Nanostructure and Microstructure Fabrication: From Desired Properties to Suitable Processes

Abstract

When designing a new nanostructure or microstructure, one can follow a processing-based manufacturing pathway, in which the structure properties are defined based on the processing capabilities of the fabrication method at hand. Alternatively, a performance-based pathway can be followed, where the envisioned performance is first defined, and then suitable fabrication methods are sought. To support the latter pathway, fabrication methods are here reviewed based on the geometric and material complexity, resolution, total size, geometric and material diversity, and throughput they can achieve, independently from processing capabilities. Ten groups of fabrication methods are identified and compared in terms of these seven moderators. The highest resolution is obtained with electron beam lithography, with feature sizes below 5 nm. The highest geometric complexity is attained with vat photopolymerization. For high throughput, parallel methods, such as photolithography (≈10 m h ), are needed. This review offers a decision-making tool for identifying which method to use for fabricating a structure with predefined properties.

Anisotropic Stiffness Adhesives for High Shear Forces on Soft Substrates

“…Alternative 3D printing methods deserve to be explored to obtain higher resolutions, taking into account the balance between feature size and adhesive dimensions on one side, and processing time and structural strength on the other side. [44] Potentially, surface patterns could be optimized for attachment to rough substrates, for example, by introducing patterns that promote interlocking, [45,46] or for attachment to wet or flooded substrates, by introducing water-draining surface patterns. [47] Immersion brings additional viscous dissipation and associated timescales into the mechanics of these substrates which allows for further optimization of adhesion performance.…”

“…We used 3D printing, because it is one of the few methods suitable for fabrication of overhanging features. [44] With stereolithography, designs are printed in consecutive layers of 50 µm in thickness. We printed the adhesives in upright position (i.e., with the 5 × 20 mm 2 side of the adhesive facing down).…”

Effect of lateral reinforcements on the adhesion and friction of micropillar adhesives

“…In future work, it is undoubtedly meaningful to investigate the precise formation mechanism of bridge structures, such as concentration dependence. If future work led to a thorough understanding on the relation between the settings of the spin-coating procedure and obtained bridge properties, the presented fabrication method could be a valuable addition to the currently available microfabrication toolbox [33]. Combining bridges with mushroom-shaped and spatula-shaped micropillar tips could be considered as well, for enhancing friction in particular.…”

2D auxetic metamaterials with tuneable micro-/nanoscale apertures

“…In recent years, ground-breaking advances in the field of rapid prototyping have contributed to the realization of micro-and nano-architectured materials which were previously unachievable using traditional macro-scale manufacturing processes. Depending on the geometric complexity, dimensionality, scale, resolution and material requirements of the micro-/nanostructure in question, a variety of advanced fabrication techniques may be used nowadays to produce small scale architecture systems [1,2]. These include a wide range of stereolithography methods [3][4][5][6], droplet deposition systems [7], self-assembly macromolecules [8,9] and vat photopolymerization [10,11] techniques amongst others.…”