Highly sensitive sensors for strain or stress measurements are of increasing interest for industrial applications in areas like automotive, aerospace, process control, automation and biotechnology. In comparison to classical metallic or piezoresistive strain gauges, magnetostrictive thin film sensors show a higher sensitivity, almost no substrate limitations, and allow the fabrication of small sensor elements. Furthermore, the LC circuit sensor design allows wireless operation using either radar reflectivity or inductive coupling. Inverse magnetostriction (Villari effect) is a powerful transducer mechanism for strain sensors. As a result of the inverse magnetostriction the orientation of the magnetic domains changes in response to an applied strain. An illustration of this mechanism is given in Fig. 1. The figure shows domain rotation of small FeCoBSi discs on a Si substrate. The stress was applied perpendicular to the initial domain orientation and increased from left to right. The sense of the rotation is determined by the sign of both the magnetostriction and the strain and by the initial magnetic domain pattern. In materials with positive magnetostriction the saturation domain orientation will be preferably parallel or antiparallel to the direction of the tensile strain, while compressive strains will induce a perpendicular domain pattern. This relationship is reversed for materials with negative magnetostriction. In combination with other effects this change of the domain pattern can be transferred into an electrical signal. The rotation of the domains influences e.g. the magnetic permeability of the magnetostrictive material as shown in a VSM measurement in Fig. 2. This change in permeability can also be detected by impedance- 1,2) or inductivity measurements. 3)