The dongle, containing a microfluidic chip, is powered by plugging into a smartphone's audio jack. | Samiksha Nayak
A smartphone can now perform rapid diagnostic tests for HIV and syphilis, thanks to a new dongle, which was successfully field-tested in Rwanda. With accuracy that rivals the current gold standard of diagnostics, the dongle, a small piece of computer hardware, could help scale up early detection of these diseases in resource-limited or field clinics.
Diagnostic tests are critical to prevention and early treatment of disease but often require expensive laboratory equipment. To make diagnostics cheaper and more accessible, Samuel Sia and colleagues from Columbia University coupled a microfluidic chip with a smartphone to design a lab-on-a-chip dongle.
"Instead of having to do everything in a hospital, which is very expensive and infrastructure-heavy, you can now decentralize these services and bring them to the patient," said Sia, senior author of the study.
The findings are published in the 4 February issue of Science Translational Medicine.
The device simultaneously tests a blood sample for HIV and both active and latent syphilis. It mimics the enzyme-linked immunosorbent assay (ELISA), the leading lab-based diagnostic, which detects antibodies for diseases in the blood. Thanks to its cheap components, such as the plastic microfluidic cassette, the dongle's manufacturing cost is only $34, compared to $18,000 or more for ELISA.
Replicating a full laboratory test on a chip "requires miniaturizing a variety of components — mechanical component, electronic component, optical component," said Sia. "It's really coming up with an entire package that could work with a smartphone."
The dongle draws all the power it needs to run when it is plugged into the smartphone's audio jack. It also comes with software or an "app" that provides instructions on the screen.
"What we really aimed for in the design of the dongle was something with a very simple user interface…so that anybody can use it," said Tiffany Guo from Columbia University.
Researchers show how the dongle works, from finger prick to phone plug-in to test results. | Tiffany Guo and Tassaneewan Laksanasopin
With minimal training, Rwandan health care workers used the tool to test blood finger-pricked from 96 patients, many of whom were women at risk of transmitting HIV or syphilis to their children.
The device performed almost as well as the ELISA test and delivered results on the phone screen within 15 minutes. Nearly all patients preferred the dongle to lab-based tests, which could take two or more hours.
"It is too early to say that this device is going to be adopted in Rwanda widely, but these results are impressive and may inform a number of policy reviews," said Sabin Nsanzimana from the Ministry of Health in Rwanda, also an author of the study.
The researchers are continuing to improve and streamline the device. "We still have to tweak some parameters to get a better performance," said Tassaneewan Laksanasopin from Columbia University. For instance, the current setup requires the user to manually initiate the second half of the diagnostic test. "We will get rid of that step to make it a truly plug-and-play platform," said Laksanasopin.
According to Sia, they are planning a larger-scale clinical trial in hopes of getting the device approved by the World Health Organization and on the market in developing countries.
The researchers are also exploring ways to adapt the technology for consumer health in the United States and Europe, said Sia. The device can potentially be redesigned for a host of other applications, from diagnosing cancer to monitoring diabetes and hormone levels.
"Core health services on the smartphone may be the start of seeing the health care system being transformed in a fundamental way," said Sia.