Powerful, soft combustion actuators for insect-scale robots

• Published in: Science (American Association for the Advancement of Science) Vol. 381; no. 6663; pp. 1212 - 1217
• Main Authors: Aubin, Cameron A., Heisser, Ronald H., Peretz, Ofek, Timko, Julia, Lo, Jacqueline, Helbling, E. Farrell, Sobhani, Sadaf, Gat, Amir D., Shepherd, Robert F.
• Format: Journal Article
• Language: English
• Published: Washington The American Association for the Advancement of Science 15.09.2023
• Subjects: Actuators; Chemical fuels; Combustion; Directional control; Insects; Locomotion; Microrobots
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.adg5067

Insects perform feats of strength and endurance that belie their small stature. Insect-scale robots—although subject to the same scaling laws—demonstrate reduced performance because existing microactuator technologies are driven by low–energy density power sources and produce small forces and/or displacements. The use of high–energy density chemical fuels to power small, soft actuators represents a possible solution. We demonstrate a 325-milligram soft combustion microactuator that can achieve displacements of 140%, operate at frequencies >100 hertz, and generate forces >9.5 newtons. With these actuators, we powered an insect-scale quadrupedal robot, which demonstrated a variety of gait patterns, directional control, and a payload capacity 22 times its body weight. These features enabled locomotion through uneven terrain and over obstacles. A key challenge for microrobotic systems is the efficient delivery of power and the conversion of that power into mechanical forces and displacements. Aubin et al . developed a lightweight actuator that can be driven at high frequencies by the combustion of chemical fuels (see the Perspective by Truby). Key to achieving this fast performance is the passive quenching of the combustion, which eliminates the need for valves. Using this actuator, the authors fabricated an insect-scale quadruped robot that is capable of walking, turning (directional control), and jumping, a combination of locomotion capabilities that is unusual in a microrobot. —Marc S. Lavine Microactuators fueled by energy dense hydrocarbons produce large forces to power a microrobot that can crawl and jump.