Inside the chip, a tiny diving-board like cantilever vibrates at a high frequency. When a virus particle lands on it, the frequency changes slightly. "This work is particularly important because it demonstrates the sensitivity to detect a single virus particle," said researcher Amit Gupta of the Birck Nanotechnology Center Purdue University. "Also, the device can allow us to detect whole, intact virus particles in real time. Currently available biosensing systems for deadly agents require that the DNA first be extracted from the agents, and then it is the DNA that is detected."
The cantilever is four microns long and 30 nanometres thick, and the virus detected – vaccina, a relative of cowpox – weighed about nine femtograms. In the future, the researchers plan to coat the cantilever with antibodies to filter for specific species. “The long-term goal is to make a device that measures the capture of particles in real time as air flows over a detector," said Rashid Bashir, an associate professor of electrical, computer and biomedical engineering who also worked on the project.
The researchers said that this technology could be used for checking for pathogens used in biological warfare, as well as for general health and environmental monitoring. The goal of MEMS research is to produce devices that are as easy and cheap to make as computer chips, potentially leading in this case to home diagnostic kits that can screen for hundreds of diseases in minutes.
The findings will be detailed in a paper to be published next month in Applied Physics Letters.