Figure 1.

A schematic diagram of each step for preparing the active hydrogel actuator to stimulate with bi-layered hydrogel. The hydrogel actuator was assembled by preparing 1st thin layer (a), and subsequently, 2nd layer was prepared over the 1st layer (b). The subsequent immersion of the prepared bi-layered hydrogel in an aqueous solution triggered self-folding with designated curvatures (c). Finally, a live cell cluster was introduced inside of the self-folded hydrogel (d) and stimulated by compression and tension repeatedly, in response to temperature (e,f).