Fig. 3: Unidirectional and reciprocating electrostatic actuation processes of the SSL actuator.

a SEM image series of continuous unidirectional multi-step actuation process. The form of voltage applied at each step is as follows. Step 1 from (i) to (ii): 10 kHz AC square wave, 150 V amplitude, 50% duty cycle, actuation distance about 1.76 μm. Step 2 from (ii) to (iii): 10 kHz AC square wave, 200 V amplitude, 50% duty cycle, actuation distance about 1.18 μm. Step 3 from (iii) to (iv): DC, 200 V amplitude, actuation distance about 9.41 μm. b Corresponding position of the graphite flake during the actuation process in (a) as a function of time, where the moment of charge injection (the lightning symbol) and applied voltage form are marked in the figure. c SEM image series of two continuous reciprocating actuation processes. d Corresponding position of the graphite flake during the actuation process in (c) as a function of time. The actuation direction (arrow directions), applied voltage forms (arrow colors and circular marks), and moments of charge injection (lightning symbols) are indicated in (c and d). The white dashed line in (a and c) indicates the geometric center of the buried electrode gap, corresponding to \(x=6.5\,{{{\rm{\mu }}}}{{{\rm{m}}}}\). Source data are provided as a Source Data file.