Microfabrication of magnetostrictive beams based on NiFe film doped with B and Mo for integrated sensor systems

Abstract

This paper reports the development of integrated micro-sensors consisting of 1 -µm-thick magnetostrictive cantilevers or bridges with 500 µm in length and conducting interrogation elements. The thin films are fabricated by sputter deposition of NiFe doped with B and Mo, and the magnetic properties are enhanced by field annealing, resulting in a coercivity of 2.4 Oe. In operation, an alternating current applied to the interrogation elements magnetizes the magnetostrictive structures. The longitudinal resonant frequency is detected as an impedance change of the interrogation elements. The magnetostrictive micro-beams provide high resonant frequencies—2.95 MHz for the cantilever and 5.46 MHz for the bridge—which can be exploited to develop sensors of high sensitivity.

Magnetostrictive effect in micro-dotted FeCo film coated surface acoustic wave devices

“…Magnetostrictive composites are a class of functional materials which can convert electromagnetic energy into mechanical energy and vice versa, and very promising for sensors and actuators with excellent performance [1][2][3][4][5][6][7][8]. Interestingly, higher magnetic sensitivity of the magnetostrictive thin-film and fast response towards external perturbation of the surface acoustic wave (SAW) devices makes them to be a good candidate of exploiting magnetic field sensing.…”