Fluid filling into micro-fabricated reservoirs

This study reports that the success of reservoir-filling strongly depends on the designs of the hydrophilic wall surface and the well shape/size of the flow network. The idea is illustrated both by experiments and numerical simulations: micro-particle-image-velocimetry (μ-PIV) system is setup to monitor the process of a liquid slug moving in and out of the micro-reservoir and numerical computations are performed by solving first principle equations to provide the details of the flow process. The cross-check between measurements and computations validate the computations. Numerical computations solve conservation equations similar to homogeneous flow model used in two phase flow calculation in cooperation with volume-of-fluid (VOF) interface tracking methodology and continuum surface force (CSF) model. The simulations show that wall surface property as hydrophilic/hydrophobic is a dominating factor in filling processes of reservoirs of various shapes. A flow system consisting of micro-channels and micro-wells is fabricated using MEMS technology to demonstrate the filling process and validate numerical simulation. The agreement between measurement and computation helps to fully understand the process.