Partic. vol. 14 pp. 91-97 (June 2014)
doi: 10.1016/j.partic.2013.09.001

Stop flow lithography synthesis of non-spherical metal oxide particles

David Baah^a, Tobias Donnell^b, Julaunica Tigner^a, Tamara Floyd-Smith^a,b,*,

tfloyd@mytu.tuskegee.edu

Abstract

Non-spherical micron and nano-sized particles and their composites have become essential in select application areas of optics, wear resistance, personnel protection, chemical mechanical polishing, and biomedicine. In this paper, the synthesis of composite and ceramic non-spherical particles using stop flow lithography is reported. Precursor suspensions of poly(ethylene glycol) diacrylate, 2-hydroxy-2-methylpropiophenone and SiO₂ or Al₂O₃ are prepared. The precursor suspension flows through a microfluidic device mounted on an upright microscope and is polymerized in an automated process. A photomask patterned with transparent geometric features, which define the cross-sectional shapes of the particles, masks the UV light to synthesize micron sized particles. Particles with axial dimensions ranging from 35 to 167 μm were synthesized. Control of device channel depth and objective lens magnification enables the manipulation of the particle size. Composite particles in triangular, square, pentagonal, hexagonal, and circular cross sections were synthesized. Subsequently, the transformation of the composite particles into the corresponding metal oxide particles was achieved through polymer burn-off and sintering.

Graphical abstract

Keywords

Microfluidics; Stop flow lithography; Electron microscopy