Implementation of a Single Emulsion Mask for Three-Dimensional (3D) Microstructure Fabrication of Micromixers Using the Grayscale Photolithography Technique

Three-dimensional (3D) microstructures have been exploited in various applications of microfluidic devices. Multilevel structures in micromixers are among the essential structures in microfluidic devices that exploit 3D microstructures for different tasks. The efficiency of the micromixing process is thus crucial, as it affects the overall performance of a microfluidic device. Microstructures are currently fabricated by less effective techniques due to a slow point-to-point and layer-by-layer pattern exposure by using sophisticated and expensive equipment. In this work, a grayscale photolithography technique is proposed with the capability of simultaneous control on lateral and vertical dimensions of microstructures in a single mask implementation. Negative photoresist SU8 is used for mould realisation with structural height ranging from 163.8 to 1108.7 µm at grayscale concentration between 60% to 98%, depending on the UV exposure time. This technique is exploited in passive micromixers fabrication with multilevel structures to study the mixing performance. Based on optical absorbance analysis, it is observed that 3D serpentine structure gives the best mixing performance among other types of micromixers.

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A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs

Applied Sciences ◽

10.3390/app11083404 ◽

2021 ◽

Vol 11 (8) ◽

pp. 3404

Author(s):

Majid Hejazian ◽

Eugeniu Balaur ◽

Brian Abbey

Keyword(s):

Molecular Dynamics ◽

Flow Rate ◽

Numerical Study ◽

Three Dimensional ◽

Microfluidic Devices ◽

Liquid Jets ◽

Mixing Efficiency ◽

X Ray Diffraction ◽

Cross Sectional ◽

Time Required

Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.

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3D Printing of High Viscosity Reinforced Silicone Elastomers

Polymers ◽

10.3390/polym13142239 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2239

Author(s):

Nicholas Rodriguez ◽

Samantha Ruelas ◽

Jean-Baptiste Forien ◽

Nikola Dudukovic ◽

Josh DeOtte ◽

...

Keyword(s):

Mechanical Properties ◽

High Performance ◽

New Technologies ◽

Three Dimensional ◽

High Viscosity ◽

Layer By Layer ◽

Silicone Elastomers ◽

Uv Curable ◽

Octet Truss ◽

Tunable Mechanical Properties

Recent advances in additive manufacturing, specifically direct ink writing (DIW) and ink-jetting, have enabled the production of elastomeric silicone parts with deterministic control over the structure, shape, and mechanical properties. These new technologies offer rapid prototyping advantages and find applications in various fields, including biomedical devices, prosthetics, metamaterials, and soft robotics. Stereolithography (SLA) is a complementary approach with the ability to print with finer features and potentially higher throughput. However, all high-performance silicone elastomers are composites of polysiloxane networks reinforced with particulate filler, and consequently, silicone resins tend to have high viscosities (gel- or paste-like), which complicates or completely inhibits the layer-by-layer recoating process central to most SLA technologies. Herein, the design and build of a digital light projection SLA printer suitable for handling high-viscosity resins is demonstrated. Further, a series of UV-curable silicone resins with thiol-ene crosslinking and reinforced by a combination of fumed silica and MQ resins are also described. The resulting silicone elastomers are shown to have tunable mechanical properties, with 100–350% elongation and ultimate tensile strength from 1 to 2.5 MPa. Three-dimensional printed features of 0.4 mm were achieved, and complexity is demonstrated by octet-truss lattices that display negative stiffness.

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Improving 3D-3D facial registration methods: potential role of three-dimensional models in personal identification of the living

International Journal of Legal Medicine ◽

10.1007/s00414-021-02655-3 ◽

2021 ◽

Author(s):

Daniele Gibelli ◽

Andrea Palamenghi ◽

Pasquale Poppa ◽

Chiarella Sforza ◽

Cristina Cattaneo ◽

...

Keyword(s):

Three Dimensional ◽

3D Models ◽

Personal Identification ◽

Surveillance Systems ◽

3D Registration ◽

Three Dimensional Models ◽

Point To Point ◽

Point Distance ◽

Male Subjects

AbstractPersonal identification of the living from video surveillance systems usually involves 2D images. However, the potentiality of three-dimensional facial models in gaining personal identification through 3D-3D comparison still needs to be verified. This study aims at testing the reliability of a protocol for 3D-3D registration of facial models, potentially useful for personal identification. Fifty male subjects aged between 18 and 45 years were randomly chosen from a database of 3D facial models acquired through stereophotogrammetry. For each subject, two acquisitions were available; the 3D models of faces were then registered onto other models belonging to the same and different individuals according to the least point-to-point distance on the entire facial surface, for a total of 50 matches and 50 mismatches. RMS value (root mean square) of point-to-point distance between the two models was then calculated through the VAM® software. Intra- and inter-observer errors were assessed through calculation of relative technical error of measurement (rTEM). Possible statistically significant differences between matches and mismatches were assessed through Mann–Whitney test (p < 0.05). Both for intra- and inter-observer repeatability rTEM was between 2.2 and 5.2%. Average RMS point-to-point distance was 0.50 ± 0.28 mm in matches, 2.62 ± 0.56 mm in mismatches (p < 0.01). An RMS threshold of 1.50 mm could distinguish matches and mismatches in 100% of cases. This study provides an improvement to existing 3D-3D superimposition methods and confirms the great advantages which may derive to personal identification of the living from 3D facial analysis.

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A guideline for 3D printing terminology in biomedical research utilizing ISO/ASTM standards

3D Printing in Medicine ◽

10.1186/s41205-021-00098-5 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Amy E. Alexander ◽

Nicole Wake ◽

Leonid Chepelev ◽

Philipp Brantner ◽

Justin Ryan ◽

...

Keyword(s):

3D Printing ◽

Medical Literature ◽

Three Dimensional ◽

Physical Object ◽

Medical Community ◽

Layer By Layer ◽

Digital File ◽

Standardized Terminology ◽

Standard Terms ◽

The Impact

AbstractFirst patented in 1986, three-dimensional (3D) printing, also known as additive manufacturing or rapid prototyping, now encompasses a variety of distinct technology types where material is deposited, joined, or solidified layer by layer to create a physical object from a digital file. As 3D printing technologies continue to evolve, and as more manuscripts describing these technologies are published in the medical literature, it is imperative that standardized terminology for 3D printing is utilized. The purpose of this manuscript is to provide recommendations for standardized lexicons for 3D printing technologies described in the medical literature. For all 3D printing methods, standard general ISO/ASTM terms for 3D printing should be utilized. Additional, non-standard terms should be included to facilitate communication and reproducibility when the ISO/ASTM terms are insufficient in describing expository details. By aligning to these guidelines, the use of uniform terms for 3D printing and the associated technologies will lead to improved clarity and reproducibility of published work which will ultimately increase the impact of publications, facilitate quality improvement, and promote the dissemination and adoption of 3D printing in the medical community.

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Three-dimensionally printed polycaprolactone/multicomponent bioactive glass scaffolds for potential application in bone tissue engineering

Biomedical glasses ◽

10.1515/bglass-2020-0006 ◽

2020 ◽

Vol 6 (1) ◽

pp. 57-69

Author(s):

Amirhosein Fathi ◽

Farzad Kermani ◽

Aliasghar Behnamghader ◽

Sara Banijamali ◽

Masoud Mozafari ◽

...

Keyword(s):

Tissue Engineering ◽

3D Printing ◽

Bone Tissue Engineering ◽

Bone Tissue ◽

Three Dimensional ◽

Layer By Layer ◽

Composite Scaffolds ◽

3D Printed ◽

Co Doped

AbstractOver the last years, three-dimensional (3D) printing has been successfully applied to produce suitable substitutes for treating bone defects. In this work, 3D printed composite scaffolds of polycaprolactone (PCL) and strontium (Sr)- and cobalt (Co)-doped multi-component melt-derived bioactive glasses (BGs) were prepared for bone tissue engineering strategies. For this purpose, 30% of as-prepared BG particles (size <38 μm) were incorporated into PCL, and then the obtained composite mix was introduced into a 3D printing machine to fabricate layer-by-layer porous structures with the size of 12 × 12 × 2 mm3.The scaffolds were fully characterized through a series of physico-chemical and biological assays. Adding the BGs to PCL led to an improvement in the compressive strength of the fabricated scaffolds and increased their hydrophilicity. Furthermore, the PCL/BG scaffolds showed apatite-forming ability (i.e., bioactivity behavior) after being immersed in simulated body fluid (SBF). The in vitro cellular examinations revealed the cytocompatibility of the scaffolds and confirmed them as suitable substrates for the adhesion and proliferation of MG-63 osteosarcoma cells. In conclusion, 3D printed composite scaffolds made of PCL and Sr- and Co-doped BGs might be potentially-beneficial bone replacements, and the achieved results motivate further research on these materials.

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Direct Patterning and Spontaneous Self-Assembly of Graphene Oxide via Electrohydrodynamic Jet Printing for Energy Storage and Sensing

Micromachines ◽

10.3390/mi11010013 ◽

2019 ◽

Vol 11 (1) ◽

pp. 13 ◽

Cited By ~ 2

Author(s):

Bin Zhang ◽

Jaehyun Lee ◽

Mincheol Kim ◽

Naeeung Lee ◽

Hyungdong Lee ◽

...

Keyword(s):

Graphene Oxide ◽

Energy Storage ◽

Self Assembly ◽

High Performance ◽

Three Dimensional ◽

Chemical Properties ◽

Layer By Layer ◽

Energy Storage Devices ◽

Laminar Structure ◽

Jet Printing

The macroscopic assembly of two-dimensional materials into a laminar structure has received considerable attention because it improves both the mechanical and chemical properties of the original materials. However, conventional manufacturing methods have certain limitations in that they require a high temperature process, use toxic solvents, and are considerably time consuming. Here, we present a new system for the self-assembly of layer-by-layer (LBL) graphene oxide (GO) via an electrohydrodynamic (EHD) jet printing technique. During printing, the orientation of GO flakes can be controlled by the velocity distribution of liquid jet and electric field-induced alignment spontaneously. Closely-packed GO patterns with an ordered laminar structure can be rapidly realized using an interfacial assembly process on the substrates. The surface roughness and electrical conductivity of the LBL structure were significantly improved compared with conventional dispensing methods. We further applied this technique to fabricate a reduced graphene oxide (r-GO)-based supercapacitor and a three-dimensional (3D) metallic grid hybrid ammonia sensor. We present the EHD-assisted assembly of laminar r-GO structures as a new platform for preparing high-performance energy storage devices and sensors.

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Research on the Reliability of Box for Gear Test Bed

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.121-126.1744 ◽

2011 ◽

Vol 121-126 ◽

pp. 1744-1748

Author(s):

Xiang Yang Jin ◽

Tie Feng Zhang ◽

Li Li Zhao ◽

He Teng Wang ◽

Xiang Yi Guan

Keyword(s):

Power Flow ◽

Dynamic Performance ◽

Three Dimensional ◽

Design Parameters ◽

The Finite Element Method ◽

Test Bed ◽

Kinematics Simulation ◽

Beveloid Gears ◽

Overall Performance

To determine the efficiency, load-bearing capacity and fatigue life of beveloid gears with intersecting axes, we design a mechanical gear test bed with closed power flow. To test the quality of its structure and predict its overall performance, we establish a three-dimensional solid model for various components based on the design parameters and adopt the technology of virtual prototyping simulation to conduct kinematics simulation on it. Then observe and verify the interactive kinematic situation of each component. Moreover, the finite element method is also utilized to carry out structural mechanics and dynamics analysis on some key components. The results indicate that the test bed can achieve the desired functionality, and the static and dynamic performance of some key components can also satisfy us.

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Evaluation of Parts Produced by a Novel Additive Manufacturing Process

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.315.63 ◽

2013 ◽

Vol 315 ◽

pp. 63-67 ◽

Cited By ~ 1

Author(s):

Muhammad Fahad ◽

Neil Hopkinson

Keyword(s):

Additive Manufacturing ◽

Rapid Prototyping ◽

Manufacturing Process ◽

High Speed ◽

Three Dimensional ◽

Coordinate Measuring Machine ◽

Layer By Layer ◽

Nylon 12 ◽

Measuring Machine ◽

End Use

Rapid prototyping refers to building three dimensional parts in a tool-less, layer by layer manner using the CAD geometry of the part. Additive Manufacturing (AM) is the name given to the application of rapid prototyping technologies to produce functional, end use items. Since AM is relatively new area of manufacturing processes, various processes are being developed and analyzed for their performance (mainly speed and accuracy). This paper deals with the design of a new benchmark part to analyze the flatness of parts produced on High Speed Sintering (HSS) which is a novel Additive Manufacturing process and is currently being developed at Loughborough University. The designed benchmark part comprised of various features such as cubes, holes, cylinders, spheres and cones on a flat base and the build material used for these parts was nylon 12 powder. Flatness and curvature of the base of these parts were measured using a coordinate measuring machine (CMM) and the results are discussed in relation to the operating parameters of the process.The result show changes in the flatness of part with the depth of part in the bed which is attributed to the thermal gradient within the build envelope during build.

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Porous PLAs with Controllable Density by FDM 3D Printing and Chemical Foaming Agent

Micromachines ◽

10.3390/mi12080866 ◽

2021 ◽

Vol 12 (8) ◽

pp. 866

Author(s):

A. R. Damanpack ◽

André Sousa ◽

M. Bodaghi

Keyword(s):

3D Printing ◽

Flow Rate ◽

Three Dimensional ◽

Poly Lactic Acid ◽

Layer By Layer ◽

Printing Technology ◽

Material Density ◽

Foaming Agent ◽

3D Printing Technology ◽

Fabrication Parameters

This paper shows how fused decomposition modeling (FDM), as a three-dimensional (3D) printing technology, can engineer lightweight porous foams with controllable density. The tactic is based on the 3D printing of Poly Lactic Acid filaments with a chemical blowing agent, as well as experiments to explore how FDM parameters can control material density. Foam porosity is investigated in terms of fabrication parameters such as printing temperature and flow rate, which affect the size of bubbles produced during the layer-by-layer fabrication process. It is experimentally shown that printing temperature and flow rate have significant effects on the bubbles’ size, micro-scale material connections, stiffness and strength. An analytical equation is introduced to accurately simulate the experimental results on flow rate, density, and mechanical properties in terms of printing temperature. Due to the absence of a similar concept, mathematical model and results in the specialized literature, this paper is likely to advance the state-of-the-art lightweight foams with controllable porosity and density fabricated by FDM 3D printing technology.

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Heteroepitaxial Nucleation and Growth of Ge ON Si(100) Surfaces Using Remote Plasma Enhanced Chemical Vapor Deposition

MRS Proceedings ◽

10.1557/proc-116-519 ◽

1988 ◽

Vol 116 ◽

Cited By ~ 2

Author(s):

R.A. Rudder ◽

S.V. Hattangady ◽

D.J. Vitkavage ◽

R.J. Markunas

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Photoelectron Spectroscopy ◽

Three Dimensional ◽

Chemical Vapor ◽

Layer By Layer ◽

Heteroepitaxial Growth ◽

Remote Plasma ◽

Dimensional Growth ◽

Diffraction Patterns

Heteroepitaxial growth of Ge on Si(100) has been accomplished using remote plasma enhanced chemical vapor deposition at 300*#x00B0;C. Reconstructed surfaces with diffraction patterns showing non-uniform intensity variations along the lengths of the integral order streaks are observed during the first 100 Å of deposit. This observation of an atomically rough surface during the initial stages of growth is an indication of three-dimensional growth. As the epitaxial growth proceeds, the diffraction patterns become uniform with extensive streaking on both the integral and fractional order streaks. Subsequent growth, therefore, takes place in a layer-by-layer, two-dimensional mode. X-ray photoelectron spectroscopy of the early nucleation stages, less than 80 Å, show that there is uniform coverage with no evidence of island formation.

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