We survey progress over the past 25 years in the development of microscale devices for pumping fluids. We attempt to provide both a reference for micropump researchers and a resource for those outside the field who wish to identify the best micropump for a particular application. Reciprocating displacement micropumps have been the subject of extensive research in both academia and the private sector and have been produced with a wide range of actuators, valve configurations and materials. Aperiodic displacement micropumps based on mechanisms such as localized phase change have been shown to be suitable for specialized applications. Electroosmotic micropumps exhibit favorable scaling and are promising for a variety of applications requiring high flow rates and pressures. Dynamic micropumps based on electrohydrodynamic and magnetohydrodynamic effects have also been developed. Much progress has been made, but with micropumps suitable for important applications still not available, this remains a fertile area for future research.

https://microfluidics.stanford.edu/Publications/Micropumps_Cooling/Laser%20Review%20of%20Micropumps%20in%20JMM.pdf

A review of micropumps

Experimental investigation into convective heat transfer of nanofluids at the entrance region under laminar flow conditions

The suitability of electrowetting-on-dielectric (EWD) microfluidics for true lab-on-a-chip applications is discussed. The wide diversity in biomedical applications can be parsed into manageable components and assembled into architecture that requires the advantages of being programmable, reconfigurable, and reusable. This capability opens the possibility of handling all of the protocols that a given laboratory application or a class of applications would require. And, it provides a path toward realizing the true lab-on-a-chip. However, this capability can only be realized with a complete set of elemental fluidic components that support all of the required fluidic operations. Architectural choices are described along with the realization of various biomedical fluidic functions implemented in on-chip electrowetting operations. The current status of this EWD toolkit is discussed. However, the question remains: which applications can be performed on a digital microfluidic platform? And, are there other advantages offered by electrowetting technology, such as the programming of different fluidic functions on a common platform (reconfigurability)? To understand the opportunities and limitations of EWD microfluidics, this paper looks at the development of lab-on-chip applications in a hierarchical approach. Diverse applications in biotechnology, for example, will serve as the basis for the requirements for electrowetting devices. These applications drive a set of biomedical fluidic functions required to perform an application, such as cell lysing, molecular separation, or analysis. In turn, each fluidic function encompasses a set of elemental operations, such as transport, mixing, or dispensing. These elemental operations are performed on an elemental set of components, such as electrode arrays, separation columns, or reservoirs. Examples of the incorporation of these principles in complex biomedical applications are described.

/pdf/digital-microfluidics-is-a-true-lab-on-a-chip-possible-2w1y39xegp.pdf

Digital microfluidics: is a true lab-on-a-chip possible?

Single-phase Convective Heat Transfer in Microchannels: a Review of Experimental Results

Entransy—A physical quantity describing heat transfer ability

http://www.wanglab-tsinghua.com/pdf/2007IJTS_I.pdf

A lattice Boltzmann algorithm for fluid–solid conjugate heat transfer

Size effect on microscale single-phase flow and heat transfer

Size effect on single-phase channel flow and heat transfer at microscale

Glass, silicon, and stainless steel microtubes with diameters of 79.9–166.3 μm, 100.25–205.3 μm, and 128.76–179.8 μm, respectively, were employed to study the characteristics of frictional resistance for deionized water flow in microtubes. Glass and silicon microtubes can be treated as smooth ones, whereas stainless steel microtubes with 3%–4% relative roughness has to be treated as coarse ones. It can be concluded from experimental results that for fully-developed water flow in smooth glass and silicon microtubes, the product of Darcy friction factor f and Reynolds number Re remains approximately 64, which is consistent with the results in macrotubes. While the value of f ˙ Re for water flow in rough stainless steel microtubes is 15%–37% higher than 64, it is distinctly different from the conventional conclusion that relative roughness below 5% has no effect on the flow resistance for incompressible fluid flow in macrotubes.

Zhixin Li

Papers

A lattice Boltzmann algorithm for fluid–solid conjugate heat transfer

Size effect on microscale single-phase flow and heat transfer

Size effect on single-phase channel flow and heat transfer at microscale

Experimental study on flow characteristics of liquid in circular microtubes

Simulations for gas flows in microgeometries using the direct simulation Monte Carlo method