Droplet impact on solid surfaces has been studied extensively due to its importance in nature and technology. A drop striking a flat surface retains its circular symmetry throughout the impact process. Research on controlling such impact dynamics has focused on optimizing pre-impact parameters, e.g., droplet size and velocity. Here we show that chemically patterned surfaces can affect and control the bouncing dynamics of droplets with distinct asymmetric morphing behavior during and after impact. Substrates were modified using combinations of surface modification chemistry and UV photolithography designed to form surfaces that exhibit extreme superhydrophobicity tailored with hydrophilic domains of precise shape, size and orientation. Droplets impacting such surfaces in precise position relative to the hydrophilic domain can be morphed to complex shapes during restitution and rebound in prescribed directions with substantial controllable lateral distances. The impact position and size of the hydrophilic domain play important roles in the trends of morphing and directing, while the impact velocity amplifies the asymmetric deformation during the process. The study shows a versatile approach to manipulate bouncing droplets with ramifications for novel microfluidic systems.

Directing and morphing bouncing water droplets using chemically patterned surfaces

253rd National Meeting (2017)

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