Finally, a useful dongle

Engineers have created a smartphone HIV test that costs $35 to make

Let’s be honest: Smartphones aren’t necessarily thought of as devices that help to slow the spread of sexually transmitted diseases. In fact, research has found that transmission rates go up when hookup sites – even ones on the tamer end, like CraigsList – come to town.

But smartphones are also capable of transforming into competitive diagnostic tools, as a team of biomedical engineers out of Columbia University is showing with their new attachment that can detect both HIV and syphilis in a single 15-minute test.

The dongle, as the team writes in the journal Science Translational Medicine, costs just $34 to make (an amount that could drop further if mass produced). It uses the phone’s power and data collection, and incorporates simple optics and fluid control to process a finger prick of blood.

While paper-based options for home testing do exist, and work much in the way that a home pregnancy test does, they are not nearly as sensitive, and thus reliable, as those that perform the current gold standard, what is called an enzyme-linked immunosorbent assay (ELISA). This test looks for either how much of an antibody is contained within the sample, or how much protein is bound by an antibody; if HIV positive, antibodies to HIV bind to the antigens on the plate.

For this test, the team was able to perform an objective read-out similar to an ELISA assay but without the spending the typical $18,450 equipment cost involved. And the dongle is small and light enough to fit in the palm of one’s hand, making its use in remote or mobile clinics far more practical.

To whittle the device’s power consumption down — especially since electricity might be a limiting factor in parts of the world where this kind of quick, accurate testing could be especially helpful — the team devised a “one-push vacuum” in place of an electrical pump; instead the end user pushes against a negative-pressure chamber to move the sequence of reagents onto the cassette. They say it requires minimal training and no routine maintenance.

What’s more, they were able to use the audio jack for both power and data transmission, enabling the dongle to connect to a range of devices (i.e. both iPhones and Android phones) thanks to the compatibility of the jacks themselves.

So the achievement isn’t so much in the test itself as it is in the components used to run that test simply and efficiently. It means that similar tests screening for other diseases may be just around the corner.

“Our work shows that a full laboratory-quality immunoassay can be run on a smartphone accessory,” one researcher said in the school news release. “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.”

The device certainly has the potential to help slow the spread of HIV around the world. Early detection is helpful, for instance, in pregnant women; the sooner they start taking antiretroviral meds, the less likely they are to pass the disease to their babies. This is why HIV screening is common in all pregnant woman across the US. The CDC reports that the risk of transmission to the fetus can be reduced to 1 percent when meds are taken as recommended.

[pullquote person=”Karen Lightman” attribution=”Karen Lightman, MEMS Industry Group” id=”916338″]“We are on the cusp of a lot of exciting technology being connected to smartphone devices.”[/pullquote]

“It has huge implications,” Karen Lightman, executive director of the trade association MEMS Industry Group, told me. “We are on the cusp of a lot of exciting technology being connected to smartphone devices. But security, ramping up volume, price, all those things are really important.”

One potential roadblock is that when it comes to STDs, and HIV in particular, cultural stigmas easily run the show. Lightman points out that in the US, if someone has a one-night stand and is “freaked out” but doesn’t want to go to a clinic, $34 is a small price to pay for peace of mind. In many parts of the world, though, the price tag is prohibitive, so while more testing may become available in rural clinics, the dongle isn’t necessarily going to mitigate the nervousness one might feel about walking through a clinic’s doors.

All that said, the infrastructure is forming. A 2013 Pew Research Center survey found that while smartphones are still rare in many parts of the emerging and developing world, cell phones are “ubiquitous.” Meanwhile in Lebanon, Chile, Jordan, China, Argentina, South Africa, Malaysia, and Venezuela, at least one in three people now own a smartphone. And when narrowing the findings to just young people ages 18 to 29, the percentage of people going online every day jumps from a tiny minority to at least 50%.

As for the dongle, field testing went according to plan in Rwanda last year. The team reports that it took just 30 minutes of training to fully familiarize health care workers with how to use the device and administer the test, while 97% of patients surveyed said they’d recommend it because it is fast, simple, and tests for more than one disease.

This kind of development is about to be the new norm as diagnostic tools begin to be compatible with our portable devices as well as capable of spitting out results screening for multiple infectious diseases in just minutes. The key is being competitive with the most accurate tests; especially when it comes to highly-stigmatized STDs, false positive and false negative results are never ideal.