Pressure driven digital logic in PDMS based microfluidic devices fabricated by multilayer soft lithography

Lab on a Chip ◽  
2012 ◽  
Vol 12 (22) ◽  
pp. 4809 ◽  
Author(s):  
Naga Sai Gopi K. Devaraju ◽  
Marc A. Unger
Keyword(s):  
Soft Lithography ◽  
Microfluidic Devices ◽  
Digital Logic ◽  
Multilayer Soft Lithography ◽  
Pressure Driven

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 Measurement and control of pressure driven flows in microfluidic devices using an optofluidic flow sensor

2014 ◽  
Vol 8 (5) ◽  
pp. 054123 ◽  
Author(s):  
Mohammad Sadegh Cheri ◽  
Hamidreza Shahraki ◽  
Jalal Sadeghi ◽  
Mohammadreza Salehi Moghaddam ◽  
Hamid Latifi
Keyword(s):  
Microfluidic Devices ◽  
Flow Sensor ◽  
And Control ◽  
Measurement And Control ◽  
Pressure Driven

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.

scholarly journals Rheology and microstructural evolution in pressure-driven flow of a magnetorheological fluid with strong particle–wall interactions

2012 ◽  
Vol 23 (9) ◽  
pp. 969-978 ◽  
Author(s):  
Murat Ocalan ◽  
Gareth H. McKinley
Keyword(s):  
Microfluidic Devices ◽  
Magnetorheological Fluid ◽  
Time Dependent ◽  
Mr Fluid ◽  
Flow Through ◽  
Fluid Particles ◽  
And Performance ◽  
Pressure Driven Flow ◽  
Actuator Design ◽  
Pressure Driven

The interaction between magnetorheological (MR) fluid particles and the walls of the device that retain the field-responsive fluid is critical as this interaction provides the means for coupling the physical device to the field-controllable properties of the fluid. This interaction is often enhanced in actuators by the use of ferromagnetic walls that generate an attractive force on the particles in the field-on state. In this article, the aggregation dynamics of MR fluid particles and the evolution of the microstructure in pressure-driven flow through ferromagnetic channels are studied using custom-fabricated microfluidic devices with ferromagnetic sidewalls. The aggregation of the particles and the time-dependent evolution in the microstructure is studied in rectilinear, expansion and contraction channel geometries. These observations help identify methods for improving MR actuator design and performance.

Finger-powered microfluidic systems using multilayer soft lithography and injection molding processes

Lab on a Chip ◽  
2014 ◽  
Vol 14 (19) ◽  
pp. 3790 ◽  
Author(s):  
Kosuke Iwai ◽  
Kuan Cheng Shih ◽  
Xiao Lin ◽  
Thomas A. Brubaker ◽  
Ryan D. Sochol ◽  
...  
Keyword(s):  
Injection Molding ◽  
Soft Lithography ◽  
Microfluidic Systems ◽  
Multilayer Soft Lithography

A Microfluidic Assay for Metastasis Potential Analysis

2010 ◽  
Author(s):  
Smitha M. N. Rao ◽  
Uday Tata ◽  
Victor K. Lin ◽  
Jer-Tsong Hsieh ◽  
Kytai Nguyen ◽  
...  
Keyword(s):  
Cell Migration ◽  
Cancer Progression ◽  
Soft Lithography ◽  
Microfluidic Devices ◽  
Time Lapse ◽  
Microfluidic Channels ◽  
Control Groups ◽  
Dimethyl Siloxane ◽  
Microfluidic Assays ◽  
Migration Response

We have designed and characterized a poly-dimethyl-siloxane (PDMS) based microfluidic device called MiMiC™ that enables time-lapse study of cell migration. Cell migration is a key step of malignant metastasis during cancer progression. The device mimics the narrow confines the cells need to traverse and the microenvironments that are similar to the ones inside human body. Photolithography and soft lithography processes were used to fabricate the microfluidic devices. The device consists of two separate chambers connected by microfluidic channels allowing introduction of cells in one chamber and chemoattractants in the other. The response of lung-metastasized prostate cancer (PC-3-ML) cells and their migration response to chemoattractants were observed and analyzed. The numbers of cells under migration were determined from time-lapse images and compared to control groups. Our microfluidic assays provide advantages over the traditional Boyden chambers such as time-lapse observation, use of smaller amounts of reagents and direct assessment of cells under migration.

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