a) Patterned Self-Assembled Monolayers

The conventional photolithography and the new soft-lithography can be a great foundation for  surface patterning work.  I have done the surface patterning to engineer surfaces for fabricating devices, such as photonic wave-guide, opto-electric devices and sensors, and bio-sensors and chips[1]^-[2].  Because nature prefers random mixed functionality on surfaces, engineering surfaces and interfaces requires processes.  For the micro-process, I have focused on soft-lithography using micro-contact printing, but I started to design a tool for soft-lithography using conventional photolithography.  An overall schematic of a micro process is briefly explained in Figure 2.  A Cr photo mask (Advanced Reproductions, Andover) and a corresponding silicon master (Microsystems Technology Lab, MIT) were prepared to make a PDMS (Dow Corning) stamp which contains various sizes of the circle feature in a square grid pattern. A patterned surface with adhesion-promoting (16-mercaptohexadecanoic acid; COOH; Aldrich) and adhesion-resistant regions (11-mercaptoundecanoic triethyleneglycol (EG; synthesized) was prepared by micro contact printing (mCP) technique on test-grade silicon wafers (Silicon Sense) coated with a thermally evaporated 10 Å thick chromium film and a 1000 Å gold film using micro-contact printing of alkane thiols.

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