Flexible oximeter maps blood-oxygen anywhere on the body

Oximeters use light to detect the ratio of oxygen-rich red blood to darker, less oxygenated blood. Until now, this has only worked on areas of the body that are partially transparent, like the fingertips or the earlobes. Using flexible electronics combined with a new way of measuring oxygenation with reflected light rather than transmitted light, the UC Berkeley team can now measure oxygen levels anywhere in the body. The research could lead to improved wound monitoring and more accurate assessment of transplant patients.

"All medical applications that use oxygen monitoring could benefit from a wearable sensor," said Ana Claudia Arias, a professor of electrical engineering and computer sciences at UC Berkeley. "Patients with diabetes, respiration diseases and even sleep apnoea could use a sensor that could be worn anywhere to monitor blood-oxygen levels 24/7."

Described in the journal Proceedings of the National Academy of Sciences, the oximeter is made of organic electronics printed on bendable plastic that moulds to the body’s contours. Arias and her team had previously shown that printed organic LEDs could be used to create thin, flexible oximeters for fingertips or earlobes. Since then, they have developed a new method known as reflection-mode pulse oximetry, whereby LEDs and photodiodes (PDs) operate at red and near-infrared (NIR) wavelengths as part of the same array. This allows blood-oxygen readings to be taken on any part of the body.