The development of a low-cost, sensitive colorimetric sensor array for the detection and identification of volatile organic compounds (VOCs) is reported. Using an array composed of chemoresponsive dyes, enormous discriminatory power is possible in a simple device that can be imaged easily with an ordinary flatbed scanner. Excellent differentiation of closely related organic compounds can be achieved, and a library of 100 VOCs is presented. The array discriminates among VOCs by probing a wide range of intermolecular interactions, including Lewis acid/base, Brønsted acid/base, metal ion coordination, hydrogen bonding, and dipolar interactions. Importantly, by proper choice of dyes and substrate, the array is essentially nonresponsive to changes in humidity.

A simple colorimetric sensing array based on four different types of molecular recognition allows the discrimination of functionalized organic vapors. Sensitivities well below 1 ppmv have been observed for amines and the technique even allows the discrimination of isomers. More about this approach can be found in the Communication by K. S. Suslick and co-workers on the following pages.

Rapid identification of both species and even specific strains of human pathogenic bacteria grown on standard agar have been achieved from the volatiles they produce using a disposable colorimetric sensor array in a Petri dish imaged with an inexpensive scanner. All ten strains of bacteria tested, including E. faecalis and S. aureus and their antibiotic resistant forms, were identified with 98.8% accuracy within 10 h, a clinically important timeframe. Furthermore, the colorimetric sensor arrays also prove useful as a simple research tool for the study of bacterial metabolism and as an easy method for the optimization of bacterial production of fine chemicals or other fermentation processes.

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