Rapid COVID-19 testing with a portable PCR system

Researchers from the National University of Singapore (NUS) have developed a portable, easy-to-use, point-of-care diagnostic system for COVID-19 — one that can deliver patients their test results around one hour from the time of their nasal swab.

Current procedures for COVID-19 diagnosis see nasal swab samples collected at a clinic or testing site and sent to a specialised laboratory for processing to extract the RNA, before a polymerase chain reaction (PCR) test is conducted; it can take anywhere from a few hours to a few days for results to be made known. Now researchers from the NUS Institute for Health Innovation & Technology (iHealthtech) have developed their own diagnostic system, called Epidax, in just two months. A project of this scale would typically take at least one to two years to complete.

Epidax, which is a microfluidics-based PCR diagnostic system, is about the size of a toaster and can be deployed quickly and easily onsite for virus infection screening. It uses a specially designed microfluidic chip that comprises micro-channels where samples are processed. By employing microfluidic technology, the system is able to process a smaller amount of sample for quicker detection of COVID-19 infection.

Using a reagent that enables both RNA extraction and amplification on the chip, the PCR test can be performed right after a nasal swab sample is collected, thus bypassing the intermediate step of RNA extraction. All these features significantly minimise sample handling and shorten the test and waiting time, so patients can get their test results in about an hour.

“We have designed the Epidax system to be very easy to use,” said iHealthtech Director Professor Lim Chwee Teck, leader of the project. “The lab technician operating the system only needs to pipette the sample and reagent into the microfluidic chip and load it into the Epidax system for processing. These simple steps can be easily executed within five minutes.”

The research team found that the Epidax system has the same or even higher sensitivity than some current PCR systems. In fact, the sensitivity of detection can achieve at least 10 copies of RNA per microlitre of sample. The team is currently improving the limit of detection, aiming to reach one copy of RNA per microlitre of sample.

“The standard PCR diagnostic test is currently the gold standard test conducted in a centralised laboratory to identify SARS-CoV-2 viral infection,” Prof Lim added. “Our Epidax system is a unique microfluidic chip-based diagnostic system that can conduct PCR tests onsite for the rapid screening of infection, whether it is at a local clinic, a nursing home or the airport. In this way, we can quickly identify infected individuals and take swift action to prevent transmission.”

The NUS team has filed a patent for this invention, and is currently in talks with a medical technology company to commercialise this technology. Prof Lim said, “Moving forward, we are keen to further develop our portable micro-PCR diagnostic system that can even be deployed at home. For example, it can resemble a small capsule coffee machine: portable, affordable, easy to use, and we can insert different ‘capsules’ to test for a variety of diseases. With the current advances in science and technology, I believe this is highly achievable in the near future.”

Image caption: Epidax, a point-of-care diagnostic system for COVID-19, is portable, easy to use and completes screening in about an hour.

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