An Implantable Wireless Charger System with ×8.91 Increased Charging Power Using Smartphone and Relay Coil

Implantable biomedical devices are spotlighted as promising diagnostic and treatment solutions for chronic diseases providing continuous management. In order to expand its applications, wireless charging technology is essential in that it can significantly reduce the system volume without additional surgery for battery replacement for decades. However, current implantable devices require a dedicated wireless charger optimized for a specific device, which is cumbersome in terms of cost and convenience. Here, we propose a highly efficient wireless charging solution for the implantable biomedical devices using a common smartphone without any physical modifications. To achieve high power transfer efficiency, we adopt a relay coil and an impedance matching technique, enhancing the amount of power transferred to a great extent. With these approaches, we have shown that the battery charging power was remarkably increased by ×8.91 at an implant depth of 1cm. All these measurements were achieved with a Samsung Galaxy Note 10 as a wireless power transmitter. Based on our measurement results, it (b) is highly expected to broaden user experience and contribute to the rapid growth of the implantable biomedical device market as well as provide huge potential to fuse the mobile electronics and medical devices.