Generation of micrometer-sized patterns for microanalytical applications using a laser direct-write method and microcontact printing

This paper describes a procedure that allows the rapid generation of elastomeric masters for microcontact printing ([micro]CP) and for a new variant of this technique: controlled sagging microcontact printing (CS[micro]CP). Using a low-power laser (10 mW) operating at 532 nm, the desired pattern is ablated in a thin poly(methyl methacrylate) film doped with a dye (rhodamine B base). Subsequent pattern transfer into poly(dimethylsiloxane) (PDMS) produces an elastomeric stamp for either [micro]CP or CS[micro]CP. Printing on the surface of gold gives patterns (wires or trenches) with feature sizes as small as 5 [[micro]meter] ([micro]CP) and trenches (but not wires) as small as 1 [[micro]meter] (CS[micro]CP). The ability of this technique to generate functional systems was demonstrated with an array of gold minielectrodes printed on a silicon wafer and an array of chemical microreactors molded in PDMS. The performance of the electrode array was characterized using cyclic voltammetry with Ru(III)[(N[H.sub.3]).sub.6][Cl.sub.3], as the substrate. Microreactors were used as vessels to grow crystals of KN[O.sub.3] with a narrow dispersion in sizes and with largest dimensions of [approximately]15 [[micro]meter].