Magnetostrictive type inductive sensing pressure sensor

This study presents a magnetostrictive type inductive sensing pressure sensor which consisted of a planar coil, CoFeB magnetic films, and a Si diaphragm. As the Si diaphragm deformed by a pressure load, the inverse-magnetostriction effect would cause permeability changes of the CoFeB magnetic films. Thus, the permeability changes as well as the pressure load can be detected by the inductance change of a planar inductor. To demonstrate the feasibility of the proposed pressure sensor, the planar inductor designs of different coil turns and in-plane patterns of magnetic films are fabricated and tested. Preliminary measurements show that the pressure sensors with 6 and 12 coil turns have sensitivities of 0.079 %/kPa and 0.064 %/kPa, respectively. In addition, based on the in-plane pattern design of the magnetic films, the gauge factor could be tuned from 55 to 852.