Design of a novel millimeter size wireless electrical stimulator and its targeting effect on the Schaffer-CA1 pathway in rat hippocampus

Traditional tethered nerve implants have many limitations since they rely on physical wires for power and signal transmission. Wireless stimulation technology can promote the exploration of neurological diseases and meet patient requirements, stemming from its portability and efficiency. In this paper, the link transmission characteristics of a sub-millimeter inductor are investigated by simulation, electrical tests, and theoretical analysis. The inductor acts as the receiving coil of a wireless stimulation device, and the wireless energy transmission process based on magnetic induction coupling is analyzed. Second, a novel millimeter-scale wireless stimulator device for neuromodulation is designed based on the parameters of transmitting and receiving coils obtained from the simulation. Finally, rat electrophysiological experiments are conducted to assess the feasibility of the device. The field Excitatory Post Synaptic Potential baseline is first recorded in the CA1 radiation area for 10 min, followed by the addition of high-frequency stimulation, and after successful induction of long-term potentiation (LTP) and recording for 10 min, the two coils are fixed at a distance of 1 cm and the hippocampal Schaffer-CA1 pathway is added. The experimental results show that the addition of wireless stimulation can modulate the transmission of synaptic electrical activity in the hippocampal Schaffer-CA1 pathway and significantly increase the level of (LTP) induction. A millimeter-scale wireless stimulation device is investigated and designed in this paper, the feasibility of the device is demonstrated through ex vivo electrophysiological experiments, and its effects on the targeted modulation of the Schaffer-CA1 pathway in the rat hippocampus are described.