Trapping Microfluidic Drops in Wells of Surface Energy

• DOI: 10.1103/physrevlett.107.124501
• Publication Date: 2011-09-15T19:38:59Z
• Authors: Rémi Dangla; Sungyon Lee; Charles N. Baroud
• Keywords: Microchannel

A small hole etched in the top of a wide microchannel creates well surface energy for confined drop. This produces an attractive force ${F}_{\ensuremath{\gamma}}$ equal to gradient, which is estimated from geometric arguments. We use drag ${F}_{d}$ outer flow probe trapping mechanism. When ${F}_{d}<{F}_{\ensuremath{\gamma}}$, drop deforms but remains anchored hole. Its shape provides information about pressure field. At higher velocities, detaches, defining critical capillary number ${F}_{d}={F}_{\ensuremath{\gamma}}$. The measured anchoring agrees with model.