Temporal Interference Wireless Power Transfer Strategy With Passive Flexible Electrode for Vagus Nerve Stimulation

The existing vagus nerve stimulation (VNS) implant devices face the challenges of energy depletion and space constraints. To address these issues, we propose a novel strategy featuring the integration of temporal interference (TI) into a wireless power transfer (WPT) model, thereby creating a TI magnetically coupled resonant (MCR) differential frequency WPT approach. We further designed an implantable flexible passive VNS electrode using a serpentine interconnection structure. In this strategy, the flexible electrode serves a dual role as both a differential frequency WPT receiver coil and a VNS electrode. The control of the WPT system parameters allows for a corresponding low-frequency envelope alternating current to be coupled within the flexible electrode. This enables electrical stimulation of the vagus nerve at varying frequencies and intensities. We validate our proposed model using numerical calculations and experiments. Flexible electrodes were tested in three environments with different impedance parameters: air, tissue-simulating liquid, and fresh pork. When the electrode inside fresh pork was put in the middle of two transmitting coils and 10-cm away from the transmitting coil, the minimum induced current in the electrode made it to 3.35 mA. The results affirm the effectiveness of the TI MCR differential frequency WPT model paired with passive flexible electrodes for VNS. This new strategy could potentially advance the development of vagus nerve modulation technology.