Soft sonocapacitor with topologically integrated piezodielectric nanospheres enables wireless epidural closed-loop neuromodulation

Capacitively coupled electrical stimulation modulates neuronal activity through reversible charging and without charge transfer reactions. This represents a promising and safe neuromodulation scheme but achieving wireless and high capacitive charge density injection remains challenging. Here, we developed a topological fibrous-architecture sonocapacitor (SonoCap) that assembled from piezoelectric-dielectric composite nanosphere (UCapT) and two-dimensional cellulose. UCapT features a unique piezoelectric core-hollow cavity-dielectric cage structure that can efficiently couples ultrasound excitation to achieve piezoelectric electron-capacitance transfer, and its highly assembled SonoCap achieves cumulative charge storage, a high ion-accessible surface area, and macroscopic softness, thereby enabling wireless and high capacitive charge density injection. SonoCap can achieve a capacitive charge density output of up to 9.7 mC cm^-2 under 0.63 W cm^-2 ultrasound excitation, while generating a negligible Faradaic charge of 2 nC cm^-2. We demonstrated that SonoCap can transcranially and epidurally modulate neural circuit dynamics in rat and pig brains, without introducing intracerebral foreign bodies and maintaining ventricular homeostasis. By integrating a deep learning-based closed-loop diagnostic system, on-demand, wireless, and epidural capacitive electrical stimulation treatment for temporal lobe epilepsy can be achieved. The design concept of SonoCap is expected to inspire expanding development of functional capacitive stimulators, potentially promoting the widespread application of capacitive electrical neuromodulation.