FeCoSiBアモルファス薄膜を用いた高感度歪センサ  [in Japanese] Highly Sensitive Strain with FeCoSiB Amorphous Films  [in Japanese]

Amorphous FeCoSiB films with high saturation magnetostriction and excellent soft magnetic properties were studied to determine their strain sensitivity. The films were subjected to strain by bending of their substrates, which caused a change in the magnetic anisotropy of films via magnetoelastic coupling. The films exhibited a figure of merit F=(∂μ/∂ε)/μ (change in film permeability μ per unit of strain ε) of 1.2×10^5, which is comparable to that of amorphous ribbons. To study the use of the magnetostrictive films as strain sensor elements, we prepared meander-patterned films by means of the photolithograpy and ion milling processes. The impedance change in the patterned films when strain was applied was measured in the frepuency range from 1 MHz to 1 GHz. Reflecting the large value of F, the high-frequency impedance of the films was changed considerably: a change in impedance of 46% was observed at 100 MHz when a strain of 300×10^<-6> was applied. It is also demonstrated that, by using the straindependent impedance,a small strain of 1×10^<-7> can be detected by means of the film pattern.