Calixarene membranes on semiconductor substrates for EIS chemical sensors

Thin p-tert-butyl calix[4]arene and p-tert-butyl calix[6]arene films were deposited using the technique of thermal evaporation under vacuum to fabricate chemical microsensors based on an E.I.S. (Electrolyte-Insulator-Semiconductor) structure. Electrochemical capacity measurements were made to test and calibrate physico-chemical sensors with regards to their sensitivity and selectivity. The sensing properties of calix[it]arene and calix[6]arene towards alkaline and heavy metal ions were tested. Both devices have shown Nernstian response and a wide working pH range. The former responded well to sodium ions and the latter to nickel ions, thus partial selectivity for these ions is shown. The improved lifetime (compared with membranes prepared by physical adsorption techniques) and sensitivity observed for these films indicates that these structures are worthy of further developments. (C) 1997 Elsevier Science Ltd. All rights reserved.