Breakthrough in purification of fossil pollen for dating of sediments by a new large-particle on-chip sorter.

Particle sorting is a fundamental method in various fields of medical and biological research. However, existing sorting applications are not capable for high-throughput sorting of large-size (>100 micrometers) particles. Here, we present a novel on-chip sorting method using traveling vortices generated by on-demand microjet flows, which locally exceed laminar flow condition, allowing for high-throughput sorting (5 kilohertz) with a record-wide sorting area of 520 micrometers. Using an activation system based on fluorescence detection, the method successfully sorted 160-micrometer microbeads and purified fossil pollen (maximum dimension around 170 micrometers) from lake sediments. Radiocarbon dates of sorting-derived fossil pollen concentrates proved accurate, demonstrating the method's ability to enhance building chronologies for paleoenvironmental records from sedimentary archives. The method is capable to cover urgent needs for high-throughput large-particle sorting in genomics, metabolomics, and regenerative medicine and opens up new opportunities for the use of pollen and other microfossils in geochronology, paleoecology, and paleoclimatology.