Ca2+ ion transport through channels formed by α-hemolysin analyzed using a microwell array on a Si substrate

► The stable confinement of the fluorescent probes in microwells by a lipid bilayer. ► The small microwell volume results in a big change in the ion concentration. ► The detection limit for Ca2+ transport was several tens of ions/s/μm2. ► Microwell array sealed by a lipid membrane can act as a highly sensitive sensor.