A simple technique to achieve meniscus-free interfaces

Liquid wetting on a container wall forms a meniscus that causes the reading uncertainty of interface measurement, which was considered as an “inevitable” interference in experiments. For minimizing the meniscus interference, the dynamic instead of the static contact angle should be focused on and θr ≤ 90° ± e ≤ θa is the guideline to achieve a meniscus-free interface for a practical experiment, where θr, θa, and e are the receding and advancing contact angles, and image measuring uncertainty, respectively. A simple and systematic technique to achieve the meniscus-free interface has been proposed and visualized.