Researchers have created a disposable HIV test that requires a single drop of blood. The inexpensive, portable test could be used in remote areas where medical facilities are scarce and will allow people to monitor their condition at home. The team described their progress in the journal Nature Scientific Reports.

Scientific understanding of human immunodeficiency virus (HIV) has advanced tremendously since the disease was identified in 1981. There’s still no cure, but a diagnosis of HIV is no longer a death sentence, and the progression to AIDS is no longer inevitable.

The treatment for HIV is a combination of drugs, known collectively as antiretroviral therapy (ART). The drugs keep the virus from multiplying, which keeps it from progressing. It’s important for people on ART to keep an eye on their viral load, or the amount of the virus in their bodies, in order to be sure their treatment is working. But in many parts of the world—including sub-Saharan Africa, where HIV and AIDS are most prevalent—blood tests and doctors can be hard to find. So a cheap, easy-to-use, at-home test could mean the difference between life and death for millions of people.

Researchers at Imperial College London and a company called DNA Electronics decided to create the smallest, most portable version of the test they could. The resulting technology fits onto a computer chip and ingeniously combines chemistry and electronics. Users prick their fingers and deposit a single drop of blood on the chip. If the viral load in the blood meets a certain threshold, the blood will cause a change in the chip’s acidity, which the chip then transforms into an electrical signal. The USB drive containing the stick can then be plugged into a computer and its results read.

The chip’s designers tried out their device on 991 blood samples taken from people with HIV. The results were very encouraging: the chip detected the virus with 88.8 percent accuracy. This is slightly behind the traditional test setup, which yielded a 95 percent accuracy rate, but for a test on a flash drive, the new technology fared surprisingly well.

The researchers will continue to develop their test, and are interested in learning if it could also be used for other diseases like hepatitis.