Smartphone Clip-On Device Detects Zika Infection in Minutes

Researchers at the University of Illinois Urbana-Champaign have developed a small, easy-to-device that can rapidly test for Zika virus in a single droplet of blood with the help of a smartphone camera.

Zika virus is primarily transmitted through Aedes aegypti mosquitoes. Although the disease is largely asymptomatic or results in mild symptoms in adults, it causes developmental disorders in newborn babies if their mothers are infected during early pregnancy. Currently, the virus is circulating in more than 87 countries, infecting thousands of people annually, necessitating better testing and control measures.

“Mosquito-borne viruses cause serious diseases, but they have similar symptoms. If you have Zika, malaria, dengue, or chikungunya, you just might show up to the doctor with a fever and they won't know why,” says Brian Cunningham, the Intel Alumni Endowed Chair of Electrical and Computer Engineering. “But it's important to know whether it's Zika, especially if the patient is a pregnant woman, because the consequences to a developing fetus are really severe.”

Zika virus infections are currently detected through PCR tests performed in a laboratory. In the new study, researchers used Loop-Mediated Isothermal Amplification (LAMP) to detect the virus in the blood samples using an approach suitable for point-of-care clinics. While PCR requires 20-40 repeated temperature shifts to amplify the genetic material, LAMP only requires one temperature (65 °C), making it easier to control.  PCR tests are also very sensitive to the presence of contaminants, especially the other components in a blood sample. As a result, the sample has to be purified before it can be used. LAMP does not require any such purification step.

The device is made up of a cartridge that contains reagents required to detect the virus. The cartridge is inserted into the instrument to perform the test while the instrument is clipped onto a smartphone. Once the patient adds a drop of blood, one set of chemicals break open the viruses and the blood cells within five minutes. A heater below the cartridge heats it up to 65 °C. A second set of chemicals then amplifies the viral genetic material, and the liquid inside the cartridge fluoresces bright green if the blood sample contains the Zika virus. The entire process takes 25 minutes.

“The other cool aspect is that we're doing the readout with a smartphone,” Cunningham adds. “We've designed a clip-on device so that the smartphone’s rear camera is looking at the cartridge while the amplification occurs. When there's a positive reaction, you see little green blooms of fluorescence that eventually fill up the entire cartridge with green light.”

The researchers are now developing similar devices to simultaneously detect other mosquito-borne viruses and are working on making the devices even smaller. “Although our clip-on detector is pretty small, a lot of the space is taken up by the batteries. In the next version, it will be powered by the phone's battery,” Cunningham said.

The device is described in more detail in a recent issue of Analyst.