Editing Microfluidics (section)

===Continuous-flow microfluidics===

Continuous flow microfluidics rely on the control of a steady state [[steady flow|liquid flow]] through narrow channels or porous media predominantly by accelerating or hindering fluid flow in capillary elements.<ref name="Morin 8393–8400"/> In paper based microfluidics, capillary elements can be achieved through the simple variation of section geometry. In general, the actuation of [[steady flow|liquid flow]] is implemented either by external [[pressure]] sources, external mechanical [[pump]]s, integrated mechanical [[micropump]]s, or by combinations of capillary forces and [[Electrohydrodynamics|electrokinetic]] mechanisms.<ref name=Chang>{{cite book|vauthors = Chang HC, Yeo L|title=Electrokinetically Driven Microfluidics and Nanofluidics|year=2009|publisher =[[Cambridge University Press]] }}</ref><ref>{{cite web|url=http://www.cytonix.com/fluid%20transistor.html|title=fluid transistor|archive-url=https://web.archive.org/web/20110708215908/http://www.cytonix.com/fluid%20transistor.html|archive-date=July 8, 2011}}</ref>  Continuous-flow microfluidic operation is the mainstream approach because it is easy to implement and less sensitive to protein fouling problems. Continuous-flow devices are adequate for many well-defined and simple biochemical applications, and for certain tasks such as chemical separation, but they are less suitable for tasks requiring a high degree of flexibility or fluid manipulations. These closed-channel systems are inherently difficult to integrate and scale because the parameters that govern flow field vary along the flow path making the fluid flow at any one location dependent on the properties of the entire system. Permanently etched microstructures also lead to limited reconfigurability and poor fault tolerance capability. 
[[File:Mikrofluidik_sensor.jpg|thumb|Micro fluid sensor]]
Process monitoring capabilities in continuous-flow systems can be achieved with highly sensitive microfluidic flow sensors based on [[Microelectromechanical systems|MEMS]] technology, which offers resolutions down to the nanoliter range.<ref>{{cite book |last1=Wu |first1=S. |title=Proceedings IEEE Thirteenth Annual International Conference on Micro Electro Mechanical Systems (Cat. No.00CH36308) |chapter=MEMS flow sensors for nano-fluidic applications |chapter-url=https://ieeexplore.ieee.org/document/838611 |website=IEEE Explore |date=2000 |pages=745–750 |publisher=IEEE |doi=10.1109/MEMSYS.2000.838611 |isbn=0-7803-5273-4 |url=https://resolver.caltech.edu/CaltechAUTHORS:WUSmems00 |access-date=24 January 2024}}</ref>