Now, an app to detect Zika, dengue, chikungunya within 30 minutes

Now, detecting a mosquito-borne illness will be as easy as clicking a smartphone app - thanks to a team of scientists.

Researchers at Sandia National Laboratories developed a smartphone-controlled, battery-operated diagnostic device that weighs under a pound, costs as little as 100 dollars and can detect Zika, dengue and chikungunya within 30 minutes.

Testing for these mosquito-borne viruses currently requires a laboratory, and patients can wait days for results. The tests require instruments that are roughly the size of a microwave oven and can cost up to 20,000 dollars. This makes rapid testing unrealistic for limited-resource clinics in developing countries where the viruses are prevalent.

Smartphone technology is a key feature of the device. "In addition to creating an app that serves as a simple interface to operate the device, we were able to adapt smartphone camera sensors to replace traditional laboratory sample analysis tools, allowing for unprecedented mobility," chemical engineer and lead author Aashish Priye said.

The Sandia team's device is based on the loop-mediated isothermal amplification (LAMP) diagnostic method, which eliminates the need to process a biological sample, such as blood or urine, before testing. Conventional viral testing involves transporting a sample to a laboratory, extracting DNA or RNA from it and then multiplying the genetic materials through a process called polymerase chain reaction (PCR). This process involves heating and cooling the sample many times, so that any viral DNA/RNA in the sample is replicated enough to be detected.

"We've demonstrated that the chemistry we're using can amplify viral RNA directly from raw, unprocessed samples," said lead author Robert Meagher. "That is the ideal for a point-of-care testing scenario because you don't want to have extra equipment for isolating DNA or RNA."

For the Zika project, Meagher's team developed a novel algorithm that allows a smartphone sensor to act as a fluorimeter, detecting QUASR LAMP light signals if they appear. LAMP works so simply that the user need only place the smartphone on top of the LAMP box and open an app. The app turns on the heater to initiate the LAMP reaction.

Once the 30-minute testing period is up, the smartphone photographs the sample. The app then employs a novel image analysis algorithm to accurately determine the color and brightness of the glow emitted from the LAMP reaction. This smartphone-based image analysis offers much greater detection certainty than the lab technician's naked eye.

The cost of making a LAMP box prototype to test for these viruses depends largely on the cost of the phone selected for use with it.

The study is published in the journal Scientific Reports.