Tag Archives: fluidics

Using a culinary technique to change fluid drops into exotic shapes

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I always enjoy a culinary reference (h/t Nanowerk) such as the one in Lynne Yarris’ Dec. 2, 2013 science short for the Lawrence Berkeley National Laboratory (California, US),

Oil and water don’t mix, as any chemist or cook knows. Tom Russell, a polymer scientist from the University of Massachusetts who now holds a Visiting Faculty appointment with Berkeley Lab’s Materials Sciences Division, is using that chemical and culinary truth to change the natural spherical shape of liquid drops into ellipsoids, tubes and even fibrous structures similar in appearance to glass wool. Through the combination of water, oil and nanoparticle surfactants plus an external field, Russell is able to stabilize water drops into non-equilibrium shapes that could find valuable uses as therapeutic delivery systems, biosensors, microfluidic lab-on-a-chip devices, or possibly as the basis for an all-liquid electrical battery.

More technical details follow,

n a study he carried out at UMass with Mengmeng Cui and Todd Emrick, a drop of water was suspended in silicone oil and carboxylated nanoparticles were added to the water. The nanoparticles self-assembled at the oil/water interface to form a sphere-shaped surfactant drop – like a soap bubble. Applying an electric field to the drop overcame the equilibrium energy that stabilizes its spherical shape and deformed the sphere into an ellipsoid.

Since an ellipsoid has a greater surface area than a sphere of the same volume, a great many more nanoparticles can attach themselves to it. When the electric field was removed, the nanoparticle drop tried to return to the spherical shape of its equilibrium energy. However, the swollen number of nanoparticles jammed together at the oil/water interface, essentially “gridlocking” the drop into a stable ellipsoid shape.

“You can think of it like traffic getting jammed at an exit ramp or particles of sand getting jammed in an hourglass,” Russell says. “We start out by deforming a drop shaped like a basketball into a drop shaped like a football. The jamming effect locks in the football shape. If we continue the deforming and jamming process, we can create a wide assortment of shapes that are stable even though far removed from equilibrium.”

Here’s a link to and a citation for the paper,

Stabilizing Liquid Drops in Nonequilibrium Shapes by the Interfacial Jamming of Nanoparticles by Mengmeng Cui, Todd Emrick, & Thomas P. Russell. Science 25 October 2013: Vol. 342 no. 6157 pp. 460-463 DOI: 10.1126/science.1242852

The paper is behind a paywall but there is a transcript of a recent (Oct. 25, 2013) Science podcast interview with Russell. Go here and scroll down for access to the transcript (he’s the 2nd interviewee).

Liquid lenses and integrated research into nanotechnology safety

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A flexible, fluid micro lens has been created by engineers at Penn State University. Here’s why it’s interesting news (from Nanowerk News),

Like tiny Jedi knights, tunable fluidic micro lenses can focus and direct light at will to count cells, evaluate molecules or create on-chip optical tweezers, according to a team of Penn State engineers. They may also provide imaging in medical devices, eliminating the necessity and discomfort of moving the tip of a probe.

For more about the work, go here. On a sidenote, this is the first time I’ve seen a Star Wars metaphor used. Depending on the nature of the breakthrough, you usually get Spiderman, Harry Potter, or Star Trek if they’re using a science fiction metaphor.

In other news, the Institute of Occupational Medicine (IOM) in Scotland will be leading a multi-million Euro project, Engineered NanoParticle Risk Assessment (ENPRA). From Nanowerk News (again),

The 3 ½ year IOM-led project, worth €3.7 million, harnesses the knowledge and capabilities of 15 European and 6 US partners including three US Federal Agencies: EPA, NIOSH and NIH-NIEHS. Under the coordination of Dr Lang Tran, IOM’s Director of Computational Toxicology, ENPRA will utilise the latest advances within in vitro, in vivo and in silico approaches to nanotechnology environment, health & safety (EHS) research to realise its aims.

There’s more about the project here. For anyone not familiar with the US abbreviations, EPA = Environmental Protection Agency, NIOSH = National Institute of Occupational Safety and Health, and NIH-NIEHS = National Institutes of Health – National Institute of Environmental Health and Safety.

I don’t know but this seems like a lot of governments and it could take them years to figure out what the multiple agency abbreviations stand for. Even so, bravo for taking the first steps.