A Single RGB LED as Photoplethysmography Sensor

Abstract

This letter presents a low-cost, compact and simplified photoplethysmography (PPG) sensor based on a single red green blue light emitting diode (RGB LED). Unlike conventional systems that use separate light sources and photodetectors, the proposed approach uses the RGB LED both as a light emitter and as a sensor. By using two color channels for sensing and the third for illumination, the system achieves optical sensing and indication within one device. The letter describes the sensing principle, hardware design, and software implementation. Experimental validation demonstrates that the RGB LED based sensor exhibits sufficient sensitivity for a range of optical sensing applications. To benchmark its performances the proposed approach is evaluated in a PPG application, noninvasive technique for monitoring blood volume variations in microvascular tissue, and widely used in wearable devices and medical sensors to track heart-related signals. Preliminary results indicate that the proposed RGB LED sensor can capture physiologically relevant PPG signals with comparable characteristics to conventional sensors, highlighting its potential as a cost-effective and highly integrated solution for wearable and biomedical sensing systems.