Protein‐Based Hydrogels that Actuate Self‐Folding Systems

An approach to build a chemomechatronic system inspired by self‐folding robots is described. This system, which comprises a protein‐based hydrogel bound to a low‐profile laminate, responds to different aqueous environments by undergoing geometric transformations. This response is dependent on the thickness and stiffness of the templating hydrogel, which directly regulates the diffusion of water into and out of the platform to initiate its reversible shape changes. When modified to include more complex geometries, these controllable shape changes can also be used to selectively trigger multiple folding events, illustrating a new platform for chemically initiated mechatronic devices. Together, these data show how compositionally discrete components are physically, chemically, and mechanically coupled together to generate a new actuator for biohybrid self‐folding systems. A protein‐based hydrogel is coupled to a hinged metal scaffold, creating a new biohybrid self‐folding system. The folding behavior of the system is tracked and characterized using a lumped capacitance model to elucidate the effects that hydrogel dimensions, cross‐linking, and water diffusion have on the self‐folding behavior.