Ziplining droplets on oil-impregnated fibers

Presenter: Abir Malakar, Engineering Mechanics, Mechanical Engineering

Authors: Y. Lolla, A. Cornish, Y. Yang, J. Boreyko

Abstract: Droplets on oil-impregnated surfaces exhibit the rare combination of high work of adhesion and ultra-low contact angle hysteresis.  Here, we exploit this confluence to enable ziplining droplets on inclined superhydrophobic fibers that were impregnated with silicone oil. We explore how the terminal ziplining velocity, as well as the range of droplet volumes where ziplining is possible, vary with droplet viscosity, oil viscosity, fiber incline, and fiber diameter.  The terminal velocity was found to represent a balance between gravity and viscosity-regulated braking of the oleoplaning oil meniscus that forms about the droplet.  We suggest that ziplining droplets on oil-impregnated fibers showcases a new context for microfluidics that is open-air and driven purely by gravity.