Ultrasound Sensor-Based Wireless Power Transfer for Low-Power Medical Devices

Mustafa F Mahmood,Saleem Latteef Mohammed,Sadik Kamel Gharghan

doi:10.3390/jlpea9030020

Mustafa F Mahmood, Saleem Latteef Mohammed + Show 1 more

Open Access

https://doi.org/10.3390/jlpea9030020

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Abstract

Ultrasonic power transfer (UPT) is a promising method for wireless power transfer technology for low-power medical applications. Most portable or wearable medical devices are battery-powered. Batteries cannot be used for a long time and require periodic charging or replacement. UPT is a candidate technology for solving this problem. In this work, a 40-KHz ultrasound transducer was used to design a new prototype for supplying power to a wearable heart rate sensor for medical application. The implemented system consists of a power unit and heart rate measurement unit. The power unit includes an ultrasonic transmitter and receiver, rectifier, boost converter and super-capacitors. The heart rate measurement unit comprises measurement and monitoring circuits. UPT-based transfer power and efficiency were achieved using 1-, 4- and 8-Farad (F) super-capacitors. At 4 F, the system achieved 69.4% transfer efficiency and 0.318 mW power at 4 cm. In addition, 97% heart rate measurement accuracy was achieved relative to the benchmark device. The heart rate measurements were validated with statistical analysis. Our results show that this work outperforms previous works in terms of transfer power and efficiency with a 4-cm gap between the ultrasound transmitter and receiver.

Highlights

Implantable biomedical devices such as blood pressure monitors, cardiac defibrillators, electrocardiograms, electromyography, thermometers, pacemakers, neural stimulators, heart rate sensors, and glucose meters are commonly used to improve the quality of life of millions of patients [1]
The results show that the corresponding transfer efficiency for varying frequencies was 35–100% whereas it was 8–25% for fixed frequencies
Mean absolute error (MAE), absolute percentage error (APE) and mean absolute percentage error (MAPE) in the heart rate measurements of the Heart rate monitoring (HRM) with respect to those of JJ

Summary

Introduction

Implantable biomedical devices such as blood pressure monitors, cardiac defibrillators, electrocardiograms, electromyography, thermometers, pacemakers, neural stimulators, heart rate sensors, and glucose meters are commonly used to improve the quality of life of millions of patients [1]. To improve medical implant devices, several investigators [3,4] have used ultrasonic waves to optimize transfer efficiency and increase transfer distances in percutaneous coronary intervention. The measurement unit involves a microcontroller heart rate sensor and wireless protocol nRF24L01. The main objective of the present study is to optimize the transfer distance, power and efficiency. With a 4-cm gap between the ultrasound transmitter and receiver, this work outperforms previous works in terms of transfer power and efficiency. The rest of the paper is as follows

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