From Sarracenia to scientific application: harnessing the potential of porous bionic cones for accelerated directional movement of droplets

Abstract

Directional droplet transport with high speed is essential for improving the performance of passive fog harvesting, oil–water separation, and phase-change heat transfer systems. However, the transport velocity of droplets driven by conventional mechanisms, such as surface energy gradients and non-equilibrium Laplace pressure gradients, remains limited due to insufficient driving forces and contact-line resistance. Inspired by the conical hair structures of Sarracenia, we develop a porous bionic cone through metal powder sintering, integrating macroscopic geometric gradients with microscale porous capillary networks. Experimental investigations and molecular dynamics simulations reveal that the porous bionic cone not only enhances the non-equilibrium Laplace force but, more importantly, generates a substantial asymmetric capillary force within the porous network while reducing contact-line hysteresis during droplet motion. The synergistic regulation of multiple driving forces and transport resistance significantly enhances droplet mobility, enabling an order-of-magnitude increase in directional transport speed from 22 to 242 mm s−1 under identical conditions. Furthermore, fog collection experiments demonstrate that the accelerated droplet removal enabled by the porous bionic cone effectively improves fog harvesting efficiency. This work provides a bioinspired strategy for designing high-performance passive liquid transport systems by synergistically regulating driving forces and transport resistance.