Robust microdevice manufacturing by direct lithography and adhesive-free bonding of off-stoichiometry thiol-ene-epoxy (OSTE+) polymer

Abstract

We here demonstrate, for the first time, the use of direct lithography in off-stoichiometry thiol-ene-epoxy (OSTE+) to fabricate a microdevice. First, the photolithographic property of OSTE+ is shown by using a photomask to create micropillars with an aspect-ratio of 1:10 in a 2 mm thick layer. Secondly, a three-layer OSTE+ microdevice containing in-/outlet holes, channels, and pillars is fabricated by using a combination of direct lithography and adhesive-free dry bonding. The resulting microdevice shows desirable properties, such as leak-free filling and hydrophilic surfaces. This fabrication method enhances the microstructurability of OSTE+ beyond that of conventional soft lithography replica molding of other polymers, such as PDMS.

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

“…To create the rubbery properties, compared to previous OSTE+ mixtures [2,3], we lowered the crosslink density of the new polymer by reducing the amount of functional groups per monomer and by substituting the epoxy monomer with a rubbery copolymer variant, as shown in table 1: comparing the monomers between rubbery and stiff OSTE+, the thiol monomers are tetra-instead of trifunctional; the allyl monomers are tri-instead of difunctional; and the epoxy monomer is Albipox® 1000, which is a copolymer consisting of long rubbery segments and short epoxy functional group segments that bind into the polymer matrix upon cure. The mechanical properties were further tuned by modifying the stoichiometric ratio and with the use of a stabilizing tri-azine ring on the thiol instead of on the allyl as used in the stiff OSTE+.…”

“…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].…”

Polymer nanoliter well arrays for liquid storage and rapid on-demand electrochemical release

“…OSTE and gold are suitable materials from an application perspective because they are both stable under the conditions demonstrated in this study. The monomers used for synthesis of OSTE were selected since they are readily available and have previously been shown to enable facile photostructuring of polymer microfluidic devices [23]. The inherent thiol-functional surface chemistry of OSTE enables a versatile surface modification by utilizing a thiol-x reaction to a wide variety of moieties including −ene, −yne, epoxide, and isocyanate functional groups [22].…”

Synthetic microfluidic paper

“…Photolithographic definition of the slanted pillars [15] is performed using a collimated, near-UV mercury lamp (OAI, Milpitas) (12 mW/cm 2 @ 365 nm) and the development process is done in acetone (VWR, USA) under ultrasonication (Model B220).…”