Three-dimensional fluidic devices

Schilling KM, Jauregui D, Marinez AW (2013) Paper and toner three-dimensional fluidic devices programming fluid flow to improve point-of-care diagnostics. Lab Chip 13(4) 628-631... 

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]. 

Nanoparticle (NP) controllable assemblies are of considerable interest for both fundamental research and applications, since they provide direct bridges between nanometer-scale objects and the macroscale world. Generally speaking, nanoparticle (NP) controllable assemblies can be classified into three categories one-dimensional (ID), two-dimensional (2D), and three-dimensional (3D) NP assemblies. These controllable assemblies are likely to play critical roles in the improvement of the efficiencies of various electronic, optoelectronic, magnetic, and other devices and also nanostrucmre-based micro-nano fluidic systems. 

The deep reactive ion etching (DRIE) technique, first presented in the mid- to late 1990s, facilitated the fabrication of numerous innovative microsystems, especially power-MEMS systems. Since most MEMS devices involve some form of lithography-based microfabrication, the use of flat substrates is required. Often, these flat substrates involve the use of DRIE methods and result in structures characterized by extrusion of two-dimensional features into the third dimension as illustrated in Fig. 2. Therefore, microfluidic components are often limited in their geometrical appearance, which precludes full three-dimensional shapes commonly found in many large-scale fluidic devices such as pumps hydrofoils, turbine blades and vanes, mixers, etc. 

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