Development of a Miniaturized BLE-Enabled Transmitter for Wireless Charging of Active Implantable Medical Devices

The growing trend of Active Implantable Medical Devices (AIMDs) usage is driven by notable innovations, with the integration of Wireless Power Transfer Systems (WPTS) taking center stage. These systems, marked by advancements in size reduction and enhanced power efficiency, represent a transformative force in the field of AIMDs. WPTS has transcended traditional boundaries, eliminating the need for impractical wired connections, thereby obtaining new benefits in terms of care and comfort for patients while also enhancing the convenience of patient monitoring and diagnostics for healthcare professionals. At the core of this research domain lies the Nanochannel Delivery System (nDS), a wireless enabled AIMD designed for drug delivery with remote control capabilities. It takes advantage of both Near Field Resonant Inductive Coupling (NRIC) for wireless power transfer (WPT) and Bluetooth Low Energy (BLE) for communication. Specifically, our focus centers on exploiting BLE connectivity for the wireless charging and power development of the nDS, thereby enhancing its interoperability with central devices and facilitating remote monitoring and control. The essence of this thesis revolves around developing a Miniaturized BLE Enabled Transmitter (TX) designed precisely for the wireless charging of nDS. It is important to note that, until now,in vivo testing has been challenging, primarily due to the reliance on a wired power supply for the TX. However, this work marks a turning point, as it enables the realization of in vivo tests. In order to achieve this, one of the main tasks is the migration of the TX into a peripheral role, enhancing the system's Internet of Things (IoT) capabilities. This shift allows us to control not just the receiver (RX) from a central device but also our TX, simplifying the control interface and enhancing the user experience, ensuring non invasive and patient friendly healthcare. Regarding the hardware aspect of the project, our efforts are dedicated to the miniaturization, as well as the custom board development and implementation of a self powering system (SPS) for the TX. The SPS enhances portability and reliability, embarking o n a quest to find the ideal battery. This research includes studying diverse battery options considering different factors such as capacity, chemical composition, maximum charge and discharge rates, and market availability. Additionally, we evaluate the efficiency of voltage regulators and the TX current requirements to guarantee a robust power supply. In order to gauge the TX efficiency, the system was tested in different ways based on a closed-loop control closed via BLE. Different TX sizes and TX coil positions were studied in order to achieve maximum power transfer efficiency, always keeping an eye on the final packaging for device compactness. The final system under test includes commercial wireless power transfer integrated circuits: the LTC4125 fulfilled the role of the TX, while the LTC4124 roles the RX. As in previous studies, the coil with 19mm diameter for the RX has been used, delivering 30\% efficiency at 6.5 mm separations between the RX and TX coils. As regards the SPS, a prototype has been tested, featuring a Buck Converter (TPS82740) generating a 3V output for the TX’s microcontroller (MCU) and a Boost Converter (TPS61023) with a 5V output for the LTC4125. Powering the SPS, a 3.7V Polymer Li ion battery with a capacity of 2000 mAh was selected (SR674361P), ensuring the necessary support for nDS battery charging.