*2.2.3 Contact angle hysteresis*

Contact angle hysteresis (CAH) is an important physical phenomenon. Contact angle hysteresis reflects the activation energy required to move a droplet from one metastable state to another on a surface. CAH refers to the difference value between the advanced CA (θAdv) and the receding CA (θRec). An analysis software usually measures θAdv and θRec after a microscopy system reordered real-time images.
