UB Professor Looking To Identify Mechanism Behind Observation Of Negative Electrical Resistance

July 16, 1998

BUFFALO, N.Y. -- A University at Buffalo professor who last week reported at a scientific meeting that she had observed apparent negative electrical resistance at the interfaces between layers of carbon fibers in a composite material is conducting additional studies to clarify the mechanism behind the phenomenon.

Deborah D. L. Chung, Ph.D., professor of mechanical and aerospace engineering at UB, said that while she also observed the conduction of electricity with zero resistance when the composite was combined with another carbon composite that is a conventional, positive resistor -- an indication of superconduction -- her findings do not indicate that the combination is itself a superconductor.

Chung, who holds the Niagara Mohawk Chair in Materials Research at UB and is recognized internationally for her work in smart materials and carbon composites, presented the results on July 9 in a keynote address at the fifth International Conference on Composites Engineering in Las Vegas.

She said that she and Shoukai Wang, a doctoral candidate in UB's Department of Mechanical and Aerospace Engineering, observed continuous negative electrical resistance in a carbon-fiber composite in a direction perpendicular to the fiber layers.

According to Chung, negative resistance indicates that the electrons in the system are flowing in a direction opposite to that in which they normally flow.

She stressed that the mechanism behind the observation of negative resistance at the geometrically complex interface between fiber layers is still unclear.

Chung said that she is working to identify an energy source responsible for the negative-resistance phenomenon.

She and Wang made the observations while evaluating how different curing pressures and matrix materials affected the junction between carbon-fiber layers.

Chung said that they looked at their initial results skeptically, doubting at first that what they were seeing was correct. After checking and rechecking the connections, and after using different meters over a period of time, they concluded that it was truly negative resistance that they were seeing.

Chung and Wang are continuing to study the phenomenon.

Chung's presentation at last week's conference included a demonstration of the negative-resistance phenomenon, in which a carbon fiber-cement-matrix composite was hooked up to a voltmeter that indicated negative electrical resistance.

A paper describing the research has been submitted to a peer-review journal.

A patent application has been filed.

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University at Buffalo

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