Thermodynamic cycles for modelling the motion of a liquid drop on a solid surface

Advances in interfacial science have resulted in several methods for moving liquid drops along a solid surface. The driving forces employed for such motion range from thermal gradients to the electric fields. The ability... [ view full abstract ]

Advances in interfacial science have resulted in several methods for moving liquid drops along a solid surface. The driving forces employed for such motion range from thermal gradients to the electric fields. The ability to maintain such motion indefinitely by the input of suitable forms of energy, and to predict the energy-efficiency of such systems will be beneficial for applications in microfluidics. In this poster, we present the reversible analogs of the above systems. We model a system containing a liquid drop moving along a solid surface as a thermodynamic cycle whose work-output is used to move the drop. The quantities associated with the cycle, like energy-input, work-output, efficiency, et cetera, are related to the interfacial and bulk properties of the components of the system. The generic nature of our model enables us to study systems that may employ different mechanisms like thermal gradients, chemical gradients, electric fields, or their combinations. Due to the reversible nature of our model, the computed energy-efficiencies provide approximate bounds to those of the real systems. The above approach can also help in rational design of droplet-based microfluidics. As an example, we discuss our results for a liquid drop moving along a surface in the presence of thermal gradients.