Tailoring the surface topography and wetting properties of oxygen-plasma treated polydimethylsiloxane

Abstract

In this work, we address the issue of controlled modification of the surface topography of polydimethylsiloxane ͑PDMS͒ when subjected to oxygen-based plasma treatments, and we investigate the resulting enhanced surface area as a means of controlling the surface wetting properties. We fabricate wavy structures of controllable nanoscale amplitude and periodicity in the range 50-300 nm, spontaneously formed on PDMS surfaces, by means of appropriate plasma processing conditions and radiation pretreatment. Such structures are desirable for applications in sensor microdevices, the development of biocompatible materials, and micro-and nanosystems in general. Ordered structures fabricated on polydimethylsiloxane of relatively high amplitude and small periodicity are chosen as appropriate surfaces for the enhancement of the surface wetting properties, which can be tuned from highly hydrophilic to hydrophobic when combined with a hydrophobic coating applied on the rich surface nanotexture. This fact underlines the potential application of the proposed technique in the field of microfluidics, where polydimethylsiloxane is gaining popularity as structural material for microfluidic devices.

Prototyping of microfluidic systems using a commercial thermoplastic elastomer

“…PDMS-based devices have been shown, for example, to be effective tools for DNA amplification or hybridization reactions (Zhang et al 2006;Benn et al 2006). However, PDMS is not very well suited for commercial applications given the relatively elevated cost of the prepolymer components, low throughput of production, and limited stability of modified surfaces (Efimenko et al 2002;Tserepi et al 2005;Kim et al 2001;Lee et al 2003). Several attempts to use alternative materials that could replace PDMS have been undertaken over the last few years.…”

A review of line edge roughness and surface nanotexture resulting from patterning processes

“…Our first results using software for LER metrology [24][25][26] and LER simulation [32,59] point out to the need for developing molecular photoresists in order to reduce the effect of LER from lithography to transistor operation. We have also shown that nanotexturing is possible with plasma processing of polymers, such as polydimethylsiloxane, creating very hydrophobic surfaces of the Wenzel or Cassie-Baxter type [61,62], while plasma etching of silicon creates rough surfaces for which a control is needed in order to meet the specifications of MEMS fabrication [71].…”

“…We have shown that k decreases with etching time while the sigma value remains constant after an initial increase [62,73].…”

“…Oxygen plasma treatment of silicon polymers creates spaghetti-like surfaces with a high degree of periodicity [61,62]. This phenomenon is due to the formation of a hard oxide layer on top of siloxane polymers in the O 2 plasma, which has a different thermal expansion coefficient compared to the underlying siloxane polymer.…”

Effects of PDMS curing ratio and 3D micro-pyramid structure on the formation of an in vitro neural network

“…The siloxane linkages allow PDMS molecules to flex, and this flexibility can be varied by adjusting the curing ratio, i.e., the relative proportions of siloxane oligomer and cross-linker [3]. As the range of PDMS application continues to expand, so does the investigation of relevant PDMS properties, including surface contact angle for fabricating microbioarrays, the hydrophobicity for cell adhesion, and the topography of oxygen plasma-treated surfaces [4,5].…”