Anisotropic aerogel induced gelatin hydrogel actuator with favourable mechanical properties and multiple solvent responsiveness

Abstract

As an important part of biomimetic/intelligent new materials, the hydrogel actuator can sense changes in the external environment and convert external energy into mechanical energy, therefore attracting extensive attention in many fields. However, the relative weak mechanical properties, small driving force and single responsiveness to external stimuli of hydrogel-based actuators are still the main factor restricting their practical application and future development. In this paper, a heterogeneous hydrogel-based actuator with favourable mechanical properties and multiple solvent responsiveness is constructed via the synergistic action of anisotropic chitosan aerogel as the skeleton and solvent-sensitive gelatin hydrogel as muscle in the actuator framework. The addition of aerogel skeleton and the salting out of gelatin favor the actuator favourable mechanical behavior with maximum tensile stress and compressive stress up to MPa level. Furthermore, the heterogeneous aerogel/hydrogel composite structure greatly improves the driving capability of actuator, presenting multiple solvent responsiveness with the maximum driving amplitude up to 730° in the ion solution. The well-designed actuators can be exploried as intelligen microfluidic valves that recognize and pass specific solutions at different flow rates. This aerogel/hydrogel composite actuator has broad application prospects in microfluidic systems, smart valves, artificial muscles and intelligent human-machine interaction.