Archive for December, 2013

Re-Writable Microfluidics? New Device Points the Way

Researchers from the University of Tokyo and the CEA-Leti research institute in France have designed a platform that allows channels to be written and rewritten at will in a fluid layer atop a grid of electrodes.

In their recent cover article in Lab on a Chip, Raphael Renaudot and colleagues describe this novel device, which is based on the Electrowetting on Dielectric (EWOD) and Liquid Dielectrophoresis (LDEP) phenomena1. Their goal was to create a flexible, reusable platform that would enable the creation of microfluidic devices without the use of expensive microfabrication techniques. The fluid layer of the device is filled with liquid paraffin, which can easily be solidified and re-melted via thermoelectric cooling and heating (its melting temperature is 35° C.) Water is injected into the paraffin layer, and its flow path is controlled via the underlying electrode layer, which is made up of a grid of 83 electrodes (the small squares seen in the figure). By tuning the interfacial tension between the water and the surface of each electrode via the independently controlled electrode voltages, it is possible to guide a channel (or “finger”) of water along the desired path on the grid (see figure).

After the water is guided into the desired path, the device is cooled, solidifying the paraffin and setting the channels in place. Later, the device can be reheated to erase the existing channels, and a new design can be drawn. The chip can be reused multiple times, reducing waste and making it very useful for prototype testing and low-cost applications. The authors demonstrated two chip designs using the reconfigurable platform: a droplet generator and a device for E. coli confinement within a fluidic cavity.

A water channel is drawn through a paraffin matrix via control of an underlying grid of electrodes (from Figure 2b)

Read this HOT article in Lab on a Chip today!

A Programmable and Reconfigurable Microfluidic Chip, Raphael Renaudot, Vincent Agache, Yves Fouillet, Guillaume Laffite, Emilie Bisceglia, Laurent Jalabert, Momoko Kumemura, Dominique Collard and Hiroyuki Fujita. DOI: 10.1039/c3lc50850a

References:

  1. T. B. Jones and K. L. Wang, Langmuir 2004, 20 (7), 2813–2818.
Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Seasons Greetings from Lab on a Chip!

The holidays are nearly here!!

We know everyone’s been working hard to finish off semesters and write up those papers. Here in Cambridge we’ve been working hard too, planning for the New Year and wrapping up 2013.

To spread the holiday cheer, we’ve chosen three highly accessed papers and made them *FREE TO ACCESS* for the next four weeks. Enjoy!

Merry Christmas from the LOC team!




Paper: Albumin testing in uring using a smartphone, by Aydogan Ozcan, UCLA

Critical Review: Paper-based microfluidic point-of-care diagnostic devices, by Ali Kemal Yetisen, Cambridge

Paper: Cholesterol testing on a smartphone, by David Erickson, Cornell




Access is free through a registered RSC account – click here to register

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

1024 samples analysed on a single chip

Researchers in Switzerland have developed a microfluidic platform able to measure four protein biomarkers in over 1000 blood samples on a single microfluidic chip. With a dramatic reduction in reagent consumption, time and cost, this new high-throughput technology could make early disease diagnosis more affordable.

Many clinical diagnostic tests measure the amount of a specific protein in a patient’s blood. If the levels of this protein are abnormal it is often an indicator for a disease. Currently these tests are very expensive and time-consuming and are only used once a certain condition is suspected, so the patient is already showing symptoms.

Jose Garcia-Cordero and Sebastian Maerkl at the Swiss Federal Institute of Technology in Lausanne hope to change this with their new microfluidic platform capable of measuring protein biomarkers from just 5nL of human blood with comparable results to a conventional enzyme-linked immunosorbent assay (ELISA), which typically uses a 50μL sample volume. The platform uses a microspotting technique to deliver a large number of blood samples to the chip combined with a microfluidic circuit that runs four parallel immunoassays.

The microfluidic device can perform over 4000 disease biomarker assays in a single run

‘The throughput of our device is roughly 10–100 times that of current microfluidic platforms with an estimated reagent cost of US$ 0.1 per chip,’ says Maerkl. ‘By drastically reducing the cost of diagnostic tests, we hope that everyone will be able to measure a number of biomarkers on a continuous basis, allowing people to take either preventive measures or to seek early treatment for diseases such as cancer.’

Michele Zagnoni, an expert in microfluidic techniques for cancer research at the University of Strathclyde in the UK, commends the ‘outstanding increase in analytical throughput’ and adds that ‘the choice of producing a microfluidic device which can be interfaced with robotic dispensers is an appealing one for pharmaceutical companies, offering a technology that can be easily integrated with existing industrial instrumentation and procedures.’

While their current platform is based on fluorescence to quantify biomarker levels, Maerkl hopes to move to an electronic readout to make smaller and cheaper point-of-care instruments.

Read this full Chemistry World story, by Michael Parkin, here.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

DIY cholesterol monitoring

A team of scientists from the US have developed a simple system that will allow people to test their blood cholesterol levels at home, using a smartphone.

Cholesterol is an important organic molecule that performs a crucial role in modulating the permeability and fluidity of animal cell membranes, but having too much cholesterol in the blood can be a real problem. In particular, high blood cholesterol levels are known to be a risk factor for coronary heart disease. For many people, blood cholesterol levels can be controlled through diet, by eating less saturated fat. A simple system that enables people to routinely monitor their blood cholesterol levels, using a device that many people already own, would undoubtedly save lives.

David Erickson and co-workers from Cornell University in New York may have developed just that. Their system consists of a small accessory device that attaches onto a smartphone, an app, and dry reagent test strips for measuring blood cholesterol levels that are already commercially available. A drop of blood is placed onto the test strip and an enzymatic, colorimetric reaction occurs. This strip is then placed into the accessory device and an image of the strip is generated using the camera on the phone. The app then quantifies the colour change and converts this into a blood cholesterol concentration using a calibration curve.

A screenshot of the cholesterol monitoring app (left) and the algorithm to process images of the test strips (right)

The achievement of Erickson and his colleagues should not be understated. Although what they have done may sound simple, developing a smartphone-based system that enables precise and reproducible diagnostic measurements to be taken is actually very difficult. The largest challenge comes from having to account for different lighting conditions and reaction times, differences between the cameras and camera settings in different types of phone, and the potential for misalignment of the test strip. The team overcame the lighting problem by using the accessory device to block out external light so that the test strip would be uniformly illuminated by the flash on the camera. Meanwhile, algorithms in the app account for the other potential variables.

‘This work is another excellent demonstration of cellphone-based sensing,’ says Aydogan Ozcan, a point-of-care diagnostics expert at the University of California in Los Angeles, US. Ozcan himself has developed numerous smartphone-based systems and he sees the value in this work: ‘it will provide numerous opportunities, especially for home monitoring and testing of chronic and elderly patients.’

Erickson and co-workers are now working to commercialise their system, so it may be available for the general public to purchase in the near future.

Click here to watch Erickson demonstrate the test in this great video from the Cornell Chronicle.

Or read this news article by Megan Tyler, and many more, on the Chemistry World website.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Altmetrics now featured on Lab on a Chip

 We are pleased to announce the inclusion of Altmetrics on Lab on a Chip.

With a constantly changing publishing landscape and changes to the way people use scientific literature, altmetrics is a measure that can monitor the level of conversation and interest in a particular piece of research at the article level. Thus altmetrics provides an additional modern metric for our authors to measure the impact of their work, rather than rely solely on citations and impact factor.

To view altmetrics on Lab on a Chip articles, use the Metrics tab as pictured below on the article landing page.

 Altmetrics for LOC 

A press release from Altmetrics is available on our website.

What do you think? We are interested to hear your feedback on this new development and how you are utilising these new types of metrics. Please leave your comments below.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)