Size Based Droplet Sorting with Wide Tuning Range Using Tensiophoresis

Size-based droplet sorting can be used to improve the monodispersity of droplet populations in chemical assays, and as a label-free measurement in cell-in-droplet assays. Several microfluidic approaches can efficiently perform binary sorting based on a size threshold; however, the thresholds are typically fixed by the channel design. This paper presents a passive drop sorting technique in which the size threshold can be dynamically adjusted. Based on a previously reported concept of tensiophoresis, this technique also provides high sorting precision. Droplets over a 10 fold range (diameters 50-500 μm) are sorted in a 800 μm channel with a precision of 3.3%.