New Device to Enable Covid-19 Cases in Less than an Hour

Engineers at MIT and Harvard University have designed a small tabletop device that can detect Covid-19 from a saliva sample in about an hour. MIT said in a press statement that the new study in Science Advances showed it is as accurate as PCR tests.

Researchers said the device can also be used to detect specific viral mutations linked to some of the variants now circulating. The tool is called miSHERLOCK. The new diagnostic, which depends on CRISPR technology, can be assembled for about $15, but those costs could come down significantly if the devices were produced at large scale, the researchers say. It is based on SHERLOCK, a CRISPR-based tool.

First, a pre-processing step disables enzymes called salivary nucleases, which destroy nucleic acids such as RNA. Once the sample goes into the device, the nucleases are inactivated by heat and two chemical reagents. The viral RNA is extracted and concentrated bypassing the saliva through a membrane.

This RNA sample is then exposed to freeze-dried CRISPR/Cas components. The reaction amplifies the RNA sample and then detects the target RNA sequence if present. The researchers designed the device, which they call minimally instrumented SHERLOCK (miSHERLOCK) so that it can have up to four modules that each look for a different target RNA sequence. The original module detects any strain of SARS-CoV-2. Other modules are specific to mutations, including B.1.1.7, P.1, and B.1.351.The Covid-19 variant Delta was not widespread when the researchers performed this study, but they say that the device should be straightforward to design a new module to detect that variant.