AVS 49th International Symposium
    Biomaterials Wednesday Sessions
       Session BI-WeP

Paper BI-WeP11
Silicone Transfer during Microcontact Printing

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Biointerfaces and Surfaces II
Presenter: K. Glasmästar, Chalmers University of Technology, Sweden
Authors: K. Glasmästar, Chalmers University of Technology, Sweden
J. Gold, Chalmers University of Technology, Sweden
A.-S. Andersson, Chalmers University of Technology, Sweden
D. Sutherland, Chalmers University of Technology, Sweden
B. Kasemo, Chalmers University of Technology, Sweden
Correspondent: Click to Email
Microcontact printing, muCP, is a widely used technique for fast and low-cost micropatterning of large surface areas. Within the field of biointerfaces it is routinely used to directly pattern SAM's and proteins or indirectly control cell adhesion and growth. During microcontact printing a stamp of an elastomer, typically PDMS, inked with molecules of interest, is brought into contact with the substrate and then removed, leaving a pattern of the "ink" on the surface of the substrate. Several reports have indicated that PDMS can be transferred to the substrate under particular conditions. However, this issue has earned surprisingly little attention so far. We have systematically studied the transfer of PDMS to the substrate during muCP. XPS, ToF-SIMS and water condensation patterns were used to identify and measure the transfer. Stamps were cast from Sylgard 184 silicone elastomer (Dow Corning). Stamps were used without further treatment or after UV/ozone treatment and no external force was applied during stamping. Significant amounts of PDMS were transferred from non-treated stamps during muCP under the model conditions used. The XPS results showed that the transfer of PDMS onto both Ti and Au was significantly lowered by UV/ozone treatment of the stamp. ToF-SIMS of Au samples stamped with flat stamps confirmed the XPS results. However, the use of a patterned stamp (5 µm lines, 15 µm space) transferred more silicone to Au than a flat stamp, and UV/ozone treatment appeared to be less effective in reducing PDMS transfer. In this work we show that the UV/ozone treatment of PDMS stamps before printing lowers the amount of silicone transferred to the substrate. Oxygen plasma treatment of the stamp is likely to have the same effect. It is important to consider the potential for transfer of PDMS onto substrates when using muCP to pattern SAM's or biological molecules for biointerface applications.