Three‐Dimensional Fabrication at Small Size Scales

Abstract

Despite the fact that we live in a three-dimensional (3D) world and macroscale engineering is 3D, conventional sub-mm scale engineering is inherently two-dimensional (2D). New fabrication and patterning strategies are needed to enable truly three-dimensionally-engineered structures at small size scales. Here, we review strategies that have been developed over the last two decades that seek to enable such millimeter to nanoscale 3D fabrication and patterning. A focus of this review is the strategy of self-assembly, specifically in a biologically inspired, more deterministic form known as self-folding. Self-folding methods can leverage the strengths of lithography to enable the construction of precisely patterned 3D structures and “smart” components. This self-assembling approach is compared with other 3D fabrication paradigms, and its advantages and disadvantages are discussed.

Green Routes for Graphene Oxide Reduction and Self- Assembled Graphene Oxide Micro- and Nanostructures Production

“…Different assembly stages are shown in Figure 6, initially any material can be patterned as isolated blocks, Figure 6(a), and then the metallic frame is deposited by a photolithographic process, Figure 6(b). The metallic frame is constituted by two different metals, which linked the assembly blocks and allow the self-folding [91].…”

Three-dimensional polymeric microtiles for optically-tracked fluidic self-assembly

“…SA represents a pervasive, bottom-up and massively parallel methodology for the fabrication of heterogeneous microand nanobiosystems [6,2,9]. It is also a key coordination task for distributed robotic systems, especially those consisting of a large number of nodes [7,10].…”

Molding topologically-complex 3D polymer microstructures from femtosecond laser machined glass

“…Mask-based photolithography processes in particular are primarily restricted to multiple two-dimensional layers, or to forming structures of limited three-dimensionality through undercutting [3] or greyscale lithography. Additionally, features in the third dimension can be formed post-lithography through self-assembling mechanisms [4,5] using for example thin-film stresses [6] or capillary forces [7]. Alternative approaches such as 2-photon polymerization [8][9][10] and electron-beam lithography [11] have been demonstrated, but are slow to process, and still serial in nature.…”