Energy scavenging from insect flight

This paper reports the design, fabrication and testing of an energy scavenger that generates power from the wing motion of a Green June Beetle (Cotinis nitida) during its tethered flight. The generator utilizes non-resonant piezoelectric bimorphs operated in the d31 bending mode to convert mechanical vibrations of a beetle into electrical output. The available deflection, force, and power output from oscillatory movements at different locations on a beetle are measured with a meso-scale piezoelectric beam. This way, the optimum location to scavenge energy is determined, and up to ∼115 μW total power is generated from body movements. Two initial generator prototypes were fabricated, mounted on a beetle, and harvested 11.5 and 7.5 μW in device volumes of 11.0 and 5.6 mm3, respectively, from 85 to 100 Hz wing strokes during the beetle’s tethered flight. A spiral generator was designed to maximize the power output by employing a compliant structure in a limited area. The necessary technology needed to fabricate this prototype was developed, including a process to machine high-aspect ratio devices from bulk piezoelectric substrates with minimum damage to the material using a femto-second laser. The fabricated lightweight spiral generators produced 18.5–22.5 μW on a bench-top test setup mimicking beetles’ wing strokes. Placing two generators (one on each wing) can result in more than 45 μW of power per insect. A direct connection between the generator and the flight muscles of the insect is expected to increase the final power output by one order of magnitude. (Some figures in this article are in colour only in the electronic version)