Visby Medical, a San Jose, California, startup, is changing the game in Covid testing. It built the world’s first portable PCR machine, a pocket-size handheld device that can diagnose the virus ...

PCR machines cycle temperature to enable DNA-copying reagents, including primers, nucleotides, and the enzyme Taq polymerase. 201ºF DNA temporarily unzips into two strands.

The process was first described in 1985 by scientists at Cetus Corporation, the San Francisco biotech startup, who called it the "polymerase chain reaction," or PCR.

In order to keep themselves and their guests safe, Angus says they'll be testing everyone with PCR tests at their house hours before their Friday night gathering. MARIN COUNTY, CA.

The incorporation of fluorescent tags meant that the PCR machines could also indicate how much virus was in a person’s system. If the fluorescent light shined more strongly and sooner in the ...