A MEMS-Based Sensor System Towards Combined Magnetic Field and Movement Detection

This paper presents a novel MEMS and ASIC-based sensor system for simultaneous detection of magnetic fields and patient movement. The prototype system integrates a three-channel current-reuse amplifier and three MEMS cantilevers on independent PCBs. The amplifier, fabricated in 350 nm CMOS technology, exhibits a closed-loop gain of 10 V/V, a low power consumption, and a noise floor of 18 $\text{nV} / \sqrt{\text{Hz}}$. In combination with three MEMS cantilevers (3 mm x 1 mm) in a 3D-configuration this setup is able to detect vibrations and movement. The cross-axis sensitivity of this setup was measured as 20% for one directional vibration on a shaker. The system successfully detected the 3D-acceleration of human footsteps.