Professor Seunghyup Yoo and his research team members developed the ultra-low power pulse oximetry senor by using OLED and OPD

Professor Seunghyup Yoo and his research team members developed the ultra-low power pulse oximetry sensor by using OLED (Organic light emitting diode) and OPD (Organic photodiode).

It is expected that pulse oximetry sensors will be applied to various wearable devices through this technology. This work was cooperated by professor Hoi-Jun Yoo’s research team and it was published in Science Advances on November 9. Hyeonwoo Lee is the first author of this paper.

paper: Toward all-day wearable health monitoring: An ultralow-power, reflective organic pulse oximetry sensing patch


Pulse oximetry sensor has been playing a key role as devices to monitor elemental yet critical human health states such as heart rate and oxygenated hemoglobin. Conventional pulse oximetry sensors use an optical method based on a LED and a photodiode. This technology is widely used not only hospital equipment but also smart wearable devices because it is a simple and non-invasive method.

The power consumption is the most important issue of wearable devices because of its limited battery life. Conventional pulse oximetry sensors, however, have relatively large power consumption, impeding their use as stand-alone continuous monitoring systems that can easily be integrated with everyday life.

The research team exploits the design freedom offered by organic technologies to realize a reflective patch-type pulse oximetry sensor with ultralow power consumption. On the basis of a flexible organic light emitting diode and organic photodiodes designed via an optical simulation of color-sensitive light propagation with human skin, the proposed monolithically integrated organic pulse oximetry sensor heads exhibit successful measurement operation at electrical power as low as 0.03 mW on average.

In addition to very low power consumption, this technology has the flexibility of the shape of the flexible element of the organic device. Therefore, it is possible to minimize the limitations of battery life in wearable devices such as smartwatches, small wireless earphones, smart rings. It is expected that this sensor will be possible to continuously monitor vital signs without interfering with everyday life.

Professor Yoo said, “Continuous monitoring the vital sign can detect changes of patient’s health condition in real time, and the collected bio-health signals may carry even more profound implications by serving as a basis for medical “big data” that could identify unknown linkages between diseases and certain patterns.”

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