Hydrodynamic on-rail droplet pass filter for fully passive sorting of droplet-phase samples

Abstract

A hydrodynamic droplet pass filter for droplet-phase sample sorting was developed in this study.

PDMS-based microfluidic devices using commoditized PCBs as masters with no specialized equipment required

“…Multi-height structures for passive droplet sorting were fabricated according to a literature procedure. 27 Briey, two PCB masters were prepared to construct the multi-height device. The rst PCB master contained a 70 mil (about 1778 mm) wide channel.…”

“…In a channel with a parallel groove structure on the main route, a main ow exists in the channel direction and a side ow exists in the parallel groove direction. 27 The side ow produces a driving force on the droplets in the main route. If the size or deformation of a droplet is large enough to be partially located on the new groove, the droplet experiences Laplace pressure in the new groove.…”

A high-resolution passive droplet-phase sample sorter using multi-stage droplet transfer

“…Because of Laplace pressure in the microchannel, introduced droplets can move along the rail way. 29,30 In the ow eld, when a new rail appears downstream, lateral ow into the new rail occurs and the droplet deforms to that direction. The droplet reaches the new rail and is newly inuenced by Laplace pressure if it is large or deformed enough.…”

“…In contrast, we reported a fully passive and highly accurate droplet sorting method using a rail-like channel structure. 29 Droplets were simply guided on a rail and those of target size were selectively transferred to other rails. The droplets were sorted into a maximum of ve steps on the serial rails.…”

Sensitive and predictable separation of microfluidic droplets by size using in-line passive filter

“…Hydrodynamic methods such as shear-induced migration 13,14 and hydrodynamic separation in W-shaped forked channel 15 can distinguish droplets that differ by a factor of $1000 in volume, which is inadequate for accurate sorting. The use of hydrodynamic on-rail filters can achieve sensitive separation by size 16 but this requires fabrication of complicated multi-layered devices. Deterministic lateral displacement (DLD) 17 can separate droplets having a two-fold volume difference; 18,19 however, DLD devices are typically space-consuming, especially when the droplet-size is large.…”