Optical sensing methods have shown their potential in
measuring
environmental properties such as temperatures and sample concentrations,
increasing the convenience and speed of such measurements. Carbon
dots (CDs) are readily available, easy-to-synthesize, and non-toxic
luminescent colloidal nanoparticles that have gained prominence as
optical probes in recent years. A disadvantage of CDs used for optical
sensing is their broad emission profile, leading to unspecific sensing
and a potential overlap of their luminescence with the autofluorescence
of the samples. Machine learning approaches can address these shortcomings
and greatly enhance sensing accuracy. In this study, CDs were employed
as optical probes, while machine learning methods were applied to
optimize ethanol content determination in ethanol/water mixtures as
well as in alcohol-containing beverages. A simple neural network was
used to understand the importance of different optical parameters
on sensing, while a modular deep learning model was developed for
increased generalizability towards samples with strong autofluorescence.
Drawing from multiple input channels, the deep learning model was
able to predict ethanol concentrations with a mean absolute error
of 0.4 vol % in pure solvents and 6.7 vol % in beverages (beers, wines,
and spirits). While CDs are excellent candidates to demonstrate deep
learning for optical sensing, the methods discussed in this work are
promising for improving chemical sensing using various luminescent
materials.