Management of microscale two-phase transport through surface structure and wettability control
Abstract
The surface structure modification and wettability control are very crucial issues for the technological advancement in microfluidic systems. This thesis utilizes two unique approaches to improve the water and air management of micro Direct Methanol Fuel Cell (DMFC). The silicon wafer is formed of the alternate strips of hydrophobic and hydrophilic channels with different array of opening sizes. Water will be guided along the hydrophilic wetting channels with large opening holes; it is then collected while the air goes into the cathode from the hydrophobic dry areas with smaller holes. The second approach utilizes the pumpless water management system. The present approach uses a Teflon membrane, with hydrophobic features instead of carbon paper to build a hydraulic pressure that forced some or most of the liquid-water back to the anode. As a result, there is no need for a pump. The overall test is successful and the present Teflon sheet is able to prevent the liquid from penetrating through the sheet while allowing the feeding of gas molecules across the sheet. Therefore, it clearly indicated that the concept of pumpless water management system is feasible although some improvements could be made in the future. Therefore, this study demonstrates successfully that the proper modification of surface structure and wettability control leads to solving many difficult concerns not specific in DMFC but also in other applications as in the case of the bio-chip systems.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 2004
- Bibcode:
- 2004PhDT.......118A