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Updated: Dec 13, 2025
Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment
Published on: November 9, 2015
Argon and oxygen plasma treatment increases hydrophilicity and reduces adhesion of silicon-incorporated diamond-like
Saeid Movahed1, Alexander K Nguyen1, Peter L Goering2
1UNC/NCSU Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, North Carolina 27695.
Abstract:
In this study, the structure, adhesion, and cell viability characteristics of silicon-incorporated diamond-like carbon (Si-DLC) coatings on fused silica substrates were investigated. The effects of argon and oxygen postprocessing plasma treatments on the Si-DLC coatings were also studied. The contact angle results showed that the Si-DLC coatings were more hydrophilic than the uncoated surfaces, and postprocessing plasma treatment increased the hydrophilicity of the Si-DLC coatings. Atomic force microscopy and profilometry confirmed that postprocessing plasma treatment increased the thickness and roughness of the Si-DLC coatings. The results of microscratch testing indicated that the plasma treatments reduced the adhesion of the coatings. The x-ray photoelectron spectroscopy (XPS) showed the presence of carbon, oxygen, and silicon in the Si-DLC coatings before and after the plasma treatments. These results show that the postprocessing plasma treatment significantly reduced the atomic percentage of the carbon in the Si-DLC coatings. XPS also confirmed the presence of carbon in the form of sp3(C-C), sp2(C=C), C-O, and C=O bonds in the Si-DLC coatings; it showed that postprocessing treatments significantly increased the percentage of oxygen in the Si-DLC coatings. Fourier transform infrared spectroscopy (FTIR) analysis showed features associated with C-OH stretching, C-H bending, as well as Si-CH2 and C-H bending in the Si-DLC coating. The XPS and FTIR results confirmed that the plasma treatment caused dissociation of the sp2 and sp3 bonds and formation of C-OH bonds. The contact angle data indicated that postprocessing treatment increased the hydrophilicity of the Si-DLC coating. Similar to the uncoated substrates, L929 cells showed no change in cell viability when cultured on Si-DLC coatings. These results of the study indicate the suitability of Si-DLC coatings as inert coatings for medical and biotechnology applications.
