Chemical Selection for the Calibration of General-Purpose Electronic Noses Based on Silhouette Coefficients

Sensor drift is often application-dependent and results in a reduction in the overall long-term performance of electronic noses. Even with drift compensation it is remains challenging to transfer these models to other application scenarios. In order to remedy this deficiency, different/generic chemicals are needed to provide a general-purpose calibration approach that can be applied to a wide range of electronic noses. In this article, we investigated a method to identify these chemicals based on four criteria (universality, safety, sensibility, and differentiation). This concept was tested on an in-house electronic nose comprising 37 gas sensors and four environmental sensors combined with an automatic gas acquisition system. The 14 different volatile compounds were tested over four months. The silhouette coefficient was used to evaluate the extent of the sensor drift. Six different chemicals (acetone, alcohol, ethyl acetate, tetrahydrofuran, acetaldehyde, and n-hexane) were finally selected as the most appropriate to calibrate our electronic nose (E-nose). We believe our research may motivate the design of a reasonable chemical selection method for the calibration of general-purpose E-noses.