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

To promote the development of artificial muscle in the practical application, it is urgent to study its deflection response behavior. In the paper, a sodium alginate-based biocompatible hydrogel artificial muscle (BHAM) is fabricated. For the deflection response performance of the BHAM, an output displacement measuring system is established, and the effect and mechanism of the BHAM manufactured via the freeze-drying technique at different pre-freezing temperatures are researched in depth. The deflection response reflected by the output displacement of the BHAM is significantly related to the pre-freezing temperature. The ideal temperature is −50 °C owing to the evenly distributed pores in the BHAM; furthermore, the connectivity between these pores is optimal at this time. In addition, the elastic modulus of the BHAM is small, and it wastes less energy to conquer the bending strain produced by itself. The porosity and water retention rate are excellent, generating many spacious channels for promoting ion transport inside the BHAM. Moreover, the BHAM has outstanding specific capacitance, providing a suitable environment for the migration of internal charged ions with a deflection response of the optimized BHAM. It has become an important goal of intelligent materials for actuating development, and improving work stability and reliability of the BHAM, which is of great significance to further eliminate obstacles between functional materials and structural materials.