Fig. 4. Control of cooperative deformations by selective preswelling.

A mask with holes was put on top of the patterned gel to selectively swell the regions under the holes, leading to programmed cooperative deformations after the gel was further swollen in water. (A and B) Mask (A) and the corresponding combined triangular- and rhombic-mode cooperative deformations in one composite gel (B). (C and D) Mask (C) and programmed cooperative deformations with desired mode and direction (D). Scale bars, 1 cm.