Rice University engineers have developed a new diagnostic tool that can be plugged into an off-the-shelf cellphone can diagnose COVID-19 in 55 minutes or less.
The stamp-sized microfluidic chip measures the concentration of SARS-CoV-2 nucleocapsid 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 said their 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.
The research appears in the American Chemical Society journal ACS Sensors.
The new tool relies on a slightly more complex detection scheme but delivers accurate, quantitative results in a short amount 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.
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.
A capillary tube is used to deliver the sample to the chip, which is then placed on a magnet that pulls the beads toward an electrochemical sensor coated with capture antibodies. The beads bind to the capture antibodies and generate a current proportional to the concentration of biomarker in the sample.
The potentiostat reads that current and sends a signal to its phone app. If there are no COVID-19 biomarkers, the beads do not bind to the sensor and get washed away inside the chip.