Design and Implementation of Wireless Power Transfer for Wireless Heart Rate Monitoring System

Ultrasonic Power Transfer (UPT) is a technology for wireless power transfer that can be used for medical uses with low power. Batteries are used as power sources for most wearable or portable medical systems. The battery of these systems cannot operate for a long period and need to be charged or replaced from time to time. UPT is a candidate technology that can be adopted to solve this problem. In this paper, UPT operates at a 40-kHz ultrasound transducer was employed for providing the power to low power heart rate sensor. The proposed system includes a heart rate monitor (HRM) and power units. An ultrasonic receiver and transmitter, bridge rectifier, supercapacitors, and converter are the main components of the power unit. While the HRM contains measurement and monitoring parts. The nRF24L01 wireless technology, a microcontroller-based Arduino Nano, and a heart rate sensor are the main components of the measuring circuit. The monitoring part involves nRF24L01 wireless technology, a microcontroller-based Arduino Mega 2560, and a laptop. The transfer power and efficiency achieved by UPT with a 4-Farad supercapacitor were 55.1% and 0.06318 mW at 6 cm, respectively. The heart rate measurement accuracy was 97% as compared with a consumer-ready device. These findings show that the proposed system is stronger than previous studies at 6 cm in terms of transfer power efficiency and transfer power.