Capillary Channel: a Numerical and Experimental Study
March 2014 - May2014, Course Project
Institute of Microelectronics, Tsinghua University, China
This is a course project for MEMS and Microsystems. We designed a capillary channel for transporting methanol in fuel cell, and investigated its performance numerically and experimentally. This work was presented at COMSOL Annual Conference 2015, Boston, US.
Motivate
-
Capillary flow is commonly seen in microfluidic systems. Because of large surface-to-volume ratio, flow inside microchannels can be driven automatically by capillary effect without any external means.
-
This can be applied in biochemical analysis, where capillary flow is used for the transport of liquid and mixing enhancement.
Ideate
-
Our design consists of a capillary channel between two reservoirs, represented by loading pad and vent respectively and connected to the main channel through micro parallel channels.
-
Once loaded on the pad, methanol will automatically move towards the vent driven by capillary force. An SEM photo of typical structures is shown in (c).
Develop
-
A CFD simulation is carried out with COMSOL Multiphysics, using the Two-Phase Flow, Laminar, Level Set application mode. This application mode uses the Navier-Stokes equations to describe the momentum transport, including the surface tension and the conservation of mass, and also a reinitialized level set method to represent a discrete fluid interface between the air and methanol.
-
Experiments are conducted as comparison.
Test
-
Different concentration of methanol has been simulated and tested.
-
Both simulation and experiments haven confirmed an increased flow rate with a reduced contact angle.
Deliver
-
Presentation: Presented at COMSOL Annual Conference 2015, Boston, US.
-
Rank 2/40 in the course of MEMS and Microsystems.
Skill Sets
COMSOL Multiphysics
FEA/CFD
SEM operation
MEMS Fabrication