An Implantable In‐Hydrogel Wireless Supercapacitor‐Activated Neuron System Enables Bidirectional Modulation

The bidirectional modulation of cerebral neurons in the brain possesses enhancement and inhibition of neural activity, which is of great interest in the treatment of motor nerve disorders and emotional disorders, and cognitive defects. However, existing approaches usually rely on electrical/electrochemical stimulations, which show low security by implanting metal probes and unidirectional currents with single modulation. Herein, an implantable in-hydrogel wireless supercapacitor-activated neuron system consisting of the coil, diode bridge circuit, in-hydrogel supercapacitor, and stimulation electrodes is fabricated, which provides a bidirectional and adjustable ion diffusion current to safely and effectively excite and inhibit brain neurons. The designed in-hydrogel supercapacitor exhibits a high storage charge ability of ≈90 times larger than the devices without hydrogel encapsulation, owing to the in situ radical addition mechanism. Moreover, the in-hydrogel electrodes are implanted into the thalamus, amygdala, and prefrontal lobes of the brain to evoke the corresponding changes in potential intensity and frequency through the external chargeable coil and diode bridge circuit, which verifies the potential of the multimodule supercapacitor in amelioration and treatment Parkinson's, severe depression, and Alzheimer's disease.