Control of Mixing Driven by Coalescence of Sessile Drops

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

This proposal will address issues of sessile droplet coalescence, such as what role does asymmetries in bulk fluid properties, contact angle, and drop size have on mixing in two drops coalescing on a surface, and what different effects could occur when the surfaces are either homogeneous or heterogeneous. The work will use a testing platform, in which specimen drop and satellite drops of reagent are allowed to mix. The research plan is organized into three Objectives. In the first the PIs aim to investigate the effects of properties, contact angle and size on coalescence in homogeneous surfaces. The second objective will consider interfacial tension asymmetry, and the third will examine coalescence in more interesting surfaces, including superhydrophobic substrates. This proposal has a strong, clearly developed research plan that, if successful, can have a technologically broad impact since many applications such as spray coating and inkjet printing rely on the coalescence of drops on surfaces. Control over these mixing patterns during coalescence can lead to new applications that take advantage of this control including medical diagnostic platform based on the merging of a central target specimen drop with several satellite drops containing reagents. The proposal also includes educational broad impact through developing and teaching new graduate-level courses, supervising students, and outreach programs.