Researchers at the University of Washington are working on a sensor-enabled smartphone app that could possibly detect anemia, the MIT Technology Review reports. While the technology is in relatively early stages and questions remain about its accuracy up against conventional blood tests, researchers believe it holds promise as a non-invasive tool in places where there are large populations of people with anemia, or as a complement in blood centers or home care.

In the lab of Shwetak Patel, a professor in the university’s electrical engineering department, researchers are exploring ways of using the sensors to make health tests more accessible by using machine-learning algorithms that recognize symptoms from sensor readings. The lab has developed a few apps already, ranging from breath-tracking (using a smartphone’s microphone) to jaundice detection in infants. The latest project, HemaApp, uses light to detect anemia, and the group will present their findings at an upcoming conference.

Patel’s group realized that the camera in a Nexus 5 smartphone could be used to detect anemia because the light passing through a person’s finger could measure hemoglobin. They developed a system using video to record light from the phone’s flash, plus an additional array of LED lights and an incandescent light bulb that shines through the user’s fingertip. The system learned to recognize changes in the color of the blood as it pumps through the finger, possibly signaling a deficiency in red blood cells.

A smartphone-enabled light test for anemia isn’t an entirely new idea. Commercially-available LED tests like the Masimo’s oximetry monitors use similar technologies. However, quick and easy such solutions may be, the system falls short on accuracy. While a test of 31 people conducted in collaboration with Seattle Children’s Hopsital worked as well as a commercial LED-based anemia test, it still isn’t nearly as accurate as a conventional blood test.

But for a condition that requires constant monitoring and is prevalent in many poor countries, where malnutrition and parasitic infections can cause anemia, researchers think the technology could still hold promise. Additionally, experts think the technology could be used for people such as pregnant women to avoid additional blood drawing, but the weak resolution with smartphones would need to be worked around to improve accuracy.

“There is the issue of the penetration of smartphones,” Caroline Buckee, an assistant professor and epidemiologist at Harvard who studies the use of mobile devices in global health told MIT Technology Review. “Although it would be useful in many places where there is high smartphone penetration and lots of anemia, like India; and community health workers could use it in places without high penetration in rural areas where anemia affects many people, such as West Africa.”