Table of Contents
Smart Materials Research
Volume 2012, Article ID 210748, 4 pages
http://dx.doi.org/10.1155/2012/210748
Research Article

A Surface Acoustic Wave Ethanol Sensor with Zinc Oxide Nanorods

Department of Mechanical Engineering, The University of Auckland, Auckland 1142, New Zealand

Received 7 October 2011; Accepted 29 November 2011

Academic Editor: Tao Li

Copyright © 2012 Timothy J. Giffney et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Surface acoustic wave (SAW) sensors are a class of piezoelectric MEMS sensors which can achieve high sensitivity and excellent robustness. A surface acoustic wave ethanol sensor using ZnO nanorods has been developed and tested. Vertically oriented ZnO nanorods were produced on a ZnO/128 rotated Y-cut LiNbO3 layered SAW device using a solution growth method with zinc nitrate, hexamethylenetriamine, and polyethyleneimine. The nanorods have average diameter of 45 nm and height of 1 μm. The SAW device has a wavelength of 60 um and a center frequency of 66 MHz at room temperature. In testing at an operating temperature of 270 C with an ethanol concentration of 2300 ppm, the sensor exhibited a 24 KHz frequency shift. This represents a significant improvement in comparison to an otherwise identical sensor using a ZnO thin film without nanorods, which had a frequency shift of 9 KHz.