Thermal drift in convective micromachined accelerometers

A convection-based micromachined accelerometer without moving elements has previously been developed and reported. Significant features of this class of accelerometer include low cost and the combination of high sensitivity with high survivability. However, one of its big disadvantages is thermal drift: the sensitivity changes rapidly as the ambient temperature changes. A recent numerical and experimental study has shown that the sensitivity of the convective accelerometer is a function of the Rayleigh number of the working fluid. The Computational Fluid Dynamics program `FLOTRAN' is used to model the accelerometer performance using each of these fluids. Based on FLOTRAN modeling, some fluids are selected for experimental investigation. The thermal drift of the accelerometer using different working fluids is documented and the reasons for this thermal drift determined. Based on this observation, some possible solutions are proposed to reduce or eliminate the thermal drift.