Pressure-Driven Laminar Flow in Tangential Microchannels:  an Elastomeric Microfluidic Switch

Abstract

This paper describes laminar fluid flow through a three-dimensional elastomeric microstructure formed by two microfluidic channels, fabricated in layers that contact one another face-to-face (typically at a 90 degree angle), with the fluid flows in tangential contact. There are two ways to control fluid flow through these tangentially connected microchannels. First, the flow profiles through the crossings are sensitive to the aspect ratio of the channels; the flow can be controlled by applying external pressure and changing this aspect ratio. Second, the flow direction of an individual laminar stream in multiphase laminar flow depends on the lateral position of the stream within the channel; this position can be controlled by injecting additional streams of fluid into the channel. We describe two microfluidic switches based on these two ways for controlling fluid flow through tangential microchannels and present theoretical arguments that explain the observed dependence of the flow profiles on the aspect ratio of the channels.

Liquid Aspiration and Dispensing Based on an Expanding PDMS Composite

“…From an environmental stability point of view, the presented devices can be compared to other PDMS-based applications and studies recently presented in literature [7], [8], [28].…”

“…They exploit a variety of both mechanical and chemical actuation principles, such as external pressure sources [7], [8], stimuli responsive polymers [9]- [11], centrifugal forces on a rotating disk [12], electrochemical gas generation through electrolysis [13], [14], decomposition of hydrogene peroxide [15] or azobis isobutyronitrile [16], melting of paraffin [17], thermal expansion of gas [18], [19], or expansion of a condensed gas encapsulated in chemically inert microspheres [20].…”

Formation of Arrayed Droplets by Soft Lithography and Two‐Phase Fluid Flow, and Application in Protein Crystallization

“…Elastomeric properties of the materials used in soft lithography may be utilized to change the shape of droplets. [6,23] Patterning inside confined spaces can be achieved using arrays of droplets-either by chemical reactions which occur inside the droplets, or by removal of the solvent from the droplets. [24] These applications will require that the material properties of microchannels-for example, compatibility with organic solvents, [25,26] permeability to gases and liquids, and mechanical properties-can be controlled.…”

Modeling of cell sorting and rare cell capture with microfabricated biodevices

“…The laminar flow characteristics enable miscible fluids to flow next to each other without turbulent mixing and without the necessity for physically separating the flows [16]. Concomitantly, in microchannels, the mass transport between parallel-flowing fluids occurs mainly by diffusion [17].…”