The new sensor technology, which was more sensitive and much more stable than its predecessors, was featured on this week's cover of Applied Physics Letters. The researchers' highlighted study demonstrated the sensor's potential ability to detect a single molecule of the nerve gas, sarin, the most toxic of biological warfare agents.

The researchers, led by Dr. Li Shi, designed and tested a nanometer-thin crystal of tin oxide sandwiched between two electrodes. When a built-in micro-heater heated the super-thin device, the tin oxide reacted with exquisite sensitivity to gases.

Shi's group experimented with a non-toxic gas, dimethly methylphosphonate (DMMP) widely used to accurately mimic sarin and other nerve agents. The sensor element responded to as few as about 50 molecules of the DMMP in a billion air molecules.

Both the nano-sizing of the metal-oxide and the unique micro-heater element of the sensor gave the detector its high sensitivity, stability and low power consumption, said Shi, assistant professor of mechanical engineering.

The thinner a metal-oxide sensor becomes, the more sensitive it becomes to molecules that react with it. In addition to improved sensitivity, the group found its single-crystal metal-oxide nanomaterials allowed the detector to quickly dispose of previously detected toxins and accurately warn of new toxins' presence.

Shi's engineering collaborator, Zhong Lin Wang from Georgia Institute of Technology, provided single crystals of tin oxide as thin as 10 nanometers, and with the ability to rapidly recover from chemical exposure. The researchers found that the sensor was refreshed immediately after the DMMP molecules were purged from the small flow-through chamber whe
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Contact: Becky Rische
brische@mail.utexas.edu
512-471-7272
University of Texas at Austin
10-Feb-2005