Active microcantilevers based on piezoresistive ferromagnetic thin films

We report the piezoresistivity in magnetic thin films of $Fe0.7Ga0.3$ and their use for fabricating self-transducing microcantilevers. The actuation occurs as a consequence of both the ferromagnetic and magnetostrictive properties of $Fe0.7Ga0.3$ thin films, while the deflection readout is achieved by exploiting the piezoresistivity of these films. This self-sensing self-actuating micromechanical system involves a very simple bilayer structure, which eliminates the need for the more complex piezoelectric stack that is commonly used in active cantilevers. Thus, it potentially opens opportunities for remotely actuated cantilever-based sensors.