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 (μCP) and for a new variant of this technique: controlled sagging microcontact printing (CSμCP). 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 μCP or CSμCP. Printing on the surface of gold gives patterns (wires or trenches) with feature sizes as small as 5 μm (μCP) and trenches (but not wires) as smalll as 1 μm (CSμCP). 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)(NH3)6Cl3, as the substrate. Microreactors were used as vessels to grow crystals of KNO3 with a narrow dispersion in sizes and with largest dimensions of ∼15 μm.