Infrared Hyperspectral Microscope for Rapid Characterization of Microplastics

The EPA has identified a need for new methods and instrumentation to characterize size, shape, and composition of microplastics, especially in the size range of 1 µm – 1 mm. To meet the needs identified by EPA, we propose development of a portable sensor for improved microplastic sampling and characterization useable at remote measurement sites or fixed installations. The sensor would be connected to water sampling lines placed in regions where microplastic characterization is desired. Particulates in the size range 10 µm – 1 mm filtered from the water stream onto a micro-mesh metal substrate will be probed using high-performance infrared laser hyperspectral imaging/microscopy, based on swept-external cavity quantum cascade lasers. This powerful spectroscopic imaging technique will measure size and shape of any particles collected from the microscope images, while at the same time determining the chemical composition via infrared spectroscopic analysis. A wide range of pure and weathered polymer/plastic materials will be identifiable using this technique and distinguished from inorganic particles or biological materials. By automating sample collection, measurement, and analysis, while eliminating the costly and labor-intensive steps of sample purification and cleaning, the sensor will operate continuously and autonomously. This operation mode will allow large volumes of data to be collected for microplastic characterization at multiple sites, as is needed to improve the understanding of the full effects of microplastics on the environment and human health. The technology will be immediately usable by researchers at academic institutions or government research laboratories to improve quality and quantity of microplastic data. In the future, these sensors would be installed in fixed locations at industrial sites, municipal water supplies, or other areas at high risk for microplastic contamination, ultimately allowing online monitoring for safety or regulatory purposes. The technology developed may also be applied to new markets where particle characterization is required, such as environmental monitoring or detection of explosives.