Effect and mechanism of various pre-freezing temperatures on the deflection response of a highly biocompatible hydrogel artificial muscle

Helical plants have the ability of tropisms to respond to natural stimuli, and biomimicry of such helical shapes into artificial muscles has been vastly popular. However, the shape‐mimicked actuators only respond to artificially provided stimulus, they are not adaptive to variable natural conditions, thus being unsuitable for real‐life applications where on‐demand, autonomous operations are required. Novel artificial muscles made of hierarchically patterned helically wound yarns that are self‐adaptive to environmental humidity and temperature changes are demonstrated here. Unlike shape‐mimicked artificial muscles, a unique microstructural biomimicking approach is adopted, where the muscle yarns can effectively replicate the hydrotropism and thermotropism of helical plants to their microfibril level using plant‐like microstructural memories. Large strokes, with rapid movement, are obtained when the individual microfilament of yarn is inlaid with hydrogel and further twisted into a coil‐shaped hierarchical structure. The developed artificial muscle provides an average actuation speed of ≈5.2% s−1 at expansion and ≈3.1% s−1 at contraction cycles, being the fastest amongst previously demonstrated actuators of similar type. It is demonstrated that these muscle yarns can autonomously close a window in wet climates. The building block yarns are washable without any material degradation, making them suitable for smart, reusable textile and soft robotic devices.

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“…Sodium alginate, infused with a liquid electrolyte; ref. [29] Flat rectangular bar Electrochemical ≈0.002 Not reported…”

Section: Yarn Washability and Environmental Adaptabilitymentioning

confidence: 99%

Plant‐Like Tropisms in Artificial Muscles

et al. 2023

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“…Furthermore, the obtained operating values for comparison were the water retention rate (w%), tensile strength (MPa), ion channel (v%), deflection displacement (mm) and bending strain (%), and the other works dedicated for artificial muscles were the ionic polymer artificial muscle [23] and biocompatible hydrogel artificial muscle [24], as shown in figure 14. In the previous works, both of the ionic polymer artificial muscle and biocompatible hydrogel artificial muscle were made from the SA hydrogel based on the low-temperature freeze-drying process with different technique flow and parameters.…”

Section: Surface Microtopography Of the Actuating Film Under Differen...mentioning

confidence: 99%

“…Xu and Sun et al [8,21,22] have explored effects of the moisture content and ionic liquid of the hydrogel-based electrolyte membrane made from sodium alginate (SA)/cellulose on the enhancement of electromechanical properties of a soft ionic actuator or nano-biocomposite artificial muscle, whereas the modification methods are cumbersome and the mechanism is too complex, which can only be applied in the laboratory without being popularized. Yang et al [6,[23][24][25] have tried a variety of methods to improve the electrically response performance of artificial muscle, whereas they only roughly utilize a freeze-drying process without in-depth excavation, resulting in the unsatisfactory mechanochemical properties of artificial muscle. Nevertheless, compared with the traditional heat-drying process, the freeze-drying process has a wide application prospect due to its advantages of faster forming speed.…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical characteristics and influence mechanisms of a biomass hydrogel artificial muscle based on different parameters of the sodium alginate adjustment

Yang¹,

Wang²,

Yao³

et al. 2022

Smart Mater. Struct.

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Biomass Hydrogel Artificial Muscle (BHAM) is a kind of ionic electroactive polymers (EAPs), such as ionic polymer gels (IPGs) of good biocompatibility and stimulus responsiveness under electric field, which is largely used in the fields of soft robots and electric actuators. In this paper, based on the freeze-drying process, effect and influence mechanisms of Sodium Alginate (SA) parameters adjustment on the BHAM mechanochemical characteristics were researched extensively, which was verified by a set of perfect characteristic evaluation and experimental test methods, such as the porosity P (v%), water retention rate Wr (w%), mechanochemical property testing and SEM shots. The results showed that when the concentration of SA was 20 g/L, the actuating film of BHAM had suitable thickness and stomata in macroscopic appearance, and its micro pore distribution and size were uniform with the thin pore wall, which resulted in the highest porosity (i. e. ion channel) of 73.5 v%, the largest water retention rate of 76.2 w% and the optimum tensile strength of 0.38 MPa. Furthermore, calcium chloride (CaCl2) was adopted as a cross-linking agent to react with the SA to form Calcium Alginate (CA) by different CaCl2 cross-linking ratios, that was to modify the three-dimensional microstructure of the BHAM to improve its mechanical properties with the best deflection displacement of 23.9 mm and bending strain of 3.45% under the ideal CaCl2 cross-linking ratio of 1%. Besides, the diffraction of x-rays (XRD) analysis and thermal decomposition experiments of the BHAM were performed, which was demonstrated that the thermal stability of the CA-based BHAM was higher than that of the SA-based BHAM.

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“…Sun et al proposed a renewable microporous ionic electrolytes made of cellulose dissolved in ionic liquid, and applied it to nano-biocomposite artificial muscles, obtaining good flexibility and ionic conductivity [35]. However, the industrialization progress of bio-gel artificial muscle was always limited by the problems of short cycle life, small bending deflection and output force, so we intends to improve the output characteristics of bionic artificial muscle under the action of electric field through material composition and process improvement [36,37]. In this study, sodium alginate was doped with CMC to prepare a gel driving membrane, and the synergistic effect of sodium alginate and CMC on material properties was utilized to modify the gel driving membrane of artificial muscle by the doping technique and freeze drying.…”

Section: Introductionmentioning

confidence: 99%

Investigation into a conductive artificial muscle based on sodium alginate/cellulose with good response characteristics

Jia¹,

Wang²,

Fang³

et al. 2022

Smart Mater. Struct.

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In this study, two common natural bio-gel materials were used to prepare the driving membrane applicable to the artificial muscle structure, and the electrolyte layer was assembled to generate the conductive artificial muscle based on sodium alginate/cellulose (SCAM). By studying the influences of different addition amounts of carboxymethyl cellulose (CMC) on the response characteristics, electrochemical characteristics and microstructure characteristics of artificial muscle, the optimal addition amount was determined. The results showed that the addition amount of CMC in the sample affected the internal structural changes, and the appropriate addition amount could improve the compactness of the sample by giving play to the synergistic effect of the two, thereby significantly promoting the response characteristics and improving its capacity of holding electrons, which was macroscopically manifested by great force and displacement. Based on the microstructure and porosity analysis, the internal mechanism of improving the response characteristics of the sample was clarified. With good response characteristics in the electric field, SCAM has great potential to be applied in flexible machinery and bio-gel artificial muscle.

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Effect and mechanism of various pre-freezing temperatures on the deflection response of a highly biocompatible hydrogel artificial muscle

Cited by 4 publications

References 18 publications

Plant‐Like Tropisms in Artificial Muscles

Plant‐Like Tropisms in Artificial Muscles

Mechanochemical characteristics and influence mechanisms of a biomass hydrogel artificial muscle based on different parameters of the sodium alginate adjustment

Investigation into a conductive artificial muscle based on sodium alginate/cellulose with good response characteristics

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