Titania nanotubes make super sensors

Titania nanotubes are 1,500 times more effective than any other type of sensor for sensing hydrogen, according to new research from Penn State University.

When hydrogen enters an array of such nanotubes, it flows around the surface of the material, where it gets dissociated. The hydrogen ions created in the process then diffuse into the titania lattice where they act as electron donors. This changes the conductance of the nanotubes, signalling that hydrogen, above the background level, is present.

One problem often found in sensors is that they become poisoned, either by the gas they test, or by other gases in the atmosphere, and no longer operate. But not with the new sensors. The researchers tested the titania nanotubes with carbon dioxide, carbon monoxide, ammonia and oxygen finding little interference.

Craig A. Grimes, associate professor of electrical engineering and materials science and engineering, at the University notes that the material can be made by the mile and is very cheap. The material is also not ‘used up’ when sensing hydrogen, but once the gas clears from the tubes, can be used again.

‘Many researchers have tried to use carbon nanotubes as gas sensors, but they do not work very well,’ says Grimes. ‘Titania has really great sensitivity and a nice response.’

‘Our results show that titania nanotube sensors can monitor hydrogen levels from 1 part per million to 4%,’ he added.