If you wear a smartwatch, like a FitBit or Apple Watch, you might be able to use it to detect COVID-19. These devices can detect changes in health parameters like elevated resting heart rate or body temperature that could indicate viral infection. Researchers at Stanford are studying the effectiveness of these devices to indicate COVID-19. They say that they detect changes about four days before coronavirus patients develop symptoms. You can get one of these devices for $100 to $300, but you have to wear it for about a month to have useful baseline data before this technique would work.