Lab on a Chip Blog

US researchers have used ferrofluids as liquid pistons that could be used to make adjustable liquid lenses with nearly perfect spherical interfaces for applications such as an optometrist’s phoropter. A phoropter measures the way light is focused in the eye and is used to determine prescriptions for glasses and contact lenses.

Ferrofluids are colloidal solutions of ferromagnetic nanoparticles suspended in a dispersing liquid. Ferrofluid droplets can be manipulated by a magnetic field, so they could be used in systems that need precise control, such as optics, drug delivery, and electronic devices.

Amir Hirsa and colleagues from Rensselaer Polytechnic Institute in Troy, New York, have made such a device by filling three of four holes in a substrate with ferrofluid; the ferrofluid’s surface tension allows droplets to protrude from either side of the substrate. They filled the fourth hole with 1-methylnaphthalene, a compound used as a liquid lens. They sealed the system and filled it with water, producing two chambers, with the substrate as the separator and the ferrofluid and 1-methylnaphthalene being the only connections between them.

As a magnetic field was applied to the device, the ferrofluid moved further into one chamber, pushing the 1-methylnaphthalene liquid lens and changing its curvature

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Link to journal article
Electromagnetic liquid pistons for capillarity-based pumping 
Bernard A. Malouin Jr, Michael J. Vogel, Joseph D. Olles, Lili Cheng and Amir H. Hirsa,
Lab Chip, 2011, DOI: 10.1039/c0lc00397b

Artificial lung technology could reduce the death rate for patients awaiting a lung transplant, say US scientists.

Advanced lung disease is characterised by an inability to remove carbon dioxide from the blood and reduced oxygen uptake efficiency. A shortage of donors can mean long delays and high mortality rates for those awaiting a transplant. The only technology available to aid sufferers during this time is based in intensive care units, hindering quality of life.

Now, Joseph Vacanti and coworkers at Massachusetts General Hospital, Boston, have developed a device that achieves the CO2/O2 gas exchange that, when implanted in the body, could allow patients more freedom when awaiting a transplant. Their design is a microfluidic branched vascular network through which blood flows, separated from a gas-filled chamber by a silicone membrane less than 10um thick. The network is formed by casting polydimethylsiloxane, a biocompatible polymer, on a micro machined mould.

A device that achieves carbon dioxide/oxygen gas exchange could allow patients more freedom when awaiting a lung transplant

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Link to journal article
Lung assist device technology with physiologic blood flow developed on a tissue engineered scaffold platform
David M. Hoganson, Howard I. Pryor II, Erik K. Bassett, Ira D. Spool and Joseph P. Vacanti, Lab Chip, 2011
DOI: 10.1039/c0lc00158a