Conducting polymer based electrochemical sensors on thick film substrate

New types of electroconducting conjugated polymer (ECP) based enzymatic and gas sensors were developed by using thick film technology. In order to pre pare a stable polymeric film which is suitable for the enzyme immobilizatio n and for gas detection itself, a special conducting salt (sodium dodecyl s ulfate, 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 t he 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 rime in the same solution. The sensor give s an easily measurable stationary response in the physiological concentrati on range of uric acid. Using a similar electropolymerization method, a sele ctive ECP based sensor was prepared as part of a sensor array for intellige nt gas monitoring. The changes in conductivity of the polypyrrole film in t he presence of different gases were registered. A reversible sensor respons e of about 30% in saturated methanol/air mixture and 50% at 1000 ppm ammoni a 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 respon se was obtained for ethanol, NO and CO. The sensor proved to be insensitive for H-2.