Artificial olfaction is a fast growing field aiming to mimic natural olfactory systems. Olfactory systems rely on a first step of molecular recognition where volatile organic compounds (VOCs) bind to an array of specialized olfactory proteins. As a result, electrical signals are transduced to the brain where pattern recognition is performed. An efficient approach in artificial olfaction combines gas-sensitive material arrays with dedicated signal processing and classification tools. 

Supramolecular self-assembly provides the possibility to generate modular and tunable materials with stimuli-responsive properties. This field is attracting enormous interest as an approach to functional materials design, and has tremendous, mostly untapped opportunities in creating new types of sensors. My research group has recently developed the concept of hybrid gels. These materials result from the combination of functional components – liquid crystals for reporting, ionic liquid as solvent, biopolymer as matrix - which give rise to molecular recognition properties not seen in the individual components. Each component has its own role, yet in combination, they provide a molecular environment and compartmentalization that provides the selectivity required for sensing. When casting the hybrid gels as thin films, they exhibited dual optical and electrical stimuli-responsive properties in the presence of VOCs. 

In this work, films of hybrid gels were studied as gas sensing materials in a custom-built electronic nose. Several features were extracted from the signals obtained upon VOC exposure, and then used to implement a dedicated automatic classifier based on support vector machines for data processing. As an optical signature could be associated to each VOC, the developed algorithms classified eleven distinct VOCs with high accuracy and precision (higher than 98%), using optical signals from a single film composition. This shows an unprecedented example of soft matter in artificial olfaction, where gelatin hybrid gels can provide enough information to accurately classify VOCs with small structural and functional differences. Furthermore, we show that the developed device can be used in the quantification of ethanol in automotive fuel or in fish spoilage monitoring. The versatility shown by the developed opto-electronic gas sensing materials opens a wide range of applications in different areas such as medical diagnostics, food or agriculture.

Gas-sensing materials by cooperative assembly

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.