PHTHALOCYANINE LANGMUIR-BLODGETT-FILM MICROSENSORS FOR HALOGEN GASES

Microsensors for halogen gases fabricated by Langmuir-Blodgett films of phthalocyanine [(C6H13)3SiOSiPcOGePcOH] (where Pc is the phthalocyanato dianion) and planar microelectronic technologies are evaluated. The sensor incorporates a micro heater and a diode to control the temperature of the film. The gas concentration is measured by the conductance change. The film temperature effects on sensitivity, rise and decay times, as well as pulsed operation have been studied experimentally. The Cl2 sensor reaches a sensitivity peak at 130 °C and the conductivity of the film changes from 10-10 to 10-6 mho cm-1 in 111 ppm pre-mixed Cl2/N2 mixture. The response and recovery times are about 1 min at 130 °C. For the I2 sensor, the peak response is at 20 °C and the conductivity changes from 10-9 to 10-8 mho cm-1 for 40 ppm I2 in air. The response and recovery times are about 20 s. © 1990.