Microfluidics

Abstract

The field of microfluidics has become one of the most dynamic disciplines of microtechnology. On the one hand, microfluidics offers the mere benefits of miniaturization, enabling many fields of application, in particular where small liquid volumes, transportable and cheap devices, or integrated process control are beneficial. On the other hand, microfluidics provides an elegant and often exclusive access to the nanoworld of biomolecular chemistry and cell handling, leveraging many novel biotechnological applications. This chapter first outlines the fluidic properties and working principles underlying microfluidic devices, such as diffusion, heat transport, interfacial surface tension, and electrokinetic effects. It then introduces fabrication techniques and sketches microfluidic components for flow control, pumping, physical sensing, and dispensing and their applications in (bio-)analytical chemistry, drug discovery, and chemical process engineering.Microfluidic devices are one of the earliest success stories in the commercialization of microelectromechanical systems (MEMS). Efforts to dispense minute amounts of liquid at high precision date back to the early 1950s and constitute the basics of contemporary inkjet technology. Since then, enterprises have continuously improved and diversified this technology, the worldwide annual revenues of which currently approach $10 billion.With the groundbreaking progress in microtechnology, starting in the 1970s, other types of microdevices were developed in academic and industrial labs. "Killer" applications such as microelectronic memory chips and processors as well as microelectromechanical read/write heads for hard disks shine, with staggering growth rates in performance and revenues. When MEMS were still chiefly an academic topic in the 1980s, microfluidic research focused on miniaturized conventional components. The first microfabricated pumps and valves were presented; they relied basically on the same principles as their macroscopic counterparts.

Stable microfluidic flow focusing using hydrostatics

“…1,2 Such LOC devices demonstrate the potential of replacing existing larger scale technologies in bio-chemical, bio-physical, and bio-medical processes. [3][4][5] A major advantage of LOC devices is the ability to provide a quasi-natural environment to cells that are under observation by controlling flow properties such as laminarity, 6,7 physical parameters such as flowrate, 7,8 and the size of the microchannels. 7 The application of hydrodynamic focusing in these microfluidic flows provides an additional advantage by narrowing the flows toward the size of a single cell.…”

“…[3][4][5] A major advantage of LOC devices is the ability to provide a quasi-natural environment to cells that are under observation by controlling flow properties such as laminarity, 6,7 physical parameters such as flowrate, 7,8 and the size of the microchannels. 7 The application of hydrodynamic focusing in these microfluidic flows provides an additional advantage by narrowing the flows toward the size of a single cell. 9 For example, in a flow cytometer, 10 single cells are hydrodynamically flow focused to a narrow stream that passes through an interrogating zone where the individual cells are interrogated by optical 11 or electrical systems 12,13 for diagnostics and sorting applications.…”

Improvement of the Positional Dispensing in the Washing Machine MW 2001

“…In our case, it is constant and equal to 8π. 6 Because the analysis is made for a flexible tube (hose) and the liquids (water and Tween 20) are invariant, we chose to investigate a change in the radius of the hose.…”

A low-energy, turning microvalve with high-pressure seals: scaling of friction

“…One such field is drug delivery for which micropumps have been under development ever since the late 1970s [1] and up until today [2]. In a survey on the commercial opportunities of microfluidics, it was stated that one of the reasons for lacking or postponed success for applications in drug delivery was the immaturity of the technology [3]. One possible methodological approach to reach the required maturity level is robust design, which ensures optimal performance for a given range of parameters [4].…”