$34 Diagnostic Tool for STDs Plugs into Smartphone, Rivals $18,000 Lab Equipment

Photo: Tassaneewan Laksanasopin

Public health workers in Africa place HIV and syphilis at the top of their lists of diseases they see among pregnant women, and a new tool recently tested in Rwanda may help ease their diagnostic burden. The portable device, which plugs into a smartphone’s audio jack, performs three tests (one for HIV, two for syphilis) using just a fingerprick of blood, and displays results in 15 minutes.

In their report, the inventors estimate the tool’s cost at $34 plus the cost of a smartphone. They say it provides comparable results to gold-standard lab tests, whose cost they estimate at $18,450 plus the cost of a computer. 

“Lots of newborns are dying every year from congenital syphilis,” says Samuel Sia, one of the device’s inventors and an associate professor of biomedical engineering at Columbia University. “Should we be looking at new drugs for syphilis? No, it’s a diagnostic issue,” Sia says, noting that treatment for syphilis typically requires only one dose of penicillin. 

As for HIV, global health agencies have recently rallied around the goal of ensuring that at least 90 percent of people living with HIV know their HIV status. Right now that figure stands at less than 50 percent. Knowing one’s status is the obvious first step to getting access to anti-retroviral drug treatments. 

The new dongle draws all its power from a smartphone via its audio jack. It performed 41 tests when attached to an older Apple device; Sia says a new smartphone could perform many more before depleting the phone’s battery. His team ensured that the dongle would be low-power by doing away with the pump that often drives blood samples through microfluidic testing devices. Instead, the health care worker depresses a button to activate a vacuum chamber that sucks the sample through microfluidic channels, where reagents react to the presence of HIV or syphilis biomarkers. The dongle draws power only when it performs the optical assessment of the reactions, and when it transmits data back to the phone for read-out.   

Spectrum recently reported on dedicated diagnostic devices that are portable, cheap, and rugged enough to bring lab testing to remote African villages. Sia says his team initially built its own hardware and software, “but then we realized it was a losing proposition.” They decided to work off existing smartphone technology instead. 

That may be a good bet. Africa has been called “the mobile continent” in recognition of the many ways cheap mobile phones are transforming society. According to an Ericsson research report, Sub-Saharan Africa will have about 930 million mobile phones by 2019, three-quarters of which will be smartphones. 

However, the dongle will have to prove more useful than even cheaper paper-based diagnostic tests (based on the same principle as a home pregancy test), which are already widely available for HIV testing. Sia argues that his device is more accurate and reliable, and can also be used to conduct many lab tests at once from a single fingerprick of blood. He also sees value in the digital record of the tests that the phone can transmit to the cloud for integration into an electronic medical record. “It’s all part of leveraging the smartphone platform,” he says.  

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