Two-Photon Photopolymerization and 3D Lithographic Microfabrication

Sun, Hong–Bo; Kawata, Satoshi

doi:10.1007/b94405

Cited by 360 publications

(247 citation statements)

References 172 publications

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“…We chose to work with sputter-deposited Zr-NiAl as the thin film metallic glass "coating" for the nanolattices based on this material's substantial tensile ductility at dimensions up to ~150 nm [11]. Nanolattices, or architected structural metamaterials, exhibit hierarchical ordering ranging from nanometer length scales in wall thickness to micron length scales in defining unit cells and beyond millimeter scales in the overall macroscale architecture, with many nano-architectures produced by using direct-laser-writing two-photon lithography [14][15][16][17]. Existing work on nanolattices has primarily focused on hollow ceramic nanolattices [18][19][20][21][22], due to the ease of depositing conformal coatings of ceramic materials by atomic layer deposition (ALD) and the M A N U S C R I P T 4 inertness of these ceramic materials to oxygen plasma, which has thus far been the plasma of choice for etching away the internal polymer scaffold to produce nanolattices.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

3D nano-architected metallic glass: Size effect suppresses catastrophic failure

Liontas

Greer

2017

Acta Materialia

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We investigate the mechanical behavior of 3D periodically architected metallic glass nanolattices, constructed from hollow beams of sputtered Zr-Ni-Al metallic glass. Nanolattices composed of beams with different wall thicknesses are fabricated by varying the sputter deposition time, resulting in nanolattices with median wall thicknesses of ~88 nm, ~57 nm, ~38 nm, ~30 nm, ~20 nm, and ~10 nm. Uniaxial compression experiments conducted inside a scanning electron microscope reveal a transition from brittle, catastrophic failure in thickerwalled nanolattices (median wall thicknesses of ~88 and ~57 nm) to deformable, gradual, layerby-layer collapse in thinner-walled nanolattices (median wall thicknesses of ~38 nm and less).As the nanolattice wall thickness is varied, large differences in deformability are manifested through the severity of strain bursts, nanolattice recovery after compression, and in-situ images obtained during compression experiments. We explain the brittle-to-deformable transition that occurs as the nanolattice wall thickness decreases in terms of the "smaller is more deformable" material size effect that arises in nano-sized metallic glasses. This work demonstrates that the nano-induced failure-suppression size effect that emerges in small-scale metallic glasses can be proliferated to larger-scale materials by the virtue of architecting.

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Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

3D nano-architected metallic glass: Size effect suppresses catastrophic failure

Liontas

Greer

2017

Acta Materialia

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“…Ablation via laser is a direct subtractive method for patterning substrates 27 . (2) Additive patterning is an approach that involves building up pillars, ridges, and 3D structures, often by exposing resists that are crosslinked upon exposure and wet development (that is, rinsing the noncrosslinked resist) [28][29][30][31] . (3) Finally, moulding techniques can be used to transform a pattern, for example, to mould high ridges from deep trenches and vice versa [32][33][34][35] .…”

Section: High-aspect-ratio Microstructures (Harms)mentioning

confidence: 99%

High-aspect-ratio nanoimprint process chains

et al. 2017

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Different methods capable of developing complex structures and building elements with high-aspect-ratio nanostructures combined with microstructures, which are of interest in nanophotonics, are presented. As originals for subsequent replication steps, two families of masters were developed: (i) 3.2 μm deep, 180 nm wide trenches were fabricated by silicon cryo-etching and (ii) 9.8 μm high, 350 nm wide ridges were fabricated using 2-photon polymerization direct laser writing. Both emerging technologies enable the vertical smooth sidewalls needed for a successful imprint into thin layers of polymers with aspect ratios exceeding 15. Nanoridges with high aspect ratios of up to 28 and no residual layer were produced in Ormocers using the micromoulding into capillaries (MIMIC) process with subsequent ultraviolet-curing. This work presents and balances the different fabrication routes and the subsequent generation of working tools from masters with inverted tones and the combination of hard and soft materials. This provides these techniques with a proof of concept for their compatibility with high volume manufacturing of complex micro-and nanostructures.Keywords: cryo-etching; direct 6 write laser lithography; high aspect ratio; moulding; nanoimprint lithography; Ormocer; photonic nanofences; 2-photon polymerization INTRODUCTION High-aspect-ratio microstructures (HARMS), that is, structures with a large height/width ratio, have found many applications 1,2 such as X-ray gratings 3 , gas chromatography columns 4 , magnetic coils 5 , X-ray telescopes 6 , micro-gears 7 , micro-capacitors with highaspect-ratio (HAR) cantilevers 8 , and micromechanical and microoptical elements 9,10 . These structures exhibit aspect ratios (ARs) of over 10 and almost vertical sidewalls, making them much more challenging to develop than the structures typically used in planar technology with moderate ARs of 1 to 2. They are therefore characterized by an intermediate state between two-and threedimensional (2D and 3D), that is, a 2D planar design that is extended into the vertical dimension and often called . There are several methods to produce HAR structures on typical planar substrates, most of them relying on the anisotropy of subtractive pattern transfer of a low AR masking layer into an underlying resist or substrate, that is, by using mask based ultraviolet (UV)-photolithography (PL) with an AR up to 5, silicon etching (for example, dry etching) with an AR up to 20, and direct write laser lithography (DWL) and X-ray lithography with ARs 420 (Refs. 12-15). These methods are continually being improved to produce a higher AR and smaller lateral dimensions. Furthermore, they are enlarged by new techniques that are often subsets of etching processes with different advantages and disadvantages. One of those challenges is the suitability for submicron and nanopatterning, that is, structures with lateral sizes much smaller than 1 μm and the possibility to combine micro-with nanostructures in the same material.There are three main approaches: (1)...

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“…The forces produced by optical tweezers (tens of picoNewton) are in the same order of magnitude of hydrodynamic forces in a laminar flow [16]. However, the use of OT inside a lab-on-chip apparatus presents some issues, and it is mainly implemented with bulky microscope s6,7,10 or by counter-propagating beams [18][19][20]. In microscope-based OT, the tight focusing of a laser through a high numerical aperture (NA) objective allow achieving optical trapping.…”

Section: Optical Tweezers Integrated In Microfluidic Devicesmentioning

confidence: 99%

“…An alternative solution consists in integrating vertical-cavity surface-emitting lasers (VCSEL) or GaAl/AlGaAs heterostructures that are able to trap and move microspheres and biological samples in microfluidic systems [19], however the complexity to fabricate these devices and low tenability of power limit their use. Recently counter propagating beams, properly faced on microfluidic channels through integrated waveguides fabricated on a glass substrate, were reported [14,20]. This approach was used also to realize fluorescence-activated optical-sorting of cells.…”

Section: Optical Tweezers Integrated In Microfluidic Devicesmentioning

confidence: 99%

Optofluidics for handling and analysis of single living cells

Perozziello¹,

Candeloro²,

Coluccio³

et al. 2017

Optofluidics, Microfluidics and Nanofluidics

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Abstract:Optofluidics is a field with important applications in areas such as biotechnology, chemical synthesis and analytical chemistry. Optofluidic devices combine optical elements into microfluidic devices in ways that increase portability and sensitivity of analysis for diagnostic or screening purposes .In fact in these devices fluids give fine adaptability, mobility and accessibility to nanoscale photonic devices which otherwise could not be realized using conventional devices. This review describes several cases in which optical or microfluidic approaches are used to trap single cells in proximity of integrated optical sensor for being analysed.

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Two-Photon Photopolymerization and 3D Lithographic Microfabrication

Cited by 360 publications

References 172 publications

3D nano-architected metallic glass: Size effect suppresses catastrophic failure

3D nano-architected metallic glass: Size effect suppresses catastrophic failure

High-aspect-ratio nanoimprint process chains

Optofluidics for handling and analysis of single living cells

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