A steel air cylinder (10 L) is serially connected between the pump and air tank (1L) to investigate the influence of a large air tank on the actuation performance. All other experimental configurations except the air cylinder are kept the same as Double Bellows.

The experimental results in Figure S9d and e show that a large-scale air tank can decrease actuation speed and increase energy consumption per cycle, either for DIDO or IEAR. However, the influence is not remarkable based on existing experiments. This slight deterioration of actuation performance  might be caused by the increase in air tank volume, which makes it more difficult for the pump to quickly pressurize the air tank and maintain the pressure \(p_{tank-high}\)  above the working pressure \(p_{high}\)  under steady-state response.