Magnetostrictive GMR sensor on flexible polyimide substrates

The feasibility of a stress sensor based on giant magneto-resi stance (GMR) on a flexible polyimide substrate is presented. Therefore, a stack system with a GMR effect of up to 8.6% has been deposited on a polyimide substrate and patterned to micrometer scaled sensor elements. An in-plane tensile stress was applied to the sensor to achieve a rotation of the anisotropy of the magneto strictive free layer. The magneto-optical and magneto-resistive effect was measured. The stress dependence of the Co50Fe50 free-layer magnetization was measured up to an elongation of 2.5% in a CoFe/Cu/CoFe spin valve. The magneto-optical results are compared to the resistance loops of the sample. Furthermore, the normalized sensor output is shown as a function of the applied stress at several bias fields and at the remanent state. (c) 2006 Elsevier B.V. All rights reserved.