Hybrid Coils-Based Wireless Power Transfer for Intelligent Sensors

Area of Science:

• Biomedical Engineering
• Electrical Engineering
• Wireless Power Transfer

Background:

• Wearable biomedical sensors often rely on batteries, which are bulky, heavy, and require frequent charging or replacement.
• The limitations of batteries pose significant challenges for the long-term usability and invasiveness of implanted or wearable devices.

Purpose of the Study:

• To design and implement a prototype energy harvesting system using wireless power transfer/magnetic resonator coupling (WPT/MRC) for powering a heart rate sensor.
• To overcome the power limitations of batteries in wearable biomedical sensors.
• To optimize power transfer and efficiency across varying distances between transmitter and receiver coils.

Main Methods:

• Developed a WPT/MRC system comprising power, measurement, and monitoring units.
• Integrated an Arduino Nano microcontroller, heart rate sensor, and nRF24L01 wireless protocol for the measurement unit.
• Tested three coil topologies (spiral-spiral, spider-spider, spiral-spider) to evaluate performance.
• Optimized power transfer and efficiency at different coil separation distances.

Main Results:

• The spiral-spider topology demonstrated the highest performance, achieving 10 W power transfer at 87% efficiency over a 5 cm air gap with a 200 Ω load.
• The spider-spider topology achieved 7 W power transfer at 93% efficiency under the same conditions.
• The proposed WPT/MRC topologies surpassed previous studies in power transfer, efficiency, and operational distance.

Conclusions:

• The developed WPT/MRC system effectively addresses the battery power issue for wearable heart rate sensors.
• The spiral-spider coil topology offers a promising solution for efficient wireless power delivery in biomedical applications.
• This technology has the potential to enhance the reliability and reduce the invasiveness of wearable biomedical devices.