TRENDS IN ODOR INTENSITY FOR HUMAN SIND ELECTRONIC NOSES - RELATIVE ROLES OF ODORANT VAPOR-PRESSURE VS. MOLECULARLY SPECIFIC ODORANT BINDING

Response data were collected for a carbon black-polymer composite elec tronic nose array during exposure to homologous series of alkanes and alcohols. The mean response intensity of the electronic nose detectors and the response intensity of the most strongly driven set of electro nic nose detectors were essentially constant for members of a chemical ly homologous odorant series when the concentration of each odorant in the gas phase was maintained at a constant fraction of the odorant's vapor pressure, A similar trend is observed in human odor detection th reshold values for these same homologous series of odorants, Because t he thermodynamic activity of an odorant at equilibrium in a sorbent ph ase is equal to the partial pressure of the odorant in the gas phase d ivided bq the vapor pressure of the odorant and because the activity c oefficients are similar within these homologous series of odorants for sorption of the vapors into specific polymer films, the data imply th at the trends in detector response can be understood based on the ther modynamic tendency to establish a relatively constant concentration of sorbed odorant into each of the polymeric films of the electronic nos e at a constant fraction of the odorant's vapor pressure. Similarly, t he data are consistent with the hypothesis that the odor detection thr esholds observed in human psychophysical experiments for the odorants studied herein are driven predominantly by the similarity in odorant c oncentrations sorbed into the olfactory epithelium at a constant fract ion of the odorant's vapor pressure.