Microreactors and microfluidic systems: an innovative approach to gas sensing using tin oxide-based gas sensors

A highly innovative approach of using tin oxide-based gas sensors is presented. Miniaturised tin oxide gas sensors were mounted inside micromachined cavities to form microreactors. These microreactors, with an internal volume of 45 μl, are surrounded by a microfluidic system containing valves and pumps. As already known [1] tin oxide-based gas sensors are highly sensitive towards oxidising and reducing gas species but there is a lack of selectivity and a certain amount of baseline drift. We show how smart microfluidic systems are able to solve these problems by operating microreactor systems alternately in constant-flow and no-flow modes of operation.