A hydrogen sensor uses small, zincoxide nanorods, located within the black dots in the triangular base, to gauge the amount of hydrogen in the air. The card-deck-sized sensor node has been tested successfully in a UF lab. Researchers say the next step is to miniaturize, then test it at NASA labs and in field conditions.

The sensor "nodes" would work in concert with dozens or hundreds like it to sniff out leaks, before trouble starts. Hydrogen gas is invisible, odorless, and explosive at high concentrations, posing a safety problem for hydrogenpowered cars, filling stations, and other infrastructure.

Nodes use a zinc-oxide nanorod sensing element that becomes more electrically conductive with increasing hydrogen concentration. A circuit amplifies a small electrical current passed through the nanorod. A wireless transmitter then forwards the information to a central base station.

Power for the nodes comes from conventional solar cells or from a piezoelectric system that collects vibrational energy produced by mechanical and electrical equipment to which the nodes mount. Laboratory tests of a node attached to a mechanical shaker shows it can detect hydrogen concentrations down to 10 ppm — well below the level at which hydrogen becomes explosive. In these tests, nodes have transmitted their information up to 20 m, or about 65 ft.

"You need lots of hydrogen sensors to detect leaks, but you don't want to maintain them or change the battery every couple of months," says Jenshan Lin, an associate professor of electrical and computer engineering and the lead investigatoron the NASA-funded project. "Our sensor can operate independently."

Lin and his colleagues developed the sensor node as part of the NASA Hydrogen Research Program at UF.