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Search Publications by: Darwin Reyes-Hernandez (Fed)

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Displaying 26 - 50 of 53

Dielectrophoretic Trapping of P19 Cells on Indium Tin Oxide based Microelectrode Arrays

November 8, 2013
Aveek Gangopadhyay, Saugandhika Minnikanti, Darwin Reyes-Hernandez, Mulpuri V. Rao, Nathalia Peixoto
A microfabricated device comprised of a microelectrode array (MEA) and a microfluidic channel is presented here for the purpose of trapping cells using positive dielectrophoresis (DEP). Transparent indium tin oxide (ITO) electrodes are patterned in an

Optical Coherence Tomography for Dimensional Metrology of Lab-on-a-chip devices

October 27, 2013
Darwin R. Reyes-Hernandez, Michael W. Halter, Jeeseong Hwang
Here we present a new metrology tool for the determination of the dimensions of channels from final product Lab-on-a-chip devices. Using Optical Coherence Tomography (OCT) areas of up to 12 mm x 12 mm can be imaged in less than 1 second, without the need

Metrology for Lab-on-a-Chip Final-Product Devices

May 12, 2013
Darwin R. Reyes-Hernandez, Michael W. Halter, Jeeseong Hwang
New metrology tools to measure the critical parameters of internal structures in lab on a chip devices are greatly needed in order to develop standard tests for this technology. Here we present a method that combines a custom made optical coherence

Dielectrophoretic Cell Capture on Polyester Membranes

April 2, 2012
Conni Hanke, Petra S. Dittrich, Darwin Reyes-Hernandez
A new system for dielectrophoretic cell capture on porous polyester (PET) membranes is presented. Conventional photolithographic techniques were used to fabricate gold microelectrodes on a PET membrane. We characterized these electrodes to proof that there

Trapping and Release of Citrate-Capped Gold Nanoparticles

August 1, 2011
Darwin R. Reyes-Hernandez, Geraldine I. Mijares, Brian J. Nablo, Kimberly A. Briggman, Michael Gaitan
An electrical method to trap and release charged gold nanoparticles on and from the surface of alkanethiol self-assembled-monolayer (SAM) modified gold electrodes is presented. Gold nanoparticle (GNP) coated electrodes were formed by immersing amine

Microfluidic Based Contactless DielectrophoreticDevice: Modeling and Analysis

September 1, 2010
Saugandhika Minnikanti, Darwin Reyes-Hernandez, Ruben C. Aguilar, Joseph Pancrazio, Michael Gaitan, Nathalia Peixoto
While there have been many attempts at patterning cells onto substrates, a reliable method for trapping cell clusters and forming cell arrays in a predefined geometry remains to be demonstrated. We intend to develop a multielectrode array platform to

Quantum Dot FRET Sensor for Enzymatic Activity in Microfluidic Device

June 22, 2010
Georgeta Crivat, Sandra M. Da Silva, Darwin Reyes-Hernandez, Samuel Forry, Laurie E. Locascio, Michael Gaitan, Nitsa Rosenzweig, Zeev Rosenzweig
This paper describes the development of new fluorescence resonance energy transfer (FRET)-based quantum dot probes for proteolytic activity. The CdSe/ZnS quantum dots are incorporated into a thin polymeric film, which is prepared by layer-by-layer

Electrical Manipulation of Gold Nanoparticles for Microfluidic Applications

October 16, 2008
Darwin R. Reyes-Hernandez, Geraldine I. Mijares, Kimberly A. Briggman, Jon C. Geist, Michael Gaitan
An electrical method to trap and release gold nanoparticles to and from the surface of alkanethiol-modified gold electrodes is presented. When a positive bias versus a Ag/AgCl reference electrode was applied to gold electrodes, negatively-charged gold

Microfluidic DNA Analysis Systems for Forensic Applications

July 18, 2008
Michael Gaitan, Jayna J. Shah, Darwin Reyes-Hernandez, Pierre-Alain Auroux, Jon Geist, Laurie E. Locascio, Wyatt N. Vreeland, David J. Ross, Peter Vallone, Paul Smith, Nicole Morgan, Tom Pohida, John Kakareka, Annelise Barron
This report summarizes the NIST effort on microfluidic DNA analysis systems for forensic applications sponsored by the National Institute of Justice. Currently emerging microfluidics-based forensic systems are implemented in silica (glass) because the

Fast and High Efficient Microfluidic PCR By Microwave Dielectric Heating

October 15, 2007
Pierre-Alain Auroux, Darwin R. Reyes-Hernandez, Jayna J. Shah, Michael Gaitan
We report 100% yield and 40% reaction-time reduction for on-chip DNA amplification using microwave dielectric heating. A passivation protocol has also been developed to suppress the inhibition of PCR in PMMA chips used with a temperature sensor. We finally

Microwave Dielectric Heating of Fluids in an Integrated Microfluidic Device

October 3, 2007
Jayna J. Shah, Siddarth Sundaresan, Jon Geist, Darwin Reyes-Hernandez, James Booth, Rao Mulpuri, Michael Gaitan
Rapid, selective, and uniform heating of sub-microliter size fluid volumes is vital for micro total analysis system (?gTAS) applications. In this work, we present an approach to localized and selective heating of fluids in a microfluidic network. This is

Photopatterned Polyelectrolyte Multilayers for Cell Culture

November 9, 2006
Darwin Reyes-Hernandez, J. Brian Hutchison, Laurie E. Locascio, Michael Gaitan
Patterned two-dimensional cell cultures are increasingly important for constructing bioanalytical tools for cell and molecular biology to address questions about interactions, signaling, migration, and differentiation, among others. This contribution

Polyelectrolyte Multilayers

January 23, 2006
Darwin Reyes-Hernandez, Laurie E. Locascio, Michael Gaitan
The process of self-assembly occurs naturally in living systems to form complex structures out of random events in an incredibly accurate way. Order out of disorder is achieved in a fashion that is analogous to a jigsaw puzzle where each piece fits