A team of scientists from Scotland’s University of Strathclyde and the Indian Institute of Technology (IIT) Bombay has developed a low-cost sensor that detects the presence of SARS-CoV-2, the virus responsible for COVID-19, in wastewater.

The biosensor developed by the team uses printed circuit board (PCB) electrodes to detect the presence of SARS-CoV-2 nucleic acid combined with methylene blue, a salt used in both medication and dye, which was added to the sample to generate an electrochemical signal. The team determined that the sensor detected the genetic material at concentrations of 10 picograms per microlitre (pg/μl).

Paired with portable equipment that uses a standard polymerase chain reaction (PCR) test, the sensor could be used to test wastewater in low-income countries that have struggled to administer mass testing or that have limited access to mass testing facilities.

Such testing could potentially reveal data about the prevalence of the virus in these low-income locations, thereby leading to improved understanding among public health experts. Already, the team has tested the sensor on wastewater samples spiked with SARS-Cov-2 ribonucleic acid (RNA) taken from a Mumbai sewage treatment plant.

"Testing of wastewater for the presence of SARS-CoV-2 nucleic acid is already widely recognized as a tool to identify areas where the case numbers are likely to be increasing and therefore allow more targeted action to be taken to limit viral spread in specific regions. However, the current gold-standard method of real-time PCR testing (qPCR) requires expensive laboratory equipment and skilled scientists to complete. Furthermore, if resources are limited, testing of human samples would most likely take precedence over wastewater epidemiology surveillance. Therefore, lower cost, alternative approaches are required in order to support wastewater surveillance," explained Dr. Andy Ward, from the University of Strathclyde’s Department of Civil & Environmental Engineering.

The research appears in the journal Sensors and Actuators B: Chemical

To contact the author of this article, email mdonlon@globalspec.com