Influence of Wire-Connecting With Ni Electro-Plating on GMI Output Stability of Co-Rich Amorphous Microwires

We present systematic studies on the effect of Ni electro-plated wire-connecting technique on giant magneto-impedance (GMI) output stability of melt-extracted amorphous CoFeSiB microwires for potential sensor applications. The electro-plated microstructure was observed by scanning electron microscopy (SEM) and the GMI output stability was characterized by a precision impedance analyzer and a magnetically shielded space. Experimental results indicated that Ni electro-plating (at 4.0 A/dm² for 230 s) caused the microwires to show homogeneous pyramid structures, better wettability and weldability, so improving the GMI output for reducing the RF wave emission and signal attenuation, minimizing the disturbance of stray capacity, and suppressing the destabilization and concussion at relatively high frequency, especially near RLC parallel resonance frequency, fp. Moreover, the wire-connecting by Ni electro-plating could enhance the GMI output stability under different applied magnetic fields and frequencies. It can therefore be concluded that the microwires with Ni electro-plated two-terminal are suitable as stable GMI sources of high-resolution magnetic sensors.