Taro powder hydrogel flexible conductive sensor and preparation method and application thereof

Abstract

The invention belongs to the technical field of flexible sensors, and particularly discloses a taro powder hydrogel flexible conductive sensor and a preparation method and application thereof, and the taro powder hydrogel flexible conductive sensor comprises the following raw materials: 5-10 parts of taro powder, 5-10 parts of polyvinyl alcohol, 40-50 parts of tetraethylene glycol, 10-15 parts of potassium pyrophosphate and 100 parts of water. The taro powder hydrogel flexible conductive sensor has the mechanical properties of high stress, high strain, high elasticity and the like; the cable can bear 75Kg of weight without being snapped, has very strong freezing resistance and drying resistance, and can be normally used in an extremely low temperature environment; the compound has the advantages of compatibility with normal cells of human bodies, simple preparation method and the like.

Description

Technical Field

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

[0002] Hydrogel flexible sensors are a new type of flexible sensor developed in recent years. They can record the movement information of humans and machines and are widely used in the fields of bionic skin, wearable devices, soft robots, etc. However, it is difficult for existing hydrogel flexible sensors to maintain strong mechanical properties while also having cell compatibility, antifreeze ability, anti-drying ability, etc., which seriously limits the application scope of flexible sensors.

[0003] Lipu taro is produced in Lipu County, Guilin City, Guangxi Zhuang Autonomous Region. It is known as "royal product" with an output of up to 3,300 kg per mu. It contains a variety of ingredients such as protamine, starch, multiple vitamins and inorganic salts. Although taro powder can be used to construct green hydrogels, pure taro powder aqueous solution cannot form hydrogels regardless of freezing or heating treatment. Gel products can only be obtained in the presence of alkaline substances (such as sodium hydroxide) and chemical cross-linking agents (such as epichlorohydrin), after chemical reaction cross-linking and complex subsequent de-alkalinization of substances and cross-linking agent residues. There are no reports on hydrogel flexible sensors with strong mechanical properties, cell compatibility, antifreeze ability and anti-drying ability based on Lipu taro (taro powder) as raw materials. Summary of the invention

[0004] In view of the above-mentioned shortcomings, the present invention provides a taro powder hydrogel flexible conductive sensor and a preparation method and application thereof, which has the advantages of strong mechanical properties, strong antifreeze ability, strong anti-drying ability and good cell compatibility.

[0005] In order to achieve the above objectives, in a first aspect, the present invention provides a taro powder hydrogel flexible conductive sensor. The raw materials of the taro powder hydrogel flexible conductive sensor are as follows, calculated by weight: 5 to 10 parts of taro powder, 5 to 10 parts of polyvinyl alcohol, 40 to 50 parts of tetraethylene glycol, 10 to 15 parts of potassium pyrophosphate and 100 parts of water.

[0006] According to one aspect of the present invention, the weight average molecular weight of the polyvinyl alcohol is 100,000-120,000, and the alcoholysis degree is 99.5%.

[0007] In a second aspect, the present invention also provides a method for preparing the above-mentioned taro powder hydrogel flexible conductive sensor, comprising the following steps:

[0008] S1, 5-10 parts of taro powder, 5-10 parts of polyvinyl alcohol, 40-50 parts of tetraethylene glycol, 10-15 parts of potassium pyrophosphate and 100 parts of water are mixed and dispersed, and then stirred at 90-100° C. for 1-4 hours to obtain a mixed solution;

[0009] S2. Pour the mixed solution into a mold and place it at room temperature for 4 to 48 hours to obtain a finished flexible sensor.

[0010] According to one aspect of the present invention, the preparation method of the taro powder is:

[0011] T1, according to the mass fraction, weigh 1 part of fresh taro that has been washed and peeled, 2 parts of water, put into a wall breaking machine, start the wall breaking machine 5-10 times, each time for 3-5 minutes, to obtain taro slurry;

[0012] T2, filtering the taro slurry with a 200-mesh filter plug to collect the filtrate; then allowing the collected filtrate to settle to obtain wet taro powder; and freeze-drying the wet taro powder to obtain dry taro powder.

[0013] According to one aspect of the present invention, in step S1, the stirring speed is 1000-1800 r / min.

[0014] According to one aspect of the present invention, in step S2, the mold is any one of a standard dumbbell-shaped mold and a plastic tube mold.

[0015] According to one aspect of the present invention, the inner diameter of the plastic tube mold is 2 cm and the length is 4 to 6 cm.

[0016] In a third aspect, the present invention also provides an application of the above-mentioned taro powder hydrogel flexible conductive sensor in wearable flexible materials.

[0017] For example, a strain sensor includes a long flexible sensor body, two sections of the flexible sensor body in the length direction are respectively covered with copper foil connecting strips, and the copper foil connecting strips are connected to the wires.

[0018] In a fourth aspect, the present invention also provides the use of the above-mentioned taro powder hydrogel flexible conductive sensor in conductive materials.

[0019] In a fifth aspect, the present invention also provides the application of the above-mentioned taro powder hydrogel flexible conductive sensor in smart screen touch screen materials.

[0020] Beneficial effects of the present invention:

[0021] (1) Compared with the existing pure taro powder aqueous solution, no matter it is frozen or heated, it cannot form a hydrogel. It can only be obtained in the presence of alkaline substances (such as sodium hydroxide) and chemical cross-linking agents (such as epichlorohydrin), after chemical reaction cross-linking and complex subsequent removal of alkaline substances and cross-linking agent residues. The present application uses the hydroxyl groups on the polyvinyl alcohol molecular chain, the hydroxyl groups in the tetraethylene glycol molecule, and the oxygen atoms in the potassium pyrophosphate molecular structure to form hydrogen bonds with the hydroxyl groups on the taro powder molecular chain, thereby accelerating the formation of taro hydrogel, shortening the preparation time, simplifying the preparation process, and significantly strengthening its mechanical properties. At the same time, the super hydrogen bond network formed between the five components of taro powder, polyvinyl alcohol, tetraethylene glycol, potassium pyrophosphate, and water is used to reduce the freezing point of the hydrogel and inhibit the evaporation of water in the hydrogel, thereby significantly improving the antifreeze ability and anti-drying ability of the taro-based hydrogel.

[0022] (2) The huge supramolecular interaction of the taro powder hydrogel flexible conductive sensor of the present invention enables the flexible conductive sensor to have strong mechanical properties, strong antifreeze ability, and strong anti-drying ability, overcoming the defects of traditional flexible sensors with good single performance but poor other performances, and realizing the effective integration of multiple advantages. The flexible conductive sensor of the present invention can carry a weight of 75Kg without being broken, and the flexible conductive sensor of the film can be punched or cut on the side of the film without being damaged under 500% strain stretching, and has strong mechanical properties. At the same time, the flexible conductive sensor of the present invention still has good elasticity, conductivity, strong antifreeze ability and can be used in low temperature and severe cold environment in an environment of minus 100°C. Moreover, the flexible conductive sensor of the present invention still has good elasticity, toughness, and conductivity after being placed at room temperature for 9 months, can be used for a long time in an open environment, has a prolonged service life, and has strong anti-drying ability. In addition, the flexible conductive sensor of the present invention also has good cell compatibility.

[0023] (3) The preparation process of the present invention is simple and green, and can be used for wearable flexible materials, conductive materials, smart screen touch screen materials, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flexibility test diagram of the flexible sensor prepared in Example 1 of the present invention after being frozen at -75°C for 8 hours;

[0025] Figure 2 This is a test graph of the conductivity of the flexible sensor prepared in Example 1 of the present invention after being frozen at -75°C for 8 hours;

[0026] Figure 3 This is a flexibility test diagram of the flexible sensor prepared in Example 2 of the present invention after being placed in an open environment for 60 days;

[0027] Figure 4This is a test chart of the conductivity of the flexible sensor prepared in Example 2 of the present invention after being placed in an open environment for 60 days. DETAILED DESCRIPTION

[0028] To make the present invention easier to understand, the present invention is further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the professional terms used below are consistent with the meanings understood by professional and technical personnel in the field; unless otherwise specified, the raw materials and reagents involved in this article can be purchased from the market or prepared by known methods.

[0029] Example 1

[0030] A method for preparing a taro powder hydrogel (taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate water-resistant type) flexible conductive sensor comprises the following steps:

[0031] (1) According to the weight percentage (based on the weight of water), the concentration of taro powder is 5%, the concentration of polyvinyl alcohol is 10%, the concentration of tetraethylene glycol is 50%, and the concentration of potassium pyrophosphate is 15%. Weigh 2.5g of taro powder, 5g of polyvinyl alcohol, 25g of tetraethylene glycol, and 7.5g of potassium pyrophosphate, add 50g of deionized water, and stir at 90°C (speed of 1500r / min) for 4h to obtain a taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate mixed solution for standby use;

[0032] (2) pouring the taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate mixed solution prepared in step (1) into a standard dumbbell-shaped mold at room temperature;

[0033] (3) placing the mold containing the mixed solution in step (2) at room temperature for 12 hours to obtain a finished flexible sensor.

[0034] It was determined that the finished flexible sensor obtained in this embodiment had a stress of 23 MPa, a strain of 650%, a Young's modulus of 0.4 MPa, and an electrical conductivity of 18 S / m, as shown in Table 1, and had good flexibility.

[0035] Example 2

[0036] A method for preparing a taro powder hydrogel (taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate water-resistant type) flexible conductive sensor comprises the following steps:

[0037] (1) According to the weight percentage (based on the weight of water), the concentration of taro powder is 10%, the concentration of polyvinyl alcohol is 5%, the concentration of tetraethylene glycol is 50%, and the concentration of potassium pyrophosphate is 15%. Weigh 5g of taro powder, 2.5g of polyvinyl alcohol, 50g of tetraethylene glycol, and 7.5g of potassium pyrophosphate, add 50g of deionized water, and stir at 95°C for 4h to obtain a taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate mixed solution for standby use;

[0038] (2) pouring the taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate mixed solution prepared in step (1) into a standard dumbbell-shaped mold at room temperature;

[0039] (3) placing the mold containing the mixed solution in step (2) at room temperature for 48 hours to obtain a finished flexible sensor.

[0040] It was determined that the finished flexible sensor obtained in this embodiment had a stress of 21 MPa, a strain of 600%, a Young's modulus of 0.3 MPa, and a conductivity of 20 S / m, as shown in Table 1, and had good flexibility.

[0041] Example 3

[0042] A method for preparing a taro powder hydrogel (taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate water-resistant type) flexible conductive sensor comprises the following steps:

[0043] (1) According to the weight percentage (based on the weight of water), the concentration of taro powder is 5%, the concentration of polyvinyl alcohol is 10%, the concentration of tetraethylene glycol is 45%, and the concentration of potassium pyrophosphate is 15%. Weigh 2.5g of taro powder, 5g of polyvinyl alcohol, 45g of tetraethylene glycol, and 7.5g of potassium pyrophosphate, add 55g of deionized water, and stir at 95°C for 4h to obtain a taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate mixed solution for standby use;

[0044] (2) pouring the taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate mixed solution prepared in step (1) into a standard dumbbell-shaped mold at room temperature;

[0045] (3) placing the mold containing the mixed solution in step (2) at room temperature for 24 hours to obtain a finished flexible sensor.

[0046] It was determined that the finished flexible sensor obtained in this embodiment had a stress of 24 MPa, a strain of 670%, a Young's modulus of 0.4 MPa, and a conductivity of 20 S / m, as shown in Table 1, and had good flexibility.

[0047] Example 4

[0048] A method for preparing a taro powder hydrogel (taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate water-resistant type) flexible conductive sensor comprises the following steps:

[0049] (1) According to the weight percentage (measured by the mass of water), the concentration of taro powder is 5%, the concentration of polyvinyl alcohol is 10%, the concentration of tetraethylene glycol is 50%, and the concentration of potassium pyrophosphate is 15%. Weigh 2.5 g of taro powder, 5 g of polyvinyl alcohol, 50 g of tetraethylene glycol, and 7.5 g of potassium pyrophosphate, add 50 g of deionized water, and stir at 90° C. for 4 h to obtain a taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate mixed solution for later use;

[0050] (2) at room temperature, pour the taro powder / tetraethylene glycol / polyvinyl alcohol / potassium pyrophosphate mixed solution prepared in step (1) into a mold with a diameter of 2 cm and a length of 6 cm;

[0051] (3) placing the mold containing the mixed solution in step (2) at room temperature for 48 hours to obtain a finished flexible sensor.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 1 is that polyvinyl alcohol is replaced by polyacrylamide, and the other steps and parameters are the same as those in Example 1.

[0054] It was determined that the finished flexible sensor obtained in this comparative example had a stress of 0.1 MPa, a strain of 400%, a Young's modulus of 0.3 MPa, and an electrical conductivity of 18 S / m, as shown in Table 1, and had good flexibility.

[0055] Comparative Example 2

[0056] The difference between this comparative example and Example 1 is that tetraethylene glycol is replaced by DMSO, and the other steps and parameters are the same as those in Example 1.

[0057] It was determined that the finished flexible sensor obtained in this embodiment had a stress of 1 MPa, a strain of 200%, a Young's modulus of 0.35 MPa, and an electrical conductivity of 18 S / m, as shown in Table 1, and had good flexibility.

[0058] Comparative Example 3

[0059] The difference between this comparative example and Example 1 is that potassium pyrophosphate is replaced by sodium glycine, and the other steps and parameters are the same as those in Example 1.

[0060] It has been determined that the finished flexible sensor produced in this embodiment cannot bear a weight of 75 kg.

[0061] Performance testing and result analysis

[0062] The stress, strain, Young's modulus and conductivity properties of the finished flexible sensors prepared in Examples 1 to 3 and Comparative Examples 1 to 2 of the present application are shown in Table 1 below.

[0063] Table 1:

[0064] Stress / MPa strain / % Young's modulus / MPa Conductivity / S / m Example 1 23 650 0.4 18 Example 2 21 600 0.3 20 Example 3 24 670 0.4 20 Comparative Example 1 0.1 400 0.3 18 Comparative Example 2 1 200 0.35 18

[0065] (1) Strong mechanical properties test

[0066] The flexible sensor prepared in Example 4 of the present invention was used to conduct a mechanical property test. The flexible sensor prepared in Example 4 was placed on a horizontal bar. A male student weighing 75 kg held the flexible sensor with his hands and his feet were suspended in the air. The flexible sensor was not broken. This proves that the flexible sensor has strong mechanical properties. The flexible sensors of Comparative Examples 1-3 could not bear a weight of 75 kg.

[0067] (2) Freeze resistance test

[0068] The flexible sensor prepared in Example 1 of the present invention was tested for its antifreeze performance. Figure 1 As shown in the figure: After being frozen at -75℃ for 8 hours, the flexible sensor has good flexibility and is not frozen solid. Moreover, when the flexible sensor is connected to a circuit at -75℃, the LED bulb still maintains a high brightness, as shown in the figure. Figure 2 It is shown in the figure. It proves that it has strong antifreeze ability and can be used in extremely low temperature environment.

[0069] (3) Anti-drying ability test

[0070] The flexible sensor prepared in Example 2 of the present invention was tested for its anti-drying performance. Figure 3 As shown in the figure: After being placed in an open environment for 60 days, the flexible sensor has good flexibility and has not dried into a solid. Moreover, after the flexible sensor is placed in an open environment for 60 days, it is connected to a circuit and the LED bulb still maintains a high brightness, as shown in the figure. Figure 4 It is shown that it has strong anti-drying ability and can be used for a long time in an open environment.

[0071] (4) Cytocompatibility test

[0072] The flexible sensor prepared in Example 1 of the present invention was subjected to a cell compatibility test: the MTT cytotoxicity test was used to analyze the effect of the flexible sensor on human renal epithelial 293T cells. The cell survival rate after 24 hours was as high as 99%, indicating strong cell compatibility.

[0073] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A taro flour hydrogel flexible conductive sensor, characterized in that: The raw materials of the taro powder hydrogel flexible conductive sensor are as follows, calculated by weight: 5-10 parts of taro powder, 5-10 parts of polyvinyl alcohol, 40-50 parts of tetraethylene glycol, 10-15 parts of potassium pyrophosphate and 100 parts of water.

2. The taro powder hydrogel flexible conductive sensor according to claim 1, characterized in that: The weight average molecular weight of the polyvinyl alcohol is 100,000-120,000, and the alcoholysis degree is 99.5%.

3. The method for preparing the taro powder hydrogel flexible conductive sensor according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1, 5-10 parts of taro powder, 5-10 parts of polyvinyl alcohol, 40-50 parts of tetraethylene glycol, 10-15 parts of potassium pyrophosphate and 100 parts of water are mixed and dispersed, and then stirred at 90-100° C. for 1-4 hours to obtain a mixed solution; S2. Pour the mixed solution into a mold and place it at room temperature for 4 to 48 hours to obtain a finished flexible sensor.

4. The method for preparing the taro powder hydrogel flexible conductive sensor according to claim 3, characterized in that: The preparation method of the taro powder is: T1, according to the mass fraction, weigh 1 part of fresh taro that has been washed and peeled, 2 parts of water, put into a wall breaking machine, start the wall breaking machine 5-10 times, each time for 3-5 minutes, to obtain taro slurry; T2, filtering the taro slurry with a 200-mesh filter plug to collect the filtrate; then allowing the collected filtrate to settle to obtain wet taro powder; and freeze-drying the wet taro powder to obtain dry taro powder.

5. The method for preparing the taro powder hydrogel flexible conductive sensor according to claim 3, characterized in that: In step S1, the stirring speed is 1000-1800 r / min.

6. The method for preparing the taro powder hydrogel flexible conductive sensor according to claim 3, characterized in that: In step S2, the mold is any one of a standard dumbbell-shaped mold and a plastic tube mold.

7. The method for preparing the taro powder hydrogel flexible conductive sensor according to claim 6, characterized in that: The inner diameter of the plastic tube mold is 2 cm and the length is 4 to 6 cm.

8. Use of the taro powder hydrogel flexible conductive sensor according to any one of claims 1 to 2 or the taro powder hydrogel flexible conductive sensor prepared by the preparation method according to any one of claims 3 to 7 in wearable flexible materials.

9. Use of the taro powder hydrogel flexible conductive sensor according to any one of claims 1 to 2 or the taro powder hydrogel flexible conductive sensor prepared by the preparation method according to any one of claims 3 to 7 in conductive materials.

10. Application of the taro powder hydrogel flexible conductive sensor according to any one of claims 1 to 2 or the taro powder hydrogel flexible conductive sensor prepared by the preparation method according to any one of claims 3 to 7 in smart screen touch screen materials.

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