  We report on a flow velocity measurement technique based on snap-through
detection of an electrostatically actuated, bistable micromechanical beam. We
show that induced elecro-thermal Joule heating and the convective air cooling
change the beam curvature and consequently the critical snap-through voltage
($V_{ST}$). Using single crystal silicon beams, we demonstrate the snap-through
voltage to flow velocity sensitivity of $dV_{\text{ST}}/du \approx0.13$ V s
m$^{-1}$ with a power consumption of $\approx360\; \mu$W. Our experimental
results were in accord with the reduced order, coupled,
thermo-electro-mechanical model prediction. We anticipate that
electrostatically induced snap-through in curved, micromechanical beams will
open new directions for the design and implementation of downscaled flow
sensors for autonomous applications and environmental sensors.
