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9.2 Microfluidic system 229

FIGURE 9.8
The different models of the parallel lamination micromixer: (A) the basic T-mixer and (B)
Y-mixer, (C) the concept of parallel lamination, and (D) the concept of hydraulic focusing.

external magnetic field is needed to apply DC voltages on the electrodes to induce
a mixing movement in the chamber [28,29] and in thermal disturbances, thermal
energy enhances mixing of the fluid layers. Therefore, heating devices are used to
regulate temperature causing thermal energy.

9.2.1.4 Types of materials
Material properties basically have an impact on functionality and production capabil-
ity. Successful design and fabrication require an appropriate selection of material. As
well, if the material selection is suitable, it causes to balance functional requirements
such as biocompatibility, mechanical resilience, optical transparency, and chemical
resistance. For fabrication, the behavior of material determines which processes are
favorable, unfavorable, or impossible [30].
Generally, materials that are used for microfluidic devices are categorized into
polymers, silicones, glass, and metals. The use of ceramics, composites, and other
materials is less common [30]. Properties that should be attended in microfluidic
devices manufacturing as follow:
1. Mechanical properties: The mechanical properties are more important for
microfluidic devices, such as flexures, flaps, membranes, and other structures,
in which deformation is an essential part of their functionality. Mechanical
properties are commonly dependent on temperature, though the degree of
dependency is variable and relates to the type of material. By increasing
temperature, most of the materials tend to exhibit higher ductility and lower
stiffness and thermoplastics being most extreme in these regards.
2. Thermal properties: For microfluidic devices, thermal properties are
important from several aspects. Geometric design parameters such as