Secondary Reorientation and Hygroscopic Forces in Chitinous Biopolymers and Their Use for Passive and Biochemical Actuation

Abstract Passive actuation is the production of movement or deformation without external power sources or control systems. This phenomenon has been gaining significant attention in the engineering community due to its potential use in energy‐efficient systems, in which part of the functionality is programmed in the material composition to reduce overall cost and complexity. Biological organisms, formed through millennia of evolution in a paradigm of limited resources and energy and at a multiscale equilibrium with their environment, have developed a myriad of outstanding materials and strategies for integrating complex functionalities into their multiscale structural design. In this study, the arthropod exoskeleton's chitinous composition and manufacturing strategies are used to reproduce its complex relations with external forces and water‐driven molecular rearrangement and use them to produce electricity and actuate a mechanical hand. The proposed technology is unique in combining the generation of strong forces and the integration of the principles and materials of biological organisms, leading to significant advances in the design and performance of passive solutions integrated into biological systems for a wide range of applications, such as biorobotics, medical devices, and energy harvesting.