Study On The Output Force Performance Enhancement And Mechanism Of Calcium Alginate Gel-based Artificial Muscle

Gel-based artificial muscle was a category of emerging polymer material that combined perception and actuation functions with good biocompatibility and environmental compatibility.As the advantages of light weight,large deformation,cheap price,and the potential for application in the engineering fields such as agriculture,environmental management,corrosion prevention and protection,etc.It had become the research focus of scientific and technological innovation in recent years.However,in the process of serving various fields,it was limited by its poor output force performance.Thus,the main research of this paper was as followed:（1）The gel-based artificial muscle was prepared using natural polymer sodium alginate as the main raw material,and an evaluation system of the output force performance of its was established.The effect of sodium alginate concentration on the output force performance was also investigated.When the concentration of alginate was in the range of 14 g/L-20 g/L,the inner structure of the gel-based artificial muscle would gradually perfect with the increase of concentration,but when the concentration was in the range of 20 g/L-24 g/L,the aggregation phenomenon would occur and the output force performance of its inner structure would show a decreasing trend.By comparison,the optimal concentration of sodium alginate was determined to be 20 g/L.Based on this concentration,the output force performance（peak force density of19.657 mN/g,working life of 843 s,rise time of 124 s,and peak force density response rate of0.06880 mN/g·s）was used as the basis for output force performance.（2）The output force performance of the gel-based artificial muscle was investigated and the mechanism of improving the output force performance of the gel-based artificial muscle by calcium iodide cross-linking process was elucidated.When the concentration of calcium iodide was in the range of 0.0 g/L-2.0 g/L,the G-G blocks in alginate molecular chains would combine with Ca²⁺in the calcium iodide to transform the spatial structure from"two-dimensional"to"three-dimensional"in the gel-based artificial muscle,At this time,its peak force density,peak force density response rate,elastic modulus,yield strength,and ion channel were all at their maximum values,which have been increased by 15.9%,51.8%,150%,57.3%,and 83%.But in the range of 2.0 g/L to 2.5 g/L,the excessive addition of Ca²⁺formed a long alternating"compression"sequence of MG/MG connections in the molecular chain,which led to partial collapse of the gel network and a decrease in its output force performance.（3）The output force performance of the gel-based artificial muscle was studied under different calcium salt cross-linking processes and the effect mechanism of different calcium salt cross-linking processes was also clarified.When the pH of the actuating solution was in the range of 5-6,the gel-based artificial muscle had good output force performance,and when its actuation membrane was crosslinked with iodine-calcium,its peak force density,peak force density response rate,elastic modulus,yield strength,and ion channel were all at their maximum values,which had increased by 22.4%,19.4%,28.2%,106.2%,and 52.2%compared to the minimum values.but when the pH was greater than 6,the crosslinking degree of calcium ions and the actuating membrane decreased with the increase of the pH value of the actuating fluid.When the pH of the solution was greater than 7,the gel formed was in the worst state and corresponds to the worst output force performance.（4）The gel-based artificial muscle output force performance was studied at different volume fractions and the output force improvement mechanism of its was also clarified.When the volume fraction of ethanol was in the range of 0%-25%,a suitable amount of doping would improve the diffusion degree of Ca²⁺in the gel-based artificial muscle cross-linking system and would make more physical cross-linking points between alginate molecular chains.And at this time,its optimum specific capacitance and working life were 96.2 m F/g and 1287 s and increased by 7%and 20.7%compared with those without ethanol.But when the volume fraction of ethanol was in the range of 25%-30%,too much ethanol would undergo complexation reaction with calcium iodide in the case of excess volume fraction of ethanol,making the degree of crosslinking weakened in the gel-based artificial muscle system and at this time its output force performance was the worst.