Fig. 3. Multimodal control over the magnetically driven transformation.

(A) (i) Scheme showing the thermal response of gelatin from the gel state to sol state. (ii) Transformation of a flower-shaped hydrogel precursor at different temperatures until it is melted at 33°C. (B) The radius of the curvature (R) when the flower-shaped hydrogel precursor was placed in water with increasing temperature. A blue circle was drawn under the image of the transformed hydrogel scaffolds to measure the radius. (C) Effect of magnetic center on 3D transformation. (i) Flat hydrogel precursors with increasing magnetic center area (the white dotted lines highlight the edge of the magnetic center in each hydrogel precursor and its distance from the center and the edge of the hydrogel precursor) and (ii) the corresponding 3D transformation of the precursors. (D) Effect of the gravity ink on 3D transformation. (i) Flat hydrogel precursors with two branches with the gravity ink (white tips) and two without. (ii) Schematic and (iii) experimental images of the transformed precursor with different levels of bending when viewed from the two different angles. (E) Effect of the 2D precursor structure designs. (i) Flat hydrogel precursors with different edge to center branch width ratio (2:1, 1:1, and 2:3) and corresponding 3D transformation; and (ii) corresponding 3D transformation of the precursors. Scale bars, 5 mm.