The engineered deposition of self-assembled coatings of micro- and nano-particles on solid surfaces has applications in photonic crystals, optoelectronic devices, sensors, waveguides and antireflective coatings. Besides lithographic, etching or vapor deposition methods, these coatings can be self-assembled on small (<O(1mm²) circular surfaces by the deposition and drying of drops on surfaces, or on larger (O(cm²)) rectangular surfaces by pulling an evaporating meniscus, in a process called convective deposition. Both processes involve multiscale phenomena such as transient fluid dynamics with wetted regions, DLVO forces, heat and mass transfer in the deforming geometry of a complex fluid. These competing phenomena control the self-assembly of micro- and nano-particle deposits. A simple phase diagram is presented, that describes the mechanisms governing the transition between different patterns during the evaporation of a drop. A multiphysics modeling of the convective deposition process is also presented, which provides insight on ways to improve the reliability of the deposition process. Finally, an outlook is given on technical applications related to the use of convective deposition techniques in manufacturing.

Date Published: 13 May 2011
PDF: 11 pages
Proc. SPIE 8031, Micro- and Nanotechnology Sensors, Systems, and Applications III, 80310X (13 May 2011); doi: 10.1117/12.884552

Published in SPIE Proceedings Vol. 8031:
Micro- and Nanotechnology Sensors, Systems, and Applications III
Thomas George; M. Saif Islam; Achyut K. Dutta, Editor(s)