scholarly journals Omnidirectional 3D printing of metal micro-architectures via droplet sliding over curved surfaces

2021 ◽  
Author(s):  
Jun Luo ◽  
Jingyuan Cheng ◽  
Yacong Dong ◽  
Lehua Qi ◽  
Ni Li ◽  
...  
Keyword(s):  
3D Printing ◽  
Impact Angle ◽  
Heat Sinks ◽  
Process Window ◽  
Free Standing ◽  
Metal Structures ◽  
Research Fields ◽  
Aspect Ratios ◽  
Drop Adhesion ◽  
Tunable Morphology

Abstract As a simple, fast, and green 3D printing method, droplet-based manufacturing is suitable to print various materials to manufacture structures. However, up to now, it has hardly been capable of manufacturing omnidirectional designs with slender horizontal or upside-down sections, since the required rotation of the nozzle or workpiece negatively affects printing performance. Here, we employed a novel slide-guided droplet deposition method for printing parts with arbitrary-angle overhangs up to 180o. Arc-shaped slides with metallophobic surfaces are used to smoothly deflect droplets and provide a full control of droplets’ impact angle onto the workpiece. We show that gently curved impact surfaces prevent droplet bouncing, and quantitatively describe the transition from sliding to bouncing by measurements, simulations, and theory that predict our process window. Furthermore, the temperature of the slides is controlled to modify the temperature of droplets after they leave the generator, enabling fabrication of horizontal pillars with locally tunable morphology and optimization of drop-to-drop adhesion. The versatility of the slide-guided deposition is highlighted by fabricating structures with high aspect ratios and free-standing branches in arbitrary angles including hung sections where droplets are deposited from a fully reversed direction. Since the proposed slide-guided deposition uniquely facilitates fabrication of slender metal structures from arbitrary angles without rotating the workpiece or nozzle, it helps advance the development of many other research fields, such as antennas, branch-like heat sinks, and metal micro-lattices, where complex structures are needed.

scholarly journals Ubiquitous organic molecule-based free-standing nanowires with ultra-high aspect ratios

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Koshi Kamiya ◽  
Kazuto Kayama ◽  
Masaki Nobuoka ◽  
Shugo Sakaguchi ◽  
Tsuneaki Sakurai ◽  
...  
Keyword(s):  
Critical Dimension ◽  
High Energy ◽  
Free Standing ◽  
Dry Process ◽  
3D Space ◽  
Aspect Ratios ◽  
Structural Functions ◽  
Planar Structures ◽  
Organic Nanostructures ◽  
Straight Trajectory

AbstractThe critical dimension of semiconductor devices is approaching the single-nm regime, and a variety of practical devices of this scale are targeted for production. Planar structures of nano-devices are still the center of fabrication techniques, which limit further integration of devices into a chip. Extension into 3D space is a promising strategy for future; however, the surface interaction in 3D nanospace make it hard to integrate nanostructures with ultrahigh aspect ratios. Here we report a unique technique using high-energy charged particles to produce free-standing 1D organic nanostructures with high aspect ratios over 100 and controlled number density. Along the straight trajectory of particles penetrating the films of various sublimable organic molecules, 1D nanowires were formed with approximately 10~15 nm thickness and controlled length. An all-dry process was developed to isolate the nanowires, and planar or coaxial heterojunction structures were built into the nanowires. Electrical and structural functions of the developed standing nanowire arrays were investigated, demonstrating the potential of the present ultrathin organic nanowire systems.

scholarly journals On-Chip Fabrication and In-Flow 3D-Printing of Cell-Laden Microgel Constructs: From Chip to Scaffold Materials in One Integral Process

2021 ◽  
Author(s):  
Stephan Förster ◽  
Jürgen Groll ◽  
Benjamin Reineke ◽  
Stephan Hauschild ◽  
Ilona Paulus ◽  
...  
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Cross Linking ◽  
Cell Protection ◽  
Free Standing ◽  
Produce Cell ◽  
Chip Fabrication ◽  
Integral Process ◽  
Scaffold Materials ◽  
On Chip

Bioprinting has evolved into a thriving technology for the fabrication of cell-laden scaffolds. Bioinks are the most critical component for bioprinting. Recently, microgels have been introduced as a very promising bioink enabling cell protection and the control of the cellular microenvironment. However, their microfluidic fabrication inherently seemed to be a limitation. Here we introduce a direct coupling of microfluidics and 3D-printing for the microfluidic production of cell-laden microgels with direct in-flow bioprinting into stable scaffolds. The methodology enables the continuous on-chip encapsulation of cells into monodisperse microdroplets with subsequent in-flow cross-linking to produce cell-laden microgels, which after exiting a microtubing are automatically jammed into thin continuous microgel filaments. The integration into a 3D printhead allows direct in-flow printing of the filaments into free-standing three-dimensional scaffolds. The method is demonstrated for different cross-linking methods and cell lines. With this advancement, microfluidics is no longer a bottleneck for biofabrication. <br>

Fine Pitch Copper Interconnects for Next Generation Package-on-Package (PoP)

2012 ◽  
Vol 2012 (1) ◽  
pp. 001137-001142 ◽  
Author(s):  
Ilyas Mohammed
Keyword(s):  
High Performance ◽  
Copper Interconnects ◽  
Free Standing ◽  
Positional Accuracy ◽  
Aspect Ratios ◽  
Fine Pitch ◽  
Wire Bonds ◽  
Solder Balls ◽  
The Wire ◽  
Interconnect Technology

For low power processors, stacking memory on top offers many advantages such as high performance due to memory-processor interface within package, small footprint and standard assembly. Package-on-package (PoP) is preferred method of stacking as it offers two discrete packages that are tested separately and can be sourced independently. However, current PoP interconnect technologies do not efficiently scale to meet the memory bandwidth requirements for new generations of multi-core applications processors. The current interconnect technologies such as stacking with smaller sized solder balls, using solder filled laser drilled vias in the mold cap, or using organic interposers are not practically achieving the high IO requirements, since the aspect ratios of these interconnects are limited. To address the gap in PoP interconnect density, a wire bond based package stacking interconnect technology called Bond Via Array (BVA™) is presented that enables reduced pitch and a higher number of interconnects in the PoP perimeter stacking arrangement. The main technological challenges are identified and the research results explained. The three main challenges were forming free standing wire-bonds, molding the package while exposing the tips of the wire-bonds, and package stacking. The assembly results showed that the wire tips were within the desired positional accuracy and height, and the packages were stacked without any loss of yield. These results indicate that the BVA interconnect technology is promising for the very high density and fine pitch required for upcoming mobile computing systems.

3D printing vertically: Direct ink writing free-standing pillar arrays

2020 ◽  
Vol 35 ◽  
pp. 16-24 ◽  
Author(s):  
Bo Nan ◽  
Francisco J. Galindo-Rosales ◽  
José M.F. Ferreira
Keyword(s):  
3D Printing ◽  
Free Standing ◽  
Direct Ink Writing ◽  
Pillar Arrays

3D Printing of Free Standing Liquid Metal Microstructures

2013 ◽  
Vol 25 (36) ◽  
pp. 5081-5085 ◽  
Author(s):  
Collin Ladd ◽  
Ju-Hee So ◽  
John Muth ◽  
Michael D. Dickey
Keyword(s):  
3D Printing ◽  
Liquid Metal ◽  
Free Standing

Optimization of Heat Transfer Rate in the Rectangular Microchannel of Different Aspect Ratios With Constant Cross Sectional Area

2008 ◽  
Author(s):  
F. Kowsary ◽  
N. Noroozi ◽  
M. Rezaei Barmi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Cross Sectional Area ◽  
Heat Sinks ◽  
Sectional Area ◽  
Cross Sectional ◽  
Aspect Ratios

The increased power dissipation and reduced dimensions of microelectronics devices have emphasized the need for highly efficient compact cooling technologies. Microchannel heat sinks are of particular interest due to the very high rates of heat transfer they enable in conjunction with greatly reduced heat sink length scales and coolant mass flow rate. Therefore, in the present work, optimization of laminar convective heat transfer in the microchannel heat sinks is investigated for uniform heat flux and different cross sectional areas of different aspect ratios. Three-dimensional numerical simulations of general form of energy equation were performed to predict Nusselt number in the laminar flow regime. Using these results, an optimum forced convective heat transfer coefficient was computed for several cross sectional areas and Reynolds numbers, utilizing the univariable search method. Different aspect ratios have different influences on Nusselt number in thermally developing and fully developed regions for different cross sectional areas and Reynolds numbers. There exists an optimum Nusselt number for each Reynolds number and cross sectional area by varying aspect ratio. Thus, optimized state is computed and related graphs are presented.

scholarly journals On-Chip Fabrication and In-Flow 3D-Printing of Cell-Laden Microgel Constructs: From Chip to Scaffold Materials in One Integral Process

2021 ◽  
Author(s):  
Stephan Förster ◽  
Jürgen Groll ◽  
Benjamin Reineke ◽  
Stephan Hauschild ◽  
Ilona Paulus ◽  
...  
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Cross Linking ◽  
Cell Protection ◽  
Free Standing ◽  
Produce Cell ◽  
Chip Fabrication ◽  
Integral Process ◽  
Scaffold Materials ◽  
On Chip

Bioprinting has evolved into a thriving technology for the fabrication of cell-laden scaffolds. Bioinks are the most critical component for bioprinting. Recently, microgels have been introduced as a very promising bioink enabling cell protection and the control of the cellular microenvironment. However, their microfluidic fabrication inherently seemed to be a limitation. Here we introduce a direct coupling of microfluidics and 3D-printing for the microfluidic production of cell-laden microgels with direct in-flow bioprinting into stable scaffolds. The methodology enables the continuous on-chip encapsulation of cells into monodisperse microdroplets with subsequent in-flow cross-linking to produce cell-laden microgels, which after exiting a microtubing are automatically jammed into thin continuous microgel filaments. The integration into a 3D printhead allows direct in-flow printing of the filaments into free-standing three-dimensional scaffolds. The method is demonstrated for different cross-linking methods and cell lines. With this advancement, microfluidics is no longer a bottleneck for biofabrication. <br>

scholarly journals Characterization of Slurry-Cast Layer Compounds for 3D Printing of High Strength Casting Cores

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6149
Author(s):  
Patricia Erhard ◽  
Jan Angenoorth ◽  
Joachim Vogt ◽  
Johannes Spiegel ◽  
Florian Ettemeyer ◽  
...  
Keyword(s):  
3D Printing ◽  
Bending Strength ◽  
State Of The Art ◽  
Temperature Stability ◽  
High Strength ◽  
Process Window ◽  
Drying Process ◽  
The Mean ◽  
Drying Conditions

Additive manufacturing of casting cores and molds is state of the art in industrial application today. However, improving the properties of chemically bonded casting cores regarding temperature stability, bending strength, and surface quality is still a major challenge. The process of slurry-based 3D printing allows the fabrication of dense structures and therefore sinterable casting cores. This paper presents a study of the slurry-based fabrication of ceramic layer compounds focusing on the drying process and the achievable properties in slurry-based 3D printing of casting cores. This study aims at contributing to a better understanding of the interrelations between the drying conditions in the 3D printing process and the properties of sintered specimens relating thereto. The drying intensity influenced by an IR heater as well as the drying periods are varied for layer thicknesses of 50, 75, and 100 µm. Within this study, a process window applicable for 3D printing of sinterable casting cores is identified and further indications are given for optimization potentials. At layer heights of 75 µm, bending strengths between ~8 and 11 MPa as well as densities of around 50% of the theoretical density were achieved. Since the mean roughness depth Rz is determined to be <30 µm in plane, an application of slurry-based 3D printing in investment casting is conceivable.

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