scholarly journals On-ratio PDMS bonding for multilayer microfluidic device fabrication

2018 ◽  
Author(s):  
Andre Lai ◽  
Nicolas Altemose ◽  
Jonathan A. White ◽  
Aaron M. Streets
Keyword(s):  
Conventional Method ◽  
Material Properties ◽  
Soft Lithography ◽  
Crosslinking Agent ◽  
Microfluidic Devices ◽  
Device Fabrication ◽  
Common Variants ◽  
Precise Control ◽  
Multilayer Soft Lithography ◽  
Bonding Technique

AbstractIntegrated elastomeric valves, also referred to as Quake valves, enable precise control and manipulation of fluid within microfluidic devices. Fabrication of such valves requires bonding of multiple layers of the silicone polymer polydimethylsiloxane (PDMS). The conventional method for PDMS-PDMS bonding is to use varied base to crosslinking agent ratios between layers, typically 20:1 and 5:1. This bonding technique, known as “off-ratio bonding,” provides strong, effective PDMS-PDMS bonding for multi-layer soft-lithography, but it can yield adverse PDMS material properties and can be wasteful of PDMS. Here we demonstrate the effectiveness of on-ratio PDMS bonding for multilayer soft lithography. We show the efficacy of this technique among common variants of PDMS: Sylgard 184, RTV 615, and Sylgard 182.

scholarly journals Rapid Manufacturing of Multilayered Microfluidic Devices for Organ on a Chip Applications

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1382
Author(s):  
Roberto Paoli ◽  
Davide Di Giuseppe ◽  
Maider Badiola-Mateos ◽  
Eugenio Martinelli ◽  
Maria Jose Lopez-Martinez ◽  
...  
Keyword(s):  
Rapid Prototyping ◽  
Soft Lithography ◽  
Microfluidic Devices ◽  
Device Fabrication ◽  
Rapid Manufacturing ◽  
Digital Manufacturing ◽  
Proof Of Concept ◽  
Cyclic Olefin ◽  
Protocol Optimization ◽  
Organ On A Chip

Microfabrication and Polydimethylsiloxane (PDMS) soft-lithography techniques became popular for microfluidic prototyping at the lab, but even after protocol optimization, fabrication is yet a long, laborious process and partly user-dependent. Furthermore, the time and money required for the master fabrication process, necessary at any design upgrade, is still elevated. Digital Manufacturing (DM) and Rapid-Prototyping (RP) for microfluidics applications arise as a solution to this and other limitations of photo and soft-lithography fabrication techniques. Particularly for this paper, we will focus on the use of subtractive DM techniques for Organ-on-a-Chip (OoC) applications. Main available thermoplastics for microfluidics are suggested as material choices for device fabrication. The aim of this review is to explore DM and RP technologies for fabrication of an OoC with an embedded membrane after the evaluation of the main limitations of PDMS soft-lithography strategy. Different material options are also reviewed, as well as various bonding strategies. Finally, a new functional OoC device is showed, defining protocols for its fabrication in Cyclic Olefin Polymer (COP) using two different RP technologies. Different cells are seeded in both sides of the membrane as a proof of concept to test the optical and fluidic properties of the device.

scholarly journals A rapid-prototyped moulding system towards optimised scalable fabrication of elastomeric microfluidic devices

2021 ◽  
Author(s):  
Christine Poon ◽  
Albert Fahrenbach
Keyword(s):  
3D Printing ◽  
Microfluidic Device ◽  
Lean Manufacturing ◽  
Soft Lithography ◽  
Low Cost ◽  
Microfluidic Devices ◽  
Petri Dish ◽  
Device Fabrication ◽  
Alternative Techniques ◽  
Optimisation Techniques

3D printing and makerspace technologies are increasingly explored as alternative techniques to soft lithography for making microfluidic devices, and for their potential to segue towards scalable commercial fabrication. Here we considered the optimal application of current benchtop 3D printing for microfluidic device fabrication through the lens of lean manufacturing and present a straightforward but robust rapid prototyped moulding system that enables easy estimation of more precise quantities of polydimethylsiloxane (PDMS) required per device to reduce waste and importantly, making devices with better defined depths and volumes for (i) modelling gas exchange and (ii) fabrication consistency as required for quality-controlled production. We demonstrate that this low-cost moulding step can enable a 40 – 300% reduction in the amount of PDMS required for making individual devices compared to the established method of curing approximately 30 grams of PDMS prepolymer overlaid on a 4” silicon wafer master in a standard plastic petri dish. Other process optimisation techniques were also investigated and are recommended as readily implementable changes to current laboratory and foundry-level microfluidic device fabrication protocols for making devices either out of PDMS or other elastomers. Simple calculators are provided as a step towards more streamlined, software controlled and automated design-to-fabrication workflows for both custom and scalable lean manufacturing of microfluidic devices.

scholarly journals A rapid-prototyped moulding system towards optimised scalable fabrication of elastomeric microfluidic devices

2021 ◽  
Author(s):  
Christine Poon ◽  
Albert Fahrenbach
Keyword(s):  
3D Printing ◽  
Microfluidic Device ◽  
Lean Manufacturing ◽  
Soft Lithography ◽  
Low Cost ◽  
Microfluidic Devices ◽  
Petri Dish ◽  
Device Fabrication ◽  
Alternative Techniques ◽  
Optimisation Techniques

3D printing and makerspace technologies are increasingly explored as alternative techniques to soft lithography for making microfluidic devices, and for their potential to segue towards scalable commercial fabrication. Here we considered the optimal application of current benchtop 3D printing for microfluidic device fabrication through the lens of lean manufacturing and present a straightforward but robust rapid prototyped moulding system that enables easy estimation of more precise quantities of polydimethylsiloxane (PDMS) required per device to reduce waste and importantly, making devices with better defined depths and volumes for (i) modelling gas exchange and (ii) fabrication consistency as required for quality-controlled production. We demonstrate that this low-cost moulding step can enable a 40 – 300% reduction in the amount of PDMS required for making individual devices compared to the established method of curing approximately 30 grams of PDMS prepolymer overlaid on a 4” silicon wafer master in a standard plastic petri dish. Other process optimisation techniques were also investigated and are recommended as readily implementable changes to current laboratory and foundry-level microfluidic device fabrication protocols for making devices either out of PDMS or other elastomers. Simple calculators are provided as a step towards more streamlined, software controlled and automated design-to-fabrication workflows for both custom and scalable lean manufacturing of microfluidic devices.

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

2018 ◽  
Vol 11 (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.

scholarly journals Micropipette-Based Microfluidic Device for Monodisperse Microbubbles Generation

Micromachines ◽  
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.

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.

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