CMOS Chemical Microsensors Based on Resonant Cantilever Beams

We present a chemical gas sensor based on a resonating cantilever beam in CMOS MEMS technology. The sensor is actuated employing electrothermal actuation. Thus, for a 300 μ m long beam vibration amplitudes of 6.5 nm per mW heating power are achieved. The vibrations are detected with piezoresistors in a Wheatstone bridge scheme. Detection sensitivities above 200 μ V per mW heating power are measured with the bridge biased at 5 V. The beams have quality factors of up to 600. The static power dissipation that goes along with the electrothermal actutation scheme leads to a small temperature elevation of 0.3 K/mW of the sensitive area.