Three-dimensional microscale

Zhang, R. R., Takebe, T., Miyazaki, L., Takayama, M., Koike, H., Kimura, M., Enomura, M., Zheng, Y. W., Sekine, K., Taniguchi, H., 2014. Efficient hepatic differentiation of human induced pluripotent stem cells in a three-dimensional microscale culture. Methods Mol. Biol. 1210, 131-41. doi 10.1007/978-l-4939-1435-7 10. 

Since the middle of the 1990s, another computation method, direct simulation Monte Carlo (DSMC), has been employed in analysis of ultra-thin film gas lubrication problems [13-15]. DSMC is a particle-based simulation scheme suitable to treat rarefied gas flow problems. It was introduced by Bird [16] in the 1970s. It has been proven that a DSMC solution is an equivalent solution of the Boltzmann equation, and the method has been effectively used to solve gas flow problems in aerospace engineering. However, a disadvantageous feature of DSMC is heavy time consumption in computing, compared with the approach by solving the slip-flow or F-K models. This limits its application to two- or three-dimensional gas flow problems in microscale. In the... 

Contaminant precipitation involves accumulation of a substance to form a new bulk solid phase. Sposito (1984) noted that both adsorption and precipitation imply a loss of material from the aqueous phase, but adsorption is inherently two-dimensional (occurring on the solid phase surface) while precipitation is inherently three-dimensional (occurring within pores and along solid phase boundaries). The chemical bonds that develop due to formation of the solid phase in both cases can be very similar. Moreover, mixtures of precipitates can result in heterogeneous solids with one component restricted to a thin outer layer, because of poor diffusion. Precipitate formation takes place when solubility limits are reached and occurs on a microscale between and within aggregates that constitute the subsurface solid phase. In the presence of lamellar charged particles with impurities, precipitation of cationic pollutants, for example, might occur even at concentrations below saturation (with respect to the theoretical solubility coefficient of the solvent). 

From the viewpoints of transport phenomena, microscale order would mean the scale of various parameters. They would be the scale of ultra-short time interval, extremely small distance, nanometer-order three dimensional structure and ultra small temperature difference, which have been introduced by the advanced engineering... 

To build an efficient, high-quality microscale fuel cell, microfabrication techniques need to be combined with appropriate materials such as Nation based membrane electrode assemblies (MEAs). These techniques must be able to produce three-dimensional structures, allow reactant and product flow into and out of the device, process appropriate materials, and should be of low cost. Fortimately, traditional thin film techniques can be modified for microscale fuel cell fabrication, while maintaining their advantages of surface preparation, sensor integration, and finishing or packaging. In addition, other techniques are also available and are discussed in the following sections. 

More often, three-dimensional gridded meteorological forecast data provided by mesoscale meteorological models such as MM5 will be available. The resolution of the grid will typically be on the order of 1 km, which is too large to capture microscale surface features. Mesoscale model results can be coupled with fine-scale models by enforcing conservation of mass to provide enhanced fine-scale detail. 

The three-dimensional electrochemical cell is a hypothetical device that illustrates how some of the advances in microscale and nanoscale electrochemistry over the past two decades may be applied to its construction (Figure 6.1). The three-dimensional electrochemical cell is a conventional battery in the sense that it has a cathode and anode, but they are configured in an interpenetrating array with electrodes anywhere from micron dimensions if they are prepared using lithographic techniques down to the nanometer scale. 

The earliest studies related to thermophysieal property variation in tube flow conducted by Deissler [51] and Oskay and Kakac [52], who studied the variation of viscosity with temperature in a tube in macroscale flow. The concept seems to be well-understood for the macroscale heat transfer problem, but how it affects microscale heat transfer is an ongoing research area. Experimental and numerical studies point out to the non-negligible effects of the variation of especially viscosity with temperature. For example, Nusselt numbers may differ up to 30% as a result of thermophysieal property variation in microchannels [53]. Variable property effects have been analyzed with the traditional no-slip/no-temperature jump boundary conditions in microchannels for three-dimensional thermally-developing flow [22] and two-dimensional simultaneously developing flow [23, 26], where the effect of viscous dissipation was neglected. Another study includes the viscous dissipation effect and suggests a correlation for the Nusselt number and the variation of properties [24]. In contrast to the abovementioned studies, the slip velocity boundary condition was considered only recently, where variable viscosity and viscous dissipation effects on pressure drop and the friction factor were analyzed in microchannels [25]. 

Three-dimensional machining (or 3D photopolymerization or stereolithography) gives the possibility to make objects, even with complex forms, for prototyping applications. A laser beam is used for the excitation. Creating 3D microscale structures for microelectromechanical, microoptics and microfluidic applications requires to use high peak power laser pulses allowing a multiphoton (typically two photon) of the photoinitiator at the focal point. 

Microfluidics handles and analyzes fluids in structures of micrometer scale. At the microscale, different forces become dominant over those experienced in everyday life [161], Inertia means nothing on these small sizes the viscosity rears its head and becomes a very important player. The random and chaotic behavior of flows is reduced to much more smooth (laminar) flow in the smaller device. Typically, a fluid can be defined as a material that deforms continuously under shear stress. In other words, a fluid flows without three-dimensional structure. Three important parameters characterizing a fluid are its density, p, the pressure, P, and its viscosity, r. Since the pressure in a fluid is dependent only on the depth, pressure difference of a few pm to a few hundred pm in a microsystem can be neglected. However, any pressure difference induced externally at the openings of a microsystem is transmitted to every point in the fluid. Generally, the effects that become dominant in microfluidics include laminar flow, diffusion, fluidic resistance, surface area to volume ratio, and surface tension [162]. 

Xu F, Wu C-AM, Rengarajan V, Finley TD, Keles HO, Sung Y, Li B, Gurkan UA, Demirci U (2011) Three-dimensional magnetic assembly of microscale hydrogels. Adv Mater (Deerfield Beach, Fla) 23(37) 4254 260... 

Digital holographic microscopy (DHM) is a promising tool to carry out three-dimensional flow field measurements at microscale. The implementation of DHM-based PIV/PTV technique can facilitate the design and understanding of various lab-on-chip devices. 

R.C. Chang, J. Nam, B. Starly, and W. Sun, Bioprinting three-dimensional structures onto microscale tissue analog devices for pharmacokinetic study and other uses, WO Patent 2007124481, assigned to Drexel University, November 1,2007. 

FIGURE 1.5. Intersite elctron hopping in a three-dimensional cubic lattice. Also illustrated is the microscale counterion displacement associated with an individual electron-hopping event between nearest neighor redox sites. Note that A denotes the cubic lattice parameter, whereas 8 denotes electron-hopping distance. To a good approximation we can set A = 6. (Ref. 17)... 

The main principle of employing microscale three-dimensional electrodes is to increase the effective surface area of the electrode to increase current, because ampero-metric and voltammetric current (i) or electrochemical flux is directly proportional to trae electrode area (A). 

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