Micromachined convective accelerometers in standard integrated circuits technology

This letter describes an implementation of micromachined accelerometers in standard complimentary metal-oxide-semiconductor technology. The devices operate based on heat convection and consist of microheaters and thermocouple or thermistor temperature sensors separated by a gap which measure temperature difference between two sides of the microheater caused by the effect of acceleration on free gas convection. The devices show a small linearity error of < 0.5% under tilt conditions (+/- 90 degrees), and < 2% under acceleration to 7g(g equivalent to 9.81 m/s(2)). Sensitivity of the devices is a nearly linear function of heater power. For operating power of similar to 100 mW, a sensitivity of 115 mu V/g was measured for thermopile configuration and 25 mu V/g for thermistor configurations. Both types of devices are operable up to frequencies of several hundred Hz. (C) 2000 American Institute of Physics. [S0003-6951(00)04002-X].