Vital signs monitoring enabled by flexible organic array of printed devices

The optical method to determine oxygen saturation in blood is limited to only tissues that can be transilluminated. With COVID-19 conventional finger pulse oximeters have surged in popularity; however, most studies of patient in-home oxygenation monitoring are conducted using only a few discrete measurement points per day. The status quo provides a single-point measurement and lacks 2D oxygenation mapping capability. We have demonstrated a flexible and printed sensor array composed of organic light-emitting diodes and organic photodiodes, which senses reflected light from tissue to determine the oxygen saturation. We use the reflectance oximeter array beyond the conventional sensing locations. The sensor is implemented to measure oxygen saturation on the forehead with 1.1% mean error and to create 2D oxygenation maps of adult forearms under pressure-cuff–induced ischemia. In addition, we present mathematical models to determine oxygenation in the presence and absence of a pulsatile arterial blood signal. The mechanical flexibility, 2D oxygenation mapping capability, and the ability to place the sensor in various locations make the reflectance oximeter array promising for medical sensing applications such as monitoring of real-time chronic medical conditions as well as postsurgery recovery management of tissues, organs, and wounds.