Rapid identification of microplastics in complex biological matrices via high-speed mid-infrared hyperspectral imaging

Rapid and reliable identification of microplastics in complex biological matrices remains challenging due to limited throughput or insufficient chemical specificity of existing techniques. Here, we demonstrate a high-speed and high-throughput mid-infrared hyperspectral imaging approach based on sub-cycle mid-infrared pulses. The system enables acquisition of centimeter-scale hyperspectral images covering the infrared fingerprint region with a spectral resolution of approximately 3 cm^-1 within seconds. Microplastic particles composed of five common polymers-polypropylene, polystyrene, polyethylene, polyvinyl chloride, and polyethylene terephthalate-were accurately identified and spatially mapped. The method was further validated in mouse embryo tissue sections, where micrometer-scale microplastics were reliably distinguished against highly complex and spatially heterogeneous infrared backgrounds. This approach combines the intrinsic chemical specificity of infrared absorption spectroscopy with large field-of-view, high-throughput, and rapid imaging, enabling efficient in situ microplastic analysis in complex biological environments.