Preparation method of gelatin-based liquid metal wearable sensing material

Abstract

The application discloses a preparation method of gelatin-based liquid metal wearable sensing material, and specifically comprises the following steps: firstly, dispersing liquid metal in a monosaccharide solution through ultrasonic, and obtaining liquid metal nanodroplets after centrifugal washing; continuously stirring gelatin under the condition of a water bath at 50 DEG C to obtain a light yellow translucent gelatin solution; mixing and stirring the liquid metal nanodroplets and the gelatin solution, and pouring into a mold to form a gelatin-based liquid metal hydrogel; and finally, soaking the gelatin-based liquid metal hydrogel in a polyol to obtain the gelatin-based liquid metal wearable sensing material. The gelatin-based liquid metal wearable sensing material prepared by the application can realize mechanical performance and ensure high conductivity, and is expected to be applied in the fields of human-computer interaction, wearable health monitoring and intelligent robots.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wearable sensing material preparation, and particularly relates to a preparation method of a gelatin-based liquid metal wearable sensing material. BACKGROUND

[0002] With the development of the increasingly diversified and complex new generation of electronic devices, sensing materials are developing in the direction of intelligence, flexibility, high integration and green. Since wearable sensing materials have good flexibility and high sensing sensitivity, they can monitor the large-scale activities and weak physiological signals of the human body in real time, and thus have important application prospects in the fields of biomedicine, flexible electronics and soft robots.

[0003] In order to meet the needs of sensing materials being attached to the human skin for a long time, natural renewable polymer materials such as gelatin, cellulose and starch are more suitable for the development of flexible wearable electronic devices than traditional synthetic materials such as polyacrylamide, polyvinyl chloride and rubber. Gelatin is a product extracted from the connective tissue of animal skin, skeleton, fascia and muscle after partial hydrolysis, and the primary structure and chemical composition remain basically unchanged, and has excellent biocompatibility. However, the mechanical properties of this hydrophilic colloid are poor and the functions are relatively single. By using the solvent replacement induced toughening strategy, the mechanical properties are effectively improved by directly soaking in polyhydric alcohol, and the introduction of nano-conductive fillers endows the gelatin-based hydrogel with good electrical conductivity. There is a problem of mechanical property mismatch between traditional conductive rigid fillers and flexible hydrogel matrix. Under excessive stretching, compression and other large deformations, stress concentration effect will occur, which will further cause damage to the colloid and even break, and will have an adverse effect on the performance and service life. As a new type of flexible electronic conductive filler, liquid metal has the advantages of non-toxicity, high electrical conductivity, high thermal conductivity, high surface tension, etc. And by properly adjusting the proportion of gallium, indium and tin, the melting point can be controlled below room temperature, so as to have excellent ductility and flowability when used as functional fillers, overcoming the stress concentration problem caused by rigid conductive fillers. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of a gelatin-based liquid metal wearable sensing material, which has not only good mechanical properties, but also self-repairing, high electrical conductivity and high sensing sensitivity.

[0005] The technical scheme adopted by the present application is a preparation method of a gelatin-based liquid metal wearable sensing material, which is specifically implemented according to the following steps:

[0006] Step 1, ultrasonically disperse the liquid metal in a monosaccharide solution, and after centrifugation and water washing, obtain liquid metal nanodroplets with uniform particle size;

[0007] Step 2, under the condition of a water bath at 50 DEG C, the gelatin is continuously stirred to obtain a light yellow translucent gelatin solution; the liquid metal nanodroplet is mixed with the gelatin solution and poured into a mold to form a gelatin-based liquid metal hydrogel;

[0008] Step 3, the gelatin-based liquid metal hydrogel is soaked in a polyol to obtain a gelatin-based liquid metal organic gel, which is a gelatin-based liquid metal wearable sensing material.

[0009] The gelatin-based liquid metal wearable sensing material of the application also has the characteristics that,

[0010] In step 1, the monosaccharide solution is obtained by mixing monosaccharide and water; the monosaccharide is any one or more of glucose, fructose and galactose; the concentration of the monosaccharide solution is 0.1-1 g / mL.

[0011] In step 1, the liquid metal is liquid gallium-indium alloy or liquid gallium-indium-tin alloy.

[0012] In step 1, the concentration of the liquid metal in the monosaccharide solution is 0.01-0.2 g / mL, and the ultrasonic time is 30-120 min.

[0013] In step 2, in the liquid metal nanodroplet, the mass percentage of gelatin is 5-40 wt%.

[0014] In step 3, the polyol is any one or more of ethylene glycol, glycerol and pentaerythritol.

[0015] In step 3, the soaking time is 2-24 hours, and the soaking temperature is 0-5 DEG C.

[0016] The gelatin-based liquid metal wearable sensing material of the application has the advantages that the preparation method of the gelatin-based liquid metal wearable sensing material of the application uses natural product gelatin as a reaction raw material, has the characteristics of abundant resources, low cost, renewable and green environmental protection, and is helpful to promote the high value-added utilization of biomass resources; the solvent replacement induced toughening strategy is simple and effective to improve the mechanical properties; at the same time, the introduction of liquid metal nanodroplets endows the gelatin-based hydrogel with good electrical conductivity and sensing performance, and the preparation process is simple and the reaction conditions are mild. The gelatin-based liquid metal wearable sensing material prepared by the application realizes mechanical properties while ensuring high electrical conductivity, and is expected to be applied in the fields of human-computer interaction, wearable health monitoring and intelligent robots. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The scanning electron microscope image of the gelatin-based liquid metal wearable sensing material of the application;

[0018] Figure 2 The stress-strain curve graph of the gelatin-based liquid metal wearable sensing material of the application before and after self-repairing;

[0019] Figure 3 This is a graph showing the relationship between strain and resistance change rate of the gelatin-based liquid metal wearable sensing material of the present invention.

[0020] Figure 4 This is a diagram illustrating the finger bending sensing effect of the gelatin-based liquid metal wearable sensing material of the present invention.

[0021] Figure 5 This is a response and recovery time diagram of the gelatin-based liquid metal wearable sensing material of the present invention. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0023] This invention discloses a method for preparing a gelatin-based liquid metal wearable sensing material, which is implemented according to the following steps:

[0024] Step 1: Disperse liquid metal ultrasonically in a monosaccharide solution, centrifuge and wash with water to obtain liquid metal nanodroplets with uniform particle size;

[0025] The monosaccharide solution is a mixture of monosaccharides and water; the monosaccharide is any one or more of glucose, fructose, and galactose; the concentration of the monosaccharide solution is 0.1–1 g / mL;

[0026] The liquid metal is either a liquid gallium-indium alloy or a liquid gallium-indium-tin alloy;

[0027] The concentration of liquid metal in the monosaccharide solution was 0.01–0.2 g / mL, and the sonication time was 30–120 min.

[0028] Step 2: Under a water bath at 50°C, gelatin is continuously stirred to obtain a pale yellow, translucent gelatin solution; liquid metal nanoparticles are mixed and stirred with the gelatin solution and poured into a mold to form a gelatin-based liquid metal hydrogel.

[0029] In liquid metal nanodroplets, the mass percentage of gelatin is 5–40 wt%.

[0030] Step 3: Immerse the gelatin-based liquid metal hydrogel in polyol to obtain gelatin-based liquid metal organic gel, which is the gelatin-based liquid metal wearable sensing material.

[0031] The polyol is any one or more of ethylene glycol, glycerol, and pentaerythritol;

[0032] Soaking time is 2 to 24 hours, and soaking temperature is 0 to 5℃;

[0033] The gelatin-based liquid metal wearable sensing material prepared by the method of this invention has self-healing properties, high biocompatibility, high sensing sensitivity (GF = 2.1-8.9) and fast response (10-50 ms).

[0034] Example 1

[0035] 10 mg of liquid gallium indium alloy (EGaIn) was ultrasonically dispersed in a glucose solution, ultrasonically treated in an ice bath for 60 min, and then centrifuged and washed with water to obtain liquid metal nanodroplets with uniform particle size. Gelatin was continuously stirred in a 50 °C water bath to obtain a pale yellow, translucent gelatin solution with a gelatin mass percentage of 25 wt%. The liquid metal nanodroplets were stirred with the gelatin solution, wherein the mass ratio of liquid metal to gelatin was 100, and then quickly poured into a mold to form a gelatin-based liquid metal hydrogel. The gelatin-based liquid metal hydrogel was soaked in ethylene glycol at 4 °C for 10 hours to obtain a gelatin-based liquid metal organic gel. Figure 1 Scanning electron microscopy revealed that liquid metal droplets exhibited excellent dispersibility and stability in gelatin-based liquid metal organogels. The gelatin-based liquid metal organogel was cut with a scalpel blade, as shown... Figure 2 As shown, a tensile testing machine was used to perform repair performance testing, achieving almost 100% of the mechanical properties of the original sample. The two ends of the sample were connected to a digital source meter via copper tape and wires to record the resistance changes. Figure 3 The resistance change rate is displayed under different strains, and the sensitivity can reach up to 4.4 as the deformation increases. Figure 4 The fact that it can be directly attached to the finger to monitor deformation in real time demonstrates its excellent sensing performance. Figure 5 The gelatin-based liquid metal organogel exhibits a response and recovery time of 50 ms under compressive force, indicating that the sensing material possesses rapid mechanical response and recovery capabilities, making it suitable for detecting human motion without significant delay. The resulting gelatin-based liquid metal wearable sensing material demonstrates self-healing properties, high biocompatibility, high sensing sensitivity, and rapid response.

[0036] Example 2

[0037] 200 mg of liquid gallium indium tin alloy (Galinstan) was ultrasonically dispersed in a fructose solution, ultrasonically treated in an ice bath for 120 min, and then centrifuged and washed with water to obtain liquid metal nanodroplets with uniform particle size. Gelatin was continuously stirred in a 50 °C water bath to obtain a pale yellow, semi-transparent gelatin solution with a mass percentage of 5 wt%. The liquid metal nanodroplets were stirred with the gelatin solution at a mass ratio of liquid metal to gelatin of 500, and then quickly poured into a mold to form a gelatin-based liquid metal hydrogel. The gelatin-based liquid metal hydrogel was soaked in glycerol at 0 °C for 24 hours to obtain a gelatin-based liquid metal organic gel, i.e., a gelatin-based liquid metal wearable sensing material.

[0038] Example 3

[0039] 100 mg of liquid gallium indium tin alloy (Galinstan) was ultrasonically dispersed in a galactose solution, ultrasonically treated in an ice bath for 30 min, and then centrifuged and washed with water to obtain liquid metal nanodroplets with uniform particle size. Gelatin was continuously stirred in a 50 °C water bath to obtain a pale yellow, translucent gelatin solution with a gelatin mass percentage of 40 wt%. The liquid metal nanodroplets were stirred with the gelatin solution, wherein the mass ratio of liquid metal to gelatin was 5, and then quickly poured into a mold to form a gelatin-based liquid metal hydrogel. The gelatin-based liquid metal hydrogel was soaked in pentaerythritol at 5 °C for 2 hours to obtain a gelatin-based liquid metal organic gel, namely, a gelatin-based liquid metal wearable sensing material.

[0040] Comparative Example 1

[0041] The specific implementation method differs from Example 1 only in that the mass percentage of gelatin is 4wt%. The prepared gelatin-based liquid metal organogel has poor mechanical properties and may not even be able to form a gel, making it easy to break under external force.

[0042] Comparative Example 2

[0043] The specific implementation method differs from Example 1 only in that no liquid metal nanodroplets are added. The gelatin-based liquid metal organic gel prepared has poor sensing performance, and the resistance change caused by the stretching or compression of the flexible liquid metal droplets disappears, resulting in decreased sensitivity.

[0044] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a gelatin-based liquid metal wearable sensing material, characterized in that, The specific steps are as follows: Step 1: Disperse liquid metal ultrasonically in a monosaccharide solution, centrifuge and wash with water to obtain liquid metal nanodroplets with uniform particle size; The monosaccharide solution is a mixture of monosaccharides and water; the monosaccharide is any one or more of glucose, fructose, and galactose; the concentration of the monosaccharide solution is 0.1~1g / mL; The concentration of liquid metal in the monosaccharide solution was 0.01~0.2 g / mL, and the sonication time was 30~120 min; Step 2: Under a water bath at 50°C, gelatin is continuously stirred to obtain a pale yellow, translucent gelatin solution; liquid metal nanoparticles are mixed and stirred with the gelatin solution and poured into a mold to form a gelatin-based liquid metal hydrogel. In liquid metal nanodroplets, the mass percentage of gelatin is 5-40 wt%. Step 3: Immerse the gelatin-based liquid metal hydrogel in polyol to obtain gelatin-based liquid metal organic gel, which is the gelatin-based liquid metal wearable sensing material. The gelatin-based liquid metal wearable sensing material prepared by the method has self-healing properties, high biocompatibility, high sensing sensitivity (GF=2.1~8.9) and fast response (10~50ms).

2. The method for preparing a gelatin-based liquid metal wearable sensing material according to claim 1, characterized in that, In step 1, the liquid metal is a liquid gallium-indium alloy or a liquid gallium-indium-tin alloy.

3. The method for preparing a gelatin-based liquid metal wearable sensing material according to claim 1, characterized in that, In step 3, the polyol is any one or more of ethylene glycol, glycerol, and pentaerythritol.

4. The method for preparing a gelatin-based liquid metal wearable sensing material according to claim 1, characterized in that, In step 3, the soaking time is 2 to 24 hours and the soaking temperature is 0 to 5°C.

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