Flow Sensor Based on the Snap-Through Detection of a Curved Micromechanical Beam

We report on a How 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 How velocity sensitivity of dV
_ST
/du ≈0.13 Vsm
^-1
with a power consumption of 360 μW. 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 How sensors for autonomous applications and environmental sensors.