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Convection-Based Accelerometer and Tilt Sensor Implemented in Standard CMOS
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1998
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EngineeringMeasurementAccelerometerEducationCalibrationThermodynamicsNovel AccelerometersInstrumentationInclinometerCmos ImplementationSolid Proof MassOn-chip SensorsElectrical EngineeringHeat TransferSensor CalibrationSensorsConvection-based AccelerometerTemperature MeasurementThermal ManagementThermal SensorThermal Engineering
This paper presents a CMOS implementation of accelerometers that use heat convection, eliminating the need for a solid proof mass. The devices employ microheaters and temperature sensors separated by a gap in differential or bridge configurations, measuring the temperature difference produced by acceleration‑induced free convection. They achieve <0.5 % linearity error over ±90° tilt, <2 % over 0–7 g, with sensitivities up to 115 μV/g (thermopile) and 185 μV/g (thermistor), and operate at several hundred hertz.
Abstract This paper describes a CMOS implementation of novel accelerometers that operate based on heat convection, requiring no solid proof mass. The devices consist of microheaters and thermocouple or thermistor temperature sensors separated by a gap and placed in differential or bridge configurations. Temperature sensors measure the temperature difference between the two sides of the microheater caused by the effect of acceleration on free convection in the surrounding gas. The devices show a small linearity error of &lt; 0.5% under tilt conditions from −90 to 90 degrees, and &lt; 2% under acceleration from 0 g to 7 g. Sensitivity of the devices is also a nearly linear function of heater power (temperature). Sensitivity of up to 115 μV/g was measured for thermopile configuration, and up to 185 μV/g for thermistor configuration. Both types of devices are operable up to frequencies of several hundred hertz.