Instantaneous room temperature bonding of a wide range of non-silicon substrates with poly(dimethylsiloxane) (PDMS) elastomer mediated by a mercaptosilane

Abstract

This paper introduces an instantaneous and robust strategy for bonding a variety of non-silicon substrates such as thermoplastics, metals, an alloy, and ceramics to poly(dimethylsiloxane) (PDMS) irreversibly, mediated by one-step chemical modification using a mercaptosilane at room temperature followed by corona treatment to realize heterogeneous assembly also at room temperature. The mercapto functional group is one of the strongest nucleophiles, and it can instantaneously react with electrophiles of substrates, resulting in an alkoxysilane-terminated substrate at room temperature. In this way, prior oxidation of the substrate is dispensed with, and the alkoxysilane-terminated substrate can be readily oxidized and irreversibly bonded with oxidized PDMS at room temperature. A commercially available Tesla coil was used for surface oxidation, replacing a bulky and expensive plasma generator. Surface characterization was conducted by water contact angle measurement and X-ray photoelectron spectroscopy (XPS) analysis. A total of fifteen non-silicon substrates including polycarbonate (PC), two types of poly(vinylchloride) (PVC), poly(methylmethacrylate) (PMMA), polystyrene (PS), polyimide (PI), two types of poly(ethylene terephthalate) (PET), polypropylene (PP), iron (Fe), aluminum (Al), copper (Cu), brass, alumina (Al2O3), and zirconia (ZrO2) were bonded successfully with PDMS using this method, and the bond strengths of PDMS-PMMA, PDMS-PC, PDMS-PVC, PDMS-PET, PDMS-Al, and PDMS-Cu assemblies were measured to be approximately 335.9, 511.4, 467.3, 476.4, 282.2, and 236.7 kPa, respectively. The overall processes including surface modification followed by surface oxidation using corona treatment for bonding were realized within 12 to 17 min for most of the substrates tested except for ceramics which required 1 h for the bonding. In addition, large area (10 × 10 cm(2)) bonding was also successfully realized, ensuring the high reliability and stability of the introduced method.

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.…”

Thermally robust and biomolecule-friendly room-temperature bonding for the fabrication of elastomer–plastic hybrid microdevices

“…Using this method, various plastics such as polycarbonate (PC), poly(ethylene terephthalate) (PET), poly(vinyl chloride) (PVC), and polyimide (PI) were permanently bonded to PDMS. In another study 9 , we utilized mercaptosilanes to instantaneously modify the surfaces of non-silicone substrates such as plastics, ceramics, and metals at room temperature via nucleophilic reactions; these substrates were then permanently bonded Please do not adjust margins Please do not adjust margins with PDMS after both substrates were oxidized. Although both studies used only one chemical, and surface coating was conducted at room temperature, the final surface oxidation process during sealing was inevitably required to form strong siloxane bond (Si-O-Si), which is the main driving force for the bonding.…”

Plant leaves as templates for soft lithography

“…29 PDMS has become the most widely adopted material in fabricating microdevices [30][31][32][33] thanks to its ease of use, optical transparency and biocompatibility. The templates used for casting have ranged from structures made in multilayer tape, 34 SU-8 or other photoresists like Norland Optical Adhesive (NOA), 35 3D printed resin, 36 printed circuit boards, or by simply gluing capillaries and other structures onto a substrate (e.g., PMMA).…”