Wearable RF plethysmography sensor using a slot antenna

This paper presents a wrist wearable wireless plethysmography sensor based on the variation of reflection coefficient (S11) of a planar H-slot antenna and a compact, efficient signal processing circuit. The sensor detects changes in the volume of human blood in the radial artery and reflects it as a change in the reflection coefficient, and hence a change in the body pulse waveform. The sensor is designed to operate at 2.4 GHz ISM band. A salient feature of the present work is improved sensitivity through slot antenna and an efficient T/R architecture with better SNR design.