110909735.6A CN202110909735A CN113776709A CN 113776709 A CN113776709 A CN 113776709A CN 202110909735 A CN202110909735 A CN 202110909735A CN 113776709 A CN113776709 A CN 113776709A
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pdms
micro
template
sided
dual
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CN113776709B (en
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李阳
李�浩
牛闳森
岳文静
高嵩
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University of Jinan
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/0028—Force sensors associated with force applying means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/22—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers
    • G01L5/226—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers to manipulators, e.g. the force due to gripping
    • G01L5/228—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers to manipulators, e.g. the force due to gripping using tactile array force sensors

Abstract

The disclosure belongs to the technical field of sensors, and particularly relates to a dual-mode flexible touch sensor and a preparation method and application thereof, wherein the dual-mode flexible touch sensor is integrated by an airflow sensor and a pressure sensor; the sensing layer of the airflow sensor is connected with the top electrode layer of the pressure sensor; and the top electrode layer of the pressure sensor is sequentially connected with the ion gel sensing layer of the double-sided hierarchical micro-cone structure and the bottom electrode layer of the pressure sensor. The dual-mode flexible touch sensor can detect two signals of a resistor and a capacitor simultaneously and without interference, and has high detection sensitivity. The pressure sensor and the airflow sensor are organically combined, so that the respiratory state and the pulse condition can be monitored in real time simultaneously, and mutual interference is avoided.

Description

Dual-mode flexible touch sensor and preparation method and application thereof
Technical Field
The disclosure belongs to the technical field of sensors, and particularly relates to a dual-mode flexible touch sensor and a preparation method and application thereof.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
Human skin, the most important physical interface between the body and the external environment, possesses a unique multi-touch sensing system that can generate electrical signals in ion exchange form from external stimuli including pressure, humidity, temperature, etc., to accomplish brain sensing. Therefore, inspired by human skin signal sensing mechanisms, flexible tactile sensors capable of converting external stimuli into resistance, capacitance, voltage, current signals have been developed and simulate human skin's perception of pressure, temperature, humidity, airflow. However, most of the existing flexible touch sensors can only detect one stimulation signal, which is very limited in the leading fields of health detection, artificial intelligence, flexible robots, intelligent artificial limbs and the like.
As a core member of a flexible electronic device, a flexible tactile sensor needs to provide advantages of high sensitivity, fast response rate, low detection limit and stability to ensure accuracy and reliability in a working state. At present, the method for improving the performance of the flexible touch sensor mainly introduces a micro-nano structure such as a micro-column, a micro-pyramid, a micro-dome, a nano-wire and the like into an active layer (a sensing layer and an electrode layer) of the sensor in a micro-nano processing mode. The micro-nano structure active layer is easy to generate chemical or physical change when micro-stimulus is applied, so that the output of an electric signal is changed. For the preparation method of the micro-nano structure, the traditional photoetching process is mainly used most commonly at present. Although the method has the advantages of accurately regulating the size and the shape of the micro-nano structure, some defects inevitably exist, such as (1) the mask plate has high cost, and is not beneficial to large-area preparation of the micro-nano structure; (2) are complex and time consuming; (3) the photoetching template is not a disposable template, so that part of polymer is inevitably adhered to the photoetching template when the pattern is copied and stripped, and the next use of the template and the integrity of a micro-nano structure are greatly influenced. In order to reduce the cost, some scientific researchers use natural biological materials such as rose petals, reed leaves, a screen, sand paper and the like as templates to process micro-nano structures. However, the micro-nano structure of the irregularity and the inherent morphology thereof limits further enhancement in performance thereof.
In order to further improve the performance of the touch sensor, taking a flexible pressure sensor as an example, the device structure of the sensor can be reasonably designed, for example, the traditional sandwich device structure is converted into an interdigital electrode structure; and laminating the two single-layer micro-nano structure active layers, and the like. Although the above methods can improve the performance of the sensor to some extent, it is far from sufficient to meet the requirements of wider application.
Disclosure of Invention
In order to solve the above problems, the present disclosure provides a dual-mode flexible tactile sensor, a method for manufacturing the same, and an application thereof, where the dual-mode flexible tactile sensor can detect two signals, namely a resistance signal and a capacitance signal, simultaneously and without interference, and has high detection sensitivity. The pressure sensor and the airflow sensor are organically combined, so that the respiratory state and the pulse condition can be monitored in real time simultaneously, and mutual interference is avoided.
Specifically, the technical scheme of the present disclosure is as follows:
in a first aspect of the present disclosure, a dual-mode flexible tactile sensor is integrated by an airflow sensor and a pressure sensor; the sensing layer of the airflow sensor is connected with the top electrode layer of the pressure sensor; and the top electrode layer of the pressure sensor is sequentially connected with the ion gel sensing layer of the double-sided hierarchical micro-cone structure and the bottom electrode layer of the pressure sensor.
In a second aspect of the present disclosure, a method of making a dual-mode flexible tactile sensor, the method comprising:
step (1): coating the PDMS solution on the Cu template with the hierarchical micro-cone structure, and curing and stripping to obtain a PDMS secondary template with a cilium array structure; coating a P (VDF-HFP)/EMIM (TFSI) ionic gel solution on a first PDMS secondary template, and symmetrically placing an opening interface of a second PDMS secondary template and the first PDMS secondary template to obtain a double-sided hierarchical micro-cone structure P (VDF-HFP)/EMIM (TFSI) ionic gel;
step (2): coating P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel on a Cu template, and stripping to obtain a secondary template of the ionic gel with the hierarchical reverse microcone structure; coating a PDMS solution on a top Cu template to obtain a cilium array structure, meanwhile, placing an ion gel secondary template as a bottom template on the PDMS solution to obtain a hierarchical microcone structure, stripping after curing, spraying a carbon nano tube on the cilium array structure, spraying gold on the hierarchical microcone structure to obtain CNTs/PDMS/Au with a double-sided heterostructure;
and (3): coating the PDMS solution on an ion gel secondary template with a grading reverse micro-cone structure, curing to obtain single-sided grading micro-cone structure PDMS, and spraying gold on the single-sided grading micro-cone structure PDMS to obtain Au/PDMS with a single-sided grading micro-cone structure;
and (4): and (3) forming the double-mode flexible tactile sensor by using CNTs/PDMS/Au with a double-sided heterostructure, P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel with a double-sided hierarchical micro-cone structure and Au/PDMS with a single-sided hierarchical micro-cone structure.
In a third aspect of the present disclosure, the bimodal flexible tactile sensor and/or the method of making the bimodal flexible tactile sensor is used in a wearable healthcare system.
One or more technical schemes in the disclosure have the following beneficial effects:
(1) the dual-mode flexible touch sensor is a device integrating the flexible airflow sensor and the pressure sensor, can detect two signals of a resistor and a capacitor simultaneously and without interference, is beneficial to copying two different structures by one template, further realizes two different sensors, effectively reduces the cost and reduces the process steps.
(2) Compared with the traditional method, the micro-nano processing technology based on the laser marking template method is simple, economical, easy to operate, controllable in appearance and capable of realizing large-area preparation, and can be completed on a Cu plate with low cost only by planning a laser path in advance.
(3) The super-capacitor type pressure sensor based on the double-interlocking structure has stronger stress concentration and increases the specific surface area compared with the traditional structure, thereby further improving the capacitance of unit area and further improving the sensitivity of the device, which is unprecedented in the capacitor type pressure sensor. Compared with the traditional capacitance type pressure sensor, under the external stimulation, the super capacitance type touch sensor can form an electric double layer in the contact area of the sensing layer and the electrode layer, so that the capacitance effect of the sensor is greatly enhanced, and the sensitivity of the super capacitance type touch sensor is far higher than that of the traditional pressure capacitance type touch sensor. The phenomenon is that the sensing layer contains a plurality of anions and cations, when the sensing layer is in stressed contact with the electrode layer, electrons on the electrode attract the reverse polarity ions of the sensing layer to migrate to the contact surface, so that an electric double layer is formed, and the electric double layer has overlarge interface capacitance.
(4) The pressure sensor and the airflow sensor are organically combined, so that the real-time monitoring of the respiratory state and the pulse condition can be realized simultaneously, and mutual interference is avoided, and the development of the wearable health care system is promoted.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
FIG. 1: a flow chart of a method of making a bimodal flexible tactile sensor as described in example 1;
FIG. 2: is a schematic diagram of the dual-mode flexible touch sensor based on the dual-interlocking structure described in embodiment 1;
FIG. 3: is a schematic diagram of a flexible pressure sensor based on a full-plane structure in comparative example 1;
FIG. 4: is a schematic diagram of a flexible pressure sensor based on a sensing layer grading micro-cone structure in a comparative example 2;
FIG. 5: is a schematic diagram of a flexible pressure sensor based on an electrode layer grading micro-cone structure in a comparative example 3;
FIG. 6: is a Field Emission Scanning Electron Microscope (FESEM) photograph of the laser marked Cu template in example 1;
FIG. 7: is a Field Emission Scanning Electron Microscope (FESEM) photograph of the double-sided hierarchical microcone structure P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel in example 1;
FIG. 8: are Field Emission Scanning Electron Microscope (FESEM) photographs of the ciliated structure PDMS (fig. 8A) and the graded micro-cone structure PDMS (fig. 8B) in example 1;
FIG. 9: is a sensitivity curve chart of the super-capacitance pressure sensor based on the double-interlocking structure in the embodiment 1;
FIG. 10: is a response/recovery time curve chart of the super-capacitive pressure sensor based on the double-interlocking structure in the embodiment 1;
FIG. 11: is a graph of the sensitivity response of the ciliated structure CNTs/PDMS based resistive airflow sensor of example 1;
FIG. 12: is the cyclic detection curve of the ciliated structure CNTs/PDMS based resistive airflow sensor in example 1;
the labels in the figure are: 1. au; 2. CNTs; 3. PDMS; 4. p (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel; 5. a copper wire.
Detailed Description
The disclosure is further illustrated with reference to specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The reagents or starting materials used in the present invention can be purchased from conventional sources, and unless otherwise specified, the reagents or starting materials used in the present invention can be used in a conventional manner in the art or in accordance with the product specifications. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred embodiments and materials described herein are intended to be exemplary only.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, and/or combinations thereof, unless the context clearly indicates otherwise.
At present, most of existing flexible touch sensors can only detect one stimulation signal, which is very limited in the leading-edge fields of health detection, artificial intelligence, flexible robots, intelligent artificial limbs and the like, and the preparation method is complex and high in cost.
In one embodiment of the present disclosure, a dual-mode flexible tactile sensor is integrated by an airflow sensor and a pressure sensor; the sensing layer of the airflow sensor is connected with the top electrode layer of the pressure sensor; and the top electrode layer of the pressure sensor is sequentially connected with the ion gel sensing layer of the double-sided hierarchical micro-cone structure and the bottom electrode layer of the pressure sensor. The flexible airflow sensor and the pressure sensor are integrated into a whole, so that two signals of a resistor and a capacitor can be detected simultaneously without interference, the breathing state and the pulse condition can be monitored in real time simultaneously, and the signals do not interfere with each other.
In one embodiment of the present disclosure, the top electrode layer of the pressure sensor, the ionic gel sensing layer of the double-sided hierarchical micro-cone structure, and the bottom electrode layer of the pressure sensor are double-interlocked structures. Compared with the traditional structure, the super-capacitor pressure sensor with the double-interlocking structure has the advantages that stress concentration is stronger, the specific surface area is increased, the capacitance per unit area is favorably improved, and the sensitivity of the device is improved.
In an embodiment of the present disclosure, the sensing layer of the airflow sensor is a PDMS cilium array structure loaded with carbon nanotubes, and based on the PDMS (polydimethylsiloxane) cilium array structure loaded with Carbon Nanotubes (CNTs), the sensing layer is a graded inverse micro-cone structure, which can improve the sensitivity of the airflow sensor.
In one embodiment of the present disclosure, the top electrode layer of the pressure sensor and the bottom electrode layer of the pressure sensor are graded micro-cone structures loaded with gold nanoparticles.
In one embodiment of the present disclosure, the ionic gel sensing layer with the double-sided hierarchical microcone structure is a double-sided hierarchical microcone structure based on polyvinylidene fluoride-hexafluoropropylene P (VDF-HFP)/1-ethyl-3-methylimidazoline bis (trifluoromethylsulfonyl) imide [ EMIM ] [ TFSI ], and this unique structure can increase the specific surface area, enhance the electron transport capability, and enhance the capacitance effect of the sensor, thereby leading to a sensitivity far higher than that of the conventional pressure-capacitance type touch sensor. Due to the introduction of the double-sided hierarchical micro-cone structure, the concentration of local stress is greatly enhanced, and better transmission of external force is facilitated. Meanwhile, the structure reduces the viscoelasticity of the surface of the film, and shortens the response and recovery time.
In one embodiment of the present disclosure, a method of manufacturing a dual-mode flexible tactile sensor includes:
step (1): coating the PDMS solution on a Cu template with a hierarchical micro-cone structure, annealing at 80-120 ℃ for 1-3h, curing, and stripping to obtain a PDMS secondary template with a cilium array structure; coating a P (VDF-HFP)/EMIM (TFSI) ionic gel solution on a PDMS secondary template, spin-coating at the speed of 800rpm of 300-; the preparation method of the double-sided structure is simple, economical and easy to operate, and can realize the preparation of a large-scale sensing layer.
Step (2): coating P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel on a Cu template, and stripping to obtain a secondary template of the ionic gel with the hierarchical reverse microcone structure; coating a PDMS solution on a top Cu template, spin-coating at the rotation speed of 500-1000rpm for 3-5min to uniformly spread the solution on the Cu template, completely permeating the solution into holes under the action of centrifugal force and gravity to prepare a cilium array structure, meanwhile, placing an ionic gel secondary template as a bottom template on the PDMS solution, flowing the ionic gel secondary template under the action of capillary force to prepare a hierarchical microcone structure, curing at 60-80 ℃ for 3-5h, stripping after curing, spraying carbon nanotubes on the cilium array structure, spraying gold on the hierarchical microcone structure to obtain CNTs/PDMS/Au with a double-sided heterostructure; in this process, the PDMS solution is at the interface of the top and bottom templates and the flow of PDMS into the top and bottom templates occurs simultaneously.
And (3): coating a PDMS solution on an ion gel secondary template with a graded reverse micro-cone structure, spin-coating at the rotating speed of 500 plus one (500 plus one) rpm for 3-5min to ensure that the solution is uniformly spread on the ion gel secondary template, completely permeates into holes under the action of centrifugal force and gravity, curing at the temperature of 60-80 ℃ for 3-5h to obtain a bottom electrode of the PDMS with the single-sided graded micro-cone structure after curing and stripping, and spraying gold on the PDMS with the single-sided graded micro-cone structure to obtain Au/PDMS with the single-sided graded micro-cone structure;
and (4): forming a double-mode flexible touch sensor by CNTs/PDMS/Au with a double-sided heterostructure, P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel with a double-sided hierarchical micro-cone structure and Au/PDMS with a single-sided hierarchical micro-cone structure;
in one embodiment of the present disclosure, the preparation of the PDMS solution includes: PDMS was mixed with a curing agent in a ratio of 10-1: 5, fully stirring for 20-60min, and placing in a vacuum drying oven for defoaming for 30-60 min; further, the curing agent is a PDMS curing agent.
In one embodiment of the disclosure, a micro-nano processing technology of a laser marking template method is adopted to prepare a hierarchical micro-cone structure Cu template; furthermore, the diameter of the bottom of the larger micro-cone structure of the Cu template is 40-80um, the height of the Cu template is 80-120um, and the diameter of the bottom of the smaller micro-cone structure of the Cu template is 20-60um, and the height of the Cu template is 40-80 um.
In one embodiment of the present disclosure, the preparation of the P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel solution comprises: dissolving a P (VDF-HFP) polymer in a solvent to obtain a solution with the solubility of 10-20 wt%, and adding [ EMIM ] [ TFSI ] ionic liquid (the volume ratio of the ionic liquid to the P (VDF-TrFE) is 0.5:1, 1:1, 2:1) to obtain a uniformly mixed solution; for the solution with the proportion, on one hand, the solution has proper viscosity, is easy to permeate into the PDMS secondary template by using a spin coating process, and can be uniformly distributed in the holes to form a sensing layer with proper thickness, thereby being beneficial to improving the stability of a device; on the other hand, the solution with the proportion can form the largest electric double layer, the mechanical property of the film is the best, and the sensitivity of the super-capacitor type pressure sensor is greatly improved.
Further, the solvent is an organic solvent, preferably, any one of acetone, N-methylpyrrolidone, dimethylacetamide, N-dimethylformamide, triethyl phosphate, methyl ethyl ketone, N-dimethylformamide, and dimethylsulfide.
In one embodiment of the present disclosure, the bimodal flexible tactile sensor and/or the method for manufacturing the bimodal flexible tactile sensor is applied to a wearable healthcare system.
In order to make the technical solutions of the present disclosure more clearly understood by those skilled in the art, the technical solutions of the present disclosure will be described in detail below with reference to specific embodiments.
Example 1
A dual-mode flexible touch sensor is prepared by the following steps, wherein a preparation flow chart is shown in figure 1:
1) a cold light laser marking machine is used for preparing a Cu template with a graded micro-cone structure, as shown in FIG. 6, the surface structure of the Cu template is regular, the diameter of the bottom of a larger micro-cone structure is 60um, the height of the larger micro-cone structure is 100um, the diameter of the bottom of a smaller micro-cone structure is 30um, and the height of the smaller micro-cone structure is 60 um;
2) PDMS was mixed with PDMS curing agent at 8: 5, fully stirring for 30min, placing in a vacuum drying oven for defoaming for 50min, then coating on a Cu template with a hierarchical micro-cone structure, annealing at 100 ℃ for 1h for curing, and obtaining a PDMS secondary template with a cilium array structure after stripping;
3) the P (VDF-HFP) polymer was dissolved in acetone to give a solution with a solubility of 15 wt%, and [ EMIM ] [ TFSI ] ionic liquid (1 Vol%) was added to give a homogeneous mixture.
4) Spin-coating the solution obtained in step 3) on a PDMS secondary template, spin-coating at a rotation speed of 500rpm for 2min to uniformly spread the solution on the PDMS secondary template, and completely permeating the solution into the holes under the action of centrifugal force and gravity, and then placing another piece of PDMS secondary template on the ionic gel to make the ionic gel flow into the upper PDMS secondary template under the action of capillary force, so as to obtain the double-sided structure P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel (as shown in FIG. 7), which is simple, economic and easy to operate, and can realize the preparation of a large-scale sensing layer.
5) Coating the P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel in the step 3) on a Cu template, drying and then peeling off to obtain the hierarchical reverse microcone structure ionic gel serving as a secondary template;
6) coating the PDMS solution mixed in the step 2) on a Cu template, spin-coating at the rotating speed of 800rpm for 4min to uniformly spread the solution on the Cu template, completely permeating the solution into holes under the action of centrifugal force and gravity, simultaneously, placing 5) ion gel on the PDMS solution as a bottom template, allowing the ion gel to flow into an ion gel secondary template under the action of capillary force, curing at 60 ℃ for 4h, stripping to obtain PDMS (cilium structure is shown in figure 8A and hierarchical microcone structure is shown in figure 8B) of a double-sided heterostructure, respectively serving as a sensing layer of an airflow sensor and a top electrode of a pressure sensor, simultaneously, spraying CNTs on the cilium structure, and spraying gold on the hierarchical microcone structure;
7) coating the PDMS mixed solution in the step 2) on the reverse micro-cone structure ion gel template in the step 5), spin-coating for 4min at the rotating speed of 600rpm to uniformly spread the solution on the ion gel secondary template, completely permeating the solution into the holes under the action of centrifugal force and gravity, curing for 4h at 70 ℃, stripping to obtain a bottom electrode of single-side grading micro-cone structure PDMS, and simultaneously spraying gold on the grading micro-cone structure;
8) the specific structure of the double-sided heterostructure PDMS in 6), the double-sided hierarchical micro-cone structure P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel in 4) and the single-sided hierarchical micro-cone structure PDMS in 7) are combined into the dual-mode flexible tactile sensor shown in FIG. 2.
Comparative example 1:
the difference compared to example 1 is that a sensor layer and electrode layer all-planar structure was prepared using the above method, as shown in fig. 3.
Comparative example 2:
compared with the embodiment 1, the difference is that the sensing layer prepared by the method is in a double-sided hierarchical micro-cone structure, and the electrode layer is in a planar structure, as shown in fig. 4.
Comparative example 3:
compared with the embodiment 1, the difference is that the sensing layer prepared by the method is in a planar structure, and the electrode layer is in a hierarchical micro-cone structure, as shown in fig. 5.
P (VDF-HFP)/[ EMIM ] based on a double interlock structure as described in example 1, compared to the pressure sensors of different structures as described in comparative examples 1-3][TFSI]The ionic gel exhibited better performance in sensitivity as shown in figure 9. The sensitivity of the sensor is shown in FIG. 9, which is the slope of the curve, e.g., 8053.1kPa-1(<1kPa)，3103.5kPa-1(1-35 kPa). The sensitivity is improved mainly by the following two aspects, on one hand, the double interlocking structure provides an ultra-large specific surface area, and the sensor is given a higher area change amount, so that the sensor has more contact area under the same pressure; on the other hand, the double interlocking structure is more beneficial to stress concentration, so that the double interlocking structure is more easily compressed when external force is applied.
As shown in FIG. 10, FIG. 10 has performed a 1kPa transient loading and unloading of the device. The sensor shows spontaneous response to external pressure, and both the response time and the recovery time are less than 5.6ms, because the touch sensor prepares a layered micro-cone structure array on both electrodes and a medium, the viscoelasticity between films is greatly reduced, and therefore ultra-fast response and recovery time are obtained.
As shown in fig. 11, fig. 11 shows a three-dimensional contour plot of the current change as a function of airflow rate and airflow angle, where the current change is positively correlated to both variables.
As shown in fig. 12, fig. 12 produces a sharp response signal once the airflow is applied to the sensor, and returns to the initial state if the airflow is subsequently turned off. Cycle reliability measurements were made by periodically turning the gas flow on/off and varying the gas flow angle while the gas flow velocity was kept constant at 0.6MPa gas flow pressure. The curve shape and the amplitude are stable, and the sensor has good reliability.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A dual-mode flexible touch sensor is characterized in that the dual-mode flexible touch sensor is integrated by an airflow sensor and a pressure sensor; the sensing layer of the airflow sensor is connected with the top electrode layer of the pressure sensor; and the top electrode layer of the pressure sensor is sequentially connected with the ion gel sensing layer of the double-sided hierarchical micro-cone structure and the bottom electrode layer of the pressure sensor.
2. The dual-mode flexible touch sensor of claim 1, wherein the top electrode layer of the pressure sensor, the two-sided graded micro-cone structured ionogel sensing layer, and the bottom electrode layer of the pressure sensor are dual-interlocking structures.
3. The dual-mode flexible touch sensor according to claim 1, wherein the sensing layer of said airflow sensor is a PDMS cilia array loaded with carbon nanotubes.
4. The dual-mode flexible touch sensor of claim 1, wherein the top electrode layer of the pressure sensor and the bottom electrode layer of the pressure sensor are graded micro-cone structures loaded with gold nanoparticles.
5. The dual-mode flexible touch sensor according to claim 1, wherein said ionogel sensing layer of the double-sided graded microcone structure is a double-sided graded microcone structure based on P (VDF-HFP)/EMIM (TFSI).
6. A preparation method of a dual-mode flexible touch sensor is characterized by comprising the following steps:
step (1): coating the PDMS solution on the Cu template with the hierarchical micro-cone structure, and curing and stripping to obtain a PDMS secondary template with a cilium array structure; coating a P (VDF-HFP)/EMIM (TFSI) ionic gel solution on a first PDMS secondary template, and symmetrically placing an opening interface of a second PDMS secondary template and the first PDMS secondary template to obtain a double-sided hierarchical micro-cone structure P (VDF-HFP)/EMIM (TFSI) ionic gel;
step (2): coating P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel on a Cu template, and stripping to obtain a secondary template of the ionic gel with the hierarchical reverse microcone structure; coating a PDMS solution on a top Cu template to obtain a cilium array structure, meanwhile, placing an ion gel secondary template as a bottom template on the PDMS solution to obtain a hierarchical microcone structure, stripping after curing, spraying a carbon nano tube on the cilium array structure, spraying gold on the hierarchical microcone structure to obtain CNTs/PDMS/Au with a double-sided heterostructure;
and (3): coating the PDMS solution on an ion gel secondary template with a grading reverse micro-cone structure, curing to obtain single-sided grading micro-cone structure PDMS, and spraying gold on the single-sided grading micro-cone structure PDMS to obtain Au/PDMS with a single-sided grading micro-cone structure;
and (4): and (3) forming the double-mode flexible tactile sensor by using CNTs/PDMS/Au with a double-sided heterostructure, P (VDF-HFP)/[ EMIM ] [ TFSI ] ionic gel with a double-sided hierarchical micro-cone structure and Au/PDMS with a single-sided hierarchical micro-cone structure.
7. The method of claim 6, wherein the preparing the PDMS solution comprises: PDMS was mixed with a curing agent in a ratio of 10-1: 5, fully stirring for 20-60min, and placing in a vacuum drying oven for defoaming for 30-60 min; further, the curing agent is a PDMS curing agent.
8. The method for preparing a dual-mode flexible touch sensor according to claim 6, wherein a hierarchical microcone structure Cu template is prepared by a micro-nano processing technology of a laser marking template method; furthermore, the diameter of the bottom of the larger micro-cone structure of the Cu template is 40-80um, the height of the Cu template is 80-120um, and the diameter of the bottom of the smaller micro-cone structure of the Cu template is 20-60um, and the height of the Cu template is 40-80 um.
9. The method of claim 6, wherein the preparing of the P (VDF-HFP)/EMIM (TFSI) ionic gel solution comprises: dissolving a P (VDF-HFP) polymer in a solvent to obtain a solution with the solubility of 10-20 wt%, and then adding [ EMIM ] [ TFSI ] ionic liquid to obtain a uniformly mixed solution; further, the solvent is an organic solvent, preferably, any one of acetone, N-methylpyrrolidone, dimethylacetamide, N-dimethylformamide, triethyl phosphate, methyl ethyl ketone, N-dimethylformamide, and dimethylsulfide.
10. Use of the dual-mode flexible tactile sensor of any one of claims 1 to 5 and/or the method of making the dual-mode flexible tactile sensor of any one of claims 6 to 9 in a wearable healthcare system.
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