‘Smart’ Test for HIV

A paper published in the journal Science Translational Medicine describes how a $34 smartphone attachment rapidly and accurately detected the presence of HIV and syphilis antibodies in drops of blood taken from pregnant women. Ninety-six people took part in the study done in Rwanda and demonstrated that laboratory-quality diagnostics can be run on a pocket-sized device that works well in field conditions.

The attachment is approximately the size of the phone itself, is made of plastic, and uses disposable cartridges costing just pennies. A worker loads a blood sample which mixes with reagents in microscale channels with the cartridge. Gold nanoparticles then bind to antibodies and silver nanoparticles form a film around the gold particles.

The silver film blocks light transmitted through the finished sample, indicating the test results within 15 minutes. The results are automatically loaded into the phone's storage. Image Credit

Over the past few years the research group has miniaturized the technology, reduced its power requirements, and integrated it with everyday mobile devices. The tiny amount of current in a smartphone's audio jack is all that's needed to power the sensing and data management. A specially created software records the results of tests and uploads those results to a server.

"This work is a proof of how technology can improve diagnosis and care, making it faster and simpler and cheaper without compromising the existing quality," says Sabin Nsanzimana, the manager of the sexually transmitted disease division at Rwanda's Ministry of Health.

The group is planning a larger-scale field trial and sees far broader implications for smartphone-based diagnostics. The technology can be used for a variety of different applications and provides easy, inexpensive, and accurate ways to test for diseases in developing countries.