MEMS- Microfluidic Systems UNIT-6 Material

MEMS- Microfluidic Systems UNIT-6 Material

MEMS- Microfluidic Systems UNIT-6 Material

Objectives :

objective of this chapter is to study the following.

• Microfluidic systems (MPS)
• The concept of Lab-on-a-chip
• Important considerations on microscale fluids and systems
• Properties of fluids
• Various phenomenological effects for fluid flow. In particula and their principles of operations are presented.

 °Dielectrophoresis (DEP)

° Electrowetting '

° Electrothermal

° Thermocapillary

° Electroosmosis

• Optoelectrowetting (OEW): Light-actuated fluid flow 
• MEMS channel, filter and micropumpr

Introducation :

The study of motion or transportation of fluids and their mixtures at a microscale level is known as

microlluidics. Microdevices, which are used to transport and store lluid are called microtluidic systems (MPS) or microlluidic devices (MFD). Typically, the MFS handle fluid volumes in the order of nanoliter.

Microfluidic systems are the subject of great scientific and commercial interest for a wide range of

applications, including the biomedical, environmental, automotive, aerospace, and defense.

Microlluidic system is a recent development, which obviously refers to the MEMS devices capable

of handling small volumes of fluids in the order of nano, pico and even femtoliter volumes, Microfluid devices are designed to inject, move, separate, and merge liquid droplets. Sometimes, the microfluidic devices have dimensions ranging from millimeter range to micrometers. 

Confusion arises in defining microscale device and microfluidic device, but in reality the latter one is much smaller than the former one, however, these terms are used synonymously. 

Microfluidic devices involve construction and design that differ from macroscale fluidic devices.

Many conventional macroscale devices have already been in use however; microfabrication conformant

devices and systems can provide greater performance over conventional devices. Nevertheless, the

microfluidic devices are fabricated by micromachining techniques that fulfil the very stringent

requirements on reliability! and compatibility issues. Design and development of microfluidic devices entails basic knowledge on the properties and dynamics of the fluids. The study also demands to acquire knowledge as far as interaction of fluid with the material and with the electrical, thermal and optical signals are concerned.

This chapter considers the fundamentals at the core of macroscalepfluid mechanics. Important

criteria such as validity theory of macroscale fluid dynamics will be presented, This includes the study of continuum phenomena, Further, the importance of surface tension in both continuous and discrete flows will be the matter of discussion. Broadly the following topics will be presented.

' Concept of lab-on-a-chip

° Properties of fluid such as density, viscosity and surface tension

° Surface wetting phenomenon such as dielectrowetting (DEW), thermalwetting, therrnocapillary wetting, electroosmosis flow (EOF) and optoelectrowetting (EOW)

° Microchannel, molecular gate as filter and micropump

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