17.8 A 2.6μW Monolithic CMOS Photoplethysmographic Sensor Operating with 2μW LED Power

摘要

Photoplethysmography (PPG) is a key technology allowing non-invasive monitoring of vital indicators such as heart rate (HR) and oxygen saturation (SpO₂). Today, the total PPG sensor power consumption is dominated by the few tens of mA of the LEDs driving current. Different solutions have been proposed to solve this bottle-neck, either by reducing the LED duty cycle [1], [2] or by nonuniform sub-sampling [3]. A heart-beat-locked loop system that significantly reduces the LED power has been recently demonstrated [4]. However, this power reduction comes at the cost of more complexity since it requires a non-trivial heart beat prediction scheme and intrinsically hinders the full PPG wave representation.