Magnetoelectric Metamaterials for Remote Control of Neural Activity

Magnetoelectric materials have applications in wireless data transmission, electronics, sensing, data storage, and biomedical applications. Recently there has been interest in using magnetoelectric materials for direct neuromodulation, but existing magnetoelectric materials struggle to provide millisecond-precision remote stimulation due to the high resonant frequencies of magnetoelectric materials. Here we discuss how we can engineer composite materials that display magnetoelectric properties not found in nature including magnetoluminescence and strong non-linear magnetoelectric coupling. These meta-atoms have magnetic coupling that enables precise activation of nerves and remote control of cell activity.<br/><br/>Specifically, we introduce the concept of self-rectifying magnetoelectric metamaterials (MNMs) that rely on nonlinear charge transport across semiconductor layers in a trilayer laminate consisting of a piezoelectric layer and two magnetostrictive layers. This innovation enables us to generate arbitrary electrical pulse sequences with a time-averaged voltage exceeding 2 V. Consequently, we can remotely stimulate peripheral nerves with repeatable latencies of less than 5 ms, a significant improvement over previous neural stimulation approaches relying on magnetic materials. This achievement holds promise for applications requiring fast neural signal transduction, such as sensory or motor neuroprosthetics.<br/><br/>Our work showcases the potential of rational design to introduce nonlinearities into the magnetic-to-electric transduction pathway, opening doors to diverse MNM designs tailored for applications spanning electronics, biotechnology, and sensing. Ultimately, this breakthrough in remote neural stimulation can be used for medical therapies, facilitating less invasive treatments and advancing neuroscience research in freely behaving animals.