Dry adhesive bonding of nanoporous inorganic membranes to microfluidic devices using the OSTE(+) dual-cure polymer

Abstract

Abstract. We present two transfer bonding schemes for incorporating fragile nanoporous inorganic membranes into microdevices. Such membranes are finding increasing use in microfluidics, due to their precisely controllable nanostructure. Both schemes rely on a novel dual-cure dry adhesive bonding method, enabled by a new polymer formulation: OSTE(+), which can form bonds at room temperature. OSTE(+) is a novel dual-cure ternary monomer system containing epoxy. After the first cure, the OSTE(+) is soft and suitable for bonding, while during the second cure it stiffens and obtains a Young's modulus of 1.2 GPa. The ability of the epoxy to react with almost any dry surface provides a very versatile fabrication method. We demonstrate the transfer bonding of porous silicon and porous alumina membranes to polymeric microfluidic chips molded into OSTE(+), and of porous alumina membranes to microstructured silicon wafers, by using the OSTE(+) as a thin bonding layer. We discuss the OSTE(+) dual-cure mechanism, describe the device fabrication, and evaluate the bond strength and membrane flow properties after bonding. The membranes bonded to OSTE(+) chips delaminate at 520 kPa, and the membranes bonded to silicon delaminate at 750 kPa, well above typical maximum pressures applied to microfluidic circuits. Furthermore, no change in membrane flow resistance was observed after bonding. Dry adhesive bonding of nanoporous inorganic membranes2

Reaction injection molding and direct covalent bonding of OSTE+ polymer microfluidic devices

“…Another advantage of using the temperature stabilized process of OSTE+RIM is that UV-light sources with higher power can be used, thus reducing the exposure time. With OSTEMER 322, we demonstrated a 30 s UV-light exposure using LED-lights during molding to fabricate a microfluidic part and a cover part in a single batch, which molding time is close to the cycle-times of industrial injection molding and at least twice as fast than what has been previously reported for producing a single OSTE+ part with casting using PDMS molds [13,16]. In this work, we fabricated a complete microfluidic OSTE+ device, including molding of OSTE+ parts and bonding in the back-end processing, in less than 20 minutes.…”

Low gas permeable and non-absorbent rubbery OSTE+ for pneumatic microvalves

“…It has the potential to bridge the gap between research prototyping and commercial manufacturing [1][2][3] due to a number of attractive characteristics, including a fast turn around fabrication process, Young's modulus similar to common thermoplastics, tunable surface properties, and adhesive-free low temperature bonding to a large range of substrates [4][5]. Moreover, OSTE+ has demonstrated preferable material properties for nucleic acid amplification detection compared to PDMS and PMMA [6].…”

OSTE: a novel polymer system developed for Lab-on-Chip

“…• Adhesive-free, room-temperature, bonding: we demonstrated adhesive-free RT bonding of OSTE+ to a multitude of substrates, including glass, Al, Si, plastics, and itself 29,30,31 . Using the vast OSTE+ toolbox, it is now possible to: seamlessly integrate fragile silicon and glass components without using any liquid glue; fabricate devices with soft and rubbery portions integrated with hard and temperature resistant regions; and bond biofunctionalised components.…”