New Device Provides Better Virus Detection

Originally Published MDDI April 2004

R&D DIGEST

Erik Swain

Environmental-health monitoring systems at hospitals could be improved with the development of a device sensitive enough to detect a single virus particle.

Purdue University (West Lafayette, IN) researchers have produced a miniature “cantilever,” a beam of silicon that vibrates at a specific frequency when undisturbed. When a single virus particle lands on the cantilever, it vibrates at a different frequency. The device can detect something one-trillionth the size of a grain of rice.

What the project team hopes to do is coat the cantilever with antibodies for a specific virus so that only those virus particles would stick to it. If that can be accomplished, scientists could develop detectors sensitive to specific pathogens, including airborne viruses and bacteria. And that could have great implications for disease and infection control in hospitals.

“This cantilever mechanically resonates at a natural frequency, just like anything that vibrates has a natural frequency,” said Richard Bashir, PhD, associate professor of electrical and computer engineering and biomedical engineering at Purdue. “What we do is measure the natural frequency of the cantilever, which is a function of its mass. As you increase the mass, the frequency decreases. And the way to increase the sensitivity is to make that starting mass very, very small. The long-term goal is to make a device that measures the capture of particles in real time as air flows over a detector.”

Bashir's collaborator Amit Gupta, a doctoral student at Purdue, noted that such a device would be a significant improvement over today's technology. “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,” he said. Thousands of cantilevers could be placed on a 1-cm2 chip and perform functions previously done by bulky laboratory equipment. 

The Purdue team created the cantilevers using the same technology the semiconductor industry uses for etching circuits in electronic chips. It involves depositing silicon onto a wafer and forming it into patterns using chemical etching and other steps. 

The team published a paper in the March 8, 2004, edition of Applied Physics Letters. Bashir and Gupta's coauthor was Demir Akin, a senior research scientist at Purdue's School of Electrical and Computer Engineering.

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