Effect of Stamp Deformation on the Quality of Microcontact Printing:  Theory and Experiment

Abstract

Microcontact printing (microCP) is an effective way to generate micrometer- or submicrometer-sized patterns on a variety of substrates. However, the fidelity of the final pattern depends critically on the coupled phenomena of stamp deformation, fluid transfer between surfaces, and the ability of the ink to self-assemble on the substrate. In particular, stamp deformation can produce undesirable effects that limit the practice and precision of microCP. Experimental observations and comparison with theoretical predictions are presented here for three of the most undesirable consequences of stamp deformation: (1) roof collapse of low aspect ratio recesses, (2) buckling of high aspect ratio plates, and (3) lateral sticking of high aspect ratio plates. Stamp behavior was observed visually with an inverted optical microscope while load-displacement data were collected during compression and retraction of stamps. Additionally, a "robotic stamper" was used to deliver ink patterns in precise locations on substrates. These monomolecular ink patterns were then observed in high contrast using the surface potential scanning mode of an atomic force microscope. Theoretical models based on continuum mechanics were used to accurately predict both physical deformation of the stamp and the resultant inking patterns. The close agreement between these models and the experimental data presented clearly demonstrates the essential considerations one must weigh when designing stamp geometry, material, and loading conditions for optimal pattern fidelity.

Design of biomimetic fibrillar interfaces: 1. Making contact

“…(b) How does a fibrillar interface behave when separated from a substrate; in particular, what is its effect on adhesion enhancement? Specific issues related to these questions have been outlined by Jagota & Bennison (2002), Arzt et al (2003) and Persson (2003a), with the first work drawing upon a detailed theory of the mechanics of micro-contact printing (see Hui et al 2002;Sharp et al 2004). It has been suggested by Arzt et al (2003) that the reduction of setal diameter with increased animal mass is directly related to the increased total adhesive force based on an application of the Johnson-Kendall-Roberts (JKR) theory of adhesive contact (see Johnson et al 1971).…”

Effects of surface deformation on the collective buckling of an array of rigid beams on an elastic substrate

“…We have a so-called plane-strain problem in elasticity. Weight has often been considered as the cause of buckling [Hui et al 2002;Sharp et al 2004]. Other effects including van der Waals, Coulomb, or capillary forces could also contribute to the situation [Evans et al 2007;Chuang et al 2005;Hsia et al 2005].…”

Topographically Flat, Chemically Patterned PDMS Stamps Made by Dip‐Pen Nanolithography

“…[23,28] Herein, we report how one can use DPN to prepare a stamp for high resolution μCP in a way that keeps the PDMS surface topographically flat but chemically patterned. The mechanically stable flat stamp is prepared without a photomask (since the structure may be directly written onto the surface by DPN), and the pattern drawn by DPN combined with subsequent chemical modification of the exposed areas of the stamp, allows one to create a surface with well-defined chemical regions that can be used to confine ink transport to sub-100 nm dimensions and prevent the lateral diffusion of the ink (Scheme 1).…”