Response collaborative visual perception flexible sensor and preparation method and application thereof

Abstract

The invention discloses a response collaborative visual perception flexible sensor as well as a preparation method and application thereof. Polyvinyl alcohol, sodium alginate, anthocyanin and other materials with good biocompatibility are used; the polyvinyl alcohol / sodium alginate / calcium ion mixed composite lower-layer hydrogel and the polyvinyl alcohol / anthocyanin mixed composite upper-layer hydrogel are self-adhered at an interface by adopting a freezing-melting method to form a double-layer structure, and the flexible strain sensor which is large in test range, high in sensitivity and good in mechanical property and can be used for intuitively observing external stimulation change is prepared. The response collaborative visual perception flexible sensor has the characteristics of high sensitivity, strong mechanical strength, excellent stability, visual motion monitoring and the like, and the practical application range of hydrogel material flexible wearable electronics is effectively expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible strain sensors, and in particular relates to a responsive collaborative visual perception flexible sensor and a preparation method and application thereof. Background Art

[0002] In recent years, flexible pressure sensors have received widespread attention in the fields of wearable electronics, robot tactile perception, and human health monitoring. Traditional pressure sensors are usually made of rigid materials, lacking flexibility and stretchability, and are difficult to meet the growing demand for flexible electronic devices. In order to achieve flexible, stretchable, and highly sensitive pressure sensors, researchers have gradually turned their attention to hydrogel materials. Inspired by the skin, many researchers have designed conductive hydrogels to be stimulus-responsive, which can convert stimuli such as pH, temperature, humidity, and pressure into electrical signals, thereby monitoring human health or detecting human movement.

[0003] At present, in order to enhance the conductivity of hydrogels, conductive fillers such as carbon nanotubes and graphene are usually introduced. However, these fillers often increase the cost of hydrogels and reduce the mechanical strength of hydrogels. By introducing salt ions into the polymer network, not only can the strength of the polymer network be increased through reactions such as hydrophobicity and salting-out to enhance the mechanical strength of the hydrogel, but it can also serve as a conductive filler to enhance the conductivity of the hydrogel.

[0004] At present, most conductive hydrogels can only detect one external stimulus, and some conductive hydrogels can detect multiple stimuli, but their sensitivity is insufficient, which is manifested in a small detection range, slow response, and long recovery time, which greatly limits their practical application. When existing conductive hydrogel flexible sensors are used as wearable devices, they often require a large number of auxiliary equipment to convert external stimuli into electrical signals and then process them, which increases the cost and complexity of conductive hydrogel sensors as wearable devices.

[0005] Therefore, in order to meet the needs of wearable electronic devices, it is of great significance to design a flexible sensor that is highly sensitive and intuitively responds to a variety of external stimuli. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention provides a responsive collaborative visual perception flexible sensor and its preparation method and application, using polyvinyl alcohol, sodium alginate, anthocyanin and other materials with good biocompatibility, and using the freeze-thaw method to self-adhere the polyvinyl alcohol / sodium alginate / calcium ion mixed composite lower layer hydrogel and the polyvinyl alcohol / anthocyanin mixed composite upper layer hydrogel at the interface to form a double-layer structure, and prepare a flexible strain sensor with a large test range, high sensitivity, good mechanical properties, and intuitive observation of changes in external stimuli. The responsive collaborative visual perception flexible sensor has the characteristics of high sensitivity, strong mechanical strength, excellent stability and visual motion monitoring, which effectively expands the practical application range of hydrogel material flexible wearable electronics.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The present invention first provides a responsive collaborative visual perception flexible sensor, which consists of a double-layer conductive hydrogel and metal conductive terminals connected to both ends of the double-layer conductive hydrogel; the double-layer conductive hydrogel includes an upper hydrogel and a lower hydrogel, the lower hydrogel is a polyvinyl alcohol / alginate / calcium ion mixed composite hydrogel, and the upper hydrogel is a polyvinyl alcohol / anthocyanin mixed composite hydrogel, and the upper hydrogel and the lower hydrogel are self-adhesive and bonded by a step-by-step freeze-thaw method.

[0009] Furthermore, the metal conductive terminal includes a copper foil electrode and a wire, the copper foil electrode is pasted on the end of the double-layer conductive hydrogel, and the wire is connected to the copper foil electrode.

[0010] Furthermore, the double-layer conductive hydrogel is a double-layer structure with a stepped pore structure, the upper layer hydrogel is dense and porous and has a color-changing function, and the lower layer hydrogel is loose and porous and has a sensing performance.

[0011] The present invention also provides a method for preparing a responsive collaborative visual perception flexible sensor, comprising the following steps:

[0012] First, prepare a double-layer conductive hydrogel:

[0013] S1. dissolving polyvinyl alcohol particles in water to form a polyvinyl alcohol solution;

[0014] S2. adding anthocyanin to the polyvinyl alcohol solution and stirring until dissolved to obtain an upper mixed solution;

[0015] S3. Adding sodium alginate to the polyvinyl alcohol solution and stirring until dissolved to obtain a lower mixed solution;

[0016] S4. The lower mixed solution was frozen at -18°C for 3h and then allowed to melt at room temperature to obtain a lower hydrogel;

[0017] S5. Pour the upper mixed solution onto the lower hydrogel, freeze it at -18°C for 3h, and then thaw it at room temperature; cycle the low-temperature freezing and room-temperature thawing process three times to obtain a precursor hydrogel;

[0018] S6. Spraying a saturated calcium chloride solution evenly below the aforementioned hydrogel to obtain a double-layer conductive hydrogel;

[0019] Then, metal conductive terminals are assembled at both ends of the double-layer conductive hydrogel:

[0020] S7. Copper foil electrodes are assembled at both ends of the double-layer conductive hydrogel, and a wire is connected to each copper foil electrode to make a strain-coordinated visual perception flexible sensor.

[0021] Furthermore, in step S1, the mass ratio of polyvinyl alcohol particles to water is 1:9.

[0022] Furthermore, in step S2, the type of anthocyanidin is black rice anthocyanidin, and its mass accounts for 0.02wt% to 0.1wt% of the mass of the polyvinyl alcohol solution.

[0023] Furthermore, in step S3, the mass of sodium alginate accounts for 2 wt % of the mass of the polyvinyl alcohol solution.

[0024] Furthermore, in step S4, the thickness of the lower layer hydrogel is 1 mm; and in step S5, the thickness of the precursor hydrogel is 2 mm.

[0025] Furthermore, in step S6, the spraying time of the saturated calcium chloride solution is 0 min to 60 min.

[0026] The responsive collaborative visual perception flexible sensor described in the present invention can be applied to electronic skin, flexible wearable devices and flexible display devices.

[0027] The present invention has the following advantages:

[0028] The present invention provides a responsive collaborative visual perception flexible sensor and a preparation method thereof. The flexible sensor uses a double-layer conductive hydrogel with a double-layer structure. The upper hydrogel is a dense and porous polyvinyl alcohol / anthocyanin mixed composite hydrogel with a color-changing function, and the lower hydrogel is a loose and porous polyvinyl alcohol / alginate / calcium ion composite hydrogel with sensing performance. The combination of the upper hydrogel and the lower hydrogel is achieved by a step-by-step freeze-thaw method, and the combination interface is stable and tight.

[0029] The polyvinyl alcohol / anthocyanin polymer network of the flexible sensor of the present invention significantly improves the mechanical properties of the hydrogel and gives the hydrogel the ability to visually monitor pH changes, and the combination of calcium ions and sodium alginate significantly improves the conductivity of the hydrogel. Therefore, the dense upper layer of hydrogel provides strong mechanical properties for the conductive hydrogel and plays a role in supporting the conductive hydrogel, and the loose lower layer of hydrogel provides a wide channel for the movement of free ions in the conductive hydrogel, thereby enhancing the conductivity of the conductive hydrogel.

[0030] In the preparation method of the present invention, the method of room temperature configuration and low temperature cycle freezing is adopted, which avoids the conditions such as complex chemical cross-linking agents and high-energy radiation light sources, and the preparation process is simple, economical and environmentally friendly. At the same time, the strain-coordinated visual perception flexible sensor obtained by the physical cross-linking method proposed in the present invention is formed by the crystallization domains and non-covalent bonds of multiple polyvinyl alcohol molecular chains. It will not produce toxicity to cells and has good biocompatibility.

[0031] In the preparation method of the present invention, calcium chloride is infiltrated into the conductive hydrogel and combined with sodium alginate in the lower hydrogel, thereby improving the mechanical strength of the lower hydrogel and increasing the density of the three-dimensional network of polyvinyl alcohol through hydrophobicity and salting-out, thereby improving the conductive properties of the hydrogel and enhancing the mechanical properties of the conductive hydrogel. By regulating the infiltration time of calcium chloride, the conductive properties and mechanical properties of the conductive hydrogel can be improved at the same time.

[0032] The strain flexible sensor of the present invention can be used as a wearable device to monitor health through the change of electrical signals and hydrogel color when different parts of the human body move. This invention expands the practical application of wearable devices used for human health monitoring. When the conductive hydrogel is used as a wearable device, the movement morphology can be monitored through the deformation of the conductive hydrogel, and the change of pH of human body fluids can be monitored by visually observing the change of the color of the conductive hydrogel. Without the need for a large number of auxiliary monitoring instruments, the change of the color of the conductive hydrogel can be used to monitor human movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of a responsive collaborative visual perception flexible sensor according to the present invention;

[0034] Figure 2 A flow chart for preparing a double-layer conductive hydrogel for a responsive collaborative visual perception flexible sensor according to the present invention;

[0035] Figure 3 This is a microscopic morphology of the responsive collaborative visual perception flexible sensor prepared in Example 2 of the present invention;

[0036] Figure 4The tensile stress-strain curves of the responsive collaborative visual perception flexible sensors prepared in Examples 1 to 3 of the present invention;

[0037] Figure 5 This is a resistance change diagram of the responsive collaborative visual perception flexible sensor under different strains prepared in Example 2 of the present invention;

[0038] FIG6( a ) is a sensitivity diagram of 600 load cycle tests of the responsive collaborative visual perception flexible sensor prepared in Example 2 of the present invention;

[0039] FIG6( b ) is an enlarged schematic diagram of the A interval in FIG6( a );

[0040] FIG6(c) is an enlarged schematic diagram of interval B in FIG6(a);

[0041] Figure 7 A curve chart showing the response of the collaborative visual perception flexible sensor to speech recognition prepared in Example 2 of the present invention;

[0042] Figure 8 This is a detection diagram of the experimenter's finger bending by the responsive collaborative visual perception flexible sensor integrated prepared in Example 2 of the present invention;

[0043] Fig. 9 This is a signal diagram of the integrated response cooperative visual perception flexible sensor prepared in Example 2 of the present invention detecting the motion state of the experimenter;

[0044] Fig.10 This is a diagram showing the color changes of the responsive collaborative visual perception flexible sensor prepared in Example 2 of the present invention under different pH environments. DETAILED DESCRIPTION

[0045] In order to better illustrate the purpose, technical features and advantages of the present invention, the present invention is further described below in conjunction with specific embodiments.

[0046] The present invention provides a responsive collaborative visual perception flexible sensor, such as Figure 1 As shown, it is composed of a double-layer conductive hydrogel and metal conductive terminals connected to both ends of the double-layer conductive hydrogel; the double-layer conductive hydrogel includes an upper hydrogel and a lower hydrogel, the lower hydrogel is a polyvinyl alcohol / alginate / calcium ion mixed composite hydrogel, and the upper hydrogel is a polyvinyl alcohol / anthocyanin mixed composite hydrogel, the upper hydrogel and the lower hydrogel are self-adhesively bonded by a step-by-step freeze-thaw method, and the bonding interface is stable and tight.

[0047] Furthermore, the metal conductive terminal includes a copper foil electrode and a wire, the copper foil electrode is pasted on the end of the double-layer conductive hydrogel, and the wire is connected to the copper foil electrode.

[0048] Furthermore, the double-layer conductive hydrogel is a double-layer structure with a stepped pore structure, the upper layer hydrogel is dense and porous and has a color-changing function, and the lower layer hydrogel is loose and porous and has a sensing performance. The dense upper layer hydrogel provides strong mechanical properties for the conductive hydrogel and plays a role in supporting the conductive hydrogel, and the loose lower layer hydrogel provides a wide channel for the movement of free ions in the conductive hydrogel, thereby enhancing the conductivity of the conductive hydrogel.

[0049] The responsive collaborative visual perception flexible sensor provided by the present invention can be applied to electronic skin, flexible wearable devices and flexible display devices.

[0050] Example 1

[0051] This embodiment is a method for preparing a responsive collaborative visual perception flexible sensor, comprising the following steps:

[0052] Preparation of double-layer conductive hydrogels, such as Figure 2 As shown:

[0053] S1: After mixing the polyvinyl alcohol particles with deionized water in a mass ratio of 1:9, stir them in a water bath at 95°C for 5 hours using a stirrer until a uniform solution is formed, and place the polyvinyl alcohol solution obtained by stirring at room temperature for later use;

[0054] S2: Add 2 mg of black rice anthocyanin powder to 10 g of polyvinyl alcohol solution, and stir magnetically at 300 rpm for 30 min until dissolved to obtain anthocyanin / polyvinyl alcohol upper mixed solution;

[0055] S3: Add 0.2 g of sodium alginate powder to 10 g of polyvinyl alcohol solution, and stir magnetically at 300 rpm for 3 h until dissolved to obtain a sodium alginate / polyvinyl alcohol lower layer mixed solution;

[0056] S4: freezing the sodium alginate / polyvinyl alcohol lower layer mixed solution at -18°C for 3 hours, and then leaving it at room temperature for 2 hours to melt, thereby obtaining a lower layer hydrogel; the thickness of the lower layer hydrogel is 1 mm;

[0057] S5: pouring the anthocyanin / polyvinyl alcohol upper layer solution onto the lower layer hydrogel, freezing at -18°C for 3 hours, and then leaving at room temperature for 2 hours to thaw; the above freezing and thawing process is repeated 3 times to obtain a precursor hydrogel; the thickness of the precursor hydrogel is 2 mm;

[0058] S6: spraying 2M calcium chloride solution evenly under the precursor hydrogel, allowing the calcium chloride solution to infiltrate for 60 minutes, and then absorbing excess calcium chloride solution with filter paper to obtain a conductive hydrogel;

[0059] Assemble metal conductive terminals at both ends of the double-layer conductive hydrogel:

[0060] S7: Take a long strip of the double-layer conductive hydrogel and attach a copper foil electrode to each of its two ends; connect a wire to each copper foil electrode so as to connect it to an external electrical signal acquisition device to make a strain-coordinated visual perception flexible sensor.

[0061] Example 2

[0062] A method for preparing a responsive collaborative visual perception flexible sensor comprises the following steps:

[0063] S1: After mixing the polyvinyl alcohol particles with deionized water in a mass ratio of 1:9, stir them in a water bath at 95°C for 5 hours using a stirrer until a uniform solution is formed, and place the polyvinyl alcohol solution obtained by stirring at room temperature for later use;

[0064] S2: Add 10 mg of black rice anthocyanin powder to 10 g of polyvinyl alcohol solution, stir magnetically at 300 rpm for 30 min until dissolved, and obtain anthocyanin / polyvinyl alcohol upper mixed solution;

[0065] S3: Add 0.2 g of sodium alginate powder to 10 g of polyvinyl alcohol solution, and stir magnetically at 300 rpm for 3 h until dissolved to obtain a sodium alginate / polyvinyl alcohol lower layer mixed solution;

[0066] S4: Freeze the sodium alginate / polyvinyl alcohol lower layer solution at -18°C for 3 hours, and then leave it at room temperature for 2 hours to melt, thereby obtaining a lower layer hydrogel; the thickness of the lower layer hydrogel is 1 mm;

[0067] S5: pour the anthocyanin / polyvinyl alcohol upper layer solution onto the lower layer hydrogel, freeze it at -18°C for 3 hours, and then leave it at room temperature for 2 hours to thaw; the above freezing and thawing process is repeated 3 times to obtain a precursor hydrogel; the thickness of the precursor hydrogel is 2 mm;

[0068] S6: Spray 2M calcium chloride solution evenly under the above-mentioned precursor hydrogel, let the calcium chloride solution infiltrate for 60 minutes, and then use filter paper to absorb excess calcium chloride solution to obtain an upper conductive hydrogel.

[0069] S7: Take a long strip of double-layer conductive hydrogel and attach a copper foil electrode at each end of it; connect two wires to the copper foil electrodes so as to connect them to an external electrical signal acquisition device to make a strain-coordinated visual perception flexible sensor based on conductive composite hydrogel.

[0070] The microscopic morphology of the responsive collaborative visual perception flexible sensor prepared in this embodiment is as follows: Figure 3 shown.

[0071] The difference between the preparation method of this embodiment and that of Embodiment 1 is that in this embodiment, the mass of anthocyanin in step S2 is 10 mg.

[0072] Example 3

[0073] A method for preparing a responsive collaborative visual perception flexible sensor comprises the following steps:

[0074] S1: After mixing the polyvinyl alcohol particles with deionized water in a mass ratio of 1:9, stir them in a water bath at 95°C for 5 hours using a stirrer until a uniform solution is formed, and place the polyvinyl alcohol solution obtained by stirring at room temperature for later use;

[0075] S2: Add 10 mg of black rice anthocyanin powder to 10 g of polyvinyl alcohol solution, stir magnetically at 300 rpm for 30 min until dissolved, and obtain anthocyanin / polyvinyl alcohol upper mixed solution;

[0076] S3: Add 0.2 g of sodium alginate powder to 10 g of polyvinyl alcohol solution, and stir magnetically at 300 rpm for 3 h until dissolved to obtain a sodium alginate / polyvinyl alcohol lower layer mixed solution;

[0077] S4: Freeze the sodium alginate / polyvinyl alcohol lower layer solution at -18°C for 3 hours, and then leave it at room temperature for 2 hours to melt, thereby obtaining a lower layer hydrogel; the thickness of the lower layer hydrogel is 1 mm;

[0078] S5: pour the anthocyanin / polyvinyl alcohol upper mixed solution onto the lower hydrogel, freeze it at -18°C for 3 hours, and then leave it at room temperature for 2 hours to thaw; the freezing and thawing process is repeated 3 times to obtain a precursor hydrogel; the thickness of the precursor hydrogel is 2 mm;

[0079] S6: Take a long strip of precursor hydrogel and stick a piece of copper foil on each end as an electrode; connect two wires to the copper foil electrodes so as to connect to an external electrical signal acquisition device to make a precursor hydrogel flexible sensor.

[0080] The difference between the preparation method described in this embodiment and that in embodiment 2 is that in this embodiment, no calcium chloride solution is used to spray the precursor hydrogel.

[0081] Comparative Example 1

[0082] A method for preparing a responsive collaborative visual perception flexible sensor comprises the following steps:

[0083] S1: After mixing the polyvinyl alcohol particles with deionized water in a mass ratio of 1:9, stir them in a water bath at 95°C for 5 hours using a stirrer until a uniform solution is formed, and place the polyvinyl alcohol solution obtained by stirring at room temperature for later use;

[0084] S2: Add 0.2 g of sodium alginate powder to 10 g of polyvinyl alcohol solution, and stir magnetically at 300 rpm for 3 h until dissolved to obtain a sodium alginate / polyvinyl alcohol lower layer mixed solution;

[0085] S3: Freeze the sodium alginate / polyvinyl alcohol lower layer mixed solution at -18°C for 3 hours, and then leave it at room temperature for 2 hours to melt, thereby obtaining a lower layer hydrogel; the thickness of the lower layer hydrogel is 1 mm;

[0086] S4: Pour the polyvinyl alcohol solution onto the lower hydrogel, freeze it at -18°C for 3 hours, and then thaw it at room temperature for 2 hours. The freezing and thawing process is repeated 3 times to obtain a precursor hydrogel. The thickness of the precursor hydrogel is 2 mm.

[0087] S5: Spray 2M calcium chloride solution evenly under the above-mentioned precursor hydrogel, let the calcium chloride solution infiltrate for 60 minutes, and then use filter paper to absorb excess calcium chloride solution to obtain a double-layer conductive hydrogel;

[0088] S6: Take a long strip of double-layer conductive hydrogel and stick a piece of copper foil on each end of it as an electrode; connect two wires to the copper foil electrodes so as to connect them to an external electrical signal acquisition device to make a strain-coordinated visual perception flexible sensor based on conductive composite hydrogel.

[0089] The preparation method described in this comparative example 1 is different from that in examples 1 and 2 in that anthocyanin is not used in the upper layer of the hydrogel.

[0090] The following briefly introduces the strain sensing mechanism of the strain-coordinated visual perception flexible sensor of the present invention:

[0091] The strain-coordinated visual perception flexible sensor prepared by the method of Example 2 has a conductive polyanionic polymer sodium alginate and an ion-conductive calcium chloride solution sprayed during its preparation. Inside the hydrogel rich in water molecules, the ionized free ions include sodium ions, calcium ions and chloride ions, which provide ionic conductivity for the hydrogel. During the stretching deformation of the flexible sensor, the reduction in the cross-sectional area of ​​the flexible sensor and the lengthening of the free ion channel will increase the resistance of the hydrogel. The deformation degree and resistance change of the flexible sensor are calibrated with each other, and the deformation of the hydrogel is detected by detecting the resistance change of the flexible sensor.

[0092] The following describes the mechanical properties test results of the embodiments of the present invention:

[0093] Mechanical tests were performed on the strain-coordinated visual perception flexible sensors prepared by the methods of Examples 1, 2 and 3 of the present invention. The tests were performed using a universal tensile testing machine (CMT5105-R) at a test temperature of 20° C. and a tensile rate of 10 mm / min.

[0094] Depend on Figure 4 It can be seen that the tensile strength of the strain-cooperative visual perception flexible sensor of Example 1 is 0.908MPa, and the elongation at break is 374.06%. The tensile strength of the strain-cooperative visual perception flexible sensor of Example 2 is 0.913MPa, and the elongation at break is 374.06%. The tensile strength of the strain-cooperative visual perception flexible sensor of Example 3 is 0.497MPa, and the elongation at break is 407.67%. From the test results, the strain-cooperative visual perception flexible sensor of Example 2 exhibits the greatest tensile strength and elongation at break, that is, the best mechanical properties. A greater anthocyanin content increases the degree of entanglement of the upper hydrogel molecular chains and improves the mechanical properties, while calcium ions increase the cross-linking density of the lower hydrogel molecular network through salting-out and the Hofmeister effect, thereby improving the mechanical properties of the strain-cooperative visual perception flexible sensor.

[0095] The following describes the sensor performance test results of the embodiment of the present invention:

[0096] The performance test of the strain-coordinated visual perception flexible sensor prepared by the method of Example 2 of the present invention was carried out. The test used a universal tensile testing machine (CMT5105-R) to apply load to the flexible sensor for cyclic stretching of different degrees, the cyclic stretching speed was 5 mm / min, the test environment temperature was 20°C, the copper wires at both ends of the flexible sensor were connected to a Keysight digital multimeter (34661a), and the relative change of resistance ΔR / R0 was measured, where ΔR is the change in resistance and R0 is the initial resistance.

[0097] Depend on Figure 5 It can be seen that the ΔR / R0 of the strain-coordinated visual perception flexible sensor of Example 2 increases from 5.01% to 52.3% as the strain increases from 5% to 50%, which proves that the strain-coordinated visual perception flexible sensor has good strain sensing characteristics.

[0098] Figure 6(a) to Figure 6(c) The strain-coordinated visual perception flexible sensor prepared in Example 2 was cyclically stretched 600 times under a strain of 60%. After repeated stretching, the flexible sensor still maintained a stable ΔR / R0 that changed with the strain, indicating that the strain-coordinated visual perception flexible sensor has good stability in use.

[0099] Figure 7 This is the resistance change rate waveform when the strain-coordinated visual perception flexible sensor obtained in Example 2 is attached to the throat and the English words A and Hello are pronounced.

[0100] Figure 8This is the detection signal of finger bending when the strain-coordinated visual perception flexible sensor obtained in Example 2 is attached to the finger.

[0101] Fig. 9 These are the related signals detected when the strain-coordinated visual perception flexible sensor obtained in Example 2 is attached to the fingers, elbows and knees and performs actions at different bending angles.

[0102] Fig.10 This is a color change diagram of the strain-synergistic visual perception flexible sensor prepared in Example 1, Example 2 and Comparative Example 1 in an environment with a pH of 2-13. When the environmental pH value changes, the pH value of the environment or the object in contact with the flexible sensor can be directly obtained through the color change of the strain-synergistic visual perception flexible sensor.

[0103] In summary, the present invention provides a strain-coordinated visual perception flexible sensor and a preparation method thereof, wherein the unique double-layer structure improves the excellent mechanical properties and conductive properties of the flexible sensor, and enables the flexible sensor to work in harsh environments. Anthocyanin and calcium chloride are used as enhancers to significantly improve the mechanical properties of the hydrogel, and also give the flexible sensor the ability to detect pH changes by visually observing color changes.

[0104] Due to its ultra-light and soft sensor body, the flexible sensor can be used for sensing detection at multiple locations on the human body, and can effectively collect various physiological indicators of the human body. For example, it can identify the wearer's throat voice, output the wrist and elbow movement status, and identify the wearer's movement status through changes in body fluid pH. The flexible sensor uses the characteristics of the flexible sensor to visually perceive pH changes and coordinate strain stretching, expanding the practical application of wearable devices for human health detection.

[0105] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention, rather than to limit the scope of protection of the present invention. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A responsive collaborative visual perception flexible sensor, characterized in that: It consists of a double-layer conductive hydrogel and metal conductive terminals connected to both ends of the double-layer conductive hydrogel; the double-layer conductive hydrogel includes an upper hydrogel and a lower hydrogel, the lower hydrogel is a polyvinyl alcohol / alginate / calcium ion mixed composite hydrogel, and the upper hydrogel is a polyvinyl alcohol / anthocyanin mixed composite hydrogel, and the upper hydrogel and the lower hydrogel are self-adhesive and bonded by a step-by-step freeze-thaw method.

2. A responsive cooperative visual perception flexible sensor as claimed in claim 1, characterized in that: The metal conductive terminal comprises a copper foil electrode and a wire. The copper foil electrode is pasted on the end of the double-layer conductive hydrogel, and the wire is connected to the copper foil electrode.

3. The responsive cooperative visual perception flexible sensor according to claim 1, characterized in that: The double-layer conductive hydrogel is a double-layer structure with a stepped pore structure, the upper layer hydrogel is dense and porous and has a color-changing function, and the lower layer hydrogel is loose and porous and has a sensing performance.

4. The method for preparing a responsive collaborative visual perception flexible sensor according to claim 1, characterized in that: The following steps are involved: First, prepare a double-layer conductive hydrogel: S1. dissolving polyvinyl alcohol particles in water to form a polyvinyl alcohol solution; S2. adding anthocyanin to the polyvinyl alcohol solution and stirring until dissolved to obtain an upper mixed solution; S3. Adding sodium alginate to the polyvinyl alcohol solution and stirring until dissolved to obtain a lower mixed solution; S4. The lower mixed solution was frozen at -18°C for 3h and then allowed to melt at room temperature to obtain a lower hydrogel; S5. Pour the upper mixed solution onto the lower hydrogel, freeze it at -18°C for 3h, and then thaw it at room temperature; cycle the low-temperature freezing and room-temperature thawing process three times to obtain a precursor hydrogel; S6. Spraying a saturated calcium chloride solution evenly below the aforementioned hydrogel to obtain a double-layer conductive hydrogel; Then, metal conductive terminals are assembled at both ends of the double-layer conductive hydrogel: S7. Copper foil electrodes are assembled at both ends of the double-layer conductive hydrogel, and a wire is connected to each copper foil electrode to make a strain-coordinated visual perception flexible sensor.

5. The method for preparing a responsive cooperative visual perception flexible sensor according to claim 4, characterized in that: In the step S1, the mass ratio of the polyvinyl alcohol particles to water is 1:

9.

6. The method for preparing a responsive cooperative visual perception flexible sensor according to claim 4, characterized in that: In the step S2, the type of anthocyanidin is black rice anthocyanidin, and its mass accounts for 0.02wt% to 0.1wt% of the mass of the polyvinyl alcohol solution.

7. The method for preparing a responsive cooperative visual perception flexible sensor according to claim 4, characterized in that: In step S3, the mass of sodium alginate accounts for 2 wt % of the mass of the polyvinyl alcohol solution.

8. The method for preparing a responsive cooperative visual perception flexible sensor according to claim 4, characterized in that: In the step S4, the thickness of the lower layer hydrogel is 1 mm; in the step S5, the thickness of the precursor hydrogel is 2 mm.

9. The method for preparing a responsive cooperative visual perception flexible sensor according to claim 4, characterized in that: In step S6, the spraying time of the saturated calcium chloride solution is 0 min to 60 min.

10. Application of a responsive collaborative visual perception flexible sensor as claimed in claim 1 in electronic skin, flexible wearable devices and flexible display devices.

Images