Fluidic Assembly

Figure 11.9. NW LED. (a) Crossed InP nanowire LED. (top) Three-dimensional (3D) plot of light intensity of the electroluminescence from a crossed NW LED. Light is only observed around the crossing region, (bottom) 3D atomic force microscope image of a crossed NW LED. (inset) Photoluminescence image of a crossed NW junction, (b-c) Multicolor nanoLED array, (b) Schematic of a tricolor nanoLED array assembled by crossing one n-GaN, n-CdS, and n-CdS NW with a p-Si NW. The array was obtained by fluidic assembly and photolithography with ca. 5- xm separation between NW emitters, (c) Normalized EL spectra obtained from the three elements. [Reprinted with permission from Ref. 59. Copyright 2005 Wiley-VCH Verlag.]...

M. T. Tolley, M. Krishnan, D. Erickson, and H. Lipson, Dynamically programmable fluidic assembly. Appl Phys Lett 93 p. 1-13 (2008). 

M. Krishnan, M. T. Tolley, H. Lipson, and D. Erickson, Hydrodynamically tunable affinities for fluidic assembly. Langmuir 25 p. 3769-3774 (2009). 

Assembly Directed assembly Fluidic assembly Self-assembly... 

The root of microscale assembly processes is the difficulty with grasping and releasing small components. At these size scales, electrostatic, capillary, and van der Waals forces dominate over gravity. This makes part release very complicated. However, in a fluid environment, many of these forces are reduced. The buoyancy of a fluid environment also reduces the effects of gravity. This permits the parts to be manipulated by small forces that might otherwise be negligible. Some types of fluidic assembly entirely eliminate the grasping of the parts and utilize stochastic interactimis to position the parts [1]. 

Fluidic assembly systems can generally be categorized into three key categories ... 

Fluidic Assembly, Fig. 1 The contact angle between a liquid and a solid with the surface tensiims illustrated... 

Fluidic Assembly, Fig. 2 A capillary bridge with the principle radii of curvature illustrated... 

Fluidic Assembly, Fig. 3 Surface tension powered rotation [3], Solder is placed over hinged components. When the solder reflows, the surface tension bends the hinge. 

Fluidic Assembly, Fig. 6 FESEM images of the assembled transistor device with unwanted particles and close-up... 

One area of particular opportunity is in the assembly of biological systems. A fluidic environment is required to maintain cell viability and the cells are of sizes that are not easily handled by traditional means. While fluidic assembly methods would be very attractive, living tissues are very complex assemblies consisting of multiple cell types, support materials, and many system constraints. Significant advances are required in the control of assembly processes in order to assemble living tissues from cells. 

Crane NB, Onen O, Carballo J, Ni Q, Guldiken R (2013) Fluidic assembly at the microscale progress and prospects. Microfluid Nanofluid 14(3 ) 383-419... 

Vanapalli SA, lacovella CR, Sung KE, Mukhija D, Millunchick JM, Bums MA, Glotzer SC, Solomon MJ (2008) Fluidic assembly and packing of microspheres in confined channels. Langmuir ACS J Surf Colloids 24(7) 3661-3670... 

Tolley MT, Kalontarov M, Neubert J, Erickson D, Lipson H (2010) Stochastic modular robotic systems a study of fluidic assembly strategies. IEEE Trans Robot 26(3) 518-530... 

Figure 7. Entire fluidic assembly for the synthesis operation.

W. Salalha and E. Zussman, Investigation of fluidic assembly of nanowires using a droplet inside microchannels, Phys. Fluids, 17, 063301 (2005). 

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