Optofluidic Device Based Microflow Cytometers for Particle/Cell Detection: A Review <s> Flow Control <s> This review describes recent developments in microfabricated flow cytometers and related microfluidic devices that can detect, analyze, and sort cells or particles. The high-speed analytical capabilities of flow cytometry depend on the cooperative use of microfluidics, optics and electronics. Along with the improvement of other components, replacement of conventional glass capillary-based fluidics with microfluidic sample handling systems operating in microfabricated structures enables volume- and power-efficient, inexpensive and flexible analysis of particulate samples. In this review, we present various efforts that take advantage of novel microscale flow phenomena and microfabrication techniques to build microfluidic cell analysis systems. <s> BIB001 </s> Optofluidic Device Based Microflow Cytometers for Particle/Cell Detection: A Review <s> Flow Control <s> Hydrodynamically confined flow device technology is a young research area with high practical application potential in surface processing, assay development, and in various areas of single cell research. Several variants have been developed, and most recently, theoretical and conceptual studies, as well as fully developed automated systems, were presented. In this article we review concepts, fabrication strategies, and application areas of hydrodynamically confined flow (HCF) devices. <s> BIB002
In microfluidics, the sheath fluids and sample fluid can be considered as Newtonian fluids, which are continuous, laminar and incompressible. In microflow cytometers, passive flow driven by capillary force or gravity or active pumps driven by an external power source are used to provide continuous flow through the devices BIB001  . Since the cross-section of the channel on the scale of a few 10s of micrometers and the sidewalls are smooth, the flow in the microchannels can be classified as a Stokes flow with a Reynolds number less than one, meaning that the flow in the channel is in the laminar regime. Small dimensions of the microchannel may raise the risk of clogging by big particles or cells, clumps of cells or even extraneous debris. Details about basic concepts, fabrication strategies and advanced applications of hydrodynamic focusing in microflow cytometers can be found in a review by Ainla et al. BIB002 .