Fig. 3. Mimosa Origami self-assembly mechanism and theoretical analysis.
(A) Optical photographs of the directional self-assembly of the Janus bilayers into a closed microchannel. (B) Schematic description of the self-assembly process: initially, a water-tight bulb is formed by the rapid folding (33 ms) of the Janus bilayer terminal around a water droplet. Thereafter, the waterfront slowly advances from the bulb to the dry PCL surface. Once sufficient water has collected, the wet Janus bilayer strip folds rapidly, forming a hollow 3D cross section. This leads to the Mimosa Origami propagation (400 ms cm−1) of the folding stimulus by longitudinal propulsion of the waterfront and orthogonal folding of the Janus bilayer strip. (C) Theoretical model of the minimal strip width required for the spontaneous Mimosa Origami self-assembly regime as a function of the surface roughness and characteristic contact angle (θe).