Dynamics of Droplet Impingement on Liquid Infused Surfaces: Tuning Surfaces for Simultaneous Reduction of Rebound and Hysteresis

The development of liquid infused slippery surfaces has opened up new arenas in manoeuvrable surfaces. The liquid film infused on these surfaces imparts a dissipative viscous damping to any applied force, giving them ability to withstand shear and self-heal. We study the dynamic properties of such surfaces via droplet impingement exploring the stress response and contact angle hysteresis (CAH) with varying viscosity of the infused oil. We explore these substrates to minimize rebound, a phenomenon commonly associated with superhydrophobic surfaces and to maximize capillary wave suppression. Using experimental results supported by numerical analysis, we develop a framework for surfaces with high capability to withstand shear from incoming droplet or jet and at the same time providing minimum CAH under transient and steady state. The droplet dynamics post impact is modelled by considering inertial, capillary and viscous forces and the alteration of behaviour from one surface to another is attributed to a competition of asymmetrical interfacial slip at the contact line contributed from the viscous term and the capillary force due to the evolving sessile droplet. Surfaces with such capabilities find immense application in microelectronic cooling and droplet based microfluidic systems.