Defined Transfer of Colloidal Particles by Electrochemical Microcontact Printing

Abstract

Soft lithography, in particular microcontact printing (µCP), represents a well-established and widespread class of lithographic patterning techniques. It is based on a directed deposition of molecules or colloidal particles by a transfer process with a micro-structured stamp. A critical aspect of µCP is the adhesion cascade that enables the directed transfer of the objects. Here, the interfacial properties of a µCP-stamp are tuned electrochemically to modify the adhesion cascade. During the printing process, the µCP-stamp is submerged in an electrolyte solution and acted as a working electrode whose surface properties depended on the externally applied potential, thus enabling in situ rapid switching of its adhesion properties. As a proof of principle, defined particle patterns are selectively removed from a monolayer of colloidal particles. The adhesion at the particle/solid interface and the transfer mechanisms are determined by using the colloidal probe technique based on atomic force microscopy (AFM). In this case, a single particle is brought into contact with an electrode with the same surface chemistry as the µCP-stamp. Hence, it became possible to determine the electrochemical potential ranges suitable to establish an adhesion cascade.