Hydrodynamic trap-and-release of single particles using dual-function elastomeric valves: design, fabrication, and characterization

Abstract

This paper introduces a simple method for trapping and releasing single particles, such as microbeads and living cells, using dual-function elastomeric valves. Our key technique is the utilization of the elastomeric valve as a dual-function removable trap instead of a fixed trap and a separate component for releasing trapped particles, thereby enabling a simple yet effective trap-and-release of particles. We designed, fabricated, and characterized a microfluidic-based device for trapping and releasing single beads by controlling elastomeric valves driven by pneumatic pressure and a fluid flow action. The fluid flow is controlled to ensure that beads flowing in a main stream enter into a branch channel. A bead is trapped by deflected elastomeric valves positioned at the entrance of a branch channel. The trapped bead is easily released by removing the applied pressure. The trapping and releasing of single beads of 21 mu m in diameter were successfully performed under an optimized pressure and flow rate ratio. Moreover, we confirmed that continuous trapping and releasing of single beads by repeatedly switching elastomeric valves enables the collection of a controllable number of beads. Our simple method can be integrated into microfluidic systems that require single or multiple particle arrays for quantitative and high-throughput assays in applications within the fields of biology and chemistry.