Novel chip simplifies Covid testing, delivers results on phone

New York, Feb 26 (IANS) A team of researchers has developed a stamp-sized chip that may help diagnose Covid-19 in just 55 minutes.

The researchers, including lead author Peter Lillehoj from Rice University in ths US, said that Covid-19 can be diagnosed in 55 minutes or less with the help of programmed magnetic nanobeads and a diagnostic tool that plugs into an off-the-shelf cell phone.

And, when paired with a Google Pixel 2 phone and a plug-in potentiostat, it was able to deliver a positive diagnosis with a concentration as low as 230 picograms for whole serum, according to a paper published in the journal ACS Sensors.

"What's great about this device is that it doesn't require a laboratory," said Lillehoj.

"You can perform the entire test and generate the results at the collection site, health clinic or even a pharmacy. The entire system is easily transportable and easy to use," Lillehoj added.

The stamp-sized microfluidic chip measures the concentration of SARS-CoV-2 nucleocapsid (N) protein in blood serum from a standard finger prick.

The nanobeads bind to SARS-CoV-2 N protein, a biomarker for Covid-19, in the chip and transport it to an electrochemical sensor that detects minute amounts of the biomarker.

The researchers say that process simplifies sample handling compared to swab-based PCR tests that are widely used to diagnose Covid-19 and need to be analyzed in a laboratory.

For the study, the team took advantage of existing biosensing tools and combined them with their own experience in developing simple diagnostics, like a microneedle patch introduced last year to diagnose malaria.

The new tool relies on a slightly more complex detection scheme but delivers accurate, quantitative results in a short span of time. To test the device, the lab relied on donated serum samples from people who were healthy and others who were Covid-19 positive.

The lab found that 55 minutes was an optimum amount of time for the microchip to sense SARS-CoV-2 N protein at concentrations as low as 50 picograms (billionths of a gram) per millilitre in whole serum.

The microchip could detect N protein in even lower concentrations, at 10 picograms per millilitre, in only 25 minutes by diluting the serum fivefold, the team said.