A method for fabricating and applying a strain sensor based on ionic dough.

Abstract

This invention discloses a method for preparing and applying a strain sensor based on ionic dough. A eutectic solvent is prepared using choline chloride as a hydrogen bond acceptor and glycerol as a hydrogen bond donor. The eutectic solvent is further mixed with water in different proportions, and wheat flour and glutinous rice flour are added and stirred evenly. After proofing, steaming, and kneading, an ionic dough is prepared. The two ends of the dough are connected by wire extension, thus constructing a strain sensor based on the ionic dough. The ionic dough of this invention exhibits good conductivity (up to 3.7 mS / cm), self-healing properties (completely healed within 1 hour), antibacterial properties, and biodegradability. Furthermore, this ionic dough also has excellent antifreeze and water retention capabilities, making it suitable for harsh environments. It can be used to monitor the movement of different parts of the human body, demonstrating rapid response, high sensitivity, and good repeatability, showing promising application prospects in wearable devices.

Description

Technical Field

[0001] This invention belongs to the field of strain sensor technology, specifically relating to a strain sensor based on ionic dough that can be used for human motion monitoring. Background Technology

[0002] In recent years, flexible sensors have received increasing attention in fields such as electronic skin, soft robots, and human-computer interaction due to their advantages of high safety, good adaptability, and high efficiency (Adv. Funct. Mater. 2018, 28, 1802576; Small 2017, 13, 1601916; Nano Lett. 2019, 19, 1143). Various intelligent sensors used for human motion monitoring, vital sign monitoring, and sweat analysis have developed rapidly. Conductive ionogels are ideal materials for fabricating flexible sensors due to their excellent flexibility and tunable mechanical properties. However, existing conductive ionogels typically exhibit low ionic conductivity, poor environmental stability, and low strain sensitivity. Furthermore, conductive ionogels inevitably suffer mechanical damage under large external forces, and since they are mostly made of petroleum-based polymers, they not only involve high-cost manufacturing processes and resource consumption, but also cause serious environmental problems after damage or disposal. Next-generation “green” conductive ion gels, characterized by high biocompatibility, biodegradability, low cost, self-healing and recyclability, promise to mitigate these adverse effects, but are often limited by the choice of materials and preparation strategies.

[0003] Inspired by the chemistry of food, traditional foods are increasingly being integrated with cutting-edge scientific research, with many common foods attracting widespread attention in the construction of flexible sensors. For example, Wu et al. constructed an ionic skin device based on the traditional sweet "stir-fried candy" (Sci. China Mater. 2021, 64, 3059), a capacitive sensor based on chewing gum (ACS Appl. Mater. Interfaces 2021, 13, 6731), and a renewable and reconfigurable ionic skin sensor inspired by ramen noodles, constructed using edible dough (Adv. Funct. Mater. 2020, 30, 1908018). Similarly, Su et al. constructed a conductive, self-healing, and remodelable flexible electronic device using amylopectin, water, and salt (J. Mater. Chem. A. 2017, 5, 13138). These attempts greatly expand the selectivity of materials and are expected to provide new ideas for the selection of future wearable materials.

[0004] Deep eutectic solvents (DES) are mixtures composed of hydrogen bond donors and acceptors, and their composition can be expanded to include three or more components. Due to the strong hydrogen bond interactions between the hydrogen bond donors and acceptors, the melting point of the mixture is much lower than that of its individual components in their pure form (Chem. Commun. 2018, 54, 9579; J. Mol. Liq. 2016, 215, 98). Deep eutectic solvents not only retain similar physicochemical properties to traditional ionic liquids, but also possess advantages such as simple preparation, 100% atom utilization in the preparation process, environmental friendliness, biodegradability, and recyclability, attracting widespread attention in many fields.

[0005] Dough sculpting is a handicraft technique that uses glutinous rice flour, wheat flour, and glycerin as raw materials to make a cooked dough, which is then shaped into various specific images such as flowers, birds, fish, and insects. After thousands of years of inheritance, dough sculpting culture has become one of the important traditional cultures of China and is receiving increasing attention. Dough sculpted artworks are characterized by moisture resistance, beauty, ease of shaping, durability, and resistance to cracking, but often lack good electrical conductivity. This invention, based on the traditional dough sculpting process, introduces a eutectic solvent composed of choline chloride and glycerin into the cooked dough, resulting in an ionic dough with conductive, reshapeable, self-healing, freeze-thaw resistant, water-retaining, antibacterial, and biodegradable properties. The unique properties of this ionic dough, along with the environmentally friendly nature of flour itself, make its application in wearable sensing devices possible. Summary of the Invention

[0006] One objective of this invention is to provide a method for preparing a strain sensor based on ionic dough. This invention uses a eutectic solvent, flour, and water as raw materials to prepare ionic dough. The ionic dough prepared by this invention exhibits good conductivity, freeze resistance, water retention, self-healing properties, antibacterial properties, and biodegradability, demonstrating excellent sensitivity and sensing capabilities when monitoring human movement.

[0007] The second objective of this invention is to provide the above-mentioned strain sensor based on ionic dough.

[0008] A third objective of this invention is to provide the application of the aforementioned strain sensor based on ionic dough in human motion monitoring. The monitoring of human motion signals includes, but is not limited to, movements such as coughing, swallowing, speaking, walking, running, knee bending, and finger, wrist, and elbow movements.

[0009] The technical solution is as follows:

[0010] Step 1: Preparation of eutectic solvent:

[0011] Mix hydrogen bond acceptors and hydrogen bond donors in a certain proportion, heat and stir until the solution is transparent and homogeneous, then remove and cool to room temperature for later use.

[0012] Step 2: Preparing ionic dough:

[0013] Mix the eutectic solvent obtained in step 1 with water in different mass ratios until uniform. Add wheat flour and glutinous rice flour and stir into a uniform, thick paste. Seal with plastic wrap and let it rest at room temperature for 10-12 hours. Then steam and knead to obtain ionic dough.

[0014] Step 3: Sensor fabrication:

[0015] By connecting the two ends of the ionic dough with wire extension, a strain sensor based on this ionic dough is constructed.

[0016] Step 4: Place the ionic dough firmly against the joints of the human body, turn on the Keithley 2450 digital source meter, set the instrument parameters, and regularly move the various joints of the human body: fingers, wrists, elbows, knees, and throat, and obtain the curves from the sensor screen.

[0017] Preferably, in step 1, the hydrogen bond acceptor and hydrogen bond donor of the eutectic solvent are choline chloride and glycerol, respectively, in a molar ratio of 1:2.

[0018] Preferably, in step 2, the mass ratio of the eutectic solvent to water is 1:4 to 4:1; the mass ratio of wheat flour to glutinous rice flour is 1:1 to 3:1; and the total mass ratio of the eutectic solvent and water to the total mass ratio of wheat flour and glutinous rice flour is 1:1 to 2:1.

[0019] Preferably, the heating temperature of the hydrogen bond acceptor and hydrogen bond donor in step 1 is 60°C to 120°C.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] Firstly, this invention utilizes traditional foods to prepare smart sensors. Dough is a viscoelastic material. During kneading, a small number of covalently cross-linked disulfide bonds are formed in the gluten. Intramolecular and intermolecular hydrogen bonds are also formed between starch and gluten, promoting the development of the dough's elastic network. In addition, the physical cross-linking of hydrogen bonds between amylopectin and water molecules endows the ionic dough with good self-healing and remodeling properties.

[0022] Secondly, this invention utilizes a eutectic solvent mixed with water to prepare ionic dough. The conductive component of the dough mainly consists of [Ch] from choline chloride. + ] and [Cl - The introduction of water molecules can effectively regulate the properties of the solvent, reduce the viscosity of the fluid, and increase the mobility of ions, thereby achieving its high conductivity.

[0023] Thirdly, this invention selects choline chloride and glycerol as hydrogen bond acceptors and hydrogen bond donors, respectively. The interaction between the two generates hydrogen bonds, resulting in a lower freezing point of the eutectic solvent and giving the ionic dough antifreeze properties. At the same time, the hydroxyl groups in the system can compete with water molecules for hydrogen bonds, inhibiting water evaporation and giving the ionic dough water retention properties. Choline cations can disrupt the integrity of bacterial cell membranes, giving the ionic dough antibacterial properties and enabling it to be stored for a long time.

[0024] Fourthly, the ionic dough prepared by this invention is derived from natural materials and can be completely degraded within 30 days when buried in natural soil, without causing any burden on the environment.

[0025] Fifthly, the flexible sensor based on ionic dough involved in this invention has a simple and easy preparation process, low cost and green environmental protection, and can meet the requirements of large-scale low-energy consumption preparation, and has great market application value.

[0026] Sixth: The intelligent sensor based on ionic dough provided by this invention exhibits excellent stability, safety, accuracy and efficiency in human motion monitoring applications, and is expected to become a new generation of wearable flexible electronic products. Attached Figure Description

[0027] Figure 1 : The chemical structural formula of the eutectic solvent obtained by the reaction of choline chloride, a hydrogen bond acceptor, and glycerol, a hydrogen bond donor.

[0028] Figure 2 Fourier transform infrared (FT-IR) spectra of eutectic solvents, ionic dough, ordinary dough, and wheat flour.

[0029] Figure 3 : Differential scanning calorimetry (DSC) plots of ionic dough with different eutectic solvent / water mass ratios.

[0030] Figure 4 : This is a graph showing the mass change of ionic dough and regular dough after 24 days at 20°C and 50% relative humidity.

[0031] Figure 5 : Graph showing the optical density (OD) value of ionic dough for antibacterial (Staphylococcus aureus) activity.

[0032] Figure 6 : Conductivity diagram of ionic dough with different eutectic solvent / water mass ratios.

[0033] Figure 7 : represents the real-time resistance change rate of an ionic dough-based strain sensor when the tensile strain is 0% to 150%.

[0034] Figure 8 : This is a sensing curve of an ionic dough-based strain sensor attached to the elbow joint. Detailed Implementation

[0035] The present invention will be further described below with reference to specific embodiments.

[0036] Example 1

[0037] Choline chloride and glycerol were mixed in a molar ratio of 1:2 and heated and stirred at 100°C to obtain a clear and transparent eutectic solvent. The mixture was then cooled to room temperature. 30g of water and 50g of the eutectic solvent were mixed evenly and added to 40g of wheat flour and 20g of glutinous rice flour. The mixture was stirred into a smooth, thick paste. The paste was sealed with plastic wrap and left to rest in a non-ventilated place for 12 hours to allow it to rise. It was then steamed for 40 minutes. After steaming, the dough was removed and kneaded to obtain an ionic dough.

[0038] Example 2

[0039] Betaine and glycerol were mixed in a molar ratio of 1:2 and heated and stirred at 100°C to obtain a clear and transparent eutectic solvent. The mixture was then cooled to room temperature. 30g of water and 50g of the eutectic solvent were mixed evenly and added to 40g of wheat flour and 20g of glutinous rice flour. The mixture was stirred into a smooth, thick paste. The paste was sealed with plastic wrap and left to rest in a non-ventilated place for 12 hours to allow it to rise. It was then steamed for 40 minutes. After steaming, the dough was removed and kneaded to obtain an ionic dough.

[0040] Example 3

[0041] (1) Mix choline chloride and glycerol in a molar ratio of 1:2, heat and stir to obtain a clear and transparent eutectic solvent, and place it at room temperature.

[0042] (2) Mix 53.5g water and 26.5g eutectic solvent evenly, add 40g wheat flour and 20g glutinous rice flour, stir into a uniform and thick paste, seal with plastic wrap, let stand in a non-ventilated place for 12 hours to let the dough rise, steam for 40 minutes, take it out and knead it after steaming to get ionic dough;

[0043] (3) Repeat the steps in (1) of Example 3, mix 40g water and 40g eutectic solvent evenly, add 40g wheat flour and 20g glutinous rice flour, stir into a uniform and thick paste, seal with plastic wrap, let stand in a non-ventilated place for 12 hours to let the dough rise, steam for 40 minutes, take it out and knead it after steaming to obtain ionic dough.

[0044] (4) Repeat the steps in (1) of Example 3, mix 30g water and 50g eutectic solvent evenly, add 40g wheat flour and 20g glutinous rice flour, stir into a uniform and thick paste, seal with plastic wrap, let stand in a non-ventilated place for 12 hours to let the dough rise, steam for 40 minutes, take it out and knead it after steaming to obtain ionic dough.

[0045] Figure 6 The conductivity graphs of ionic doughs with different eutectic solvent contents prepared in this embodiment are shown. It can be seen that when the ratio of eutectic solvent to water is 1:1, the conductivity of the ionic dough is higher.

[0046] Example 4

[0047] Choline chloride and glycerol were mixed in a 1:2 molar ratio and heated and stirred to obtain a clear and transparent eutectic solvent, which was then placed at room temperature. 40g of wheat flour and 20g of glutinous rice flour were evenly mixed, and 30g of water and 50g of the eutectic solvent were added. The mixture was stirred into a uniform, viscous paste, sealed with plastic wrap, and left to rest for 12 hours in a non-ventilated place. It was then steamed for 40 minutes. After steaming, it was removed and kneaded to obtain an ionic dough. A strain sensor based on the ionic dough was then constructed by epitaxially connecting the two ends of the ionic dough with wires.

[0048] Figure 8 This means that when a person's elbow joint is flexing and extending in a regular cycle with a speed that is fast at first and then slow, the sensor attached to this point can sensitively monitor the amplitude and speed of the elbow flexion.

Claims

1. A method for preparing a strain sensor based on ionic dough, characterized in that, The specific steps are as follows: Step 1: Preparation of eutectic solvent: Mix choline chloride and glycerol in a molar ratio of 1:2, heat and stir until the solution becomes clear and homogeneous, then remove and cool to room temperature for later use. Step 2: Preparing ionic dough: Mix 50g of the eutectic solvent obtained in step 1 with 30g of water until evenly mixed. Add 40g of wheat flour and 20g of glutinous rice flour, and stir thoroughly into a uniform, thick paste. Seal with plastic wrap and let it rest at room temperature for 10-12 hours. Then steam and knead to obtain ionic dough. Step 3: Sensor fabrication: By connecting the two ends of the ionic dough with wire extension, a strain sensor based on this ionic dough is constructed.

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