Next to heart rate and respiration, one of the most critical biometrics in healthcare is the blood-oxygen saturation level. This is a measure of how much oxygen is in the blood, and indirectly, how well the patient’s heart and lungs are working together. The normal way to monitor this level is through the use of a “pulse oximeter.” This device will be familiar to just about anyone who has been in a hospital, visited someone in a hospital, or seen a hospital bedside scene on television or in the movies. It’s a little clamp that is put over the end of a finger. The traditional device uses red and infra-red LEDs to illuminate the blood vessels in the finger, which are then viewed by optical sensors. The differences between the two light readings reveals the pulse rate and the blood-oxygen level. These devices are relatively expensive, and so are disinfected and reused.
Researchers at UC Berkeley think that they have a better solution. They have printed OLED materials on flexible substrates, along with organic photodiodes (OPD). They used readily available red and green emitter OLED materials, and have determined that these two wavelengths serve just as well at reading the pulse rate and blood-oxygen levels as the traditional inorganic LED approach.
The fact that they can be printed onto flexible plastic film substrates mean that it will be easier — and perhaps more comfortable — for patients to wear the device. Furthermore, the devices should be able to be manufactured at far less cost than the LED pulse oximeters. As a result, they could be so inexpensive that they would become a disposable item. There would be no need to disinfect them after use; you would just throw them away as you would a used Band-Aid.