Development of an efficient mid-field wireless power transmission system for biotelemetric IoT medical devices

Abstract

Wireless power transfer (WPT) technology facilitates Internet of Things medical devices (IoTMDs) for healthcare monitoring by providing reliable, continuous, and non-invasive power sources. This paper presents an efficient WPT system featuring a flexible receiver (Rx) antenna integrated with an efficient rectifier and a flexible transmitter (Tx) antenna operating in the midfield band of 1.5 GHz. The implantable Rx antenna has a small footprint with a volume of 4.9 mm3 and can be easily fitted within miniaturized IoTMDs. Extensive simulations and measurement analyses were performed to validate the versatility of the system. The Rx antenna exhibited a measured − 10 dB bandwidth of 130 MHz (1.43–1.56 GHz), whereas the rectifier demonstrated a peak measured efficiency of 80% at an input power of 0 dBm. The flexible and conformal nature of the Tx facilitates wireless power transmission by enhancing comfort and coupling to nonplanar body surfaces. Remarkably, the system yielded a measured transmission coefficient (|S21|) of − 22.5 dB at a distance of 51 mm without the use of any additional intermediate structures, such as matching layers, metamaterials, and metasurfaces. For safety reasons, the specific absorption rate was analyzed and confirmed to be within acceptable limits. Furthermore, real-time wireless power transmission capabilities and the potential for operating IoTMDs were demonstrated. In this demonstration, the rectenna’s output was used to power an IoTbased temperature sensor-integrated communication module, showcasing the real-time functionality and capability of the proposed WPT system for wirelessly powering IoTMDs.