An Approach for Irreversible Bonding of PDMS-PS Hybrid Microfluidic Chips at Room Temperature

Abstract

In some circumstances, hybrid polymer microfluidic chips composed of both elastic, gas-permeable polydimethylsiloxane (PDMS) and rigid plastics are needed. However, it is quite difficult to bond PDMS irreversibly to plastics such as polystyrene (PS). In this article, a facile method for irreversible bonding of PDMS to PS was proposed based on UV/O 3 -assisted surface modification in combination of surface silanization. Firstly, a PS sheet was exposed to UV/O 3 to produce oxygen-containing polar moieties, such as hydroxyl and carboxylic acid, on its surface. Secondly, the UV/O 3 treated PS sheet was silanized with (3-aminopropyl)triethoxysilane (APTES) via the reaction between the oxygen-containing polar moieties on the PS surface and the molecules of APTES. Thirdly, the silanized-PS sheet and the PDMS substrate with micro channel network were treated with UV/O 3 again to generate silanol moieties on both surfaces. Finally, the UV/O 3 treated PDMS was immediately brought intimate contact with the UV/O 3 treated silanized-PS, and irreversible bonding of PDMS with PS occurred after putting the PDMS-PS complex at room temperature for 1 h through the condensation reaction between silanol moieties. Contact angle measurement, X-ray photoelectron spectroscopy, total reflection Fourier transformation infrared spectrometer were applied to characterize the surface chemistry of the PS during the UV/O 3 treatment and silanization. The hybrid PDMS-PS microfludic chips prepared with the established method can bear a gas pressure higher than 0.5 MPa and a water stream at a flow rate higher than 170 µL/min (the test channels were 2.5 cm in the length, 50 µm in the width, 200 µm in the depth). A hybrid PDMS-PS microfluidic chip composed of gas-permeable PDMS substrate with channel network and excellently biocompatible PS cover sheet was fabricated for cell culture. The experimental results showed that HeLa cells cultured in the hybrid PDMS-PS microchip grew much better than those cultured in the full PS microchip, and slightly better than those in the full PDMS microchip.

Photolithography-Based Patterning of Liquid Metal Interconnects for Monolithically Integrated Stretchable Circuits

“…Before the PDMS was casted on the substrate, the surface of parylene was modified to have silanol moieties (Si–O–H) to enhance the bonding strength between the parylene and PDMS (Figure S1). , By dissolving the PAA layer within water for 12 h, the PDMS layer containing liquid metal patterns was released from the Si substrate, and then a backside capping PDMS layer was additionally casted with the same thickness as the top PDMS layer (∼500 μm).…”

Waterborne, all-polymeric, colloidal ‘raspberry’ particles with controllable hydrophobicity and water droplet adhesion properties

“…Upon reaction with dilute solutions of OTS ( [15,16], suggests that our procedure lead to a strong, probably covalent attachment of silane molecules to the surface.…”

“…Silanes bearing hydrophobic chains, such as alkyl-trichlorosilanes, are widely employed to modify the chemical properties of solid surfaces, such as wetting, adhesion, friction, and conductivity [7,8]. Although silanisation is common on metal surfaces, only a few examples exist for the modification of polymer surfaces [9][10][11][12][13][14][15][16]. The silanisation of polymer surfaces typically involves their oxidation with an oxygen plasma, leading to the formation of surface -OH groups, and the formation of an alkylsiloxane surface layer by anchoring of alkyl-trichlorosilanes from the vapor or liquid phase.…”