SMALL SCALES
A nanoscale weighing machine can now measure the mass of a single virus. The device may some day be used to detect, or even identify, small organisms. Harold Craighead and his group at Cornell University in Ithaca, New York, built microscopic cantilevers, just 4 micrometres long and 500 nanometres wide, out of silicon and silicon nitride. The cantilevers vibrate at a known frequency, but with any extra mass that frequency will change. The researchers monitor the frequency by shining a laser on the device and watching the reflection change.
The team had already measured the mass of a…
