Wettability of umbrella-like surface arrays inspired by springtail skin microstructure

The influence of geometric structural parameters of springtail-inspired surface on wetting behavior was investigated in this report. A Cassie extended wetting model for multilevel hydrophobic structures was proposed to improve the contact angle prediction accuracy. The bionic umbrella-shaped hydrophobic structure inspired by springtail was fabricated by two-photon polymerization (TPP) technology. A dendritic growth scanning method was proposed to solve the deformation problem caused by the umbrella-shaped edge separating from the main body during the traditional TPP process. By measuring the contact angles of the hydrophobic surface under structure parameters of different area fractions f, height h, and opening angles β, the results showed that the proposed mathematical model reduced the average prediction errors of contact angles by 23.8, 36.7, and 16.4%, respectively, compared with the Cassie mathematical model. This work is expected to provide references for precision design of hydrophobic structures and accurate prediction of contact angles.