Development of a ZnO-modified light-scattering sensor for the detection of alcohols

A light-scattering sensor that incorporated zinc oxide (ZnO) nanoparticles was developed and characterized in this study. Evenly distributed nanostructured ZnO materials were formed on the sensing elements through the calcination of zinc acetate-treated sensing elements in a high-temperature oven. There was a large change in the scattering properties of the nanostructured ZnO materials after adsorption of the target compounds; this behavior was exploited for quantitative purposes. To investigate the detection of volatile compounds using this method, both static and flow cell-type devices were constructed. To determine the most suitable nanostructured ZnO material for the light scattering sensors, several factors that influenced their morphologies, including the calcination temperature, calcination time, and the amount of ZnO colloidal solution for calcination, were examined. Fiber-like ZnO structures were produced at temperatures below 400 degrees C. Above 400 degrees C, particles having round shapes were observed; the higher the calcination temperature, the larger the particle sizes. Based on an examination of the signals from several volatile organic compounds, the prepared ZnO sensor was selective for the detection of alcohols, and the observed signals followed the surface-adsorption mechanism. The prepared sensor is fast in response, and the detection time can be shorter than 2 min. For quantitative purposes, the linear range was limited to low concentrations of alcohols, i.e., up to ca. 200 ppm.