Versatile surface functionalization of cyclic olefin copolymer (COC) with sputtered SiO₂ thin film for potential BioMEMS applications

Cyclic olefin copolymer (COC) is a new class of thermoplastic polymers used for a variety of applications ranging from bio-sensing to optics. However, lack of functional groups and intense surface hydrophobicity hamper further development and application of this material. Here, we describe fabrication and characterization of SiO₂–COC hybrid material (oxCOC), which provides a desirable substrate for microfluidic devices and subsequent surface modifications. The deposited SiO₂ thin film on COC surface was characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The new SiO₂–COC hybrid was found to have similar high optical transmission properties as that of pristine COC. Profilometric and AFM analysis revealed no dramatic change in morphology or surface roughness of functionalized COC. The SiO₂–COC hybrid appeared to be stable in most of the solvents evaluated and could be further modified by other compounds, such as 3-aminopropyltriethoxy silane (APTES). The new SiO₂–COC hybrid material and the robust fabrication method are expected to enable a variety of BioMEMS applications.