Wireless nonresonant stimulation of neurons on a magnetoelectric film surface.

Wireless neural interfaces are emerging as a minimally invasive treatment option for neurological disorders. Among the wireless technologies, magnetically powered systems are effective for targeting deep brain sites. However, dependence on high-frequency electromagnetic fields in such systems limits their safe implementation. In this study, we demonstrate the use of millimeter-scale magnetoelectric (ME) films as a direct neural interface for wireless neurostimulation, powered by static and alternating magnetic fields in the nonresonant regime (10 hertz). To accomplish this objective, electrical potential trends of the ME films under varying low-frequency magnetic fields are investigated and used to demonstrate neural stimulation by calcium imaging on primary neurons in vitro via a capacitive-like charge injection mechanism. In addition, electrical polarization orientation is revealed as a critical design parameter in direct neuron-ME interfaces. These findings collectively demonstrate the potential of nonresonant powering of ME films as a promising minimally invasive wireless neural stimulation technique.