Applications of microfluidic device fabricated in poly(dimethylsiloxane) (PDMS) have been limited to water-based analysis rather than nonpolar solvent based chemistry due to PDMS swelling problem occurring by absorption of the solvents. The absorption and swelling causes PDMS channel deformation in shape and changes the cross sectional area, making it difficult to control the flow rate and concentrations of solution in PDMS microfluidic channels. We propose that poly-p-xylylene polymers (parylenes) were chemical vapor deposited on the surfaces of PDMS channels to alleviate the effect of solvents on the absorption and swelling. The parylene coated surface sustains 3hours with a small volumetric change (less than 22% of PDMS swelling ratio). By generating an air-nonpolar solvent interface based on droplets in PDMS channel, we confirmed poly-p-xylylene coated PDMS microfluidic channels have the potential to be applicable to nanocrystal growth using nonpolar solvents. ⓒ 2014 DGIST
Table Of Contents
I. INTRODUCTION 1 -- 1.1 Motivations 1 -- 1.2 Objectives and Problem 3 -- 1.3 Hypothesis 6 -- 1.4 Background Information 7 -- 1.4.1 Microfluidic platforms 7 -- II. MATERIALS AND METHODS 8 -- 2.1 Microfluidic Devices 8 -- 2.1.1 PDMS microfluidic chip fabrication (Paper based master) 8 -- 2.1.2 PDMS microfluidic chip fabrication (Photolithography) 9 -- 2.2 Parylene-C film on PDMS Surfaces 10 -- 2.2.1 Parylene-C coating 10 -- 2.2.2 Thickness and porosity measurements 12 -- 2.2.3 Swelling measurements 12 -- 2.2.4 Air-nonpolar solvent interface formation 13 -- 2.3 Gold Nanoparticle Synthesis 14 -- 2.3.1 Materials 14 -- 2.3.2 Synthesis of nanoparticles in water 16 -- 2.3.3 Phase transfer of nanoparticles to hexane 16 -- 2.3.4 2D self-assembly of gold nanoparticles 19 -- III. RESULTS AND DISCUSSION 21 -- 3.1 Swelling of Millimeter Scale PDMS Pieces in Hexagonal Shape 21 -- 3.2 Swelling of PDMS Microfluidic Channel 24 -- 3.3 Droplet based An Air-nonpolar Solvent Interface 27 -- IV. CONCLUSION 29 -- 4.1 Conclusion 29 -- REFERENCES 30
