A simple method to determine the surface charge in microfluidic channels

2010 ◽  
Vol 31 (3) ◽  
pp. 563-569 ◽  
Author(s):  
Dileep Mampallil ◽  
Dirk van den Ende ◽  
Frieder Mugele
Keyword(s):  
Surface Charge ◽  
Microfluidic Channels ◽  
Simple Method

scholarly journals Rapid and simple preparation of thiol–ene emulsion-templated monoliths and their application as enzymatic microreactors

Lab on a Chip ◽  
2015 ◽  
Vol 15 (10) ◽  
pp. 2162-2172 ◽  
Author(s):  
Josiane P. Lafleur ◽  
Silja Senkbeil ◽  
Jakub Novotny ◽  
Gwenaël Nys ◽  
Nanna Bøgelund ◽  
...  
Keyword(s):  
Microfluidic Channels ◽  
Simple Method ◽  
Simple Preparation ◽  
Enzymatic Microreactors

A novel, rapid and simple method for the preparation of emulsion-templated monoliths in microfluidic channels based on thiol–ene chemistry is presented.

scholarly journals Some modification of cellulose nanocrystals for functional Pickering emulsions

2016 ◽  
Vol 374 (2072) ◽  
pp. 20150139 ◽  
Author(s):  
Dorra Saidane ◽  
Emilie Perrin ◽  
Fanch Cherhal ◽  
Florian Guellec ◽  
Isabelle Capron
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Cellulose Nanocrystals ◽  
Surface Charge Density ◽  
Colloidal Particles ◽  
Hydroxyl Groups ◽  
Layer By Layer ◽  
Pickering Emulsions ◽  
Simple Method ◽  
Oil Emulsions

Cellulose nanocrystals (CNCs) are negatively charged colloidal particles well known to form highly stable surfactant-free Pickering emulsions. These particles can vary in surface charge density depending on their preparation by acid hydrolysis or applying post-treatments. CNCs with three different surface charge densities were prepared corresponding to 0.08, 0.16 and 0.64 e nm −2 , respectively. Post-treatment might also increase the surface charge density. The well-known TEMPO-mediated oxidation substitutes C 6 -hydroxyl groups by C 6 -carboxyl groups on the surface. We report that these different modified CNCs lead to stable oil-in-water emulsions. TEMPO-oxidized CNC might be the basis of further modifications. It is shown that they can, for example, lead to hydrophobic CNCs with a simple method using quaternary ammonium salts that allow producing inverse water-in-oil emulsions. Different from CNC modification before emulsification, modification can be carried out on the droplets after emulsification. This way allows preparing functional capsules according to the layer-by-layer process. As a result, it is demonstrated here the large range of use of these biobased rod-like nanoparticles, extending therefore their potential use to highly sophisticated formulations. This article is part of the themed issue ‘Soft interfacial materials: from fundamentals to formulation’.

Microfluidic channel-integrated hanging drop array chip operated by pushbuttons for spheroid culture and analysis

The Analyst ◽  
2020 ◽  
Vol 145 (21) ◽  
pp. 6974-6980
Author(s):  
Juhwan Park ◽  
Hwisoo Kim ◽  
Je-Kyun Park
Keyword(s):  
Microfluidic Channel ◽  
Microfluidic Channels ◽  
Hanging Drop ◽  
Simple Method ◽  
Spheroid Culture ◽  
Liquid Handling

We developed a simple method for liquid handling in a hanging drop array chip for spheroid culture and analysis by integrating microfluidic channels operated by pushbuttons.

scholarly journals Fabrication of Silicon Microfluidic Chips for Acoustic Particle Focusing Using Direct Laser Writing

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 113 ◽  
Author(s):  
Anna Fornell ◽  
Per Söderbäck ◽  
Zhenhua Liu ◽  
Milena De Albuquerque Moreira ◽  
Maria Tenje
Keyword(s):  
Acoustic Waves ◽  
Microfluidic Channel ◽  
Microfluidic Channels ◽  
Glass Wafer ◽  
Microfluidic Chips ◽  
Direct Laser Writing ◽  
Laser Writing ◽  
Simple Method ◽  
Particle Focusing ◽  
Direct Laser

We have developed a fast and simple method for fabricating microfluidic channels in silicon using direct laser writing. The laser microfabrication process was optimised to generate microfluidic channels with vertical walls suitable for acoustic particle focusing by bulk acoustic waves. The width of the acoustic resonance channel was designed to be 380 µm, branching into a trifurcation with 127 µm wide side outlet channels. The optimised settings used to make the microfluidic channels were 50% laser radiation power, 10 kHz pulse frequency and 35 passes. With these settings, six chips could be ablated in 5 h. The microfluidic channels were sealed with a glass wafer using adhesive bonding, diced into individual chips, and a piezoelectric transducer was glued to each chip. With acoustic actuation at 2.03 MHz a half wavelength resonance mode was generated in the microfluidic channel, and polystyrene microparticles (10 µm diameter) were focused along the centre-line of the channel. The presented fabrication process is especially interesting for research purposes as it opens up for rapid prototyping of silicon-glass microfluidic chips for acoustofluidic applications.

Electroosmotic Flow in “Click” Surface Modified Microfluidic Channels

2006 ◽  
Author(s):  
Shaurya Prakash ◽  
Timothy M. Long ◽  
Jonathan Wan ◽  
Jeffrey S. Moore ◽  
Mark A. Shannon
Keyword(s):  
Surface Charge ◽  
Photoelectron Spectroscopy ◽  
Electroosmotic Flow ◽  
Separation Efficiency ◽  
High Surface ◽  
High Surface Area ◽  
Attenuated Total Reflection ◽  
Covalent Attachment ◽  
Microfluidic Channels ◽  
Linear Polymers

A rapid, facile, and modular surface modification scheme for the covalent attachment of pre-formed polymer moieties to self-assembled monolayers via ‘click’ chemistry within glass microfluidic channels (3 cm long, 110 μm wide and 15 μm deep) is described. The effect that different moieties have on the electroosmotic flow (EOF) within the microchannels is evaluated. The application of linear polymers such as poly(ethylene glycol) (PEG) generates hydrophilic surfaces that reduce the analyte-wall interactions, thereby increasing separation efficiency and improving resolution, especially in bio-separations. Dendritic polymers such as poly(amido amine) (PAMAM) on channel walls can provide high-surface area structures with tunable surface charge depending on the generation of the dendrimer coating. Modified surfaces are characterized by X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared-Attenuated Total Reflection spectroscopy (FTIR-ATR), and contact angle measurements. EOF measurements in modified and unmodified channels provide information about wall-analyte interactions. A PAMAM dendrimer coated channel presents an amine terminated surface with a positive charge in contrast to a negatively charged bare-glass surface. Use of surface coatings can lead to an increase of the EOF by 15% as is the case for an azide terminated surface or reverse the direction of EOF as is the case for the PAMAM coatings by changing the surface charge polarity.

3D printing of liquid metals as fugitive inks for fabrication of 3D microfluidic channels

Lab on a Chip ◽  
2016 ◽  
Vol 16 (10) ◽  
pp. 1812-1820 ◽  
Author(s):  
Dishit P. Parekh ◽  
Collin Ladd ◽  
Lazar Panich ◽  
Khalil Moussa ◽  
Michael D. Dickey
Keyword(s):  
3D Printing ◽  
Liquid Metal ◽  
Room Temperature ◽  
Liquid Metals ◽  
Microfluidic Channels ◽  
Simple Method ◽  
Sacrificial Template

This paper demonstrates a simple method to fabricate 3D microchannels at room temperature by printing liquid metal as a sacrificial template.

A simple way for producing holographic filters suitable for image improvement

1978 ◽  
Vol 36 (1) ◽  
pp. 226-227
Author(s):  
K.-H. Herrmann ◽  
E. Reuber ◽  
P. Schiske
Keyword(s):  
Transfer Functions ◽  
Diffraction Order ◽  
Lateral Position ◽  
Simple Method ◽  
Spatial Frequencies ◽  
Resolution Electron ◽  
Wiener Filters ◽  
Image Improvement ◽  
Optical Reconstruction ◽  
Set Up

Aposteriori deblurring of high resolution electron micrographs of weak phase objects can be performed by holographic filters [1,2] which are arranged in the Fourier domain of a light-optical reconstruction set-up. According to the diffraction efficiency and the lateral position of the grating structure, the filters permit adjustment of the amplitudes and phases of the spatial frequencies in the image which is obtained in the first diffraction order.In the case of bright field imaging with axial illumination, the Contrast Transfer Functions (CTF) are oscillating, but real. For different imageforming conditions and several signal-to-noise ratios an extensive set of Wiener-filters should be available. A simple method of producing such filters by only photographic and mechanical means will be described here.A transparent master grating with 6.25 lines/mm and 160 mm diameter was produced by a high precision computer plotter. It is photographed through a rotating mask, plotted by a standard plotter.

Imaging molecules adsorbed onto electrodes under potential control by scanning probe microscopy

1991 ◽  
Vol 49 ◽  
pp. 376-377 ◽  
Author(s):  
N.J. Tao ◽  
J.A. DeRose ◽  
P.I. Oden ◽  
S.M. Lindsay
Keyword(s):  
Surface Charge ◽  
Environmental Effects ◽  
Scanning Probe Microscopy ◽  
Statistical Significance ◽  
Electrochemical Methods ◽  
Surface Structures ◽  
Scanning Probe ◽  
Potential Control ◽  
Afm Imaging ◽  
Special Circumstances

Clemmer and Beebe have pointed out that surface structures on graphite substrates can be misinterpreted as biopolymer images in STM experiments. We have been using electrochemical methods to react DNA fragments onto gold electrodes for STM and AFM imaging. The adsorbates produced in this way are only homogeneous in special circumstances. Searching an inhomogeneous substrate for ‘desired’ images limits the value of the data. Here, we report on a reversible method for imaging adsorbates. The molecules can be lifted onto and off the substrate during imaging. This leaves no doubt about the validity or statistical significance of the images. Furthermore, environmental effects (such as changes in electrolyte or surface charge) can be investigated easily.

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