A DC-powered, tunable, fully mechanical oscillator using in-plane electrothermal actuation

This paper describes a fully mechanical micromachined oscillator that is driven using only a DC power source. The oscillator is made using an electrothermal actuator, that when actuated, opens a switch to cut off its supply current. Two versions of this oscillator have been designed using distinct hysteresis mechanisms: one structural, and the other thermal. The devices have 30 μm thick electroplated copper structures and 3 μm minimum features, fabricated using a single mask low temperature UV-LIGA process, with a footprint of 1 mm×1 mm. Measured results confirm the operation and show that the oscillators are capable of generating a tunable signal with a frequency range from 38 Hz to 1200 Hz and a duty cycle between 0.3 and 0.7, while requiring an operating voltage less than 0.5 V. The maximum power consumption is 180 mW.