Piezoresistive Angle Feedback Sensors With Various Schemes in MEMS Micromirrors

In recent years, the rapid development of Micro-Electro-Mechanical System (MEMS) technology has facilitated the widespread application of MEMS micromirrors in various precision instruments owing to their exceptional optical control capabilities. Meanwhile, the demand for increased accuracy in micromirror control has also grown steadily. This paper evaluates three distinct piezoresistive schemes for angle feedback in MEMS micromirrors, aiming to elucidate their key advantages and limitations while providing guidance for high-accuracy scheme selection. The comparison is based on the piezoresistive behavior of single-crystal silicon under identical n-type doping conditions. The angle feedback sensor is integrated into a custom-designed 1D MEMS electromagnetic micromirror, which features a multi-layer stacked assembly and a moving-magnet driving scheme. The peak-to-peak voltage (Vpp) in the feedback signal is comprehensively analyzed, and the rarely explored DC offset drift is also explicitly discussed. Experimental results reveal that the Wheatstone scheme provides the highest angle feedback sensitivity, measured at 6.96 mV/(V<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $</tex-math> </inline-formula>deg), while the four-terminal scheme exhibits the most stable DC offset drift, with a maximum of only 0.137 mV over the entire test period. [2024-0211]