Magnetic Field Detection Unit Based on Composite Structure of Magneto-Sensitive Elastomer and Velostat

Magneto-sensitive elastomer (MSE) samples were fabricated by dispersing carbonyl iron particles into a rubber matrix. Velostat, which can be regarded as a pressure-sensitive material with piezoresistive properties, and the prepared MSE were selected to design a composite structure, referred to as a magnetic field detection unit (MFDU). The magneto-induced properties of the MFDU were investigated by using a self-built experimental system, and the effect of the constant and dynamic magnetic fields were studied. This MFDU can generate an output voltage signal in response to the magneto-induced resistance using an external DC power supply. It was found that the relationship between the normal force of the MSE and the magnetic field, and the resistance of Velostat can be changed by the magneto-induced normal force in the MFDU. The experimental results also proved that the output voltage of the MFDU is almost linearly dependent on the constant magnetic field and exhibits loading and unloading hysteretic time of about 20 ms and 40 ms, respectively, for the magnetic-induced output under a step magnetic field. Moreover, the obvious frequency-dependent output amplitude was observed under a pulsed magnetic field, and the possible mechanism for the magneto-sensitive performance of the MFDU was proposed and analyzed. The MFDU exhibited a stable response and good magneto-sensitive performance, which provides an approach for detecting external magnetic field.