3D printed self-supporting elastomeric structures for multifunctional microfluidics

Microfluidic devices fabricated via soft lithography have demonstrated compelling applications such as lab-on-a-chip diagnostics, DNA microarrays, and cell-based assays. These technologies could be further developed by directly integrating microfluidics with electronic sensors and curvilinear substrates as well as improved automation for higher throughput. Current additive manufacturing methods, such as stereolithography and multi-jet printing, tend to contaminate substrates with uncured resins or supporting materials during printing. Here, we present a printing methodology based on precisely extruding viscoelastic inks into self-supporting microchannels and chambers without requiring sacrificial materials. We demonstrate that, in the submillimeter regime, the yield strength of the as-extruded silicone ink is sufficient to prevent creep within a certain angular range. Printing toolpaths are specifically designed to realize leakage-free connections between channels and chambers, T-shaped intersections, and overlapping channels. The self-supporting microfluidic structures enable the automatable fabrication of multifunctional devices, including multimaterial mixers, microfluidic-integrated sensors, automation components, and 3D microfluidics.

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Fused Filament Fabrication (FFF) for Manufacturing of Microfluidic Micromixers: An Experimental Study on the Effect of Process Variables in Printed Microfluidic Micromixers

Micromachines ◽

10.3390/mi12080858 ◽

2021 ◽

Vol 12 (8) ◽

pp. 858

Author(s):

Mojtaba Zeraatkar ◽

Marco D. de Tullio ◽

Gianluca Percoco

Keyword(s):

3D Printing ◽

Soft Lithography ◽

Microfluidic Devices ◽

Mixing Process ◽

Process Variables ◽

Automated Assembly ◽

Fused Filament Fabrication ◽

Mixing Performance ◽

Geometrical Features ◽

Manufacturing Methods

The need for accessible and inexpensive microfluidic devices requires new manufacturing methods and materials as a replacement for traditional soft lithography and polydimethylsiloxane (PDMS). Recently, with the advent of modern additive manufacturing (AM) techniques, 3D printing has attracted attention for its use in the fabrication of microfluidic devices and due to its automated, assembly-free 3D fabrication, rapidly decreasing cost, and fast-improving resolution and throughput. Here, fused filament fabrication (FFF) 3D printing was used to create microfluidic micromixers and enhance the mixing process, which has been identified as a challenge in microfluidic devices. A design of experiment (DoE) was performed on the effects of studied parameters in devices that were printed by FFF. The results of the colorimetric approach showed the effects of different parameters on the mixing process and on the enhancement of the mixing performance in printed devices. The presence of the geometrical features on the microchannels can act as ridges due to the nature of the FFF process. In comparison to passive and active methods, no complexity was added in the fabrication process, and the ridges are an inherent property of the FFF process.

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3D printed microfluidic devices: a review focused on four fundamental manufacturing approaches and implications on the field of healthcare

Bio-Design and Manufacturing ◽

10.1007/s42242-020-00112-5 ◽

2021 ◽

Author(s):

Viraj Mehta ◽

Subha N. Rath

Keyword(s):

Microfluidic Devices ◽

3D Printed

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Automated calibration of 3D-printed microfluidic devices based on computer vision

Biomicrofluidics ◽

10.1063/5.0037274 ◽

2021 ◽

Vol 15 (2) ◽

pp. 024102

Author(s):

Junchao Wang ◽

Kaicong Liang ◽

Naiyin Zhang ◽

Hailong Yao ◽

Tsung-Yi Ho ◽

...

Keyword(s):

Computer Vision ◽

Microfluidic Devices ◽

Automated Calibration ◽

3D Printed

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Dimensional Accuracy of Dental Models for Three-Unit Prostheses Fabricated by Various 3D Printing Technologies

Materials ◽

10.3390/ma14061550 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1550

Author(s):

Soo-Yeon Yoo ◽

Seong-Kyun Kim ◽

Seong-Joo Heo ◽

Jai-Young Koak ◽

Joung-Gyu Kim

Keyword(s):

Surface Roughness ◽

Three Dimensional ◽

Dimensional Accuracy ◽

3D Analysis ◽

Digital Light Processing ◽

Test Models ◽

Reference File ◽

Significant Difference ◽

Jet Printing ◽

3D Printed

Previous studies on accuracy of three-dimensional (3D) printed model focused on full arch measurements at few points. The aim of this study was to examine the dimensional accuracy of 3D-printed models which were teeth-prepped for three-unit fixed prostheses, especially at margin and proximal contact areas. The prepped dental model was scanned with a desktop scanner. Using this reference file, test models were fabricated by digital light processing (DLP), Multi-Jet printing (MJP), and stereo-lithography apparatus (SLA) techniques. We calculated the accuracy (trueness and precision) of 3D-printed models on 3D planes, and deviations of each measured points at buccolingual and mesiodistal planes. We also analyzed the surface roughness of resin printed models. For overall 3D analysis, MJP showed significantly higher accuracy (trueness) than DLP and SLA techniques; however, there was not any statistically significant difference on precision. For deviations on margins of molar tooth and distance to proximal contact, MJP showed significantly accurate results; however, for a premolar tooth, there was no significant difference between the groups. 3D color maps of printed models showed contraction buccolingually, and surface roughness of the models fabricated by MJP technique was observed as the lowest. The accuracy of the 3D-printed resin models by DLP, MJP, and SLA techniques showed a clinically acceptable range to use as a working model for manufacturing dental prostheses

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Fabrication of Tunable Silk Materials Through Microfluidic Mixers

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2016-65623 ◽

2016 ◽

Author(s):

Joseph R. Nalbach ◽

Dave Jao ◽

Douglas G. Petro ◽

Kyle M. Raudenbush ◽

Shibbir Ahmad ◽

...

Keyword(s):

Soft Lithography ◽

Mixing Processes ◽

Microfluidic Mixing ◽

Microfluidic Mixer ◽

Continuous Mixing ◽

Mixing Performance ◽

3D Printed ◽

Distribution Uniformity ◽

Mixing Patterns ◽

Microfluidic Mixers

A common method to precisely control the material properties is to evenly distribute functional nanomaterials within the substrate. For example, it is possible to mix a silk solution and nanomaterials together to form one tuned silk sample. However, the nanomaterials are likely to aggregate in the traditional manual mixing processes. Here we report a pilot study of utilizing specific microfluidic mixing designs to achieve a uniform nanomaterial distribution with minimal aggregation. Mixing patterns are created based on classic designs and then validated by experimental results. The devices are fabricated on polydimethylsiloxane (PDMS) using 3D printed molds and soft lithography for rapid replication. The initial mixing performance is validated through the mixing of two solutions with colored dyes. The microfluidic mixer designs are further analyzed by creating silk-based film samples. The cured film is inspected with scanning electron microscopy (SEM) to reveal the distribution uniformity of the dye particles within the silk material matrix. Our preliminary results show that the microfluidic mixing produces uniform distribution of dye particles. Because the microfluidic device can be used as a continuous mixing tool, we believe it will provide a powerful platform for better preparation of silk materials. By using different types of nanomaterials such as graphite (demonstrated in this study), graphene, carbon nanotubes, and magnetic nanoparticles, the resulting silk samples can be fine-tuned with desired electrical, mechanical, and magnetic properties.

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Rapid Production of PDMS Microdevices for Electrodriven Separations and Microfluidics by 3D-Printed Scaffold Removal

Separations ◽

10.3390/separations8050067 ◽

2021 ◽

Vol 8 (5) ◽

pp. 67

Author(s):

Alena Šustková ◽

Klára Konderlová ◽

Ester Drastíková ◽

Stefan Sützl ◽

Lenka Hárendarčíková ◽

...

Keyword(s):

Organic Dyes ◽

Microfluidic Devices ◽

Proof Of Concept ◽

Magnetic Microparticles ◽

Mechanical Removal ◽

Glass Slides ◽

Rapid Production ◽

3D Printed

In our work, we produced PDMS-based microfluidic devices by mechanical removal of 3D-printed scaffolds inserted in PDMS. Two setups leading to the fabrication of monolithic PDMS-based microdevices and bonded (or stamped) PDMS-based microdevices were designed. In the monolithic devices, the 3D-printed scaffolds were fully inserted in the PDMS and then carefully removed. The bonded devices were produced by forming imprints of the 3D-printed scaffolds in PDMS, followed by bonding the PDMS parts to glass slides. All these microfluidic devices were then successfully employed in three proof-of-concept applications: capture of magnetic microparticles, formation of droplets, and isotachophoresis separation of model organic dyes.

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Microfluidics 4: PDMS Chip Soft Lithography v2

10.17504/protocols.io.bx2apqae ◽

2021 ◽

Author(s):

Serhat Sevli ◽

not provided C. Yunus Sahan

Keyword(s):

Soft Lithography ◽

Cost Effective ◽

Cnc Machining ◽

3D Printed ◽

Low Volume ◽

Pdms Chip ◽

Application Specific ◽

Lithography Technique

Microfluidics materials are of various types and application-specific. PDMS is one of the most preferred and cost-effective solutions for research and low-volume manufacturing. After having the mold, PDMS replicas are generated by a technique called soft-lithography. This protocol describes the preparation of PDMS microchannels using SU8 molds, 3D Printed resin molds, and/or metal molds by the soft lithography technique, SLA printing, or CNC machining.

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A Very Low-Cost, Labor-Efficient, and Simple Method to Block Scattered Ultraviolet Light in PDMS Microfluidic Devices by Inserting Aluminum Foil Strips

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4041436 ◽

2018 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Shuo Wang ◽

Peter Shankles ◽

Scott Retterer ◽

Yong Tae Kang ◽

Chang Kyoung Choi

Keyword(s):

Soft Lithography ◽

Uv Light ◽

Low Cost ◽

Microfluidic Devices ◽

Aluminum Foil ◽

Material Synthesis ◽

Simple Method ◽

Micro Particles ◽

Complex Shapes ◽

The Cost

Abstract Opto-microfluidic methods have advantages for manufacturing complex shapes or structures of micro particles/hydrogels. Most of these microfluidic devices are made of polydimethylsiloxane (PDMS) by soft lithography because of its flexibility of designing and manufacturing. However, PDMS scatters ultraviolet (UV) light, which polymerizes the photocrosslinkable materials at undesirable locations and clogs the microfluidic devices. A fluorescent dye has previously been employed to absorb the scattered UV light and shift its wavelength to effectively solve this issue. However, this method is limited due to the cost of the materials (tens of dollars per microchip), the time consumed on synthesizing the fluorescent material and verifying its quality (two to three days). More importantly, significant expertise on material synthesis and characterization is required for users of the opto-microfluidic technique. The cost of preliminary testing on multiple iterations of different microfluidic chip designs would also be excessive. Alternatively, with a delicate microchannel design, we simply inserted aluminum foil strips (AFS) inside the PDMS device to block the scattered UV light. By using this method, the UV light was limited to the exposure region so that the opto-microfluidic device could consistently generate microgels longer than 6 h. This is a nearly cost- and labor-free method to solve this issue.

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Micropipette-Based Microfluidic Device for Monodisperse Microbubbles Generation

Micromachines ◽

10.3390/mi9080387 ◽

2018 ◽

Vol 9 (8) ◽

pp. 387

Author(s):

Carlos Toshiyuki Matsumi ◽

Wilson José da Silva ◽

Fábio Kurt Schneider ◽

Joaquim Miguel Maia ◽

Rigoberto E. M. Morales ◽

...

Keyword(s):

Electric Fields ◽

Microfluidic Device ◽

Soft Lithography ◽

Low Cost ◽

Characteristic Curve ◽

Microfluidic Devices ◽

Average Diameter ◽

Internal Diameter ◽

Medical Diagnostic ◽

Average Size

Microbubbles have various applications including their use as carrier agents for localized delivery of genes and drugs and in medical diagnostic imagery. Various techniques are used for the production of monodisperse microbubbles including the Gyratory, the coaxial electro-hydrodynamic atomization (CEHDA), the sonication methods, and the use of microfluidic devices. Some of these techniques require safety procedures during the application of intense electric fields (e.g., CEHDA) or soft lithography equipment for the production of microfluidic devices. This study presents a hybrid manufacturing process using micropipettes and 3D printing for the construction of a T-Junction microfluidic device resulting in simple and low cost generation of monodisperse microbubbles. In this work, microbubbles with an average size of 16.6 to 57.7 μm and a polydispersity index (PDI) between 0.47% and 1.06% were generated. When the device is used at higher bubble production rate, the average diameter was 42.8 μm with increased PDI of 3.13%. In addition, a second-order polynomial characteristic curve useful to estimate micropipette internal diameter necessary to generate a desired microbubble size is presented and a linear relationship between the ratio of gaseous and liquid phases flows and the ratio of microbubble and micropipette diameters (i.e., Qg/Ql and Db/Dp) was found.

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