Integration of dense membranes and metal-oxide semiconductors for improved performance of a dedicated artificial olfactory system

Sampling interval Resistance [Ω] Detail: –0.5 0.5 –5 strongly controlled by the membrane permselectivity, inferring in this way an overall selectivity of the system that could not be achieved with the MOS-sensors alone. An important aspect of the integrated system was the transient response of the sensor to the permeate composition: It could be shown that the membrane operated most effectively in the transient regime, being in this sense a true transport barrier rather than merely representing a matrix of a preferential sorption characteristics for certain target compounds, such as occurs in adsorptive techniques. In this way the well-known detrimental effect of the humidity on the signal of sensor arrays could be diminished substantially. The sensitivity of the MOS-sensors was slightly reduced under the vacuum conditions, however, still sufficiently high for the applications envisaged.