Rapid testing is still a cornerstone in our fight against COVID-19. Rapid testing methods help in monitoring the spread of the virus, and researchers are continuously pouring their efforts to develop such technologies. A microfluidic device can detect the characteristic spike protein of the SARS‑CoV‑2 virus from a saliva sample within one second say researchers from Florida. The electrochemical device employs antibodies against the spike protein to detect the virus and could allow for ultra-rapid COVID-19 testing.
The current gold standard for COVID testing is the PCR test, which requires highly trained staff and specialized laboratory equipment, resulting in significant lag times between sample collection and obtaining results. This latest device builds on the expertise of researchers who have previously developed technologies to detect biomarkers for heart attacks, cerebral spinal fluid leaks, and the Zika virus.
Viral detection occurs on a gold electrode studded with antibodies against the viral spike protein, which can be loaded with a sample, such as the saliva. Spike protein binding to the electrode will change the electrical charge that runs through it, allowing the device to detect the virus. The entire electrode is included in a single-use test strip that a user connects to the handset to perform the analysis.
The biosensor strip is similar to commercially available glucose test strips in shape, with a small microfluidic channel at the tip to introduce the test fluid. Within the microfluidic channel, a few electrodes are exposed to fluid. One is coated with gold, and COVID-relevant antibodies are attached to the gold surface via a chemical method. As the level of spike protein in a sample may be small, the test amplifies the signal to enable more accurate detection. The sensor system, a circuit board, uses a transistor to amplify the electrical signal, which then gets converted into a number on the screen. The magnitude of this number depends on the concentration of antigen, the viral protein, present within the test solution.