Researchers have developed a new point-of-care device that can detect markers of HIV and syphilis from a finger prick of blood – using a smartphone accessory. Samuel K Sia, associate professor of biomedical engineering at Columbia Engineering (NY, USA), led the team behind the new device, which can replicate the mechanical, optical and electronic functions of a lab-based blood test.
The small accessory is easily connected to a smartphone or computer, from which it draws all necessary power, and so performs the ELISA without requiring any stored energy. The assay can detect HIV antibody, treponemal-specific antibody for syphilis, and non-treponemal antibody for active syphilis infection; this triplexed immunoassay is not currently available in a single test format.
Having previously worked on miniaturizing diagnostic systems for diagnosing HIV, syphilis and other sexually transmitted diseases, Sia’s team built on this when designing the new smartphone accessory, which is small enough to be held in one hand. The assays can be run on disposable plastic cassettes loaded with the necessary reagents, with disease-specific zones giving an objective assay.
In order to minimize the power consumption of the device, allowing it to run from the smartphone battery, the team made two main additions. By using a ‘one-push vacuum’ the power-consuming electrical pump was eliminated; this requires the user to mechanically activate a negative-pressure chamber to move the reagents loaded on the cassette. The second modification was using the audio jack for transmitting power and data, thereby removing the need for a battery.
In a recent pilot of the device in Rwanda, health care workers received 30 minutes of training before testing whole blood samples collected by a finger prick from 96 patients enrolling into prevention-of-mother-to-child-transmission clinics or voluntary counseling and testing centers.
The project involved a numerous collaborations, with contributions from researchers at: Columbia’s Mailman School of Public Health (NY, USA); the Institute of HIV Disease Prevention and Control, Rwanda Biomedical Center (Rwanda); the Department of Pathology and Cell Biology, Columbia University Medical Center (NY, USA); the Centers for Disease Control and Prevention—Laboratory Reference and Research Branch (GA, USA); and OPKO Diagnostics (FL, USA).
Sia commented on the research: “Our work shows that a full laboratory-quality immunoassay can be run on a smartphone accessory. Coupling microfluidics with recent advances in consumer electronics can make certain lab-based diagnostics accessible to almost any population with access to smartphones. This kind of capability can transform how health care services are delivered around the world.”