Purdue University scientists have developed a scale that can weigh a 10 femtograms virus.

It uses a laser beam to measure the variation of wobble of a 30 nanometer-thick silicom springboard from the virus. Coating the springboard with antibodies will allow onlyone particular type of virus to stick to the scales. Such detectors could one day be used to monitor air purity in hospital or to assist in security checks for bioweapons.