Electrically Controllable Materials for Soft, Bioinspired Machines

Soft robotics aims to close the performance gap between built and biological machines through materials design. Soft robots are constructed from soft, actuatable materials to be physically intelligent, or to have traits that living organisms possess such as passive adaptability and morphological computation through their compliant, deformable bodies. However, materials selection for physical intelligence often involves low-performance and/or energy-inefficient, stimuli-responsive materials for actuation. Additional challenges in soft robot sensorization and control further limit the practical utility of these machines. Recognizing that electrically controllable materials are crucial for the development of soft machines that are both physically and computationally intelligent, we review progress in the development of electroprogrammable materials for soft robotic actuation. We focus on thermomechanical, electrostatic, and electrochemical actuation strategies that are directly controlled by electric currents and fields. We conclude with an outlook on the design and fabrication of next-generation robotic materials that will facilitate true bioinspired autonomy. Expected final online publication date for the Annual Review of Materials Research, Volume 53 is July 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.