scholarly journals Tactile perception of the roughness of 3D-printed textures

2018 ◽  
Vol 119 (3) ◽  
pp. 862-876 ◽  
Author(s):  
Chelsea Tymms ◽  
Denis Zorin ◽  
Esther P. Gardner
Keyword(s):  
Surface Roughness ◽  
High Resolution ◽  
3D Printing ◽  
Human Subjects ◽  
Three Dimensional ◽  
Weber Fraction ◽  
Parametric Modeling ◽  
Surface Geometry ◽  
Surface Parameters ◽  
Roughness Perception

Surface roughness is one of the most important qualities in haptic perception. Roughness is a major identifier for judgments of material composition, comfort, and friction and is tied closely to manual dexterity. Some attention has been given to the study of roughness perception in the past, but it has typically focused on noncontrollable natural materials or on a narrow range of artificial materials. The advent of high-resolution three-dimensional (3D) printing technology provides the ability to fabricate arbitrary 3D textures with precise surface geometry to be used in tactile studies. We used parametric modeling and 3D printing to manufacture a set of textured plates with defined element spacing, shape, and arrangement. Using active touch and two-alternative forced-choice protocols, we investigated the contributions of these surface parameters to roughness perception in human subjects. Results indicate that large spatial periods produce higher estimations of roughness (with Weber fraction = 0.19), small texture elements are perceived as rougher than large texture elements of the same wavelength, perceptual differences exist between textures with the same spacing but different arrangements, and roughness equivalencies exist between textures differing along different parameters. We posit that papillary ridges serve as tactile processing units, and neural ensembles encode the spatial profiles of the texture contact area to produce roughness estimates. The stimuli and the manufacturing process may be used in further studies of tactile roughness perception and in related neurophysiological applications. NEW & NOTEWORTHY Surface roughness is an integral quality of texture perception. We manufactured textures using high-resolution 3D printing, which allows precise specification of the surface spatial topography. In human psychophysical experiments we investigated the contributions of specific surface parameters to roughness perception. We found that textures with large spatial periods, small texture elements, and irregular, isotropic arrangements elicit the highest estimations of roughness. We propose that roughness correlates inversely with the total contacted surface area.

scholarly journals Rapid and Inexpensive Fabrication of Multi-Depth Microfluidic Device using High-Resolution LCD Stereolithographic 3D Printing

2019 ◽  
Vol 3 (1) ◽  
pp. 26 ◽  
Author(s):  
Mohamed Mohamed ◽  
Hitendra Kumar ◽  
Zongjie Wang ◽  
Nicholas Martin ◽  
Barry Mills ◽  
...  
Keyword(s):  
High Resolution ◽  
3D Printing ◽  
Soft Lithography ◽  
Liquid Crystal Display ◽  
Three Dimensional ◽  
Microfluidic Devices ◽  
Single Step ◽  
Droplet Generator ◽  
Rapid Fabrication ◽  
Printing System

With the dramatic increment of complexity, more microfluidic devices require 3D structures, such as multi-depth and -layer channels. The traditional multi-step photolithography is time-consuming and labor-intensive and also requires precise alignment during the fabrication of microfluidic devices. Here, we present an inexpensive, single-step, and rapid fabrication method for multi-depth microfluidic devices using a high-resolution liquid crystal display (LCD) stereolithographic (SLA) three-dimensional (3D) printing system. With the pixel size down to 47.25 μm, the feature resolutions in the horizontal and vertical directions are 150 μm and 50 μm, respectively. The multi-depth molds were successfully printed at the same time and the multi-depth features were transferred properly to the polydimethylsiloxane (PDMS) having multi-depth channels via soft lithography. A flow-focusing droplet generator with a multi-depth channel was fabricated using the presented 3D printing method. Experimental results show that the multi-depth channel could manipulate the morphology and size of droplets, which is desired for many engineering applications. Taken together, LCD SLA 3D printing is an excellent alternative method to the multi-step photolithography for the fabrication of multi-depth microfluidic devices. Taking the advantages of its controllability, cost-effectiveness, and acceptable resolution, LCD SLA 3D printing can have a great potential to fabricate 3D microfluidic devices.

Yield and shear of rough interlocked faults: analytical solution and experimental observations

2020 ◽  
Author(s):  
Amir Sagy ◽  
Vladimir Lyakhovsky ◽  
Yossef H. Hatzor
Keyword(s):  
Surface Roughness ◽  
Analytical Solution ◽  
Normal Stress ◽  
Laboratory Experiments ◽  
Three Dimensional ◽  
Elastic Half Space ◽  
Interface Roughness ◽  
Displacement Rate ◽  
Initial Surface ◽  
Surface Geometry

<p>Natural fault surfaces are interlocked, partly cohesive, and display multiscale geometric irregularities. Here we examine the nucleation of deformation and the evolution of shear in such interlocked surfaces using a closed-form analytical solution and a series of laboratory experiments.  The analytical model considers an interlocked interface with multiscale roughness between two linear elastic half-space blocks. The interface geometry is based on three-dimensional fault surfaces imaging. It is represented by a Fourier series and the plane strain solution for the elastic stress distribution is represented as a sum of the constant background stress generated by a uniform far-field loading and perturbations associated with the interface roughness. The model predicts the critical stress necessary for failure and the location of failure nucleation sites across the surface, as function of the initial surface geometry.</p><p>A similar configuration is adopted in laboratory experiments as carbonate blocks with rough interlocked surfaces generated by tensional fracturing are sheared in a servo-controlled direct shear apparatus. Resistance to shear and surface roughness evolution are measured under variable normal stresses, slip distances and slip rates.  We find that the evolution of surface morphology with shear is closely related to the loading configuration. Initially rough, interlocked, surfaces become rougher when normal stress and displacement rate are increased. Under a fixed, relatively low normal stress and fixed displacement rate however, the surfaces become smoother with increasing displacement distance.  </p><p>The shear of the interlocked slip surfaces is associated with volumetric deformation, wear and frictional slip, all of which are typically observed across natural fault zones. We suggest that their intensities and partitioning are strongly affected by the initial surface roughness characteristics, the background stress, and the rate and magnitude of shear displacement. </p>

Study of Microscale Three-Dimensional Printing Using Near-Field Melt Electrospinning

2017 ◽  
Author(s):  
Xiangyu You ◽  
Chengcong Ye ◽  
Ping Guo
Keyword(s):  
High Resolution ◽  
3D Printing ◽  
Low Cost ◽  
Near Field ◽  
Three Dimensional ◽  
Thin Wall ◽  
Direct Writing ◽  
Melt Electrospinning ◽  
Wall Structures ◽  
Jet Trajectory

Three-dimensional (3D) printing of microscale structures with high resolution (sub-micron) and low cost is still a challenging work for the existing 3D printing techniques. Here we report a direct writing process via near-field melt electrospinning to achieve microscale printing of single filament wall structures. The process allows continuous direct writing due to the linear and stable jet trajectory in the electric near-field. The layer-by-later stacking of fibers, or self-assembly effect, is attributed to the attraction force from the molten deposited fibers and accumulated negative charges. We demonstrated successful printing of various 3D thin wall structures (freestanding single walls, double walls, annular walls, star-shaped structures, and curved wall structures) with a minimal wall thickness less than 5 μm. By optimizing the process parameters of near-field melt electrospinning (electric field strength, collector moving speed, and needle-to-collector distance), ultrafine poly (ε-caprolactone) (PCL) fibers have been stably generated and precisely stacked and fused into 3D thin-wall structures with an aspect ratio of more than 60. It is envisioned that the near-field melt electrospinning can be transformed into a viable high-resolution and low-cost microscale 3D printing technology.

scholarly journals A combined 3D printing/CNC micro-milling method to fabricate a large-scale microfluidic device with the small size 3D architectures: an application for tumor spheroid production

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ebrahim Behroodi ◽  
Hamid Latifi ◽  
Zeinab Bagheri ◽  
Esra Ermis ◽  
Shabnam Roshani ◽  
...  
Keyword(s):  
High Resolution ◽  
3D Printing ◽  
Large Scale ◽  
Three Dimensional ◽  
Micro Milling ◽  
Tumor Spheroid ◽  
Microfluidic Chips ◽  
Difficult Time ◽  
Micro Channels ◽  
Milling Method

AbstractThe fabrication of a large-scale microfluidic mold with 3D microstructures for manufacturing of the conical microwell chip using a combined projection micro-stereolithography (PµSL) 3D printing/CNC micro-milling method for tumor spheroid formation is presented. The PµSL technique is known as the most promising method of manufacturing microfluidic chips due to the possibility of creating complex three-dimensional microstructures with high resolution in the range of several micrometers. The purpose of applying the proposed method is to investigate the influence of microwell depths on the formation of tumor spheroids. In the conventional methods, the construction of three-dimensional microstructures and multi-height chips is difficult, time-consuming, and is performed using a multi-step lithography process. Microwell depth is an essential parameter for microwell design since it directly affects the shear stress of the fluid flow and the diffusion of nutrients, respiratory gases, and growth factors. In this study, a chip was made with microwells of different depth varying from 100 to 500 µm. The mold of the microwell section is printed by the lab-made PµSL printer with 6 and 1 µm lateral and vertical resolutions. Other parts of the mold, such as the main chamber and micro-channels, were manufactured using the CNC micro-milling method. Finally, different parts of the master mold were assembled and used for PDMS casting. The proposed technique drastically simplifies the fabrication and rapid prototyping of large-scale microfluidic devices with high-resolution microstructures by combining 3D printing with the CNC micro-milling method.

scholarly journals Living cell-only bioink and photocurable supporting medium for printing and generation of engineered tissues with complex geometries

2019 ◽  
Author(s):  
Oju Jeon ◽  
Yu Bin Lee ◽  
Hyeon Jeong ◽  
Sang Jin Lee ◽  
Eben Alsberg
Keyword(s):  
High Resolution ◽  
3D Printing ◽  
Living Cell ◽  
Three Dimensional ◽  
Cartilage Tissue ◽  
Human Stem Cells ◽  
Engineering Technology ◽  
Biomaterial Scaffold ◽  
Manufacturing Techniques ◽  
Controlled Structure

AbstractScaffold-free engineering of three-dimensional (3D) tissue has focused on building sophisticated structures to achieve functional constructs. Although the development of advanced manufacturing techniques such as 3D printing has brought remarkable capabilities to the field of tissue engineering, technology to create and culture individual cell only-based high-resolution tissues, without an intervening biomaterial scaffold to maintain construct shape and architecture, has been unachievable to date. In this report, we introduce a cell printing platform which addresses the aforementioned challenge and permits 3D printing and long-term culture of a living cell-only bioink lacking a biomaterial carrier for functional tissue formation. A biodegradable and photocrosslinkable microgel supporting bath serves initially as a fluid, allowing free movement of the printing nozzle for high-resolution cell extrusion, while also presenting solid-like properties to sustain the structure of the printed constructs. The printed human stem cells, which are the only component of the bioink, couple together via transmembrane adhesion proteins and differentiate down tissue-specific lineages while being cultured in a further photocrosslinked supporting bath to form bone and cartilage tissue with precisely controlled structure. Collectively, this system, which is applicable to general 3D printing strategies, is paradigm shifting for printing of scaffold-free individual cells, cellular condensations and organoids, and may have far reaching impact in the fields of regenerative medicine, drug screening, and developmental biology.

scholarly journals Surface Roughness Effect on the 3d Printed Butt Joints Strength

2015 ◽  
Author(s):  
V. Kovan ◽  
G. Altan ◽  
E.S. Topal ◽  
H.E. Camurlu
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Three Dimensional ◽  
Thickness Effect ◽  
Fused Deposition Modelling ◽  
Three Dimensional Printing ◽  
Fused Deposition ◽  
3D Printed ◽  
Dimensional Object

Three-dimensional printing or 3D printing (also called additive manufacturing) is any of various processes used to make a three-dimensional object. Fused deposition modelling (FDM) is an additive manufacturing technology commonly used for modelling, prototyping, and production applications. It is one of the techniques used for 3D printing. FDM is somewhat restricted in the size and the variation of shapes that may be fabricated. For parts too large to fit on a single build, for faster job builds with less support material, or for parts with finer features, sectioning and bonding FDM parts is a great solution. The strength of adhesive bonded FDM parts is affected by the surface roughness. In this study, the layer thickness effect on bonding strength is experimentally studied and the results are discussed.

Study of Microscale Three-Dimensional Printing Using Near-Field Melt Electrospinning

2017 ◽  
Vol 5 (4) ◽  
Author(s):  
Xiangyu You ◽  
Chengcong Ye ◽  
Ping Guo
Keyword(s):  
High Resolution ◽  
3D Printing ◽  
Low Cost ◽  
Near Field ◽  
Three Dimensional ◽  
Thin Wall ◽  
Direct Writing ◽  
Melt Electrospinning ◽  
Wall Structures ◽  
Jet Trajectory

Three-dimensional (3D) printing of microscale structures with high-resolution (submicron) and low-cost is still a challenging work for the existing 3D printing techniques. Here, we report a direct writing process via near-field melt electrospinning (NFME) to achieve microscale printing of single filament wall structures. The process allows continuous direct writing due to the linear and stable jet trajectory in the electric near field. The layer-by-layer stacking of fibers, or self-assembly effect, is attributed to the attraction force from the molten deposited fibers and accumulated negative charges. We demonstrated successful printing of various 3D thin-wall structures with a minimal wall thickness less than 5 μm. By optimizing the process parameters of NFME, ultrafine poly (ε-caprolactone) (PCL) fibers have been stably generated and precisely stacked and fused into 3D thin-wall structures with an aspect ratio of more than 60. It is envisioned that the NFME can be transformed into a viable high-resolution and low-cost microscale 3D printing technology.

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