Microfluidics

Microfluidics manipulates and controls small volumes of fluid in channels typically measured in micrometers. At this scale, surface forces and laminar flow strongly shape fluid behavior.

Laminar flow: Fluid motion in which neighboring layers move smoothly with little mixing between them. Microchannels commonly keep flows laminar, making interfaces predictable but mixing difficult.
Polydimethylsiloxane: A transparent, flexible silicone polymer widely used to make laboratory microfluidic devices. Its molding, optical clarity, and gas permeability suit many research chips.
Lab-on-a-chip: A device that integrates laboratory operations on a small chip, often using microfluidic channels. It is the broad platform concept built around many microfluidic technologies.
Analytical chemistry: The branch of chemistry that identifies substances and measures their amounts in samples. Microfluidics developed partly to miniaturize and integrate chemical analysis.
Macrofluidics: The study and engineering of fluid systems at scales larger than those typical of microfluidics. Larger systems behave differently as inertia and turbulence become more prominent.
Reynolds number: A dimensionless ratio comparing inertial forces with viscous forces in fluid flow. Its low values in many microchannels explain why viscosity dominates over turbulence.
Soft lithography: A patterning technique that uses flexible molds to reproduce microscale structures. It made prototyping microchannels accessible without conventional semiconductor fabrication.
Organ-on-a-chip: A microengineered device that models aspects of an organ's structure and function. Controlled flows expose living tissues to conditions that mimic parts of organ physiology.
Gas chromatography: A separation technique that distributes volatile compounds between a gas and a stationary phase. Early microfabricated chemical-analysis systems drew on chromatographic separation.
Centrifugation: A separation method that uses rotation to generate centrifugal forces on suspended particles. It can perform sample separation without routing fluids through microchannels.

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