Low Peclet number mass and momentum transport in microcavities

Abstract

For the informed design of microfluidic devices, it is important to understand transport phenomena at the microscale. This letter outlines an analytically driven approach to the design of rectangular microcavities extending perpendicular to a perfusion microchannel for applications that may include microfluidic cell culture devices. We present equations to estimate the transition from advection- to diffusion-dominant transport inside cavities as a function of the geometry and flow conditions. We also estimate the time required for molecules, such as nutrients or drugs, to travel from the microchannel to a given length into the cavity. These analytical predictions can facilitate the rational design of microfluidic devices to optimize and maintain long-term, low Peclet number environments with minimal fluid shear stress.

Microparticle image velocimetry (μPIV) study of microcavity flow at low Reynolds number

“…techniques, low Reynolds number flows in microchannels with microcavities are attractive for precisely controlling of flow behaviors and establishing appropriate cell culture conditions, due to the unique hydrodynamic flow behaviors and the special structure of the microcavities (Fishler et al 2013;Karimi et al 2013;Liu et al 2008Liu et al , 2009Nilsson et al 2009;Tanyeri and Schroeder 2013;Yew et al 2013;Yu et al 2005). Furthermore, microcavity flows have many other promising abilities to mimic in vivo microenvironment, to use small quantities of samples/reagents, to be fabricated easily, to easily make heterogeneous cellular environment with multiplexing assay, and to analyze cellular information at the single-cell level (Yun et al 2013).…”

“…They also examined the recirculating particle behavior in microvortices by investigating the evolution of microvortex formation and structure within different microcavity configurations for various Reynolds numbers. The flow characteristics in the microcavities are crucial for optimizing the design of microfluidic devices (Karimi et al 2013;Nilsson et al 2009;Yew et al 2013;Yu et al 2005). Although these rectangular microcavities have been successfully used in capturing target cells/particles, flow behaviors in microcavities have not been fully explored, and the effects of geometrical and operational parameters are still unclear.…”

“…Moreover, well-defined ideal chemical microenvironments and controlled stable spatiotemporal chemical and thermal gradients in microfluidic devices are needed for better understanding of different fundamental processes involved in cell regulating mechanisms and molecular interactions (Nilsson et al 2009;Yew et al 2013). These two purposes have driven scientists to develop new microfluidic technologies and enabled comprehensive studies of fundamental problems in fluid mechanics, physics, chemistry, biology, and materials science (Karimi et al 2013;Tanyeri and Schroeder 2013).…”

“…Microcavity flow has been increasingly used in microfluidic devices, and various microcavity geometric configurations have been developed for cell trapping and culture, e.g., microwells (Cioffi et al 2010;Hur et al 2010;Jang et al 2011;Luo et al 2007;Manbachi et al 2008) and microgrooves (Khabiry et al 2009;Park et al 2010) located on the bottom of the microchannel for cell docking, microcavities located on the side wall of the microchannel with square (Yu et al 2005), rectangular (Yew et al 2013), cylindrical (Fishler et al 2013), diamond and trapezoidal (Chiu 2007;Shelby et al 2003) shapes, and sharp corner structures (Fan et al 2014). Besides, rectangular microcavities have also been used for cell and particle high-throughput sorting in microfluidic devices Mach et al 2011;Park et al 2009;Zhou et al 2013).…”

“…Furthermore, the transitional flow was not observed in their study. Yew et al (2013) utilized numerical simulations and μPIV experiments to study the influence of the microcavities geometry and flow conditions on the flow behaviors and the microenvironment of cell culture in rectangular microcavities. They found that the flow pattern in the microcavities is attached at very low Reynolds number, characterized by the slow flow speed in the main microchannel.…”