A near single crystalline TiO₂nanohelix array: enhanced gas sensing performance and its application as a monolithically integrated electronic nose

Abstract

We present high performance gas sensors based on an array of near single crystalline TiO(2) nanohelices fabricated by rotating oblique angle deposition (OAD). The combination of large surface-to-volume ratio, extremely small size (<30 nm) comparable to the Debye length, a near single crystallinity of TiO(2) nanohelices, together with the unique top-and-bottom electrode configuration hugely improves the H(2)-sensing performance, including ∼10 times higher response at 50 ppm, approximately a factor of 5 lower detection limit, and much faster response time than the conventional TiO(2) thin film devices. Beyond such remarkable performance enhancement, the excellent compatibility of the OAD method compared with the conventional micro-fabrication technology opens a new avenue for monolithic integration of high-performance chemoresistive sensors to fabricate a simple, low cost, reliable, yet fully functional electronic nose and multi-functional smart chips for in situ environmental monitoring.

Hydrogen sensor of Pd-decorated tubular TiO2 layer prepared by anodization with patterned electrodes on SiO2/Si substrate

“…TiO 2 nanohelix arrays prepared by oblique angle deposition were able to detect NO 2 , CO and H 2 [60]. The different selectivity of our sensor compared to other TiO 2 -based sensors can be caused by various distinctive features, such as the relatively low operating temperature (180°C), the different crystalline structure and the Pd decoration.…”

Perspectives on oblique angle deposition of thin films: From fundamentals to devices

“…Electronic noses (e-noses) are a typical example of this type of devices. Recently, Kim et al [475] developed a multi-sensor e-nose chip incorporating six different nanostructured gas-sensing layers prepared by OAD: TiO 2 thin films, TiO 2 nanohelices, ITO slanted nanorods (see Ref. [339]), SnO 2 thin films, SnO 2 nanohelices and WO 3 zig-zag nanostructures.…”

Efficient photoelectrochemical hydrogen production from bismuth vanadate-decorated tungsten trioxide helix nanostructures

“…Oblique angle deposition has been widely used in the fabrication of ordered nanostructure arrays and offers numerous advantages, such as control over thickness/shape, reproducibility and low cost 30,31 . In this study, the F:SnO 2 (FTO) substrate size was 1.5 cm  1.5 cm.…”