Engineering finger-operated peristaltic pumps

Abstract

Peristaltic pumping has been widely adopted in microfluidic systems over the past decade. Most applications lie, however, in the regime where fluids or biospecimens are continuously pumped through the entire fluidic system, leaving the initial filling stage of fluid into an air-filled channel underexplored. We propose a compact, quasi-1D, lumped element model for describing the initial filling process of liquid into microfluidic channels driven by peristaltic pumps with discrete diaphragm valves. In addition, we experimentally demonstrated that the liquid penetration length into the fluid channel could be decently controlled (~ 0.3 mm/cycle) using human fingers as the source of actuation pressures. Moreover, we show from our experiments the possibility of controlling the profiles liquid penetration lengths to be other than Lucas–Washburn’s $$ l\,\sim\,t^{{\frac{1}{2}}} $$ dependence: Linear liquid penetration length profiles can be achieved via liquid channels with exponentially decaying cross-sectional areas. In the above ways, our model has successfully demonstrated that finger-operated peristaltic pumps can serve as an upgraded alternative for capillary-driven microfluidics, offering extra runtime adjustment capability in understanding and engineering of microfluidics in the initial filling stages.