A Kuhl cell is a synthetic, excitable cell that can be activated by brief pulses of blue light and serves as a platform for screening the next generation of bio-sensors. In this live cell system, blue light activates an adenylyl cyclase enzyme (bPAC) that increases intracellular cAMP. In Kuhl cells bPAC creates a pseudo action potential in HEK293 cells with Kir2.1, NavD, and CNG channels. The behavior of HCN2 was visually different from CNG. This movie shows the movement of Ca2+ (using R-GECO1.2) across CNG and HCN2 containing cells. While both wells have random activity, there is a brief somewhat coordinated activity after a blue light stimulus. Cells containing CNG have a Ca2+ bursting rosette pattern following a stimulus, while HCN2 seems to have a spreading wave-like pattern. Finally, ArcLight is used to show voltage changes in Kuhl Cells containing CNG, Kir2.1, and NavD.