Microfluidic chips properties

Cellular studies are facilitated in the microfluidic chips because of their small dimensions. In addition, the chip provides excellent optical properties for observation and flexible fluidic control capabilities for reagent delivery. 

Yu, C., Xu, M., Svec, F., and Frechet, J. M. J., Preparation of monolithic polymers with controlled porous properties for microfluidic chip applications using photoinitiated free radical polymerization,... 

Mechanical properties of PDMS affect the hot embossing process. PDMS masters are not rigid like the nickel or silicon tools discussed earlier and have a much lower Young s modulus [16]. Thus, embossing pressure is very important. PDMS has a higher thermal expansion and will expand and deform considerably more than conventional tools. Thus optimizing temperature is equally important in order to reduce discrepancies in replication. Overall, the use of PDMS masters can substantially reduce time, complexity, and costs involved in fabricating prototype microfluidic chips, but limits the master lifetime to approximately 20 cycles. 

The materials used for the fabrication of most microfluidic chips include glass, silicon, quartz, and plastics ( Materials Used in Microfluidic Devices) In addition to cost and optical, electric, and physical properties, careful consideration must be given to the surface chemistry of the material ( Surface Modification, Methods). In fact, surface chemistry plays a major role in chemical cytometry, as protein adsorption to the channel walls can degrade the separation performance and make the electroosmotic flow unreproducible. 

For every microfluidic chip design, however, the process conditions vary slightly. Geometry of the structures is an important factor that includes feature size, aspect ratio, radius of curvature, and whether the structure is freestanding or connected, and can significantly influence the process parameters. Layout properties of the design, such as the distribution of large and small features over the wafer area and the total wafer area to be processed, also must be considered. 

The assessment of RBCs deformability can also be performed by active methods, through the application of external force fields, such as acoustic, optical, electrical, and magnetic ones. Acoustic radiation force has been reported for fast and direct measurement of the mechanical properties of cells in a microfluidic chip. This method is based on the formation of an acoustic standing wave within a straight microchannel that moves the cells to the acoustic pressure nodes, with a movement speed dependent on the compressibility (Hartono et al., 2011). 

Silicone rubber has been widely used in biomedical applications due to its biocompatibility, nontoxicity and biodurability. Therefore, attempts have been made to further improve the properties of SR by reinforcing it with various inorganic nanofillers [46,189-193]. Zhang eta/. [189] introduced gold nanoparticles in PDMS microfluidic chips and studied its applications in enzyme reactors, immunoassays and biochemical analysis. Recent studies have shown that PDMS-Ag composite exhibits good antibacterial properties... 

Borosihcate glass is used for producing microfluidic chips [2], It possessed the necessary chemical stability, optical clarity and could be easily processed with current manufacturing techniques. Current trends point towards the use of polymers [3] such as cyclic-olefin-copolymers (COC) and polymethylmethacrylate (PMMA). The reason is that these polymers possess similar or even more superior properties than glass. COCs are particularly favored for their environmental-friendliness and near-glass optical transparency. 

Mapping of transport parameters in complex pore spaces is of interest for many respects. Apart from classical porous materials such as rock, brick, paper and tissue, one can think of objects used in microsystem technology. Recent developments such as lab-on-a-chip devices require detailed knowledge of transport properties. More detailed information can be found in new journals such as Lab on a Chip [1] and Microfluidics and Nanofluidics [2], for example, devoted especially to this subject. Electrokinetic effects in microscopic pore spaces are discussed in Ref. [3]. 

Thus the study of surfaces has emerged as an important focus in the chemical sciences, and the relationship between surfaces of small systems and their performance has emerged as a major technological issue. Flow in microfluidic systems—for example, in micromechanical systems with potential problems of stiction (sticking and adhesion) and for chemistry on gene chips—depends on the properties of system surfaces. Complex heterogeneous phases with high surface areas—suspensions of colloids and liquid crystals—have developed substantial... 

CE chips are mainly obtained using various glass substrates, from inexpensive soda-lime glass to high-quality quartz.Various polymer materials are also used. The choice of a particular material depends on its surface properties, ease of fabrication, which can be quite different according to the material origin, disposability, and price. Microfabrication processes were recently reviewed and the reader is thus referred to dedicated literature for additional useful information on microfluidic device fabrication. ... 

Microfluidic devices, study of porosity, hydrodynamic properties and on-chip SPE... 

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