Highly compliant planar Hall effect sensor with sub 200 nT sensitivity.

Granell, Pablo Nicolás; Wang, Guoliang; Cañon Bermudez, Gilbert Santiago; Kosub, Tobias; Golmar, Federico; Steren, Laura; Fassbender, Jürgen; Makarov, Denys

Being a facet of flexible electronics, mechanically reshapeable magnetic field sensorics enable novel device ideas for soft robotics, interactive devices for virtual- and augmented reality and point of care diagnostics. These applications demand mechanically compliant yet robust sensor devices revealing high sensitivity to small magnetic fields. To push the detection limit of highly compliant and linear magnetic field sensors to be in the sub-µT range, we explore a new fundamental concept for magnetic field sensing, namely the planar Hall effect in magnetic thin films. With their remarkable bendability down to 1 mm, these compliant planar Hall effect sensors allow for an efficient detection of magnetic fields as small as 200 nT with a limit of detection of 20 nT. We demonstrate the application potential of these devices as a direction (angle) as well as proximity (distance) sensors of tiny magnetic fields emanating from magnetically functionalized objects. With their intrinsic linearity and simplicity of fabrication, these compliant planar Hall effect sensors have the potential to become a standard solution for low field applications of shapeable magnetoelectronics in point of care applications and on-skin interactive electronics. Highly sensitive compliant magnetic field sensor joins family: Magnetic field sensors are useful in remote sensing and now they are made more compliant and sensitive to meet the requirement for on-skin electronics. A group of international researchers led by Dr Denys Makarov from Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden, Germany developed flexible and highly sensitive magnetic field sensors relying on planar Hall effect. The key idea is to make Hall bar devices on thin polymer foils which enables superior detectivity below 200 nT while maintaining sensitivity on par with their rigid counterparts. Remarkably, the devices show no degradation in its electrical resistance or linearity behavior upon repeated bending. Based on these highly robust and compliant devices, they demonstrate direction and distance sensors of magnetically functionalized objects, which complement electronic and pressure sensors well and hold great potential for conformal low-field applications.

SOFT robotics; HALL effect transducers; MAGNETIC properties of thin films; FLEXIBLE electronics; AUGMENTED reality

NPJ Flexible Electronics, 2019, Vol 3, Issue 1, pN.PAG

2397-4621

Academic Journal

10.1038/s41528-018-0046-9