New calibration techniques for real time characterization of gas sensors

Gas sensors or gas sensor systems are normally characterized by their sensitivities to definitive gas concentrations as a function of such parameters as temperature, pressure, moisture, and flowspeed. The sensor data have to be taken under steady conditions, which means that the recorded characteristics demonstrate only the final but not the time-dependent state of the reactive physical or chemical processes. The real dynamic behavior, such as the rise (t/sub 90/) and fall time (t/sub 10/) of the sensor, is often falsified because the determining step is not caused by the reaction mechanism of the sensors but by the state of test gas transition from concentration C/sub 1/ to C/sub 2/. The calibration techniques described are powerful tools, especially for gas sensors with rise times in the range of 1 s and below. The results of a variety of examinations carried out electrochemical, catalytic, semiconducting, solid state, and thin and thick film sensors, and IDCs and SGFETs confirm the quality of these calibration techniques.<>