Single-Shot Multiplex SRS Microscopy for Label-Free Imaging, Identification, and Quantification of Microplastics

At the Special Edition Virtual Pub, "Imaging Micro- and Nanoplastics," Euro-BioImaging users, Node experts and Industry partners will explore how advanced microscopy, clinical imaging, and image analysis can be used to detect and study micro- and nanoplastic particles. 

At this event, Eric Fantuzzi, Cambridge Raman Imaging, will examine how CORAL, a broadband Stimulated Raman Scattering (SRS) imaging platform can be used to image, identify and quantify microplastic polymers. 

Join us on Friday, November 13, from 1-3 pm CEST for the Special Edition Virtual Pub! 

Abstract:

Single-Shot Multiplex SRS Microscopy for Label-Free Imaging, Identification, and Quantification of Microplastics

Speaker: Eric Fantuzzi, Cambridge Raman Imaging

Micro- and nanoplastics pollution is a growing global concern, and addressing it requires imaging technologies that can identify chemical composition quickly and reliably at high spatial resolution. Established techniques such as FTIR spectroscopy, spontaneous Raman microscopy, SEM, and Py-GC/MS are widely used, but they tend to be slow, expensive, and require demanding sample preparation, making them poorly suited to dynamic or high-throughput imaging workflows.

To address these limitations, Cambridge Raman Imaging developed CORAL, a broadband Stimulated Raman Scattering (SRS) imaging platform built around a simple idea: capture the full spectrum at every pixel in one shot, rather than building it up channel by channel. Conventional narrowband SRS needs to rescan the sample or step the excitation wavelength across the spectral range, whereas CORAL acquires all 38 channels across the C–H stretching region (2800–3100 cm⁻¹) simultaneously, within microseconds, as it scans the sample just once. This gives us label-free, chemically specific hyperspectral imaging at high speed, with the complete chemical picture built in directly, not reconstructed afterwards.

In this talk, we present a systematic evaluation of CORAL for imaging, identifying, and quantifying microplastic polymers across substrates relevant to real-world collection workflows. We built reference spectral libraries for PMMA, PS, and PE particles of varying size, and used them to generate confidence-weighted classification maps through cosine similarity and Pearson correlation analysis, working directly from the hyperspectral image cubes. We validated this approach on glass microscope slides and Anodisc membrane filters, including mixed-polymer samples, and showed that the same acquisitions also support automated particle counting and size measurement.

Because CORAL captures the full spectral window per pixel in a single pass, it opens up imaging scenarios sequential SRS approaches can't handle. We show this by imaging microplastics in flow, using custom silica microfluidic channels to detect individual particles, extract their spectra, and match them against our reference library, an early step toward real-time, in-flow monitoring in aqueous systems.