In this particular case the smartphone is used to measure hemoglobin within blood. These kinds of measurements helps to diagnose and manage a number of conditions, but this requires either blood draws or expensive pulse oximeters. The researchers, led by Edward Jay Wang, wanted to find out if a cheaper and less invasive method is available with current everyday technology.
They have developed an app called HemaApp that uses the phone’s built-in light and camera to detect the color intensity of blood passing through a finger. The user simply places a finger over the camera lens, making a solid contact, and runs the app to do its thing. The app turns on the nearby LED light, which shines light through the finger, and uses the camera to detect specific features that point to the amount of hemoglobin.
Though the built-in light is not too bad, the team also tested the app using a nearby incandescent bulb in addition to the camera light, as well as with the help of a small accessory light attached to the phone. In their small study on 31 patients, the HemaApp with the attached light accessory was as accurate (82%) as Masimo’s Pronto (81%) in estimating hemoglobin count. The app without any accessories, and relying only on its own light, had an accuracy of 69%, which is pretty impressive as well.