Smartphone dongle detects HIV, syphilis in 15 minutes

Researchers have developed a low-cost smartphone dongle that can simultaneously detect HIV and syphilis from a finger prick of blood in just 15 minutes.

The device, developed by a team of researchers led by Samuel K Sia, associate professor at Columbia University School of Engineering and Applied Science, can perform a point-of-care test that simultaneously detects three infectious disease markers.

The device replicates, for the first time, all mechanical, optical, and electronic functions of a lab-based blood test, researchers said.

The device performs an enzyme-linked immunosorbent assay (ELISA) without requiring any stored energy: all necessary power is drawn from the smartphone.

It performs a triplexed immunoassay not currently available in a single test format: HIV antibody, treponemal-specific antibody for syphilis, and non-treponemal antibody for active syphilis infection.

The accessory or dongle easily connects to a smartphone or computer and was recently piloted by health care workers in Rwanda who tested whole blood obtained via a finger prick from 96 patients who were enrolling into prevention-of-mother-to-child-transmission clinics or voluntary counselling and testing centers.

"Our work shows that a full laboratory-quality immunoassay can be run on a smartphone accessory," said Sia.

"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," he said.

Sia's team developed the dongle to be small and light enough to fit into one hand, and to run assays on disposable plastic cassettes with pre-loaded reagents, where disease-specific zones provided an objective read-out, much like an ELISA assay.

Sia estimates the dongle will have a manufacturing cost of USD 34, much lower than the USD 18,450 that typical ELISA equipment runs.

The team made two main innovations to the dongle to achieve low power consumption, a must in places that do not always have electricity.

The researchers eliminated the power-consuming electrical pump by using a "one-push vacuum," where a user mechanically activates a negative-pressure chamber to move a sequence of reagents pre-stored on a cassette.

The process is durable, requires little user training, and needs no maintenance or additional manufacturing.

Sia's team removed the need for a battery by using the audio jack for transmitting power and for data transmission.

And, because audio jacks are standardised among smartphones, the dongle can be attached to any compatible smart device in a plug-and-play manner.

The research is published in the journal Science Translational Medicine.