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 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.
Highlights
Sensing of ethanol vapour has important applications in industry and society
In order to demonstrate that the ZnO nanorods provided a benefit for ethanol sensing, the shift in the frequency response of the sensor with nanorods was compared with that of an otherwise identical device with the sputtered ZnO thin film, but lacking the ZnO nanorod layer
In the oscillator configuration commonly used for Surface acoustic wave (SAW) gas sensors, the oscillation frequency is determined by the frequency at which the phase shift around the loop is some integer multiple of 2π [16]
Summary
At high temperatures (200◦C to 300◦C) zinc oxide absorbs ethanol vapour, causing a significant change in conductivity [1, 2] and leading to a change in mass. This change in properties can be used to create an ethanol sensor. Surface acoustic wave (SAW) sensors are a class of piezoelectric MEMS sensor which can achieve high sensitivity and excellent robustness. Since their discovery by Rayleigh in 1885 [3] surface acoustic waves have been extensively researched. The propagation characteristics of surface acoustic waves are highly sensitive to any change in the properties of the surface on which they travel
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
