A calcium ion-selective electrode array for monitoring the activity of HepG2/C3As in a microchannel

Variations in calcium ion (Ca^(2+)) concentrations play a crucial role in cell–cell communication; periodic changes act as cellular signals. In this study, we developed a solid-state calcium ion-selective electrode (Ca^(2+) ISE) integrated in a microchannel to measure extracellular Ca^(2+) variations; an ISE has a high detection sensitivity (as low as 10^(−9) M) and selectivity against potassium ions (K^+). The sensor was used to monitor the cellular activities of HepG2/C3As cultured in a microchannel. We measured a periodically oscillating extracellular Ca^(2+) concentration that was superimposed on a gradual increase in the Ca^(2+) concentration after potassium chloride (KCl) stimulation. The oscillation period was in the range of 30–50 s, which was in good agreement with the literature.