Transient Filling of a Micro Protein Trap Chip Considering Surface Effect

** † † ‡ § , The Lab-on-a-Chip Application Development (LOCAD) team at NASA’s Marshall Space Flight Center is utilizing LOC to support technology development specifically for space exploration. In this paper, we investigate both numerically and experimentally, the transient “filling” two-phase flow patterns in a protein trap chip (PTC) configuration. We will describe the design and operation of an integrated microchannel/PTC configuration. Specifically, the filling processes of a liquid inside an expanded chamber hosting a dammed-structure used to block micro beads for protein trapping are studied. Numerical simulations are performed for the movement of a liquid-gas two-phase flow inside the microchannel and the PTC. The 3-D numerical simulations were conducted using the free surface Volume of Fluid method (PLIC-VOF) which allows for the interface between two immiscible fluids to be simulated while incorporating the effects of surface tension. The results are presented in terms of the movement of the gas-liquid interface. During the filling processes the two-phase flow patterns result from the competition among the inertia, adhesion and surface tension. The effects of hydrophilicity through the contact angle among gas/liquid/solid interface are investigated systematically. An experimental flow visualization system was devised to observe the characteristics of the filling process. Detailed numerical model procedures, as well as experimental results/comparison will be described.