The Trimethylamine (TMA) Sensitive Performance Of WO₃ Material

With the increasing of market demand for fish at present, it is vital to detect and evaluate its freshness exactly, which is not only an important indication to measure and judge the quality of fish, but also related to people's health and life quality. Nowadays, at home and abroad, one of the most widely used methods is judging fish freshness by detecting the compound of decomposed product caused by adenosine triphophate in the fish's tissue in a chemical way. But this method has much shortcoming like manipulating complicatedly, costing highly, consuming much effort and time. And it needs to damage fish sample, so it is difficult to generalize the method in fact. Therefore it is urgent to research and develop a rapid, easy and non-destructive way to detect fish freshness by using gas sensor.It is well known that WO3 is a conductance-type semiconductor gas sensing material, but the research on fish freshness detector with WO3-based gas sensor to trimethylamine is still at a beginning stage. In this project, the WO3-based gas sensors to trimethylamine are made, and their gas sensing performance are researched, especially at low temperature, the results are as follows:1. The nano-sized WO3 powder is prepared by sol-gel method of sodium tungstate and hydrochloric acid, and its microstructure is analyzed by using XRD, SEM and TEM, for material's microstructure is closely related to gas sensing performance. From the results, it can be shown that the flaky crystal grains of this nano-sized material has small size, and the conjunction among them is loose, which can help gas be adsorbed and improve its performance. While under Scherrer formula, the average size of this WO3 is about 17nm.2. Two kinds of WO3 powder are prepared by sol-gel method and gas-phase reaction method with tungsten filament, and heater type gas sensors to trimethylamine are made. Under different work temperatures, these sensors'sensitivities are measured, and the result indicates that WO3 by sol-gel has better gas sensing performance to trimethylamine. At the same time, the WO3-based gas sensor to trimethylamine can work at low temperature, which...