When the Cassie-Baxter and Wenzel states coexist for a liquid droplet on a micropatterned surface, the Cassie-to-Wenzel transition takes place if the energy barrier is overcome. Although multiple metastable states coexist due to the micropattern, this paper presents a simple Cassie-to-Wenzel transition of a 2 uL water droplet on a particular micropillared surface: When the droplet is gently deposited above the surface, it equalizes to the Cassie state at zero gravity; however, it transitions to the Wenzel state at the terrestrial gravity, in which the gravitational potential energy overcomes the energy barrier between the Cassie and Wenzel states.
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The authors acknowledge the Center for Innovation, Commercialization and Entrepreneurship (CICE) and the Center for Advances in Port Management (CAPM) at Lamar University for supporting this research. We acknowledge the Texas Advanced Computing Center (TACC) at UT Austin for funding computational hours (Grant #G-819854). We thank Dr. Lei Li from the University of Pittsburgh for valuable discussions.
The supplementary material for this article can be found at https://doi.org/10.1557/mrc.2019.160.
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Azimi, A., He, P. Effect of gravity in the Cassie-to-Wenzel transition on a micropatterned surface. MRS Communications 10, 129–134 (2020). https://doi.org/10.1557/mrc.2019.160