Artificial magnetoception is a new and yet to be explored path for humans to interact with the surroundings. This technology is enabled by thin film magnetic field sensors embedded in a soft and flexible format to constitute magnetosensitive electronic skins (e-skins). Being limited by the sensitivity to in-plane magnetic fields, magnetosensitive e-skins are restricted to basic proximity and angle sensing and are not used as switches or logic elements of interactive wearable electronics. Here, a novel magnetoreceptive platform for on-skin touchless interactive electronics based on flexible spin valve switches with sensitivity to out-of-plane magnetic fields is demonstrated. The technology relies on all-metal Co/Pd-based spin valves with a synthetic antiferromagnet possessing perpendicular magnetic anisotropy. The flexible magnetoreceptors act as logic elements, namely momentary and permanent (latching) switches. The switches maintain their performance even upon bending to a radius of less than 3.5 mm and withstand repetitive bending for hundreds of cycles. Here, flexible switches are integrated in on-skin interactive electronics and their performance as touchless human-machine interfaces is demonstrated, which are intuitive to use, energy efficient, and insensitive to external magnetic disturbances. This technology offers qualitatively new functionalities for electronic skins and paves the way towards full-fledged on-skin touchless interactive electronics.

Magnetic nanocomposites (NCs) are extremely appealing for a wide range of energy-related technological applications, specifically as building blocks for next-generation permanent magnets. The design of such nanostructures requires precise chemical synthesis methods, which will permit the fine-tuning of the magnetic properties. Here we present an in-depth structural, morphological and magnetic characterization of ferrite-based nanostructures obtained through a bottom-up sol−gel approach. The combination of the high coercivity of a hard phase SrFe 12 O 19 (SFO) and the high saturation magnetization of a soft phase, CoFe 2 O 4 (CFO), allowed us to develop exchange-coupled bimagnetic NCs. A symbiotic effect is observed in a SFO/CFO nanocomposite, as the unique oriented growth of SFO prevents grain growth of the CFO, thus restricting the crystallite size of both. Through X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), and magnetic measurements we clarify the relationship between the distribution and size of hard/soft particles, the optimization of interfaces and the obtained uniform magnetic response. This study allowed us to establish the potentiality of hard/soft SFO/CFO nanostructures in current permanent magnet technology.

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