Manipulation of liquids on planar surfaces in a precise and efficient manner is a key component of creating compact multifunctional fluid management devices. Utilizing wettability patterning, we achieve liquid transport by laying diverging superhydrophilic tracks on a superhydrophobic background. Liquid transport on such surfaces harnesses the force arising from the spatial contrast of surface energy as well as geometric differences in the spreading area on the substrate in order to induce pumpless motion. The technology allows for rapid liquid transport of droplets at rates up to 350 μL s<sup>−1</sup>. Taking inspiration from the venation of the banana leaf, we scale up this technology by creating an intricate pattern consisting of interdigitated superhydrophilic/hydrophilic regions. When applied in a vapor-condensing environment, this bioinspiried design is capable of inducing a 20% improvement in condensate collection and a 34% heat transfer improvement on patterned aluminum substrates. Lastly, we take advantage of the added ability of these tracks to diverge an orthogonally-impinging laminar liquid jet and transport the liquid efficiently away from the impinging spot. This approach can be utilized to selectively cool chip areas that are difficult to access physically. The potential for cooling multiple hot-spot areas by a single jet is demonstrated by minimally displacing the jet to feed different tracks or splitting the liquid between multiple tracks for simultaneous advective cooling. The present wettability-patterning techniques are not limited only to solid impermeable substrates, but can be extended to porous substrates where directional permeation and wicking through the medium can be realized in ways that allow precise multi-dimensional fluid management tasks.

Wettability patterning for efficient fluid handling in lab-on-chip and heat-transfer applications

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.