Using Machine Learning to Overcome Interfering Oxygen Effects in a Graphene Volatile Organic Compound Sensor

Nyssa S.S. Capman, V. R.Saran Kumar Chaganti, Laura E. Simms, Christopher J. Hogan, Steven J. Koester

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Discriminating between volatile organic compounds (VOCs) for applications including disease diagnosis and environmental monitoring, is often complicated by the presence of interfering compounds such as oxygen. Graphene sensors are effective at detecting VOCs; however, they are also known to be highly sensitive to oxygen. Therefore, the combined effects of each of these gases on graphene sensors must be understood. In this work, we use graphene variable capacitor (varactor) sensors to examine the cross-selectivity of oxygen at 3 concentrations and 3 VOCs (ethanol, methanol, and methyl ethyl ketone) at 5 concentrations each. The sensor responses exhibit distinct shapes dependent on the relative concentrations in mixtures of oxygen and VOCs. Because the entire response shape is therefore informative for distinguishing between each gas mixture, a classification algorithm that utilizes entire sequences of data is needed. Accordingly, a long short-term memory (LSTM) network is used to classify the mixtures and VOC concentrations. The model achieves 100% accurate classification of the VOC type, even in the presence of varying levels of oxygen. When the VOC type and VOC concentration are classified, we show that the sensors can provide VOC concentration resolution within approximately 200 ppm. Throughout this work, we also demonstrate that an effective gas mixture classification can be achieved, even while the sensors exhibit varied drift patterns typical of graphene sensors. This is made possible due to the data analysis and machine learning methods employed.

    Original languageEnglish (US)
    Pages (from-to)7554-7564
    Number of pages11
    JournalACS Applied Materials and Interfaces
    Volume16
    Issue number6
    DOIs
    StatePublished - Feb 14 2024

    Bibliographical note

    Publisher Copyright:
    © 2024 American Chemical Society.

    Keywords

    • gas sensor
    • graphene
    • machine learning
    • oxygen
    • sensing gas mixtures
    • volatile organic compounds

    PubMed: MeSH publication types

    • Journal Article

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