scholarly journals Centrifugal Casting of Microfluidic Components With PDMS

2013 ◽  
Vol 1 (2) ◽  
Author(s):  
Aaron D. Mazzeo ◽  
David E. Hardt
Keyword(s):  
Coefficient Of Variation ◽  
Soft Lithography ◽  
Centrifugal Casting ◽  
Microfluidic Channels ◽  
Active Elements ◽  
Axis Of Rotation ◽  
Multilayer Soft Lithography

This work describes the centrifugal casting and fast curing of double-sided, polydimethylsiloxane (PDMS)-based components with microfeatures. Centrifugal casting permits simultaneous patterning of multiple sides of a component and allows control of the thickness of the part in an enclosed mold without entrapment of bubbles. Spinning molds filled with PDMS at thousands of revolutions per minute for several minutes causes entrapped bubbles within the PDMS to migrate toward the axis of rotation or dissolve into solution. To cure the parts quickly (<10 min), active elements heat and cool cavities filled with PDMS after the completion of spinning. Microfluidic channels produced from the process have a low coefficient of variation (<2% for the height and width of channels measured in 20 parts). This process is also capable of molding functional channels in opposite sides of a part as demonstrated through a device with a system of valves typical to multilayer soft lithography.

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.

Latchable Phase-Change Actuators for Micro Flow Control Applications

2005 ◽  
Author(s):  
Bozhi Yang ◽  
Qiao Lin
Keyword(s):  
Phase Change ◽  
Soft Lithography ◽  
Phase Changes ◽  
Minimal Energy ◽  
Control Applications ◽  
Micro Flow ◽  
Flow Through ◽  
Multilayer Soft Lithography ◽  
Solid Liquid ◽  
Lithography Technique

This paper presents a novel latchable phase-change actuator that can potentially be used for flow valving and gating in portable lab-on-a-chip systems, where minimal energy consumption is required. The actuator exploits a low melting-point paraffin wax, whose solid-liquid phase changes allow the closing and opening of fluid flow through deformable microchannels. Flow switching is initiated by melting of paraffin, with an additional pneumatic pressure required for flow switching from open to closed state. After paraffin solidifies the switched state is subsequently maintained passively without further consumption of energy. The actuator can be fabricated from PDMS through the multilayer soft lithography technique. Testing results demonstrate that the actuator has a response time about 60-100 sec for flow switching, and can passively hold a microvalve closed under pressures up to 35 kPa.

scholarly journals Investigation of Diffusion Characteristics through Microfluidic Channels for Passive Drug Delivery Applications

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Marcus J. Goudie ◽  
Alyssa P. Ghuman ◽  
Stephanie B. Collins ◽  
Ramana M. Pidaparti ◽  
Hitesh Handa
Keyword(s):  
Drug Delivery ◽  
Surface Chemistry ◽  
Soft Lithography ◽  
Age Related Macular Degeneration ◽  
Delivery Rate ◽  
Microfluidic Channels ◽  
Age Related ◽  
Diffusion Characteristics ◽  
Drug Delivery Applications ◽  
Model Drug

Microfluidics has many drug delivery applications due to the ability to easily create complex device designs with feature sizes reaching down to the 10s of microns. In this work, three different microchannel designs for an implantable device are investigated for treatment of ocular diseases such as glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy. Devices were fabricated using polydimethylsiloxane (PDMS) and soft lithography techniques, where surface chemistry of the channels was altered using 2-[methoxy(polyethyleneoxy)propyl]trimethoxysilane (PEG-silane). An estimated delivery rate for a number of common drugs was approximated for each device through the ratio of the diffusion coefficients for the dye and the respective drug. The delivery rate of the model drugs was maintained at a physiological condition and the effects of channel design and surface chemistry on the delivery rate of the model drugs were recorded over a two-week period. Results showed that the surface chemistry of the device had no significant effect on the delivery rate of the model drugs. All designs were successful in delivering a constant daily dose for each model drug.

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 Microfluidic delivery of cutting enzymes for fragmentation of surface-adsorbed DNA molecules

2021 ◽  
Author(s):  
Julia Budassi ◽  
NaHyun Cho ◽  
Anthony Del Valle ◽  
Jonathan Sokolov
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Soft Lithography ◽  
Dnase I ◽  
Microfluidic Channels ◽  
Silicon Substrates ◽  
Dna Molecules

We describe a method for fragmenting, in-situ, surface-adsorbed and immobilized DNAs on polymethylmethacrylate(PMMA)-coated silicon substrates using microfluidic delivery of the cutting enzyme DNase I. Soft lithography is used to produce polydimethylsiloxane (PDMS) gratings which form microfluidic channels for delivery of the enzyme. Bovine serum albumin (BSA) is used to reduce DNase I adsorption to the walls of the microchannels and enable diffusion of the cutting enzyme to a distance of 10mm.  Due to the DNAs being immobilized, the fragment order is maintained on the surface. Possible methods of preserving the order for application to sequencing are discussed.

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