Bionic conductive organic hydrogel, preparation method and application of bionic conductive organic hydrogel in aspects of multiple sensing and danger early warning

Abstract

The invention provides bionic conductive organic hydrogel, a preparation method and application of the bionic conductive organic hydrogel in the aspects of multiple sensing and danger early warning, and the multi-mode sensing organic hydrogel provided by the invention is designed to be prepared by integrating gelatin, laponite and lithium chloride in a copolymer network of a glycerol / water binary solvent. The designed organic hydrogel has components, structures and moduli similar to those of skin, as well as good mechanical properties, electrical conductivity and excellent environmental tolerance. The organic hydrogel can be used as a somatosensory system of electronic skin and simulated skin to realize multi-modal sensing of strain, pressure, temperature and humidity. The electronic skin can be combined with a designed data recognition and analysis system, physiological and motion states of the infant are monitored on a mobile phone, and an alarm can be given out in real time under abnormal dangerous conditions, such as chest compression suffocation, fever and plenty of sweating. The bionic biological material opens up a way for the next generation of wearable electronic skin for human physiological monitoring and danger alarm.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a bionic conductive organic hydrogel, a preparation method and applications thereof in multiple sensing and danger warning. Background Art

[0002] In recent years, with the rapid development of artificial intelligence, electronic skin has gradually come into the public eye. Electronic skin has similar properties to human skin, as well as excellent stretchability, resilience and perception ability, and is often used in soft robots, medical monitoring and danger warning. Human skin not only protects body tissues, but is also responsible for sensing and sensing external stimuli. The skin's perception system is a complex and delicate structure, which consists of tactile receptors, pain receptors, temperature receptors and pressure receptors. These receptors work together to enable the body to detect a variety of external stimuli in a timely manner and respond quickly. Recently, hydrogel materials have attracted widespread attention from scientific researchers, and have shown significant application prospects in many fields such as biomedicine, flexible electronics, 3D printing, and drug delivery. However, in order to expand the application field of traditional hydrogels, conductive fillers are added to hydrogels to give them excellent electrical properties, thereby expanding their application fields. Therefore, it is very necessary to try to use conductive hydrogels as electronic skins to achieve multiple sensing of simulated skin. In conventional hydrogel-based electronic skins, there are problems of water molecule evaporation or crystallization, which limits its scope of application. By imitating the water retention mechanism of the epidermis and dermis in the skin, a method of introducing a large number of hydrogen bonds between polyols and water molecules is introduced to avoid the evaporation and crystallization of water molecules in the hydrogel network. Therefore, the organic hydrogel constructed using a binary solvent composed of polyols and water has good environmental tolerance and a wide working range, making it useful as an electronic skin for multimodal sensing in complex environments.

[0003] In this study, we developed a conductive organic hydrogel inspired by the skin sensing system as an electronic skin that can achieve multimodal sensing of temperature, humidity, strain, and pressure. The organic hydrogel network is made of acrylamide (AM), acrylic acid (AA), gelatin, lithium chloride (LiCl), laponite, polyethylene glycol diacrylate (PEGDA), and ammonium persulfate (APS) by heating copolymerization in a binary solvent of glycerol and water. The organic hydrogel has a skin-like composition and modulus, and has good mechanical properties, adhesion, conductivity, and temperature sensitivity. In addition, the introduction of a binary solvent into the gel adds abundant hydrogen bonds to the covalent network, giving it excellent elasticity and outstanding environmental resistance. Since the electronic skin can accurately monitor the baby's limb movements, body temperature, and humidity changes, combined with the analysis system, the baby's physiological status and danger warnings can be displayed on the smartphone. Summary of the invention

[0004] The purpose of the present invention is to provide a bionic conductive organic hydrogel, a preparation method and its application in multiple sensing and danger warning.

[0005] The method first prepares a binary solvent of glycerol and water, then adds gelatin and lithium algae to heat and mix evenly, then adds acrylamide (AM), acrylic acid (AA), and lithium chloride (LiCl) in turn and mixes evenly, adds reactants polyethylene glycol diacrylate (PEGDA) and ammonium persulfate (APS) and stirs to react to obtain a mixed reaction solution. Then the mixed reaction solution is poured into a PTFE mold, N2 is passed through to eliminate bubbles and sealed, and after heating and polymerization at 60°C, it is cooled to room temperature. It is placed in a refrigerator at 0°C and refrigerated for 12 hours to finally obtain this conductive organic hydrogel. It can imitate the function of the skin and has the advantages of stable mechanical properties, conductivity, adhesion, and environmental tolerance in complex environments. As an electronic skin device, it realizes accurate and stable multi-mode sensing of strain, temperature, and humidity, and can provide real-time early warning of dangers to infants and young children by identifying the intensity of the sensing signal.

[0006] The method for preparing the conductive organic hydrogel of the present invention comprises the following specific steps:

[0007] (1) First, 1.5-3 mL of glycerol and 4.5-6 mL of deionized water were mixed in proportion. The mixed liquid was placed on a magnetic stirrer, the stirring speed was adjusted to 1200 rpm, and the stirring was continued for 10-15 minutes to obtain a binary solvent with a concentration of 20-30 wt%. During the mixing process, a digital viscometer was used to continuously monitor the viscosity change of the solution to ensure that its viscosity was moderate and met the experimental requirements. Then 30-40 mg of Laponite powder was added to the binary solvent and treated with an ultrasonic oscillator at a frequency of 20 kHz and a power of 50%. After the ultrasonic treatment was completed, the solution was transferred to a 35±0.5℃ constant temperature water bath and stirred vigorously for reaction. The stirring speed should be maintained at 1200 rpm for 2-3 hours to ensure that the Laponite powder was completely reacted and dispersed in the solution to form a uniform transparent mixed solution A. During the stirring process, a laser particle size analyzer was used to monitor the change in particle size in the solution to ensure the best dispersion effect.

[0008] (2) Add 60-100 mg of gelatin powder to the mixed solution A. The gelatin powder should be dried in a drying oven before addition to ensure its solubility and stability in the reaction. To ensure the full dissolution of gelatin, use ultrasonic treatment to evenly disperse its particles. Subsequently, adjust the pH value to 6.5 and react in a 60-70°C water bath for 1-2 hours. During this process, use a pH meter to monitor the pH change of the solution in real time to ensure that the reaction environment is stable and meets the requirements. Then slowly and repeatedly add 75-300 mg of LiCl powder and react with ultrasonic oscillation for 1 hour.

[0009] (3) Then, 0.5-1.5 g of AM was slowly added to the mixed solution, while stirring vigorously at 1500 rpm. 0.5-1.5 mL of AA was slowly added dropwise and kept stirring for 1 h. 10-25 μL of PEGDA and 30-70 mg of initiator APS were added and stirred at 45 °C for 4-6 h to obtain a uniform mixed solution B. During the reaction, the viscosity of the solution was monitored in real time using an online viscometer to ensure that it was within the required range. Then the mixed solution B was poured into a PTFE mold. In order to avoid bubbles during the injection process, ultrasonic treatment was used for 10 minutes at a frequency of 40 kHz to ensure that the bubbles in the solution could be completely eliminated. The mold was then placed in a sealed environment and passed through high-purity nitrogen. The sealed mold was placed at 60 °C for thermal polymerization for 2-2.5 hours. After the reaction was completed, the mold was placed at room temperature for natural cooling. Finally, the mold was transferred to a low-temperature refrigerator at 0 °C for a refrigeration reaction time of 12-14 hours to finally obtain a conductive organic hydrogel.

[0010] The present invention has the following advantages: 1. The main raw material sources of the synthesized conductive organic hydrogel are wide, which is conducive to the commercialization of the product; 2. The preparation process of the conductive organic hydrogel is simple, and multiple functions of mimicking the skin are obtained; 3. The prepared conductive organic hydrogel has excellent mechanical properties, stable mechanical properties, conductivity, and adhesion in complex environments; 4. The conductive organic hydrogel is endowed with good environmental tolerance by introducing a binary solvent; 5. The conductive organic hydrogel can be applied as electronic skin to achieve multi-mode sensing of strain, temperature, and humidity at the same time; 6. The conductive organic hydrogel has high sensitivity and stability as an electronic skin; 7. The electronic skin is combined with the designed early warning system to realize real-time early warning of dangerous situations such as abnormal body temperature, sweating, and compression of infants and young children by identifying the intensity of the sensor signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 : Figure 1 The phase change diagram of the conductive organic hydrogel of Example 1. It can be seen from the reagent bottle tilting experiment that the organic hydrogel is obtained by heating the monomer mixed solution for polymerization and low temperature refrigeration reaction.

[0012] Figure 2 : Figure 2 The electron microscope photo and element distribution of the conductive organic hydrogel of Example 1. As can be seen from the figure, the conductive organic hydrogel has a loose and porous structure.

[0013] Figure 3 : Figure 3 The conductive organic hydrogel of Example 1 was placed at the elbow as electronic skin to monitor strain.

[0014] Figure 4 : Figure 4 The conductive organic hydrogel of Example 2 is placed on the forehead as electronic skin to monitor temperature. DETAILED DESCRIPTION

[0015] Embodiment 1:

[0016] (1) First, 2.3 mL of glycerol and 5.2 mL of deionized water were mixed in proportion. The mixed liquid was placed on a magnetic stirrer, the stirring speed was adjusted to 1200 rpm, and the stirring was continued for 12 minutes to obtain a binary solvent with a concentration of 30 wt%. During the mixing process, a digital viscometer was used to continuously monitor the viscosity change of the solution to ensure that its viscosity was moderate and met the experimental requirements. Then 35 mg of Laponite powder was added to the binary solvent and treated with an ultrasonic oscillator for 30 minutes at a frequency of 20 kHz and a power of 50%. After the ultrasonic treatment was completed, the solution was transferred to a 35 ± 0.5 ° C constant temperature water bath and stirred vigorously for reaction. The stirring speed should be maintained at 1200 rpm for 3 hours to ensure that the Laponite powder was completely reacted and dispersed in the solution to form a uniform transparent mixed solution A. During the stirring process, a laser particle size analyzer was used to monitor the changes in particle size in the solution to ensure the best dispersion effect.

[0017] (2) Add 90 mg of gelatin powder to the mixed solution A. The gelatin powder should be dehydrated in a drying oven before addition to ensure its solubility and stability in the reaction. To ensure the full dissolution of gelatin, use ultrasonic treatment to evenly disperse its particles. Subsequently, adjust the pH value to 6.5 and react in a 60°C water bath for 1 hour. During this process, use a pH meter to monitor the pH changes of the solution in real time to ensure that the reaction environment is stable and meets the requirements. Then slowly and repeatedly add 230 mg of LiCl powder and react with ultrasonic oscillation for 1 hour.

[0018] (3) Then, 1.1 g of AM was slowly added to the mixed solution while stirring vigorously at 1500 rpm. 1.1 mL of AA was slowly added dropwise and kept stirring for 1 h. 22 μL of PEGDA and 44 mg of initiator APS were added and stirred at 45 °C for 4 h to obtain a uniform mixed solution B. During the reaction, the viscosity of the solution was monitored in real time using an online viscometer to ensure that it was within the required range. The mixed reaction solution B was then poured into a PTFE mold. In order to avoid bubbles during the injection process, ultrasonic treatment was used for 10 minutes at a frequency of 40 kHz to ensure that the bubbles in the solution could be completely eliminated. The mold was then placed in a sealed environment and passed through high-purity nitrogen. The sealed mold was placed at 60 °C for thermal polymerization for 2 hours. After the reaction was completed, the mold was placed at room temperature for natural cooling. Finally, the mold was transferred to a low-temperature refrigerator at 0 °C for a refrigerated reaction time of 14 hours to finally obtain a conductive organic hydrogel.

[0019] Embodiment 2:

[0020] (1) First, 3 mL of glycerol and 6 mL of deionized water were mixed in proportion. The mixed liquid was placed on a magnetic stirrer, the stirring speed was adjusted to 1200 rpm, and the stirring was continued for 15 minutes to obtain a binary solvent with a concentration of 20 wt%. During the mixing process, a digital viscometer was used to continuously monitor the viscosity change of the solution to ensure that its viscosity was moderate and met the experimental requirements. Then 40 mg of Laponite powder was added to the binary solvent and treated with an ultrasonic oscillator for 20 minutes at a frequency of 20 kHz and a power of 50%. After the ultrasonic treatment was completed, the solution was transferred to a 35 ± 0.5 ° C constant temperature water bath and stirred vigorously for reaction. The stirring speed should be maintained at 1200 rpm for 2.5 hours to ensure that the Laponite powder was completely reacted and dispersed in the solution to form a uniform transparent mixed solution A. During the stirring process, a laser particle size analyzer was used to monitor the changes in particle size in the solution to ensure the best dispersion effect.

[0021] (2) Add 80 mg of gelatin powder to the mixed solution A. The gelatin powder should be dehydrated in a drying oven before addition to ensure its solubility and stability in the reaction. To ensure the full dissolution of gelatin, ultrasonic treatment is used to evenly disperse the particles. Subsequently, the pH value is adjusted to 6.5 and reacted in a 70°C water bath for 2 hours. During this process, a pH meter is used to monitor the pH changes of the solution in real time to ensure that the reaction environment is stable and meets the requirements. Then 200 mg of LiCl powder is slowly and repeatedly added and ultrasonic oscillation is reacted for 1 hour.

[0022] (3) Then, 0.8 g of AM was slowly added to the mixed solution while stirring vigorously at 1500 rpm. 0.8 mL of AA was slowly added dropwise and kept stirring for 1 h. 16 μL of PEGDA and 48 mg of initiator APS were added and stirred at 45 °C for 6 h to obtain a uniform mixed solution B. During the reaction, the viscosity of the solution was monitored in real time using an online viscometer to ensure that it was within the required range. The mixed reaction solution B was then poured into a PTFE mold. In order to avoid bubbles during the injection process, ultrasonic treatment was used for 10 minutes at a frequency of 40 kHz to ensure that the bubbles in the solution could be completely eliminated. The mold was then placed in a sealed environment and passed through high-purity nitrogen. The sealed mold was placed at 60 °C for thermal polymerization for 2.5 hours. After the reaction was completed, the mold was placed at room temperature for natural cooling. Finally, the mold was transferred to a low-temperature refrigerator at 0 °C for a refrigerated reaction time of 12 hours to finally obtain a conductive organic hydrogel.

Claims

1. A method for preparing a bionic conductive organic hydrogel, characterized in that: The specific steps are as follows: (1) First, 1.5-3 mL of glycerol and 4.5-6 mL of deionized water are mixed in proportion; the mixed liquid is placed on a magnetic stirrer, the stirring speed is adjusted to 1200 rpm, and the stirring is continued for 10-15 minutes to obtain a binary solvent with a concentration of 20-30 wt%; then 30-40 mg of Laponite powder is added to the binary solvent and treated with an ultrasonic oscillator at a frequency of 20 kHz and a power controlled at 50%; after the ultrasonic treatment is completed, the solution is transferred to a 35±0.5°C constant temperature water bath and vigorously stirred for reaction. The stirring speed should be maintained at 1200 rpm for 2-3 hours to ensure that the Laponite powder is completely reacted and dispersed in the solution to form a uniform transparent mixed solution A; (2) Add 60-100 mg of gelatin powder to the mixed solution A. The gelatin powder should be dried in a drying oven before addition to ensure its solubility and stability in the reaction. To ensure that the gelatin is fully dissolved, ultrasonic treatment is used to uniformly disperse the particles. Subsequently, the pH value is adjusted to 6.5 and reacted in a water bath at 60-70° C. for 1-2 hours. During this process, a pH meter is used to monitor the pH value of the solution in real time to ensure that the reaction environment is stable and meets the requirements. Then, 75-300 mg of LiCl powder is slowly and repeatedly added and ultrasonic oscillation is used for reaction for 1 hour. (3) Then, 0.5-1.5 g of acrylamide AM was slowly added to the mixed solution, and the mixture was stirred vigorously at 1500 rpm; 0.5-1.5 mL of acrylic acid AA was slowly added dropwise, and the stirring was maintained for 1 h; 10-25 μL of polyethylene glycol diacrylate PEGDA and 30-70 mg of initiator ammonium persulfate APS were added and stirred at 45 ° C for 4-6 h to obtain a uniform mixed solution B; during the reaction, the viscosity of the solution was monitored in real time using an online viscometer to ensure that it was within the required range; then the mixed solution B was poured into a PTFE mold; ultrasonic treatment was performed for 10 minutes at a frequency of 40 kHz to ensure that the bubbles in the solution could be completely eliminated; then the mold was placed in a sealed environment and passed through high-purity nitrogen; the sealed mold was placed at 60 ° C for thermal polymerization for 2-2.5 hours; after the reaction was completed, the mold was placed at room temperature for natural cooling; finally, the mold was transferred to a low-temperature refrigerator at 0 ° C for a refrigeration reaction time of 12-14 hours to finally obtain a conductive organic hydrogel.

2. A bionic conductive organic hydrogel prepared according to the preparation method according to claim 1.

3. The biomimetic conductive organic hydrogel according to claim 2, characterized in that: Conductive organic hydrogel has similar composition, structure and modulus to skin. It can maintain excellent mechanical properties, stable mechanical properties, conductivity, adhesion, and especially good environmental tolerance in complex environments. It can imitate the various functions of skin and is used in the preparation of conductive organic hydrogel electronic skin.

4. The bionic conductive organic hydrogel according to claim 2, characterized in that: Conductive organic hydrogel is used to prepare conductive organic hydrogel electronic skin with multi-modal sensing characteristics of strain, temperature and humidity.

5. The biomimetic conductive organic hydrogel according to claim 2, characterized in that: Conductive organic hydrogels can be made into wearable flexible sensors and integrated with sensor warning systems to identify and analyze dangerous conditions through sensor signal differences. They are used to prepare conductive organic hydrogel electronic skin that can detect and warn of dangerous conditions for infants and young children in real time. The dangerous conditions include one or more of abnormal body temperature, sweating, and compression.

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