MEMS resonators actuated by TbCo/FeCo Nanotructured Magnetostrictive Multilayers in Liquid Environment

摘要

This paper presents a novel type of remote chemical or bio-sensor based on the use of a multilayered (TbCo/FeCo)×25 nanostructured magnetostrictive film for the actuation of the MEMS structures. This film is polarized by a static magnetic field to induce a magnetic instability called Spin Reorientation Transition. Under these conditions, the deposited material shows a giant sensitivity to a dynamical actuation magnetic field. The advantages of this technique are remote actuation and sensing, and high frequency capability. The structure consists of a silicon cantilever packaged in a PDMS chip. The structure bears on its top the liquid to analyze and is bending over an air bubble. Presented results show a high efficiency of the actuation method in liquid environment, and a quality factor of 30. This value is high compared to other equivalent structures, thanks to the limitation of the viscous losses due to the presence of an air bubble under the resonator. Sensing results in different viscosity solutions are presented. The possibility of use of such a device for the fast determination of cellular density is demonstrated.