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SEM images of different microchromatographic columns layouts on a chip-based configuration: (a) semipacked column with embedded microposts, (b) circular spiral, (c) square spiral, and (d) radiator. Reprinted with permission from ref. [234] (a), ref. [230] (b), and ref. [244] (c,d). Copyright 2013 Elsevier (part a), Copyright 2009 IEEJ (part b) and Copyright 2006 Elsevier (part c, d).
