Microfluidically enabled high-throughput monitoring of environmental nanoparticles
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Increased environmental exposure is an unavoidable consequence of the growing prevalence of nanomaterials, posing new and largely unknown risks to human health. A variety of detection methods allow nanoparticle concentrations to be sensitively measured offline, after sampling has already taken place. But few methods integrate both sampling and detection with sufficient throughput to perform continuous environmental monitoring of room-sized volumes. We describe a new approach that enables continuous environmental sampling of airborne nanoparticles with online detection and quantification of the collected species. Our method achieves orders of magnitude higher analytical throughput than is currently possible by uniquely combining the high flow rate sampling capability of wetted wall cyclone (WWC) collectors (up to > 1,000 L/min) with a microfluidic component that permits sensitive quantitative measurement of nanoparticle concentration. By coupling these components, we demonstrate detection of airborne ultrafine Al2O3 nanoparticles at environmental concentrations below 200 g/m3 in air sampled at a 200 L/min, well within established toxicity limits.