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NMSU chemical engineering professor Julio Martinez displays a thermoelectric testing device he developed as part of his nanotechnology research.

Sending probes to Mars and harvesting energy are just two of the many applications of thermoelectric and nanotechnology research conducted by Professor Julio Martinez's group at New Mexico State University.

"One nanometer is about 10,000 times thinner than a hair," said Martinez, a chemical engineering assistant professor. "Those are the dimensions of the materials that my group works with to develop new research. Our research involves the use of advanced fabrication and characterization tools to understand the novel properties of nanostructured materials.

"We use nanomanipulation to essentially pick individual nanowires and place them in our devices. One example of nanotechnology application is converting heat into electricity by highly efficient thermoelectric materials."

Martinez explained that when heat is applied to thermoelectric materials, electric power is produced. The amount of electricity generated depends on how much heat is applied and the efficiency of the material to convert heat into electricity. That amount increases at the nano-level.

"Ten years ago, physicists developed a new theoretical framework for thermoelectrics," he said. "They found that nanostructured materials would drastically increase the thermoelectric efficiency."

Thermoelectrics can, for example, convert the heat waste from a car engine's tailpipe into electricity, thus improving gas mileage. The engine would work with the gas and the thermoelectric component would charge

"Nanowires are perhaps the best example of how to get high efficiency thermoelectric materials," Martinez said. In addition to energy harvesting, thermoelectric nanostructured materials can assist in cooling high power transistors.

Although he first began working with silicon nanowires at Livermore National Laboratory, Martinez has since moved on to experimenting with gallium nitride, which has better characteristics for computer chip applications, and silicon-germanium alloy nanowires. Silicon, he explained, works well for electronics but is "limited by its thermoelectric efficiency."

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Eye on Research: Nanotechnology holds big potential for NMSU faculty