Figure 1. Schematic of the device.

(a) Schematic of the cartilage joints and muscle patterns of a string ray. (b) Schematic illustration of the layer-by-layer structure of the construct. The bottom layer was composed of a PEG hydrogel with vertical line patterns for alignment. The upper layer in contact with the cells was made of patterned CNT-GelMA hydrogel with a pattern, which was perpendicular to the PEG hydrogel patterns. The microelectrodes were embedded in between the two layers. (c, d) Schematic design of the sting ray movement in the macro and micro scale: relaxed cardiomyocytes (c) and contracted cardiomyocytes (d).