Hybrid Coils-Based Wireless Power Transfer for Intelligent Sensors

Abstract

Most wearable intelligent biomedical sensors are battery-powered. The batteries are large and relatively heavy, adding to the volume of wearable sensors, especially when implanted. In addition, the batteries have limited capacity, requiring periodic charging, as well as a limited life, requiring potentially invasive replacement. This paper aims to design and implement a prototype energy harvesting technique based on wireless power transfer/magnetic resonator coupling (WPT/MRC) to overcome the battery power problem by supplying adequate power for a heart rate sensor. We optimized transfer power and efficiency at different distances between transmitter and receiver coils. The proposed MRC consists of three units: power, measurement, and monitoring. The power unit included transmitter and receiver coils. The measurement unit consisted of an Arduino Nano microcontroller, a heart rate sensor, and used the nRF24L01 wireless protocol. The experimental monitoring unit was supported by a laptop to monitor the heart rate measurement in real-time. Three coil topologies: spiral–spiral, spider–spider, and spiral–spider were implemented for testing. These topologies were examined to explore which would be the best for the application by providing the highest transfer power and efficiency. The spiral–spider topology achieved the highest transfer power and efficiency with 10 W at 87%, respectively over a 5 cm air gap between transmitter and receiver coils when a 200 Ω resistive load was considered. Whereas, the spider–spider topology accomplished 7 W and 93% transfer power and efficiency at the same airgap and resistive load. The proposed topologies were superior to previous studies in terms of transfer power, efficiency and distance.

Near‐field wireless power transfer used in biomedical implants: A comprehensive review

“…MRC also plays an essential role in heart rate sensors and cardiac monitoring. Mahmood et al [111] designed and implemented an MRC-WPT system using three different coil topologies (spiral-spiral, spider-spider, and spiral-spider) to supply power to a heart rate sensor. The design involves three parts: the power unit, which comprises the transmitter and receiver coils; the measurement component, which includes an Arduino Nano microcontroller and a heart rate sensor; and the nRF24L01 wireless protocol monitoring unit, as shown in Figure 12.…”

“…The resonance frequency is 6.78 MHz. The results showed that the WPT FIGURE 12 (a) Spider-Spider magnetic resonant coupling wireless power transfer system at 20 cm proposed in [111] to measure heart rate. (b) Fabricated cardiac monitoring module (bottom view on the right and top view on the left) presented in [112].…”

Design of Powering Wireless Medical Sensor Based on Spiral-Spider Coils

“…The resonator capacitors in the transmitter and receiver units are coupled in parallel with the L T and L R coils, respectively. The parallel-to-parallel compensation topology was chosen due to (i) facilitating higher power transfer between the two coils [28,29], (ii) it has a better performance than series-to-series topology in low power applications [30], where the proposed WHR consumes low power (≈0.166 W) and (iii) the ZVS oscillator (Xiongfaic Weiye Electronics Co., Ltd., Shenzhen, China) existing in our lab is restricted to the parallel topology and low oscillator frequency. The low frequency is suitable for using with parallel resonator topology, where the parasitic losses are reduced, while the series topology is more suitable for employing with high frequency [31].…”

Review of Power Converter Impact of Electromagnetic Energy Harvesting Circuits and Devices for Autonomous Sensor Applications

“…On the other hand, active low power devices are basically logic gates acting like a switch and attached with sensors [50,51]. WSNs have different applications such as bio-medical [52,53], Internet of Things (IoT) [54], and environmental monitoring [55]. An ATS can run automatically with low power mode when it is required to sense the change in any parameter, processing the change in the form of the voltage signal, and transmitting that signal [56].…”