microfluidic

Microfluidics is a field that deals with the precise control and manipulation of fluids at small scales, typically in channels with dimensions from tens to hundreds of micrometers. It enables handling of very small volumes—from nanoliters to picoliters—and the execution of complex chemical and biological processes on miniature devices, often called lab-on-a-chip systems.

Operating principles: In microchannels, flows are usually laminar, with Reynolds numbers well below typical macro-scale values, leading to predictable flow profiles and diffusion-limited mixing. The large surface-area-to-volume ratio supports rapid heat and mass transfer, while electrokinetic, pneumatic, or centrifugal actuation methods allow timed operations such as pumping, splitting, and valving.

Materials and fabrication: Common substrates include PDMS, glass, silicon, and thermoplastics. Fabrication methods include soft lithography for PDMS devices, photolithography for hard substrates, laser micromachining, and 3D printing. Devices may incorporate integrated valves, reservoirs, and sensors.

Applications: Microfluidics underpins lab-on-a-chip diagnostics, including point-of-care tests, DNA amplification, cell analysis, and single-cell assays. It also enables chemical synthesis in microscale reactors, high-throughput screening, and environmental testing, with ongoing work in drug discovery and personalized medicine.

Challenges and outlook: Key issues include manufacturing scalability, device reliability, sample preparation, and integration with detection modalities. Ongoing advances aim to increase robustness, reduce costs, and enable broader adoption in healthcare, biotechnology, and industry.