A facile route for irreversible bonding of plastic-PDMS hybrid microdevices at room temperature

Abstract

Plastic materials do not generally form irreversible bonds with poly(dimethylsiloxane) (PDMS) regardless of oxygen plasma treatment and a subsequent thermal process. In this paper, we perform plastic-PDMS bonding at room temperature, mediated by the formation of a chemically robust amine-epoxy bond at the interfaces. Various plastic materials, such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polyimide (PI), and poly(ethylene terephthalate) (PET) were adopted as choices for plastic materials. Irrespective of the plastic materials used, the surfaces were successfully modified with amine and epoxy functionalities, confirmed by the surface characterizations such as water contact angle measurements and X-ray photoelectron spectroscopy (XPS), and chemically robust and irreversible bonding was successfully achieved within 1 h at room temperature. The bonding strengths of PDMS with PMMA and PC sheets were measured to be 180 and 178 kPa, respectively, and their assemblies containing microchannel structures endured up to 74 and 84 psi (510 and 579 kPa) of introduced compressed air, respectively, without destroying the microdevices, representing a robust and highly stable interfacial bonding. In addition to microchannel-molded PDMS bonded with flat plastic substrates, microchannel-embossed plastics were also bonded with a flat PDMS sheet, and both types of bonded assemblies displayed sufficiently robust bonding, tolerating an intense influx of liquid whose per-minute injection volume was nearly 1000 to 2000 times higher than the total internal volume of the microchannel used. In addition to observing the bonding performance, we also investigated the potential of surface amine and epoxy functionalities as durable chemical adhesives by observing their storage-time-dependent bonding performances.

Organic transistor platform with integrated microfluidics for in-line multi-parametric in vitro cell monitoring

“…The poor adhesion between the two substrates results in leaks and, eventually, delamination of the PDMS structure from the substrate. Some strategies have been proposed for the irreversible bonding of PDMS and other plastic substrates 42,43 , however, on the basis of our initial experiments, it was not possible to achieve stable adhesion of PDMS and PaC using these protocols. A possible solution to this can be the complete removal of the PaC layer from the substrate, making the glass substrate available for O 2 plasma-mediated bonding with PDMS.…”

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“…The two surfaces were aligned, brought into contact, and then bonded at room temperature for one hour. A strong amineepoxy bond was formed, which has been shown to withstand flow rates of several hundred channel volumes per hour [8].…”

“…1b, by chemically bonding the two materials [8]. Hydroxyl groups were first formed on the surfaces to be bonded by exposure to an O 2 -plasma (50 W, 1 minute).…”

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“…Specifically, Figures 4(a)-4(c) illustrate the steps involved in bonding the PDMS connector to the PMMA substrates using the solvent bonding method. 15 In brief, a plasma machine [PDC-32G, Harrick Plasma, USA] was used to break the original polymer chains and create hydroxyl groups on the PMMA and PDMS surfaces (Figure 4(a)). Modified PDMS was then soaked in 1% (v/v) aqueous solutions of aminosilane (ATPES) to create amine functionalities, while the modified PMMA was soaked in 1% (v/v) aqueous solutions of epoxysilane (GTPES) to create epoxy functionalities (Figure 4(b)).…”