2011 – Page 3 – Lab on a Chip Blog

Archive for 2011

HOT: a micro-hydrocyclone for particle separation and sustainable microinjection moulding

10 Nov 2011

Hydrocyclones are widely used in industries such as petrochemicals and mining for the separation of particulates from fluids at the macro- and mesoscale. This is the first report of microscale hydrocyclone, tested on polystyrene microbeads suspended in PBS, providing continuous separation with exceptional flow rates and without clogging. Microfluidic applications potentially include chemical analysis, materials research, point-of-care and blood sample preparation.

Microfluidic device based on a micro-hydrocyclone for particle–liquid separation
P. Bhardwaj, P. Bagdi and A. K. Sen
DOI: 10.1039/C1LC20606K

Cyclic olefin copolymer has been used to create a whole microfluidic device through microinjection moulding with the aim of bridging the gap between lab techniques and mass production of lab on a chip devices. The team that successfully developed the platform have also come up with a dimensionless number μ_f to provide an insight into the physics of microinjection moulding.

Sustainable fabrication of micro-structured lab-on-a-chip
Hwa Jin Oh, Jae Hong Park, Seok Jae Lee, Byeong Il Kim, Young Seok Song and Jae Ryoun Youn
DOI: 10.1039/C1LC20441F

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Micro fuel cells for microchips

10 Nov 2011

Microfluidic devices have been hailed as the technology that will revolutionise areas such as diagnostics in medicine, food safety, drug development and genetic sequencing since their conception in the late 1980s. However, a limiting factor in translating neat microfluidic ideas to practical, portable devices has been integrating all the necessary components. The microfluidic chip may be small and perfectly formed, but the power source, pumps and control electronics for sample analysis are often external, bulky components – existing in the macroscale rather than the microscale.

Now, a team led by Neus Sabaté at the Institute of Microelectronics of Barcelona has integrated a micro direct methanol fuel cell into a microfluidic platform, which is capable of producing up to 4mW, sufficient to power the device. The carbon dioxide produced as a by-product of the fuel cell reaction is used to push liquids through the microchannels, removing the need for an external pump. The team has shown that by controlling the fuel cell operating conditions, they can control the flow rate of the liquid, which bears an almost linear relationship to the current generated in the device.

Jonathan Cooper, an expert in lab-on-a-chip technologies from the University of Glasgow, UK, comments: ‘A real strength of this work is the excellent job the researchers have done in integrating and packaging the device to show a working prototype. The flow rates are high enough for devices to function for several minutes and the device offers the prospect of enabling autonomous functionality on chip.’

The next step for Sabaté is to show that the device can truly function independently. ‘We are trying to prove that we can indeed perform measurements on analytes by integrating a low power electronic chip module and amperometric sensors,’ she says. Her team is also working on higher degrees of device integration by fabricating them from just one type of polymer and experimenting with different fuels such as glucose.

Fuel cell-powered microfluidic platform for lab-on-a-chip applications
Juan Pablo Esquivel, Marc Castellarnau, Tobias Senn, Bernd Löchel, Josep Samitier and Neus Sabaté
DOI: 10.1039/C1LC20426B

Read the original article in Chemistry World

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Lab on a Chip now publishing Accepted Manuscripts

09 Nov 2011

Lab on a Chip now offers you the chance to publish your accepted article as an Accepted Manuscript. This means that your research is available, in citable form, to the community even more rapidly. Find out more…

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HOT articles: broadband for droplets, clinical-scale bubble production and streaming potential for energy

09 Nov 2011

Broadband cavity-enhanced absorption spectroscopy has been used to increase the effective optical pathlengths in optical detection applied to microfluidic systems. The BBCEAS method was capable of in situ analyte detection quickly (273 Hz/3.66 ms acquisition time) and with high sensitivity (α_min < 10⁻² cm⁻¹).

Broadband cavity-enhanced absorption spectroscopy for real time, in situ spectral analysis of microfluidic droplets
Simon R. T. Neil, Cathy M. Rushworth, Claire Vallance and Stuart R. Mackenzie
DOI: 10.1039/C1LC20854C

The production of clinical-scale quantities of droplet emulsions for in vivo therapy uses, such as gas embolotherapy, has been achieved by researchers from the universities of California and North Carolina. Highly monodisperse liquid perfluoropentane droplets in the 3–6 μm range necessary for clinical phase-change droplets were produced at rates exceeding 10⁵ droplets per second.

High-speed, clinical-scale microfluidic generation of stable phase-change droplets for gas embolotherapy
David Bardin, Thomas D. Martz, Paul S. Sheeran, Roger Shih, Paul A. Dayton and Abraham P. Lee
DOI: 10.1039/C1LC20615J

The power generated by streaming potential from multiphase flow has been improved by the use of two phase flow in a microscale system. A two phase microfluidic system, which converts mechanical energy to electrical energy, was devised and the addition of bubbles to the device produced a significant increase in the power and energy conversion over a single phase system.

Strong enhancement of streaming current power by application of two phase flow
Yanbo Xie, John D. Sherwood, Lingling Shui, Albert van den Berg and Jan C. T. Eijkel
DOI: 10.1039/C1LC20423H

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Bubble trouble eliminated in cancer treatment

27 Oct 2011

Fixed channels direct the liquid perfluoropentane through a 7um wide orifice so that all of the droplets are the desired size for treatment

US scientists have developed a microfluidic device to manufacture droplets of a specific size at high speed for a cancer treatment called embolisation.

Embolisation involves blocking a blood vessel to restrict blood flow to a tumour. Gas embolotherapy is one such treatment, in which liquid droplets are introduced into a blood vessel and ultrasound is used to vibrate the droplets to produce enough heat to vaporise them. The liquid to gas phase change results in bubbles five to six times larger than the initial droplet, which can then block the blood vessel. Current methods to generate the droplets result in droplets of different sizes, forcing the therapies to require a higher activation power by ultrasound.

Now, droplets of a uniform size have been made by Abraham Lee at the University of California, Irvine, and co-workers. They have developed a microfluidic device to generate liquid perfluoropentane (PFP) droplets at high speed and in single file. The device is made of polydimethylsiloxane on a glass substrate and consists of fixed geometric channels designed to direct the liquid PFP through a 7µm wide orifice. The droplets were generated at a rate exceeding 100,000 droplets per second, were stable for weeks at room temperature and exhibited the desired size range for use in gas embolotherapy.

Joseph Bull, an expert in gas embolotherapy at the University of Michigan, US, states that this study has made a number of significant contributions to the field ‘including achieving a high production rate of lipid-encapsulated droplets and characterising the dynamics of droplet formation by high speed imaging’.

In the future, Lee plans to build a drug layer into the liquid PFP droplets to generate phase-change droplets for gas chemoembolotherapy. ‘Delivering a chemotherapeutic agent alongside our occlusive droplets should elevate local concentrations of the drug while minimising escape to the systemic circulation,’ he says. ‘We also plan to continue to push the limits in terms of rate and size of emulsion generation using droplet-based microfluidics,’ he adds.

Article originally published in Chemistry World.

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Call for papers for themed issue focussed around the WAM-NANO2012 conference

27 Oct 2011

Lab on a Chip is pleased to announce a themed issue guest edited by Arben Merkoçi, Catalan Institute of Nanotechnology, and Jörg Kutter, Technical University of Denmark, and to open submissions for the issue.

The issue will be focussed around the III International Workshop on Analytical Miniaturization and NANOtechnologies (WAM-NANO2012) to be hosted in Barcelona, Spain, 11-12th June 2012, and will cover the latest international developments on the use of nanotechnologies and nanomaterials for the design and applications in lab-on-a-chip and other miniaturized analytical (bio) systems. The major focus of this issue will be on clinical, food safety and security applications of analytical (bio)systems in which nanotechnology enables novel devices and systems that provide the basis for better, more accessible healthcare, safety and security with improved outcomes for the citizen’s life.

Papers on the following topics are welcome:

– Novel nanotechnology based lab-on-a-chip (LOC) system designs (NANO-LOC)
– Nanofabricated based LOC designs
– Applications of NANO LOCs in diagnostics
– NANO-LOCs for safety and security
– Environmental control using NANO-LOCs
– Industrial applications of NANO-LOCs
– Nanotechnology based microfluidic /analytical devices (microarray, lateral flow etc)

Although the issue will be focused on WAM-NANO2012 additional contributions not related to this event but that fit the above topics will also be considered. Submission to the issue can be made through the Lab on a Chip online submission portal at http://mc.manuscriptcentral.com/lc and should be received by January 4th 2012 for inclusion in the issue.

Please email the LOC editorial office for more information loc-rsc[at]rsc.org.

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Reservoir-on-a-Chip on the cover of Issue 22

26 Oct 2011

On the back cover of Issue 22 we’re featuring research from the Micro and Nano-Scale Transport Laboratory, Department of Mechanical Engineering, University of Alberta.

The Reservoir-on-a-Chip, or ROC for short, by Sushanta K. Mitra et al. is a novel miniaturization approach to study oil recovery in a microfluidic device, mimicking the pore structure of a naturally occurring oil-bearing reservoir rock in an etched silicon substrate. The device will enable researchers to better understand pore-scale transport relevant to reservoir engineering.

Download the article for the details:

Reservoir-on-a-Chip (ROC): A new paradigm in reservoir engineering
Naga Siva Kumar Gunda, Bijoyendra Bera, Nikolaos K. Karadimitriou, Sushanta K. Mitra and S. Majid Hassanizadeh
Lab Chip, 2011, 11, 3785-3792
DOI: 10.1039/C1LC20556K

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New YouTube Videos

26 Oct 2011

View the new videos on the Lab on a Chip YouTube site using the links below:

Accumulating microparticles and direct-writing micropatterns using a continuous-wave laser-induced vapor bubble

1-Million droplet array with wide-field fluorescence imaging for digital PCR

Lateral dielectrophoretic microseparators to measure the size distribution of blood cells

Guiding, distribution, and storage of trains of shape-dependent droplets

Active control of nanolitre droplet contents with convective concentration gradients across permeable walls

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On the cover: modelling sticky nanochannels and droplet traffic junctions

24 Oct 2011

On the outside front cover of Issue 22 we have an image from Aleksei Aksimentiev (University of Illinois) et al. highlighting their work modelling the transport of solutes through nanochannels with sticky surfaces. Their method allows Brownian dynamics simulations of nanofluidic systems with retention of atomic-scale precision in the description of solute interactions, without incurring the huge cost of molecular dynamics simulations.

A toms-to-microns model for small solute transport through sticky nanochannels
Rogan Carr, Jeffrey Comer, Mark D. Ginsberg and Aleksei Aksimentiev

On the inside front cover a paper from Carolyn Ren and colleagues at the University of Waterloo is displayed. They have sought to understand the chaos that can be created at junctions in microfluidic channels and have developed a model to describe droplet sorting in different geometries, droplet resistances and pressures.

Passive droplet trafficking at microfluidic junctions under geometric and flow asymmetries
Tomasz Glawdel, Caglar Elbuken and Carolyn Ren

View the rest of the issue online here

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Lab on a Chip Blog

Archive for 2011

HOT: a micro-hydrocyclone for particle separation and sustainable microinjection moulding

Micro fuel cells for microchips

Lab on a Chip now publishing Accepted Manuscripts

HOT articles: broadband for droplets, clinical-scale bubble production and streaming potential for energy

Bubble trouble eliminated in cancer treatment

Call for papers for themed issue focussed around the WAM-NANO2012 conference

Reservoir-on-a-Chip on the cover of Issue 22

Top ten most accessed articles in September

New YouTube Videos

On the cover: modelling sticky nanochannels and droplet traffic junctions

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