Synthesis of colloidal microgels using oxygen-controlled flow lithographyElectronic supplementary information (ESI) available. See DOI: 10.1039/c4sm01400f

We report a synthesis approach based on stop-flow lithography (SFL) for fabricating colloidal microparticles with any arbitrary 2D-extruded shape. By modulating the degree of oxygen inhibition during synthesis, we achieved previously unattainable particle sizes. Brownian diffusion of colloidal discs in bulk suggests the out-of-plane dimension can be as small as 0.8 μm, which agrees with confocal microscopy measurements. We measured the hindered diffusion of microdiscs near a solid surface and compared our results to theoretical predictions. These colloidal particles can also flow through physiological microvascular networks formed by endothelial cells undergoing vasculogensis under minimal hydrostatic pressure (∼5 mm H 2 O). This versatile platform creates future opportunities for on-chip parametric studies of particle geometry effects on particle passage properties, distribution and cellular interactions. We report the synthesis of non-spherical, Brownian microparticles with sub-micron height using a modified flow lithography technique.