Highly compliant planar Hall effect sensor with sub 200 nT sensitivity

Abstract

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.

A bimodal soft electronic skin for tactile and touchless interaction in real time

“…Our here-developed m-MEMS platform is very general and can be realized based on magnetic field sensors other than those relying on the GMR effect. Concepts including compliant Hall effect 24,39 (sensitive to out-of-plane magnetic fields) and compliant planar Hall effect 40 (sensitive to in-plane magnetic fields) sensors might offer further advantages to m-MEMS platforms. They are linear sensors of magnetic field and also possess high sensitivity to small magnetic fields.…”

Two Orders of Magnitude Boost in the Detection Limit of Droplet-Based Micro-Magnetofluidics with Planar Hall Effect Sensors

“…Further improvement of this conjunction and lower detection limits include optimization of the connecting electronic devices and shielding geometries. Furthermore, utilization of PHE sensors on flexible substrates 68 can greatly improve the system sensitivity since the sensing structures can be brought in very close contact to the rounded tubing. 69 Additionally, the use of nanoparticles with larger magnetization can lead to further improvement in the limit of detection since they will be better aligned in the same magnetic field compared to ferrofluids used in this work.…”

Ultrasensitive Magnetic Field Sensors for Biomedical Applications

“…Magnetometers based on the Hall effect [160] are suitable for the detection of labelled molecules or proteins in point-of-care [161,162] devices due to the low energy costs, ease of use and a detection level limit of the order of 10 nT/ √ Hz [163][164][165]. There are several different geometries of magnetic field sensors based on the Hall effect [166][167][168][169].…”