Engineers at the University of California, Berkeley, have developed a wearable sensor capable of mapping blood-oxygen levels through the skin. The device could be used by doctors to monitor the healing process in real-time.
Traditional blood-oxygen sensors, oximeters, tend to be both clunky and limited. They sit on a patient’s finger to monitor oxygen saturation over time.
Yasser Khan, a graduate student in electrical engineering and computer sciences at UC Berkeley, said: “We wanted to break away from that, and show oximeters can be lightweight, thin and flexible.”
That flexibility is enabled by a new sensor made of organic electronics. It’s printed onto bendable plastic to help it adjust to whichever part of the body it needs to take a reading from.
Unlike fingertip oximeters, the new sensor can detect localised blood-oxygen levels. In theory, it could be placed anywhere on the skin to monitor the blood-oxygen saturation: above a certain organ, for example.
The applications range from mapping the oxygenation – and therefore health – of skin grafts, to post-transplant care.
All medical applications that use oxygen monitoring could benefit from a wearable sensor,” explains Ana Claudia Arias, a professor of electrical engineering and computer sciences at UC Berkeley.
Patients with diabetes, respiration diseases and even sleep apnea could use a sensor that could be worn anywhere to monitor blood-oxygen levels 24/7.
Moving on from LED oximeters
A traditional oximeter works by using light-emitting diodes (LEDs) to shine red and near-infrared light through the skin. It then detects how much, and what type of, light makes it through to the other side.
Depending on what state of oxygenation the blood is in, different ratios of light are transmitted through the skin.
The drawback is that the system doesn’t work unless it’s used on a part of the body that is partially transparent, like a fingertip or earlobe. And only blood-oxygen levels at that single point are measured.
“Thick regions of the body, such as the forehead, arms and legs, barely pass visible or near-infrared light, which makes measuring oxygenation at these locations really challenging,” Khan said.
Improving patient care with IoT
To solve that problem, the UC Berkeley team developed a way to measure blood oxygen levels using reflected light rather than transmitted light.
They combined that development with a breakthrough dating back to 2014, in which professor Arias and a team of graduate students proved that printed, organic LEDs could be embedded into thin, more malleable oximeters.
Bringing the two technologies together, the team has a new wearable sensor able to detect blood-oxygen levels anywhere on the body.
“After transplantation, surgeons want to measure that all parts of an organ are getting oxygen,” Khan said.
If you have one sensor, you have to move it around to measure oxygenation at different locations. With an array, you can know right away if there is a point that is not healing properly.
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The possible applications are extensive, but broadly the device promises visibility in a timely manner, where previously there was none.