ELECTROCHEMICAL GAS SENSORS USING ELECTROLYTIC FILMS OF POLY(ETHYLENE OXIDE) ZN, CU, NI TRIFLUOROMETHANE SULFONATES FOR FLOW-INJECTION ANALYSIS OF NITROGEN-DIOXIDE

Au/poly(ethylene oxide)n M(CF3SO3)2/M (M = Zn, Cu, Ni) galvanic gas sensors, consisting of a disk 13 mm in diameter and 1.1 mm thick. have been developed by using a polymeric electrolyte film (0.1 mm thick). The polymeric films are made by mixing with an acetonitrile solution both M(CF3SO3)2 and poly(ethylene oxide) (m.w. almost-equal-to 6 x 10(5)). The working electrode (25 nm thick) is made by sputtering gold in an argon atmosphere. Of the three kinds of sensors, the zinc one (n = 55) shows the greatest sensitivity. For the zinc cell, the maximum response appears within 3 s after the sample (2.6 ml) is injected into the nitrogen carrier stream, flowing at a rate of 28 ml min-1; the response returns to the baseline within 3 min at the longest. The maximum current flowing in the external circuit is linearly related to the concentration of NO2 in the range 0.02-1 ppm at ambient temperature.