Preparation method of 3D printing wearable self-powered gel sensor

Abstract

The invention belongs to the technical field of flexible sensors, and relates to a preparation method of a 3D printing wearable self-powered gel sensor, which comprises the following steps: preparing a solution by using sulfate and sulfite; adding gelatin and carrageenan into the solution, stirring at a constant temperature, and then carrying out centrifugal treatment to remove bubbles, so as to obtain gel slurry; the preparation method comprises the following steps: mixing an organic silicon thickening agent with an organic silica gel component A in liquid double-component organic silica gel in a stirring manner to obtain a mixture; adding the same amount of organic silica gel component B into the mixture, uniformly stirring, and centrifuging to obtain organic silica gel slurry; the method comprises the following steps: firstly, depositing gel slurry on a substrate by using a direct-writing forming 3D printing technology, and then printing organic silica gel slurry on the surface of the gel slurry to obtain a gel sensor sample; freezing the gel sensor sample for multiple times and then unfreezing to obtain the self-powered gel sensor. The method is simple and low in cost, and the obtained gel sensor has excellent thermoelectric output performance and can monitor environmental temperature and pressure changes without an external power supply.

Description

Technical Field

[0001] This application belongs to the field of flexible sensor technology, and more specifically, relates to a method for preparing a 3D-printed wearable self-powered gel sensor. Background Technology

[0002] Currently, most wearable devices rely on external batteries for power, severely impacting wearing comfort and long-term continuous operation. While thermoelectric materials offer the possibility of self-powered operation, traditional inorganic thermoelectric materials (such as Bi₂Te₃ and PbTe) suffer from intrinsic brittleness, high processing temperatures, and heavy metal toxicity, making it difficult to meet the mechanical adaptability and biosafety requirements of flexible devices. Although organic thermoelectric materials possess good flexibility and solution processability, their thermoelectric properties and thermal stability (long-term operating temperature <100℃) lag significantly behind inorganic materials, making it difficult to meet the demands of wearable devices for high-sensitivity signal acquisition and tolerance to complex environments. In terms of structural design, existing composite strategies are mostly limited to simple physical blending or layer-by-layer stacking to construct thin film materials, resulting in high thermal conductivity and weak mechanical durability. Especially for energy harvesting from three-dimensional complex-shaped heat sources, traditional fabrication methods struggle to achieve precise geometric matching. Furthermore, existing hydrogel ion diode sensors typically consist of two layers of hydrogel with opposite charges. This structure suffers from high interfacial resistance and a single heterojunction, leading to low sensitivity and limiting its application in precision sensing.

[0003] More significantly, most existing fabrication methods employ non-direct-write printing, which fails to achieve adaptable energy harvesting for heat sources of arbitrary geometries. This limitation results in low thermoelectric conversion efficiency, making it difficult to meet the power supply requirements of complex curved surface components in small wearable electronic devices. Therefore, it is necessary to develop a self-powered gel sensor 3D printing method that can adapt to complex geometries and possesses high thermoelectric conversion performance to promote the development of self-powered gel sensors. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide a method for fabricating a 3D printed wearable self-powered gel sensor, which aims to solve the problems of complex fabrication methods, poor electrochemical performance, and low sensitivity to changes in ambient temperature and pressure of existing self-powered gel sensor methods.

[0005] To achieve the above objectives, a method for fabricating a 3D-printed wearable self-powered gel sensor is provided, comprising: S1 prepares a solution with a concentration of 0.05 mol / L to 0.2 mol / L using sulfate and sulfite; gelatin and carrageenan are added to the solution and stirred at a constant temperature, then centrifuged to remove air bubbles to obtain a gel slurry; S2 mixes the silicone thickener with silicone A component of the liquid two-component silicone by stirring to obtain a mixture; adds silicone B component of the liquid two-component silicone to the mixture and stirs evenly, then centrifuges to remove air bubbles to obtain a silicone slurry; wherein the silicone B component and silicone A component have the same mass. S3 uses direct-write 3D printing technology to first deposit the gel slurry on a substrate, and then prints a layer of silicone slurry on the surface of the gel slurry for encapsulation to obtain a gel sensor sample. S4 Repeat the steps of freezing and thawing the gel sensor sample at room temperature multiple times to obtain a self-powered gel sensor.

[0006] Furthermore, the ratio of sulfate to sulfite is 1:1 to 2:1.

[0007] Furthermore, in step S1, the amount of gelatin is 5g~7g, the amount of carrageenan is 0.5g~2g, the constant temperature is 55℃~60℃, and the stirring time is 2h~4h.

[0008] Furthermore, in step S1, the centrifugation speed is 2000 rad / min to 3000 rad / min, and the centrifugation time is 3 min to 5 min.

[0009] Furthermore, in step S2, the mass ratio of the organosilicon A component to the organosilicon thickener is 10:1.

[0010] Furthermore, in step S2, the stirring speed when mixing by stirring is 2000 rpm to 3000 rpm, and the stirring time is 2 to 5 minutes.

[0011] Furthermore, in step S2, the centrifugation speed for removing air bubbles is 4000 rad / min to 6000 rad / min, and the centrifugation time is 3 to 5 minutes.

[0012] Furthermore, in step S3, the parameters for printing the gel slurry using direct-write 3D printing technology are as follows: the air pressure during the printing process is 100kPa~200kPa; the printing feed speed is 7mm / s~10mm / s; and the printing temperature is 35℃~40℃. The parameters for 3D printing the silicone slurry are as follows: the printing air pressure is 300kPa~450kPa; the printing feed speed is 7mm / s~10mm / s; and the printing temperature is room temperature.

[0013] Furthermore, in step S1, the carrageenan is κ-carrageenan.

[0014] Furthermore, in step S4, the freezing temperature is -25℃ to -20℃, and the freezing time is 20h to 24h; the thawing time at room temperature is 2h to 4h.

[0015] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: (1) This application employs a dual ink system of gel slurry and silicone slurry, achieving an effective balance between thermoelectric conversion performance and flexible encapsulation protection. Both slurries possess excellent rheological properties. The self-powered gel sensor prepared in this application exhibits excellent thermoelectric output performance and high sensitivity to changes in ambient temperature and pressure. The output voltage shows a good linear relationship with temperature and pressure, enabling it to collect low-grade heat energy from the environment and monitor changes in ambient temperature and pressure without the need for an external power source. The sulfate and sulfite contained in the gel slurry provide an ion-conducting pathway for the device, allowing it to directly convert heat energy (such as the difference between body surface temperature and ambient temperature) into electrical energy, thereby achieving self-powered sensing. The silicone slurry ensures the mechanical stability and biocompatibility of the device during long-term use. Furthermore, while achieving self-powering, the device's durability and wearability are also considered through direct-write 3D printing technology.

[0016] (2) This application significantly improves the uniformity and mechanical strength of the gel network structure by removing air bubbles through centrifugation and combining it with a physical cross-linking method of freeze-thaw cycles. Centrifugation helps reduce defects in the slurry, laying the foundation for printing high-precision structures. Subsequent multiple freeze-thaw cycles, as a mild physical cross-linking process, can promote the formation of stable crystalline regions or hydrogen bond connections between polymer chains, thereby greatly improving the toughness, resilience, and fatigue resistance of the gel. The comprehensive treatment enables the final sensor to better withstand complex deformations such as repeated bending and stretching caused by human activity, avoiding the brittleness problem that may occur in traditional chemically cross-linked hydrogels, and overcoming the disadvantages of some aerogel materials that are prone to shrinkage or collapse during preparation.

[0017] (3) This application employs direct-write 3D printing technology (DIW), which allows for the precise deposition of functional gel slurry and encapsulation silicone slurry on demand. This layer-by-layer manufacturing strategy enables the sensor to be designed with fully customized three-dimensional shapes according to the specific contours of the human body (such as wrists, joints, etc.) or the irregular surfaces of heat sources, achieving conformal manufacturing. Compared with existing research that is still limited by traditional mold casting or photolithography processes, making it difficult to achieve complex three-dimensional structures, this application can achieve the fabrication of complex three-dimensional structures. At the same time, it also simplifies the manufacturing process and reduces production costs by utilizing an integrated 3D printing strategy. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the fabrication process of the 3D-printed wearable self-powered gel sensor provided in this application; Figure 2 This is a schematic diagram of the steady-state voltage and output power of the gel sensor prepared by the preparation method provided in this application under a temperature difference of 20°C. Figure 3 This is a schematic diagram showing the conductivity of gel sensors prepared by the preparation method provided in this application under different sulfate and sulfite concentration ratios; Figure 4 This is a schematic diagram of the voltage output of the gel sensor prepared by the preparation method provided in this application under different compressive stresses; Figure 5 This is a schematic diagram comparing the mass ratio and voltage changes of unencapsulated gelatin and silicone-encapsulated gel sensors provided in this application under different pressures over 7 days. Figure 6 This is a schematic diagram showing the change in output voltage of the gel sensor prepared by the preparation method provided in this application as a function of deformation time after applying different pressures; Figure 7 This is the release voltage change curve of the gel sensor prepared by the preparation method provided in this application after cyclic application of external force at a temperature difference of 5℃; Figure 8 This is a schematic diagram of the stress-strain curves of the gel sensors prepared in Examples 1-3 of this application; Figure 9 These are photographs of gel sensors of different shapes prepared by the preparation method provided in this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] like Figure 1 The diagram shown is a flowchart of the fabrication method for the 3D-printed wearable self-powered gel sensor provided in this application, including the following steps: S1 uses sulfate and sulfite to prepare a solution with a concentration of 0.05 mol / L-0.2 mol / L; gelatin and carrageenan are added to the solution and stirred at a constant temperature, then centrifuged to remove air bubbles to obtain a gel slurry; S2 mixes the silicone thickener with silicone A component of the liquid two-component silicone by stirring to obtain a mixture; adds silicone B component of the liquid two-component silicone to the mixture and stirs evenly, then centrifuges to remove air bubbles to obtain a silicone slurry; wherein, the mass of silicone B component is the same as that of silicone A component. S3 uses direct-write 3D printing technology to first deposit gel paste on a substrate, and then print a layer of silicone paste on the surface of the gel paste for encapsulation to obtain a gel sensor sample. S4 repeats the process of freezing and thawing the gel sensor sample multiple times to obtain a self-powered gel sensor.

[0021] Specifically, in step S1, a solution of sulfate and sulfite with a molar ratio of 1:1 to 2:1 and a concentration of 0.05 mol / L to 0.2 mol / L is first prepared. Then, 5 to 7 g of gelatin and 0.5 to 2 g of carrageenan (preferably κ-carrageenan) are added to the solution and stirred at a constant temperature of 55 to 60°C for 2 hours. After that, the mixed gel is loaded into a 35 mL syringe and centrifuged at 2000 to 3000 rad / min for 3 to 5 minutes to remove air bubbles, thereby obtaining a gel slurry.

[0022] In step S2, the silicone thickener and silicone A component of the liquid two-component silicone are premixed in a mixer at a ratio of 10:1 at a speed of 2000~3000 rpm for 2~5 minutes. Then, an equal amount of silicone B component of the liquid two-component silicone is added to the mixture, and stirring is continued for 2~5 minutes to ensure uniformity. The resulting silicone slurry is then loaded into a 35 ml syringe and centrifuged at a speed of 4000 rad / min~6000 rad / min for 3~5 minutes to remove air bubbles, thereby obtaining a silicone slurry that can be used for printing.

[0023] The aforementioned liquid two-component silicone, also known as two-component addition-curing liquid silicone, generally includes two components of silicone, usually referred to as silicone component A and silicone component B. The two can be mixed and cured at room temperature or at high temperature. The silicone slurry prepared by this application can protect the gelatin slurry printing layer, isolate interference, and also have good mechanical tensile properties, which meets the wearable function of flexible sensors.

[0024] The prepared gel slurry and silicone slurry are loaded onto the ink-to-write 3D printing device. The slurry is extruded from its corresponding nozzle by air pressure regulation to achieve printing. During the gel slurry printing process, the air pressure is controlled at 100kPa–200kPa, the feed rate is 7mm / s–10mm / s, and the printing temperature is 35℃–40℃. During the silicone slurry printing process, the air pressure is controlled at 300kPa–450kPa, the feed rate is 7–10mm / s, and the printing temperature is room temperature.

[0025] Finally, the printed sample is frozen at -25℃ to -20℃ for 20 to 24 hours and thawed at room temperature for 2 to 4 hours. This freezing and thawing process is repeated 2 to 3 times to obtain a wearable self-powered gel sensor.

[0026] like Figure 2 The figure shows the steady-state voltage and output power of the gel sensor (i.e., gel thermoelectric device) prepared in this application under a temperature difference of 20°C. It can be seen from the figure that the gel sensor has a large output power under a temperature difference of 20°C, indicating that the gel sensor has great application potential.

[0027] like Figure 3 The figure shows a schematic diagram of the conductivity of a gel sensor prepared from gel slurries containing different molar masses of sulfate and sulfite at a mass ratio of 1:1. It can be seen from the figure that the higher the molar mass of sulfate and sulfite, the higher the conductivity of the gel sensor.

[0028] like Figure 4 As shown in the figure, the voltage output of the gel thermoelectric device prepared by the method of this application is under different temperature differences. It can be seen from the figure that the voltage output is linear with the change of temperature, indicating that the gel thermoelectric device has high temperature sensitivity and can therefore be applied to temperature change sensing. Furthermore, by calculating the slope of the curve in the figure, it can be seen that the gel thermoelectric device has a high Seebeck coefficient of about 3.9 mV / K.

[0029] like Figure 5 The figure shows a comparison of the mass ratio and voltage changes of unencapsulated gelatin and silicone-encapsulated gel sensors after applying different pressures for 7 days. As can be seen from the figure, the mass ratio of the silicone-encapsulated gel sensor slowly decreased from 100% on day 1 to 93.5% on day 7, with a relatively uniform decrease (shown by the black sphere curve), while maintaining a relatively high output voltage of over 73 mV (shown by the red sphere curve). In contrast, the mass ratio of the unencapsulated gelatin sensor decreased to approximately 54% and the voltage decreased to approximately 40 mV under the same pressure over the same period. This comparison demonstrates that the silicone-encapsulated gel sensor used in this application retains high thermoelectric performance even after prolonged operation, and the voltage output of the gel thermoelectric device exhibits only a slight change, thus making it better suited for pressure sensing applications.

[0030] like Figure 6 The figure shows the change of output voltage with deformation time after applying different pressures to the gel thermoelectric device prepared by the method of this application. The figure shows that the gel sensor can generate a regular voltage output.

[0031] like Figure 7The figure shows the release voltage change curve of the gel thermoelectric device prepared by the method of this application after cyclically applying external force at a temperature difference of 5℃. It can be seen from the figure that the output voltage produces a corresponding regular output with deformation time.

[0032] The technical solution of this application will be described in detail below with reference to the embodiments.

[0033] Example 1 The specific steps of the fabrication method for the 3D-printed wearable self-powered gel sensor provided in this embodiment are as follows: Step 1: Prepare a 0.05 mol / L solution (molar ratio 1:1) using sulfate and sulfite. Then add 5 g of gelatin and 0.5 g of carrageenan to the solution and stir at a constant temperature of 55°C for 2 minutes. After 4 hours, the mixture was transferred to a 35 ml syringe and centrifuged at 2000 rpm for 3 minutes to obtain a gel slurry.

[0034] Step 2: Premix 10g of silicone A component (such as component A in Dragon Skin 30 silicone) and 1g of silicone thickener (such as THI-VEX thickener) in a mixer at 2000rpm for 2 minutes to obtain a mixture. Then, add 10g of silicone B component (such as component B in Dragon Skin 30 silicone) to the mixture and continue stirring for 2 minutes to ensure homogeneity. Then, load the mixture into a 35ml syringe and centrifuge at 4000rad / min for 3 minutes to remove air bubbles, thus preparing the silicone gel.

[0035] Step 3: The prepared gel slurry is loaded onto the 3D direct-write printer, and the slurry is extruded from the nozzle by air pressure regulation. The air pressure during the gel slurry printing process is controlled at 100 kPa, the feed rate is 7 mm / s, and the printing temperature is 35°C. For the silicone slurry printing process, the air pressure is controlled at 300 kPa, the feed rate is 7 mm / s, and the printing temperature is room temperature. The final result is a wearable self-powered gel sensor that meets the requirements.

[0036] Example 2 The specific steps of the fabrication method for the 3D-printed wearable self-powered gel sensor provided in this embodiment are as follows: Step 1: Prepare a 0.1 mol / L solution (molar ratio 1:2) using sodium sulfate and sodium sulfite. Add 6 g of gelatin and 1 g of carrageenan to the solution and stir at 60°C for 2-4 hours. Then, transfer the solution into a 35 mL syringe and centrifuge at 2500 rpm for 3 minutes to obtain a gel slurry. Step 2: Premix 10g of silicone A component and 1g of silicone thickener from the liquid two-component silicone in a mixer at 3000rpm for 3 minutes. Then, add 10g of silicone B component from the liquid two-component silicone to the mixture and continue stirring for 3 minutes to ensure homogeneity. Then, transfer the mixture into a 35ml syringe and centrifuge at 5000rad / min for 4 minutes to remove air bubbles, thus obtaining the silicone slurry.

[0037] Step 3: Load the prepared gel slurry and silicone slurry onto the ink-to-ink 3D printing device. Extrude the slurry from the corresponding nozzles by controlling the air pressure. The air pressure during the gel slurry printing process is controlled at 150 kPa; the feed rate is 8.5 mm / s; and the printing temperature is 37°C. The air pressure during the silicone slurry printing process is controlled at 300 kPa; the feed rate is 7 mm / s; and the printing temperature is room temperature. Example 3 The specific steps of the fabrication method for the 3D-printed wearable self-powered gel sensor provided in this embodiment are as follows: Step 1: Prepare a 0.2 mol / L solution (molar ratio of 2:1) using potassium sulfate and potassium sulfite. Add 7 g of gelatin and 2 g of carrageenan to the solution and stir at a constant temperature of 60°C for 2-4 hours. Then, transfer the solution into a 35 mL syringe and centrifuge at 3000 rpm for 5 minutes to prepare a gel slurry.

[0038] Step 2: Premix 10g of silicone A component and 1g of silicone thickener in a mixer at 3000rpm for 5 minutes. Then, add 10g of silicone B component to the mixture and continue stirring for 5 minutes to ensure uniformity. Then, put the obtained mixture into a 35ml syringe and centrifuge at 6000rad / min for 5 minutes to remove air bubbles, thus obtaining silicone slurry.

[0039] Step 3: Load the prepared gel slurry and silicone slurry onto the ink-to-ink 3D printer. Extrusion of the slurry from the corresponding nozzles is achieved through air pressure regulation. During gel printing, the air pressure is controlled at 200 kPa, the feed rate at 7 mm / s, and the printing temperature at 40°C. During silicone printing, the air pressure is controlled at 300 kPa, the feed rate at 7 mm / s, and the printing temperature at room temperature, resulting in a self-powered gel sensor.

[0040] like Figure 8The figure shows the stress-strain curves of gel thermoelectric devices prepared by the preparation methods in Examples 1-3 using 0.05M, 0.10M, and 0.20M molar masses of sulfate and sulfite, respectively. The mass ratio of sulfate to sulfite in each scheme is 1:1. It can be seen from the figure that the mechanical properties of the gel thermoelectric devices prepared by the preparation methods provided in the above three examples can be adjusted over a wide range.

[0041] like Figure 9 As shown, various shapes of self-powered gel sensors can be fabricated using the method of this application. The method of this application can print gel sensors of various shapes without limitation, resulting in higher application efficiency.

[0042] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0043] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0044] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after connection. "Sliding connection" refers to a connection where the components can slide relative to each other after connection. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0045] Furthermore, the mathematical concepts mentioned in the embodiments of this application, such as symmetry, equality, parallelism, and perpendicularity, are limitations specific to the current technological level, rather than absolute and strict mathematical definitions. Slight deviations are permissible; approximations of symmetry, equality, parallelism, and perpendicularity are all acceptable. For example, "A and B are parallel" means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. "A and B are perpendicular" means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0046] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a 3D printed wearable self-powered gel sensor, characterized in that, The method comprises the following steps: S1: a solution with a concentration of 0.05 mol / L-0.2 mol / L is prepared by using sulfate and sulfite; After adding gelatin and carrageenan into the solution, the solution is stirred at a constant temperature, and then centrifuged to remove bubbles to obtain a gel slurry; S2: a mixture is obtained by mixing a silicone thickening agent and a silicone A component in a liquid two-component silicone adhesive by stirring; a silicone B component in the liquid two-component silicone adhesive is added into the mixture and stirred uniformly, and then centrifuged to remove bubbles to obtain a silicone adhesive slurry; the mass of the silicone B component is the same as that of the silicone A component; S3: a gel sensor sample is obtained by depositing the gel slurry on a substrate by using a direct writing forming 3D printing technology, and then printing a layer of silicone adhesive slurry on the surface of the gel slurry to encapsulate; S4: the gel sensor sample is repeatedly subjected to the steps of freezing and thawing at room temperature to obtain a self-powered gel sensor.

2. The production method according to claim 1, wherein In step S1, the ratio of sulfate to sulfite is 1:1-2:

1.

3. The production method according to claim 1, wherein In step S1, the gelatin is 5g-7g, the carrageenan is 0.5g-2g, the constant temperature is 55°C-60°C, and the stirring time is 2h-4h.

4. The production method according to claim 1, wherein In step S1, the centrifugal speed during centrifugal treatment is 2000 rad / min-3000 rad / min, and the centrifugal time is 3min-5min.

5. The production method according to claim 1, wherein In step S2, the mass ratio of the silicone A component to the silicone thickening agent is 10:

1.

6. The production method according to claim 1, wherein In step S2, the stirring speed during the mixing by stirring is 2000 rpm-3000 rpm, and the stirring time is 2-5 minutes.

7. The production method according to claim 1, wherein In step S2, the centrifugal speed for removing bubbles is 4000 rad / min-6000 rad / min, and the centrifugal time is 3-5 minutes.

8. The production method according to claim 1, wherein In step S3, the parameters for printing the gel slurry by using the direct writing forming 3D printing technology are as follows: the air pressure during printing is 100 kPa-200 kPa; the printing feed speed is 7mm / s-10mm / s; the printing temperature is 35°C-40°C. In step S3, the parameters for printing the silicone adhesive slurry by using the 3D printing technology are as follows: the printing air pressure is 300 kPa-450 kPa, the printing feed speed is 7mm / s-10mm / s, and the printing temperature is room temperature.

9. The production method according to claim 1, wherein In step S1, the carrageenan is κ-carrageenan.

10. The production method according to claim 1, wherein In step S4, the freezing temperature is-25°C--20°C, the freezing time is 20h-24h, and the thawing time at room temperature is 2h-4h.

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