The voltage field causes the crystal to bend, and the shape of the crystal determines the way it bends. This bending motion simulates muscle movement, and causes the wings to beat. The wings must move at 150 beats per second. Energy creation is not the only problem facing the Berkeley team. Flight stabilization is also a major challenge.
Larger aircraft achieve stability through aerodynamics.
The robofly, because it is so small and has flapping wings, doesn't possess this property, making it especially hard to achieve stable hovering. Animals and human-built devices that can hover are really part of an exclusive club. Once these problems are solved, the next step will be to look at the power source. The team hopes the final version will be powered by light-harnessing photo cells. Robofly will have to carry a small on-board capacitor, or battery, that would enable flight even when light conditions are not favorable.