FIG. 2.

Variation of curvature versus layer thickness. (A) Optical longitudinal and (B) side view of self-folded tubes composed purely of PEGDA formed by Method 1, illustrating that tubes ranging from smaller to larger diameters can be formed by varying the thickness ratio of the two layers from 1:1 to 1:4. Conditions and scale bars are (A) in water, 500 μm and (B) partially dry, 100 μm. (C) Plot of the average outer tube diameter measured in water (μm, green triangles) in relation to the thickness ratio and the average spacer thickness (μm). Blue and red bars correspond to the first (inner) and second (outer) layer thickness, respectively. Color images available online at www.liebertpub.com/tec