Optimization of the coupling between piezoresistivity and magnetoelasticity in an elastomagnetic composite to sense a spatial gradient of the magnetic field

Elastomagnetic samples made of quasi-ellipsoidal nickel microparticles separated by a thin silicone layer were produced. A static magnetic field was applied during the process of sample solidification, obtaining a preferred orientation of the particles major axis through the coupling of the magnetic moment with the easy magnetization axis. The influence of the particle pre-orientation on the elasticity, piezoresistivity and magneto-piezoresistivity were investigated and discussed in order to maximize the resistance change due to a moderate magnetic field gradient, in view of conceiving an innovative core material for sensor devices. It was shown as the relative change of resistance induced by a low magnetic field gradient can be improved of over 15% in comparison with previous results, approaching an absolute value of the magneto-piezoresistive ratio equal to 80%. Since a local magnetic field change can be also produced by a displacement of a magnetic body, in perspective the effect can be applied for sensing position or mechanical vibration too.