Fig. 1: Finite element analysis of the compressor.

a Schematic of the device with optimized structural parameters. b Stiffness modulations of the prototype. c Stiffness modulations of the optimized compressor. d Resonance frequencies are grouped by the number of input ‘1’s; the equivalent decimal value (0 to 127) of the digital input (000-0000 to 111-1111) is used for the x-axis label