Description
On small length scales, temperature gradients at fluid interfaces give rise to Marangoni stresses, a phenomenon caused by the temperature dependence of the surface tension. In a Stokes flow regime, where viscous forces dominate inertial forces, these stresses can induce fluid flow. This mechanism has previously been examined to propel micron-sized particles and to drive flow in microfluidic systems. A key disadvantage of existing pumping concepts is the requirement of a horizontal temperature gradient, which limits the achievable length and direction of such systems. In this presentation, we present a concept that overcomes these disadvantages and enables length-independent pumping with vertical instead of horizontal heat supply. The concept presented comprises a channel with integrated periodic microstructures at the bottom. These structures enclose air and vary in heat conductivity to create an environment where water can effectively be pumped through a channel of an arbitrary length. Using numerical simulations, we investigate how microstructure geometry affects the induced flow and determine the achievable flow rates. Furthermore, we discuss the potential applicability of the concept as a cooling mechanism.