Analysis and comparison of the performance of MEMS fluxgate sensors with permalloy magnetic cores of different structures

This paper presents four MEMS fluxgate sensors which were fabricated with same processes but with magnetic cores of different structures. Thick photoresist-based UV lithography and electroplating were adopted in the fabrication of the fluxgate sensors. Solenoid coils used as excitation and sensing elements were made of copper, whereas the magnetic core material was permalloy. Polyimide was used to support the structures of the sensors. An electronic testing system based on the second harmonic principle was established to characterize the fabricated devices. Each sensor was tested with the excitation coils being excited by a sine waveform current whose frequency was 100 kHz. From these experiments we can obtain some information about how the magnetic core structures affecting the magnetic field measuring performance of the fluxgate sensors, which might make some contribution to the performance improvement and miniaturization of fluxgate sensors.

► Fluxgate sensors with cores of different structures are designed and fabricated. ► The effect of the core structures on the performance of fluxgate sensors was studied. ► The performances of the sensors were characterized and compared with each other. ► Multi-ring and spiral core can be used to improve the sensitivity of fluxgate sensor.