Amorphous wire based GMI microsensor with an arch-like solenoid coil

Amorphous wire sensors have attracted significant attention in the field of weak magnetic detection owing to their extremely high sensitivity. Typically, amorphous wire sensors employ solder for the electrical connection of the magnetically sensitive material and utilize a wire winding machine to wind the signal pick-up coil. However, this method has drawbacks such as low production efficiency, poor consistency, and large size. In this paper, an amorphous wire sensor fabrication scheme based on MEMS (microelectromechanical systems) technology is proposed. The electrical connection of the amorphous wire and the fabrication of the three-dimensional coil are completed by electroplating process, which ensures the consistency of the sensor. Furthermore, polyimide was employed as the support layer in the fabrication of the arch solenoid coil, thereby eliminating the need for high-aspect-ratio pillars and simplifying the overall fabrication process of the three-dimensional coil. Using this method, a miniaturized amorphous wire sensor integrated with an arched solenoid coil was fabricated and tested. The amorphous wire sensor demonstrated good linearity in the range of 0–80000nT, with a sensitivity of 667.5 mV/Oe and a linearity of 99.97 %.