Integrated Arrays of Gas Sensors Using Conducting Polymers with Molecular Sieves

Abstract The concept of an electronic nose, mimicking the mammalian olfactory organ, is now well established. An essential feature of the man-made system is an array of odour-sensing elements, each of which responds differently to a range of gaseous molecules. The present paper describes efforts to produce an integrated array of such sensors using the conducting polymer polypyrrole as the sensing material, but avoiding a procedure in which at each step every element is treated differently, since this would be expensive and prone to faults. The technique explored here involves aiming to produce on ceramic tiles an array of electrochemically deposited sensors which are initially identical and then to modify their characteristics individually by coating each with layers of arachidic acid applied as Langmuir-Blodgett (L-B) films. These layers are subsequently skeletonized by a salting process, which leaves holes in the films comparable in size to the molecules of gases for whose discrimination the underlying polymer is designed, thus providing a molecular sieve. Testing for the effectiveness of the sieves is carried out by means of a static rig.