We have defined \(\xi=\frac{\rho RT}{M}\)  in Formula (2). The detailed modeling of m-SPAs is as follows.
Note: All the following equations defined for the first time should have the index form (SX) . Due to the compilation error of the webpage, the following display might lack an "S". However, if you export a pdf version, the display is complete.
ยทModeling of an actuator with a single chamber (Figure S3a).
The modeling is based on Clapeyron Equation (ideal gas equation).