A scientist at the University of California photographed with light micrographs of a micro- resonator. A micro-resonator is a mechanical resonator structure, made by the same silicon deposition process used in the manufacture of microcircuits. To the left in the background image is the resonant mass with the tooth-like sensor structure at right. Once motion has been electrically induced, the resonator oscillates much in the same way as a pendulum, only at around 10,000 times per second. The resonant mass of the structure is about 700 nanometres long and about 300 nanometres wide. Such resonators may be used in a variety of motion monitoring devices.