The fluff piece doesn't mention speed (1 cycle every 160 seconds) or electromechanical efficiency (0.3%) for their prototype. It expands by boiling tiny bubbles

The fluff piece doesn't mention speed (1 cycle every 160 seconds) or electromechanical efficiency (0.3%) for their prototype. It expands by boiling tiny bubbles of ethanol in a silicone matrix using resistive heating, and contracts by cooling down.