The device -- and others like it -- also could help make consumer technology an even more integral part of public health efforts.
"If you can start to bring core health services to the smartphone beyond just measuring the heart rate -- like blood tests -- then you're going to start seeing a pretty fundamental shift in the health-care system," said Samuel Sia, an associate professor of biomedical engineering at Columbia, and an author of the paper on the device published in the journal Science Translational Medicine.
It works this way. Start by attaching the dongle -- a piece of hardware that conducts the test -- to the headphone jack of a device like an iPhone or iPod Touch. Then take a small blood sample -- a simple prick of a finger will do -- and insert it into a disposable plastic collector. Connect the plastic collector to a microfluidic chip used to analyze the sample and insert the chip with the blood sample into the dongle. Open the app, wait about 15 minutes, and voila: results.
The study was partly funded by the United States Agency for International Development with a focus on reducing transmission of sexually transmitted diseases from mother to child.
The process is similar to the one diabetics use to test their blood surgar levels at home. And it requires about as much blood and perhaps even less power from the smart device.
The new device essentially replicates the HIV test considered a gold standard for laboratory testing, as well as the same kind of syphilis tests you might get in a standard laboratory. But it produces results 10 times more quickly and, in a small study, Sia's team found it to be very accurate.
Instead of using enzymes and substrates employed in a lab, the device uses gold and silver nanoparticles to isolate the anti-bodies for the diseases.
"The cost, size and power ... those three things, we just reduced it by orders of magnitude from what we did before," Sia said, noting that his team first began working on the technology about 10 years ago, before the first iPhone even existed. "It replicates all the things that a lab-based robot would do."
"We're actually not really developing a totally new way of doing things, but instead we're just replicating what lab-based instruments do, step by step," he added.
The team conducted a small field study of the device with the Rwandan Ministry of Health to see how actual patients used it. More than 90 percent of the 96 patients who used the device reported that they preferred it to other tests and that they would recommend it to others.
The dual test -- syphilis and HIV -- allows health-care workers to test pregnant women for two sexually transmitted diseases that have a high potential for mother to child transmission. The device could provide a critical asset to public health officials, said Sabin Nsanzimana, who is head of the HIV, STI and Other Blood Borne Infections Division of the Rwandan Ministry of Health.
"Early and faster diagnosis further reduces the morbidity and mortality due to HIV and STIs," Nsanzimana said in an e-mailed statement. "Technology and health must go together. This is a good example of that concept."
The technology also is cheap to manufacture -- even compared to other mobile tests currently in use. According to Sia, the smartphone dongle costs $34 to produce and the plastic card used to collect the blood sample costs about $1.44.
With a smartphone, results can be automatically sent to health-care providers without the patient seeing them on the device. It can be used as a back-up test in overburdened clinics or in remote locations where sending test results to a centralized lab might be time-consuming or impossible.
"No options are taken off the table, you are actually increasing access," Sia said.
He is eyeing the possibility of consumer use in the United States, given the interest in utilizing personal electronic devices to make health-care cheaper and more accessible.
Sia's work on microfluidic chips -- the plastic cards used to collect blood samples and conduct mobile tests --have already produced inexpensive tests for a number of other diseases, including prostate cancer.
There is always the potential to shrink the technology further, he noted, in part to make the tests more environmentally friendly.
"I think if we can make the cards smaller, for instance, that would help," Sia said. "I would list that as one of the issues, especially for global health."