Colloidal self-assembly on internal surfaces of partially sealed microchannels

• Published in: Journal of micromechanics and microengineering Vol. 16; no. 8; pp. 1667 - 1673
• Main Authors: Kuo, Chih-Jung, Lam, King Yiu, Vengallatore, Srikar, Peles, Yoav
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.08.2006; Institute of Physics
• Subjects: Applied fluid mechanics; Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fluid dynamics; Fluidics; Fundamental areas of phenomenology (including applications); General theory; Materials science; Mechanical engineering. Machine design; Methods of nanofabrication; Physics; Precision engineering, watch making; Self-assembly; Experimental study; Real time; Video techniques; Convection; Surface structure; Nanoparticles; Self-assembly; Colloidal suspension; Surface micromachining; Silicon; Micromanipulation; Video signals; Microfluidics; Fluidics
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/16/8/031

Self-assembly of micro- and nanoparticles on internal surfaces of micromachined structures can enhance the functionality of a wide range of microfluidic systems. Here, we report experimental investigations of the self-assembly of colloidal microspheres on the sidewalls of partially sealed silicon microfluidic channels. Two different approaches were studied. The first, convective self-assembly, is known to be effective in open-domain microsystems, but was found to result in assemblies with poor uniformity in the partially sealed devices. Real-time video microscopy of the assembly process indicates that these results can be attributed to the prolonged duration of evaporation and the complicated geometry of the evaporation front. In contrast, the second approach, which is a novel combination of sedimentation and hydrodynamic particle removal using a turbulent flow, resulted in the assembly of microparticles on predefined locations on the sidewalls of the microchannels. The important parameters controlling this process are discussed in the context of the literature on hydrodynamic particle removal from flat surfaces.