Efficient Implementation of MINT-Based Chemiresistor Arrays for Artificial Olfaction

Abstract

We demonstrate the possibility of using an array of MINT-based chemiresistors for the selective detection of VOCs at room temperature. Four new types of MINTs with different functional groups (MINT_ALKENE (X:–CH = CH₂), MINT_COOMe (X:–COOMe), MINT_COOH (X:–COOH), and MINT_OH (X:–CH₂OH)) were specifically synthesized to prepare a set of six sensing layers, which included, in addition to the new MINTs, a pristine SWNTs layer and a MINT_XYLENE layer. The functionalized sensing layers were tested by exposing them to NH₃, NO₂, EtOH, IPA, acetone, benzene, and NaClO vapors in the ppm range. We showed that MINT functionalization enhances response to analytes with respect to pristine SWNTs. When assembled into an array, our sensing layers can operate at room temperature as an electronic nose, disclosing the possibility of using these layers in low-power-consumption wearable devices. Correlation plots, PCA, and UMAP analysis show that a remarkable discrimination of ammonia with respect to interfering gases can be reached by the e-nose. Gas mixtures were also discriminated, as shown for NH₃/ethanol, acetone/ethanol, and isopropanol/acetone mixtures, which are relevant in view of breathomics applications. The efficient preparation method of sensing layers allows for an improvement of performance, as shown for one of the best performing chemiresistors in the set, resulting in a sensitivity increase (up to 10×) and a dramatic reduction of response and recovery times.