Estimating the Sensitivity of Microoptoelectromechanical Micro-g Accelerometer

The article studies a MOEMS-accelerometer with an optical measuring element based on an optical tunneling effect intended for measuring micro-g accelerations. The work estimates the sensitivity threshold of the accelerometer based on the Noise Equivalent Acceleration, which is stipulated by thermal Brownian motion of molecules, noises of a laser and photodiode. Shot noise has the largest effect on the MOEMS-accelerometer noise threshold and depends on its mechanical properties. The general sensitivity of the MOEMS-accelerometer equals 0.938, 3, or 6.255 A/g, depending on a chosen operational point. The sensitivity threshold in terms of photodiode dark current equals $107 \times 10^{-9} \mathrm{g}, 33.3 \times 10^{-9} \mathrm{g}$, $16 \times 10^{-9} \mathrm{g}$. The dynamic range for the photodiode equals $\pm 3.2 \times 10^{-3} \mathrm{g}$, while for the measuring transducer it is ±0.32g, ±0.1, or ±0.05g. To decrease the noise down to $0.1 \mu \mathrm{g}$, the inertial mass should amount at least to $65 \times 10^{-7} \mathrm{kg}$, and the average laser noise power should be below 1 %.