60 GHz FMCW Millimeter Wave Radar Assisted With Dual-Layer Wideband Flexible Metasurface for Accurate Wrist Pulse Monitoring

This letter presents a novel passive focusing metasurface designed for wrist pulse detection within the 60 GHz millimeter wave frequency range, incorporating a dual-layer transmitarray antenna. The proposed metasurface demonstrates exceptional polarization characteristics and a high degree of operational efficiency, as substantiated by rigorous far-field assessments. This innovative metasurface has significant potential for applications in human-device interfaces, health monitoring systems, and safety screening protocols, where the ability to focus and manipulate waves with flexibility is paramount. We rigorously evaluated its radiative safety and compared its efficacy with a conventional photoplethysmogram (PPG) reference. The results show a close agreement between our proposed design and the PPG.