Aggregate-then-concentrate microfluidics for rapid detection of nanoplastics and submicroplastics

Summary: Submicron particles (SMPs), including nanoplastics (NPs) and sub-microplastics, play significant roles in influencing physiological and ecological systems. Their diminutive size allows them to readily traverse biological barriers. Detecting these particles relies on integrating sample pre-processing methods, such as filtration, ultracentrifugation, and emerging microfluidic technologies, but they are often constrained by complex workflows and low throughput. Here, we integrate SMP aggregation with spiral inertial microfluidics (SIMF) for rapid detection of SMPs. Using NPs as proof of concept, our aggregate-then-concentrate strategy achieved >90% NP recovery in experimental settings and polluted seawater samples, facilitating quantitative and qualitative assessments of NPs via fluorescence microscopy and Raman microspectroscopy, respectively. Hence, our technology overcomes the long-standing size limitations of inertial microfluidics conventionally restricted to microscale particles by enabling the efficient aggregation and detection of nanoscale targets without downscaled channels. This broadens the applicability of microfluidics and opens new avenues for scalable, accessible detection of SMPs in the environment.