In 1995 Nonin Medical revolutionized pulse oximetry with the Onyx. Hundreds of thousands of people trust Onyx, the first self-contained digital fingertip pulse oximeter. Incorporating the electronics and sensor into one unit – the easy-to-use Onyx provides a cost-effective solution for spot-checks and short-term monitoring that is unparalleled in reliability and performance. Pulse Oximetry at Your Fingertips. The Onyx is ideal for use in any situation where a fast and accurate reading of blood oxygen saturation and pulse rate is needed. Never search for a pulse oximeter or sensor again. The portability and functionality of the Onyx makes it a valuable tool in any situation where a fast and accurate reading of blood oxygen saturation and pulse rate is needed.