Figure 2.

(A) Schematic diagram depicting the process of printing a hydrogel with a hollow space, using biomaterial ink with an unsynchronized absorption wavelength with DLP light (control) and with a synchronized absorption wavelength (yellow). The red dotted blank space indicates the focal layer, the purple arrow indicates the direction of the DLP light, and the blue arrow indicates the light due to the refraction and penetration of the DLP light. (B) Sample prints resulting from pink and yellow biomaterial ink (top view). In the control samples, hydrogels were printed to unwanted areas due to over-crosslinking. (C) Print samples resulting from pink and yellow biomaterial inks (front view). In the pink samples, hydrogels blocked hollow tube areas due to over-crosslinking.