Conducting Polymer Based Electrochemical Sensors on Thick Film Substrate

Abstract

New types of electroconducting conjugated polymer (ECP) based enzymatic and gas sensors were developed by using thick film technology. In order to prepare a stable polymeric film which is suitable for the enzyme immobilization and for gas detection itself, a special conducting salt (sodium dodecyl sulfate, SDS) was used. This combination resulted in sensors with favorable properties, i.e., higher sensitivity and longer operation stability. In the case of the ECP based uric acid biosensor a new layout was developed for the measurement of the current difference between the polymer and the enzyme electrode by using two working electrodes identically prepared (sensor and polymer electrodes) at the same time in the same solution. The sensor gives an easily measurable stationary response in the physiological concentration range of uric acid. Using a similar electropolymerization method, a selective ECP based sensor was prepared as part of a sensor array for intelligent gas monitoring. The changes in conductivity of the polypyrrole film in the presence of different gases were registered. A reversible sensor response of about 30 % in saturated methanol/air mixture and 50 % at 1000 ppm ammonia in air was obtained at room temperature. For NH3 a linear response in the 40–1000 ppm concentration range could be registered while almost no response was obtained for ethanol, NO and CO. The sensor proved to be insensitive for H2.