Wearable Magnetic Field Sensor with Low Detection Limit and Wide Operation Range for Electronic Skin Applications

TLDR

Flexible electronic devices extend human perception, and flexible magnetic field sensors are essential for detecting external magnetic field changes, yet current flexible magnetoelectronics lack both low detection limits and large working ranges, limiting their application potential. This work reports a flexible magnetic field sensor with a low detection limit of 22 nT and a wide sensing range from 22 nT to 400 mT. The sensor is built on a cantilever beam that incorporates a flexible permanent magnetic composite and an amorphous magnetic wire, using the anisotropic giant magnetoimpedance effect to detect high magnetic fields. It achieves a seven‑order‑of‑magnitude detection range, improving upon existing flexible magnetic sensors by at least one order, and its mechanical flexibility and broad range make it suitable for geomagnetic navigation, touchless interactivity, rehabilitation, and safety interfaces.

Abstract

Flexible electronic devices extended abilities of humans to perceive their environment conveniently and comfortably. Among them, flexible magnetic field sensors are crucial to detect changes in the external magnetic field. State-of-the-art flexible magnetoelectronics do not exhibit low detection limit and large working range simultaneously, which limits their application potential. Herein, a flexible magnetic field sensor possessing a low detection limit of 22 nT and wide sensing range from 22 nT up to 400 mT is reported. With the detection range of seven orders of magnitude in magnetic field sensor constitutes at least one order of magnitude improvement over current flexible magnetic field sensor technologies. The sensor is designed as a cantilever beam structure accommodating a flexible permanent magnetic composite and an amorphous magnetic wire enabling sensitivity to low magnetic fields. To detect high fields, the anisotropy of the giant magnetoimpedance effect of amorphous magnetic wires to the magnetic field direction is explored. Benefiting from mechanical flexibility of sensor and its broad detection range, its application potential for smart wearables targeting geomagnetic navigation, touchless interactivity, rehabilitation appliances, and safety interfaces providing warnings of exposure to high magnetic fields are explored.