Figure 5. Field potential propagation, pacemaking and conduction velocity of the 2D hESC-CMs.

(a–h) shows a representative activation map from day 19, 20, 21, 22, 25, 26, 28, 29, respectively. The activation map was consistent over the 20-minute recording window showing a stable pace making source, but the propagation map changed over days. (i) On day 23, a contour graph of the propagation wave was generated from the activation map. (j) The center of the propagation wavelet was identified by fitting the wavelet with a circle. The origin of the circle represented the location of the pacemaking cells. The pacemaking cells were located at the edge of the MEA.