Heat-transfer analysis of microfabricated thermocapillary pumping and reaction devices

A heat-transfer analysis was performed on thermocapillary pumping, a surfac e-tension-based drop pumping mechanism. The analysis, which incorporates bo th fluid flow and energy transport through multiple device layers, reveals effective material, design, and operational choices that result in improved pumping performance. Important design factors include thermal conductivity , channel/substrate thickness, and the velocity of the liquid drops. Result s for pumping a drop of water on a fused silica substrate with a glass chan nel show that uniform interface temperatures can be achieved with bottom he ating as lung as drop velocities remain below similar to 0.1 cm s(-1). The analysis was also extended to include thermal reaction channels. The reacto r analysis verified that relatively uniform reaction temperatures were atta inable with bottom heating as long as channel heights were below similar to 100 mu m.