Motion-Aware Low-Power Wearable Photoplethysmography System with Metamaterial-Enhanced Wireless Telemetry

Area of Science:

• Biomedical Engineering
• Wearable Technology
• Signal Processing

Background:

• Wireless photoplethysmography (PPG) systems face challenges with motion artifacts (MAs) and high power consumption, hindering long-term monitoring.
• Existing research addresses MA mitigation, power optimization, and wireless connectivity separately, lacking integrated system-level solutions.

Purpose of the Study:

• To develop and evaluate a novel motion-controlled wearable (MCW) wireless PPG sensing system.
• To address the critical bottlenecks of MAs and power consumption in wearable PPG devices.

Main Methods:

• Implemented an autonomous motion-gated sampling technique for adaptive data acquisition.
• Integrated adaptive power management and a metamaterial-enhanced telemetry link for robust data transfer.
• Utilized an electromagnetic bandgap (EBG) structured metamaterial to improve antenna performance and reduce specific absorption rate (SAR).

Main Results:

• The motion-gated sampling algorithm reduced system power consumption by 55% while ensuring accurate heart rate (HR) and blood oxygen saturation (SpO2) measurements.
• Mean Absolute Errors (MAEs) were 1.5-6.2 BPM for HR and 0.5-1.0% for SpO2 across various physical activities.
• The EBG metamaterial reduced SAR from 4.36 W/kg to 1.677 W/kg, enhancing on-body antenna performance.

Conclusions:

• The proposed MCW system offers a compact, energy-efficient platform for reliable long-term wearable cardiovascular monitoring.
• The integrated approach of motion-gated sampling, adaptive power management, and metamaterial enhancement overcomes key limitations in current wireless PPG systems.