In-plane MEMS-based nano-g accelerometer with sub-wavelength optical resonant sensor

We have successfully demonstrated a series of results that push the limits of optical sensing, acceleration sensing and lithography. Previously, we built some of the most sensitive displacement sensors with displacement sensitivities as low as 12 fm/Hz at 1kHz. Using reference detection circuitry in conjunction with correlated double sampling methods, we lowered the 1/f noise floor to 10mHz, hence improving the detection limit at low frequencies (10mHz) by 77dB to 50 fm/Hz. We converted these highly sensitive displacement sensors to highly sensitive acceleration sensors through a direct mass integration processes. Our accelerometers have resonant frequencies as low as 36Hz and thermal noise floors as low as 8 nG/Hz (where 1G=9.8m/s2). We have pushed the limits of shaker table experiments to independently verify acceleration measurements as low as 10 μG/Hz. Direct measurements with our integrated sub-wavelength optical nano-grating accelerometers have shown device sensitivities of 590V/G and noise floors corresponding to 17 nG/Hz (at 1Hz).