High-Accuracy Photoplethysmography Array Using Near-Infrared Organic Photodiodes with Ultralow Dark Current

Reflectance oximeters based on organic photodiode (OPD) arrays offer the potential to map blood pulsation and oxygenation via photoplethysmography (PPG) over a large area and beyond the traditional sensing locations. Here, an organic reflectance PPG array based on 16 x 16 OPD pixels is developed. The individual pixels exhibit near-infrared sensitivity up to approximate to 950 nm and low dark current density in the order of 10(-6) mA cm(-2). This results in high-quality PPG signals. Analysis of the full PPG waveform yields insight on the artery stiffness and the quality of blood circulation, demonstrating the potential of these arrays beyond pulse oximetry and heart-rate calculation.