Flexible Capillary Microfluidic Devices Based on Surface-Energy Modified Polydimethylsiloxane and Polymethylmethacrylate with Room-Temperature Chemical Bonding

Polydimethylsiloxane (PDMS) has been widely used for the rapid prototyping of microfluidic devices for biosensor cartridges. However, using PDMS to prototype capillary-driven microfluidic devices is often limited by the difficulty of maintaining the surface energy of surface-treated PDMS for an extended period in addition to the degradation of the biosensing elements during the bonding process at elevated temperature. Herein, prototyping of a flexible capillary microfluidic channel (FCMC) device based on the room-temperature bonding of the surface energy-modified PDMS (m-PDMS) microfluidic channel and a thermoplastic lid, polymethylmethacrylate (PMMA), is introduced for prolonged control of passive liquid flow characteristics. The m-PDMS was fabricated by blending polydimethylsiloxane-ethylene oxide (60-70%) block copolymer (PDMS-b-PEO) additive with pre-PDMS, of which the water contact angles could be controlled between 38.5 degrees and 78.5 degrees by adjusting the ratio of the two components. Room-temperature bonding of the m-PDMS and PMMA sheets functionalized by 3-glycidoxypropyltrimethoxysilane and aminopropyltriethoxysilane, respectively, was introduced to fabricate the FCMC devices via the formation of a stable linker epoxy-amine without the requirement of elevated temperatures. The FCMC device possessed longevity to passively drive liquid in the channel for 2 months under ambient conditions due to the prolonged stable hydrophilicity of m-PDMS. The proposed approaches provide great potential for prototyping passive microfluidic devices for biosensor cartridge applications.