[an error occurred while processing this directive]

A substance found in crab shells is the key component in a nano-scale sensor system developed by researchers at the University of Maryland's A. James Clark School of Engineering. The sensor can detect minute quantities of explosives, bio-agents, chemicals and other dangerous materials in air and water, potentially leading to security and safety innovations for airports, hospitals and other public locations.

Clark School engineers are using a substance called chitosan (pronounced “kite-o-san”), found in the shells of the Chesapeake Bay's blue crab, to coat components of the microscopic sensor system.

The crabs do not need to be harvested specifically for this purpose. The material is extracted from the crab shell waste.

Reza Ghodssi, associate professor in the Clark School's Department of Electrical and Computer Engineering and the Institute for Systems Research (ISR), and a member of the Maryland NanoCenter, is one of the investigators leading the project. He is joined by a multidisciplinary group: Gary Rubloff from ISR and the NanoCenter, Bill Bentley from the Fischell Department of Bioengineering and Greg Payne from the University of Maryland Biotechnology Institute (UMBI).

“Chitosan is interesting because it's a biological compound that can interact with a wide variety of substances, and also work well in a complex, sensitive device,” according to Ghodssi.

Ghodssi's graduate students are helping to develop the nanoscale “system on a chip.” It employs multiple miniature vibrating cantilevers, similar to diving boards, which are coated with chitosan, plus optical sensing technology that can see when the cantilevers' vibrations change (such devices are called micro-electromechanical systems or MEMS). Different cantilevers can detect different substances and concentrations. When a targeted substance enters the device from the air or water, the chitosan on a specific cantilever interacts with the substance and causes that cantilever's vibration to change its characteristics. The optical sensing system sees the vibration change and indicates that the substance has been detected. The technology was developed and initially tested at the Laboratory for Physical Sciences (LPS) in College Park, Md., and it is currently sponsored by LPS and the National Science Foundation (NSF).

For more information, visit www.eng.umd.edu.