Abstract
This study presents a magnetostrictive type inductive sensing transducer which consisted of a planar coil, magnetic films, and a force supporting structure. As the force supporting structure deformed by an external load, the inverse magnetostriction effect would cause permeability changes of the magnetic films. Thus, the permeability changes as well as the external load can be detected by the inductance change of a planar inductor. To demonstrate the feasibility of the proposed transducer, pressure sensor designs which include the pressure supporting diaphragm, the planar coil and the patterns of magnetic films are fabricated and tested. Preliminary measurements show that the pressure sensor with 6 coil turns has sensitivities of 0.079%/kPa. In addition, based on the pattern design of the magnetic films, the gauge factor could be tuned from 55 to 852. Moreover, the wireless sensing capability of the magnetostrictive type inductive sensing CMOS-MEMS pressure transducers are also demonstrated using the post CMOS process. Metal and dielectric layers of CMOS process are employed to form the planar coil and the pressure supporting diaphragm, respectively. An additional magnetostrictive film was patterned by the post CMOS process. This study further proposes a new process scheme to fabricate a polymer structure with embedded metal on the silicon substrate. Based on the proposed scheme, a magnetostrictive type flexible tactile transducer consisting of a polymer structure with embedded Ni coil winding is successfully exploited.