Electrically actuated characteristics and electrochemical mechanism of a flexible biomimetic artificial muscle regulated by the responsive polymer of the calcium alginate gelation

Abstract

In comparison to conventional actuated techniques, the utilization of a Flexible Biomimetic Artificial Muscle (FBAM) incorporating calcium alginate hydrogel, a type of responsive polymer, offers numerous benefits including reduced weight, lower actuated voltage requirements, enhanced specific energy density, and minimal acoustic disturbances, among others. This paper presents the fabrication of the FBAM through calcium alginate gelation utilizing six calcium salts with identical Ca2+ molar mass. Subsequently, the electrically actuated characteristics and electrochemical mechanism of the FBAM were investigated, employing four evaluation indexes: peak force density (D, mN/g), operating life (Tt, s), response speed (Vr, mN/g·s), and rise time (Ts, s). The findings of this study hold significant implications for the advancement of novel responsive polymers for artificial muscles. The findings of the study indicate that the electrically actuated characteristics of FBAM were most optimal when calcium alginate gelation with CaH8I2O4 was employed. This was evidenced by the D value of 22.807 mN/g, Tt value of 1066 s, Vr value of 98 s, and Ts value of 0.1046 mN/g·s. The sufficient degree of calcium alginate gelation between sodium alginate molecule and Ca2+ cations resulted in the formation of intermolecular bridges within the calcium alginate hydrogel, which consisted of polymer β-D-mannuronic and α-L-guluronic. Notably, this gelation process was found to be inversely related to the pH level in the aqueous solution of the electrically actuated membrane.