The response curve /spl sigma///spl sigma//sub 0/ vs P/sub NOx/ of the NO/sub x/ sensor using organic semiconductors, a power type function

One of the most sensitive and selective gas sensors for oxidising gases, like NO/sub x/, is that based on lead phthalocyanine. The theoretical sensing mechanism takes account of the relationship existing between the density of majority carriers and the partial pressure of the gas in the near environment of the sensor surface. The output signal response curve vs. NO/sub x/ partial pressure is found to be a power type function. A number of sensors were studied and their output signal was plotted. The experiment confirms the theoretical sensing mechanism. The mean value of the exponential term of the response curve is 0.38.