High-performance giant magnetoresistive sensorics on flexible Si membranes

We fabricate high-performance giant magnetoresistive (GMR) sensorics on Si wafers, which are subsequently thinned down to 100 mu m or 50 mu m to realize mechanically flexible sensing elements. The performance of the GMR sensors upon bending is determined by the thickness of the Si membrane. Thus, bending radii down to 15.5mm and 6.8mm are achieved for the devices on 100 mu m and 50 mu m Si supports, respectively. The GMR magnitude remains unchanged at the level of (15.3 +/- 0.4)% independent of the support thickness and bending radius. However, a progressive broadening of the GMR curve is observed associated with the magnetostriction of the containing Ni81Fe19 alloy, which is induced by the tensile bending strain generated on the surface of the Si membrane. An effective magnetostriction value of lambda(s) = 1.7 x 10(-6) is estimated for the GMR stack. Cyclic bending experiments showed excellent reproducibility of the GMR curves during 100 bending cycles