A Flexible Wireless Sacral Nerve Stimulator Based on Parity-Time Symmetry Condition

Lower urinary tract dysfunction (LUTD) has a great effect on patients' daily life and mental health. Currently, the most mature invasive treatment is sacral neuromodulation (SNM) that needs to be implanted into buttocks and work for 1-2 years. However, most existing SNM stimulators use disposable batteries with a limited lifespan. And existing stimulators are rigid and lack biomechanical compatibility. To address the above problems, wireless power transferring (WPT) is proposed for SNM based on parity-time (PT) symmetry principle to meet buttocks application requirements, where has thick fat and skin tissue. The receiver coil in the SNM stimulator is designed to be as small and flexible as possible to fit implantation. PT technology allows for efficient and stable wireless power transmission without being significantly affected by the misalignment and bending caused by body movement and can penetrate 15 mm fat-skin tissue and achieve 78% transmission efficiency. Furthermore, the flexible wireless sacral nerve stimulator is developed, and the effectiveness of the system is verified. The system could potentially reduce patient discomfort because the implanted device is flexible and can output a stable voltage stimulation signal.