Microfluidic fabrication using cyclic olefin copolymer and hydrocarbon solvents

Cyclic olefin copolymer (COC) is a promising material in microfluidic applications due to their unique physical, chemical, and optical properties. This study im-plements a new and versatile fabrication process to fabricate COC microchannels, combining the fabrication and bonding processes in a single step, taking advantage of COCs' swelling behavior in linear non-polar hydrocarbon solvents and their chemical compatibility with photolithography. Dodecane was selected as the hy-drocarbon solvent based on the degree of swelling and Flory-Huggins interaction parameter, which resulted in the highest degree of swelling and affinity to COC. The effect of dodecane immersion time on the COC microchannel height was investigated, achieving a maximum average height of 50 & PLUSMN; 3 & mu;m after 180 min. Bonding quality was quantified by a leakage test (maximum flow rate of 1730 & PLUSMN; 205 & mu;L/min (Re = 237)), and a tensile test (800 & PLUSMN; 90 kPa). Furthermore, the effectiveness of the implemented process was demonstrated through the successful execution of three highly diverse microfluidic applications. These applications included a serpentine microchannel featuring semicircular obstacles that facilitated passive mixing, pinched flow fractionation which enabled the separation of a system of three different sizes of microparticles, and droplet microfluidics that allowed for the efficient generation of water in oil droplets.

Automated summary

COC is a promising material for microfluidic applications due to its unique properties. A new fabrication process combining fabrication and bonding processes in a single step was implemented, utilizing COC's swelling behavior and chemical compatibility. The effect of immersion time on microchannel height was investigated, achieving a maximum height of 50 ± 3μm. Bonding quality was evaluated through leakage and tensile tests. Three diverse microfluidic applications were successfully executed, demonstrating the effectiveness of the process.