Miniature magneto-oscillatory wireless sensor for magnetic field and gradient measurements

TL;DR

This paper investigates a miniature wireless magneto-oscillatory sensor's ability to measure magnetic fields and gradients with high precision, analyzing mechanical-magnetic interactions and developing a general analytical model for such systems.

Contribution

It provides an experimental analysis and a general analytical model of a sub-millimeter magneto-oscillatory sensor's magnetic interactions, enhancing understanding of its sensing accuracy.

Findings

Detects magnetic fields with sub-μT resolution up to ±5 mT

Measures magnetic field gradients with 65 μT/m resolution up to ±50 mT/m

Develops a general analytical model for magnetic-mechanical interactions

Abstract

Magneto-oscillatory devices have been recently developed as very potent wireless miniature position trackers and sensors with an exceptional accuracy and sensing distance for surgical and robotic applications. However, it is still unclear to which extend a mechanically resonating sub-millimeter magnet interacts with external magnetic fields or gradients, which induce frequency shifts of sub-mHz to several Hz and therefore affect the sensing accuracy. Here, we investigate this effect experimentally on a cantilever-based magneto-oscillatory wireless sensor (MOWS) and build an analytical model concerning magnetic and mechanical interactions. The millimeter-scale MOWS is capable to detect magnetic fields with sub-uT resolution to at least +/- 5 mT, and simultaneously detects magnetic field gradients with a resolution of 65 uT/m to at least +/- 50 mT/m. The magnetic field sensitivity allows direct calculation of mechanical device properties, and by rotation, individual contributions of the magnetic field and gradient can be analyzed. The derived model is general and can be applied to other magneto-oscillatory systems interacting with magnetic environments.