microchannel

A microchannel is a channel with dimensions typically in the micrometer range, used to transport fluids in microfluidic systems and related technologies. In microfluidics, networks of microchannels form the core of lab-on-a-chip devices, enabling small-volume reactions, separations, and analyses. Channel dimensions commonly span tens to hundreds of micrometers in width and depth, and cross-sections are often rectangular or circular.

Microchannels are fabricated in a variety of substrates, including glass, silicon, and polymers such as polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), and polycarbonate. Common fabrication methods include photolithography and etching, soft lithography, laser micromachining, hot embossing, and increasingly additive manufacturing for complex geometries. Surface treatment and coatings are frequently used to control wettability and biocompatibility.

At microchannel scales, flows are typically laminar, with Reynolds numbers often well below 100. The high surface-area-to-volume ratio enhances heat and mass transfer, but mixing is diffusion-limited in simple straight channels, driving the use of serpentine, split-and-recombine, or chaotic-mixer geometries to promote mixing. Channel geometry, surface roughness, and sliding boundary conditions can influence fluid behavior and cell-surface interactions in bioapplications.

Major applications include microfluidic chips for chemical synthesis, DNA analysis and amplification, immunoassays, cell culture and single-cell analysis, and point-of-care diagnostics. Separations, such as capillary electrophoresis in microchannels, are also common. In engineering, arrays of microchannels serve as cooling passages in microchannel heat exchangers to remove heat from electronics and power devices.

Research continues to improve fabrication, reliability, and integration of microchannels into compact systems.

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