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Technologies that can detect and characterise particulates
in liquids have applications in health, food and environmental monitoring. Here
we present a low-cost and high-throughput multiuse counter that classifies a
particle’s size, concentration, porosity and shape. Using an additive
manufacturing process, we have assembled a reusable flow resistive pulse
sensor. The device remains stable for several days with repeat measurements. We
demonstrate its use for characterising algae with spherical and rod structures
as well as microplastics shed from teabags. We present a methodology that results in a specific signal for microplastics, namely a conductive pulse, in contrast to particles with smooth surfaces such as calibration particles or algae, allowing the presence of microplastics to be easily confirmed and quantified. In addition, the shape of the signal and particle are correlated, giving an extra physical property to characterise suspended particulates. The technology can rapidly screen volumes of liquid, 1 mL/ min, for the presence of microplastics and algae.