Paper based integrated microfluidic system using electro-osmotic pumps with liquid bridges

Abstract

This thesis demonstrates a novel paper based microfluidic device with electro osmotic pumping mechanism that was designed, optimized, simulated, fabricated and analyzed. Optimization of paper based electro-osmotic pumping was demonstrated for the first time using multi-physic finite element solver COMSOL, enabling 12 times better performance. Different fabrication methodologies were implemented, such as laser cutting, silicone melting, wax printing, and laser micromachining, providing easy, cost effective, and eco-firendly microfluidic chips. Results show that a 113 V/cm elec tric field creates a 50 µm/s electro-osmotic velocity with purified water and a 70 µA electrical current creates 1 µL/min volumetric flow rate with 2 mM NaCl solution in paper based channel. Moreover, continuous channel of paper based electro-osmotic pumps was implemented for the first time, where a 30 nL volumetric flow rate was created by 82 a V/cm electric field using 50 mM NaCl solution. Furthermore, elec tric field and volumetric fluid flow tests were done with solutions od different salinity. Hydraulic resistance was increased 57 times using papers with different porous struc tures. Finally, integration of paper based electro-osmotic pumps were demonstrated for the first time, including the paper based channel, motion control, continuous chan nel, mixing and metering units. Following the concludig remarks, necessary researches and experiments in order to improve control mechanism, understanding pH relations, integration of multiple pumping and wetting systems are discussed as a future work.