Figure 3.

Confocal images and photograph showing nonvertical side walls. (a and b) Confocal images of the top and the cross-section (along the line) of a cylindrical hydrogel object polymerized in a 180-μm-deep microchannel. A fluorescent dye was trapped inside the hydrogel for visualization purposes. b reveals a slightly tapered shape with a smaller diameter at the bottom than the top. (c and d) Confocal images of the top and the cross-section of an in situ fabricated microchannel filled with a fluorescent dye solution. d suggests near-vertical side walls with a slightly smaller channel width at the bottom than the top. (e) The photograph of a hydrogel object that flipped over during expansion. The hydrogel showed side walls that deviated from the surface normal by ≈6°. (Bar = 250 μm.)