Acoustic bubble-powered miniature rotor for wireless energy harvesting: (a) When a compressible bubble in the microtube is acoustically excited at the natural frequency of the bubble, the bubble periodically oscillates in the tube and simultaneously induces a synthetic jet providing the propulsion force; (b) Owing to the propulsion force, the miniature rotor, where bubbles are trapped in the microtube, continuously rotates under acoustic excitation. The rotating miniature rotor provides fine mechanical vibrations to the piezocantilever, which is initially set up beside the rotor tips. Consequentially, electrical energy is generated due to the piezoelectric effect and stored via an electric circuit. The proposed energy harvesting technology can extract mechanical power from acoustic energy using a miniature rotor driven by acoustically oscillating bubbles in an aqueous medium and convert mechanical power to electric power.