Reversible motion control of Vorticella stalk in microchannel

•Vorticella stalks were repeatedly contracted and extended in a microchannel.•We use a gravity pump to introduce solutions at applied pressure lower than 1kPa.•We combine gravity pumps with pneumatic valves.•The speed, displacement, and transition time of motions were characterized.•Actuator cycling time was on the order of 60s. The generation of low-speed flow by a decrease in applied pressure is required for the motion control of Vorticella stalks in a microfluidic device. We use a gravity pump to introduce solutions at applied pressure lower than 1kPa and then characterize the flow through a microchannel. We introduced Vorticella cells into a microchannel having dimensions of 200μm×30μm and cultured them. With the combined use of the pump and pneumatic valves, Vorticella stalks were repeatedly contracted and extended with actuator cycling times of the order of 60s by changing the calcium ion concentration. The speed, displacement, and transition time of motions were characterized to determine the motility of Vorticella stalks. Our developed motion control platform offers fundamental technology for a microfluidic device using Vorticella stalks.