Scaling up electrostatic actuators

I present two compliant actuators that address important limitations in electrostatic actuators: limited strain and low force. To reach high forces, we developed a scalable honeycomb architecture of dozens to hundreds of millimeter-scale electrostatic zipping units, obtained by repeatedly folding a patterned sheet. These “honeycomb” actuators generate 40 N of force in an active volume of 3.8 cm^3, with an energy density of 28 J/kg. To obtain high stroke, several tens of cm, we developed a fiber-format sliding electrostatic motor that enables continuous, backdrivable, and reversible linear motion. The thin fiber format allows operation even when bent to a mm-scale radius of curvature, with speeds of over 80 mm/s and axial forces exceeding 500 mN. We discuss the tradeoffs when designing electrostatic actuators for high force or high stroke.