Designs of planar sensing inductor on inverse-magnetostrictive type pressure sensor

This study presents a pressure sensor design which consisted of the planar coil and CoFeB magnetic films. As the Si diaphragm deformed by pressure load, the magnetostriction effect of magnetic film will cause the permeability change of CoFeB. Thus, the permeability change as well as the pressure load can be detected by the inductance difference of the planar inductor. The proposed magnetostrictive pressure sensor with planar sensing inductor had been implemented and tested in the previous work. In this study, the design of planar sensing inductor is further investigated and reported. Based on the design modification of planar sensing inductor, such as coil turns or the geometry of magnetic film, the sensitivity could be improved successfully. Preliminary measurements demonstrate a high gauge factor of near 850 can be achieved through the inverse-magnetostrictive type pressure sensor.