A micro-LC-resonator fabricated by MEMS technique for high-frequency sensor applications

A novel magnetic LC-resonator for micromagnetic sensor devices was fabricated by means of microelectromechanical system (MEMS) technique. The micro-LC-resonator consists of a solenoidal microinductor with a bundle of annealed soft magnetic Co83.2B3.3Si5.9Mn7.6 microwires as microcore and a capacitor connected in parallel to the microinductor. The dimensions of solenoidal microinductors fabricated by MEMS technique were 500-1000 μm in length with 10-20 turns. Because the permeability of the microcore is changing rapidly as a function of external magnetic field, the inductance of the microinductors can change drastically according to the external magnetic field. Therefore, the resonance frequency as well as the impedance of a micro-LC-resonator can be sensitively altered as the external magnetic field changes. The maximum magnetoimpedance ratio value for a micro-LC-resonator was reached as much as 500%. The impedance change of the LC-resonator can be greatly enhanced by selecting operating frequencies at near the resonance frequency.