Microfluidic flow control devices

#The present invention relates to microfluidic devices and the control of fluid flow within those devices.

#There has been a growing interest in the manufacture and use of microfluidic systems for acquiring chemical and biological information. In particular, when conducted in microfluidic volumes, complicated biochemical reactions may be carried out using very small volumes of liquid. Among other benefits, microfluidic systems increase the response time of reactions, minimize sample volume, and lower reagent consumption. When volatile or hazardous materials are used or generated, performing reactions in microfluidic volumes also enhances safety and reduces disposal quantities.

#Traditionally, microfluidic systems have been constructed in a planar fashion using techniques borrowed from the silicon fabrication industry. Representative systems are described, for example, in some early work by Manz et al. (Trends in Anal. Chem. (1990) 10(5): 144-149; Advances in Chromatography (1993) 33: 1-66). These publications describe the construction of microfluidic devices using photolithography to define channels on silicon or glass substrates and etching techniques to remove material from the substrate to form the channels. A cover plate is bonded to the top of the device to provide closure.

#FIGS. 1A-1C are cross-sectional views of at least a portion of microfluidic device constructed from 5 layers of material, the device having a deformable membrane separating equally-sized upper channel region and a lower channel region. FIG. 1A illustrates the membrane in a neutral position. FIG. 1B illustrates the membrane being deflected toward and into the lower channel region. FIG. 1C illustrates the membrane being deflected toward and into the upper channel region.

#FIGS. 2A-2B are cross-sectional views of at least a portion of a 5-layer microfluidic device having a larger upper channel region and a smaller lower channel region. FIG. 2A illustrates the membrane being deformed toward and into the smaller, lower channel region. FIG. 2B illustrates the membrane being deformed toward and into the larger, upper channel region.

#FIGS. 3A-3E are cross-sectional views of at least a portion of a microfluidic device having three separate channel regions (an upper, a central, and a lower channel region) divided by two deformable membranes (an upper and a lower membrane). FIG. 3A illustrates both membranes in neutral positions. FIG. 3B illustrates the upper deformable membrane being deflected toward and into the central channel region. FIG. 3C illustrates both the upper and the lower deformable membrane being deflected toward and into the central channel region. FIG. 3D illustrates the lower deformable membrane being deflected toward and into the central channel region. FIG. 3E illustrates both the upper and lower deformable membrane being deflected away from the central channel region, namely, the upper deformable membrane being deflected toward and into the upper channel region, and the lower deformable membrane being deflected toward and into the lower channel region.

#Definitions

#The term “channel” as used herein is to be interpreted in a broad sense. Thus, it is not intended to be restricted to elongated configurations where the transverse or longitudinal dimension greatly exceeds the diameter or cross-sectional dimension. Rather, the terms are meant to include cavities, tunnels, or chambers of any desired shape or configuration through which liquids may be directed. Such a fluid cavity may, for example, comprise a flow-through cell where fluid is to be continually passed or, alternatively, a chamber for holding a specified, discrete amount of fluid for a specified amount of time. “Channels” may be filled or may contain internal structures comprising valves or equivalent components.

#The term “channel segment” as used herein refers to a region of a channel.