Maximizing interfacial bonding strength between PDMS and PMMA substrates for manufacturing hybrid microfluidic devices withstanding extremely high flow rate and high operation pressure

Abstract

Polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA) are widely used in microfluidics, due to their excellent biocompatibility, high optical transparency, and ease of fabrication. This paper outlines a systematic approach to maximize the interfacial bonding strength between PDMS to PMMA. Fabrication parameters were studied by measuring bonding strength (i.e., burst test pressure) based on the Taguchi method. Under optimal bonding conditions, the microchannel assembly endured air pressure exceeding 770 kPa, liquid pressure exceeding 622 kPa, and tensile test exceeding 3000 kPa. Bonding strength was sufficient to resist the entry of liquid at a rate of 6800 times greater than the microchannel volume per minute. The ability to withstand such extremely high pressure without damage to the microdevices is an indication that interfacial bonding was indeed permanent. The proposed manufacturing method was also used to fabricate microfluidic devices capable of withstanding extremely high liquid pressure of 402 kPa, high flow rates exceeding 120 mL min−1, and dense microchannels with gap of only 30 µm. Finally, this proposed bonding process was used to fabricate a functional valve system of high-density configuration, which can be potentially used in microfluidics-based assays requiring high accuracy, rapid response, and the facile management of liquid transportation.