Professor Rashid Bashir and his research team have developed a sensor based on microelectromechanical systems (MEMS) that has successfully detected the mass of a single virus particle. The sensor is a tiny cantilever, measuring just 1x4 microns by 20 nanometers thick, that vibrates at a fixed frequency until a virus particle lands on it. This changes its resonance enough to be detected. The virus particle measured, vaccinia-a virus, weighs only 9 femtograms, or quadrillioniths of a gram. (Another way to think of it is about one trillionth as much as a grain of rice). The vaccinia-a virus is used in smallpox vaccine.

The next step in the research, according to Professor Bashir, will be to adapt the cantilever to turn it into a tiny virus detector. The cantilever will be coated with antibodies that will only allow one particular type of virus to stick to the device. If the frequency of the vibration of the cantilever changes, that would indicate that the particular virus is present in the air. Such detectors could therefore be used for both homeland security (to detect bioweapons) or consumer applications (to monitor air purity).

This research work was funded by the National Institutes of Health and the Birck Nanotechnology Center at Purdue. Additional information on the research can be found in the EE Times (http://www.eetimes.com/story/OEG20040213S0009) and Nature (http://www.nature.com/NSU/040209).