A novel magnetic-induced capacitive-sensing rotation sensor

This study presents a novel sensor to detect the angular motion (both in-plane and out-of-plane) of an object using the capacitance change induced by magnetic field. The magnet-sensitive NdFeB powder is well mixed with liquid Glycerol, and then dispensed into a cavity on silicon chip. The parylene C film is deposited to seal the cavity with NdFeB/Glycerol mixture [1]. Nevertheless, the NdFeB powder remains free to move inside the Glycerol. As the chip approach a rotating magnetic field, each NdFeB powder will spin in such field and lead to the capacitance change of the sensor. This study has implemented the presented sensor, and typical measurement show that a 100 to 300rpm/140Gauss magnetic field has been successfully detected by the sensor with capacitance varying from 0.023pF to 0.016pF.