Characterization and theoretical analysis of rapidly prototyped capillary action autonomous microfluidic systems

Capillary action arising from surface tension-based forces has been demonstrated to be an effective means of passively actuating various fluids through simple and sophisticated microfluidic channel networks. Systems based on this technique are advantageous compared with standard pumping strategies, as they have zero power requirements, are readily integrated into the overall fluidic chip design, and can be fabricated rapidly in a single manufacturing step. This paper comprehensively investigates time lapsed average velocity profiles of various capillary action microfluidic systems, including channels and pumping structures, and compares experimental data against prominent, competing, and flow-based theoretical models. We demonstrate that the average meniscus flow velocity of CO₂ laser ablated capillary systems can be adequately predicted and characterize smooth fluidic velocity profiles in simple microchannels and complex interlinking channel pump/filling structures. Such systems offer a useful, rapid, and low cost alternative to traditional fluidic actuation and flow control systems such as those found in on-chip based biological and chemical analysis.