P2.7.9 TiO2 Nanohelix Gas Sensors with Enhanced Performance and Potential Application as a Building Block of Electronic Noses

We present TiO2 nanohelix gas sensors with top-and-bottom electrodes configuration fabricated by oblique angle deposition (OAD) that is very simple, easy, and compatible with conventional microfabrication processes. The combination of large surface-to-volume ratio, extremely small size (~ 22 nm) with near single crystallinity of TiO2 nanohelices, together with the top-and-bottom electrodes configuration results in a huge enhancement in gas sensing performances including ~10 times higher sensitivity, ~5 times lower detection limit, and much faster response time than the conventional thin film device. By employing this simple, cheap, and easy method, e-nose, consisting of each sensor devices with various nanostructures and metal-oxides, can be realized, having the large freedom of tuning the sensitivity of each device.