Electronic On-skin Compass for Magnetoception and Interactive Devices

Flexible electronics has inspired novel concepts like electronic skins [1-3] equipped with e.g. pressure [4] and temperature [5] sensing capabilities, which could potentially replicate the 5 empirical senses of humans. Very recently, magnetosensitive skins [6-8] enabled by shapeable magnetoelectronics [9] were reported, allowing humans to perceive magnetic fields, which is beyond the senses developed during the evolution.

Magnetoception for humans, i.e., the ability to detect and respond to magnetic fields, has been a subject of debate and dreams since the early days of navigation when sailors used compasses to orient themselves with respect to earth’s magnetic field. Sailors of old times often had compass rose tattoos to “enable” magnetoception, assuring success and luck in their trips [10,11].

Here, we present a technology platform to turn these dreams into a functional on-skin compass system. The highly compliant compasses are prepared on 6-µm-thick polymeric foils and rely on the anisotropic magnetoresistance (AMR) effect in magnetic thin film sensors. The response of these sensors is tailored to be linear and possess maximum sensitivity around the earth’s magnetic field by using a barber pole [12] configuration and preconditioned via a Wheatstone bridge arrangement. In a barber pole configuration, conductive slabs with a 45 degrees tilt are fabricated on top of Permalloy sensing stripes to force the current to flow skewed with respect to the easy axis of the stripes. By defining the tilt angle and properly adjusting the inter-slab separation, the magnetic field dependence of the AMR on the stripes becomes even and linear around zero.

We envision that this on-skin compass can enable humans to electronically emulate the magnetoceptive sense which some mammals possess naturally [13]. Thereby, allowing us to orient ourselves with respect to earth’s magnetic field ubiquitously. This feat could open new possibilities to support research efforts on biomagnetic orientation and novel magnetic interactive devices. In the latter case, the applications span a plethora of tasks from virtual or augmented reality systems to touchless security systems and magnetic tags.

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