Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

'Watermark ink' device identifies unknown liquids instantly

04.08.2011
New 3-D-nanostructured chip offers a litmus test for surface tension (and doubles as a carrier for secret messages)

Materials scientists and applied physicists collaborating at Harvard's School of Engineering and Applied Sciences (SEAS) have invented a new device that can instantly identify an unknown liquid.

The device, which fits in the palm of a hand and requires no power source, exploits the chemical and optical properties of precisely nanostructured materials to distinguish liquids by their surface tension.

The finding, published in the Journal of the American Chemical Society (JACS), offers a cheap, fast, and portable way to perform quality control tests anddiagnose liquid contaminants in the field.

"Digital encryption and sensors have become extremely sophisticated these days, but this is a tool that will work anywhere, without extra equipment, and with a verywide range of potential applications," says co-principal investigator Marko Lonèar, Associate Professor of Electrical Engineering at SEAS.

Akin to the litmus paper used in chemistry labs around the world to detect the pH of a liquid, the new device changes color when it encounters a liquid with a particular surface tension. A single chip can react differently to a wide range of substances; it is also sensitive enough to distinguish between two very closely related liquids.

A hidden message can actually be "written" on a chip, revealing itself only when exposed to exactly the right substance. Dipped in another substance, the chip can display a different message altogether (see video).

"This highly selective wetting would be very difficult to achieve on a two-dimensional surface," explains lead author Ian B. Burgess, a doctoral candidate in Lonèar's lab and in the Aizenberg Biomineralization and Biomimetics Lab. "The optical and fluidic properties we exploit here are unique to the 3D nanostructure of the material."

The "Watermark Ink," or "W-Ink," concept relies on a precisely fabricated material called an inverse opal. The inverse opal is a layered glass structure with an internal network of ordered, interconnected air pores.

Co-authors Lidiya Mishchenko (a graduate student at SEAS) and Benjamin D. Hatton (a research appointee at SEAS and a technology development fellow at the Wyss Institute for Biologically Inspired Engineering at Harvard), recently perfected the production process of large-scale, highly ordered inverse opals.

"Two factors determine whether the color changes upon the introduction of a liquid: the surface chemistry and the degree of order in the pore structure," says Mishchenko, who works in the Aizenberg lab. "The more ordered the structure, the more control you can have over whether or not the liquid enters certain pores by just changing their surface chemistry."

Burgess and his colleagues discovered that selectively treating parts of the inverse opal with vaporized chemicals and oxygen plasma creates variations in the reactive properties of the pores and channels, letting certain liquids passthrough while excluding others.

Allowing liquid into a pore changes the material's optical properties, so the natural color of the inverse opal shows up only in the dry regions.

Each chip is calibrated to recognize only certain liquids, but it can be used over and over (provided the liquid evaporates between tests).

With the hope of commercializing the W-Ink technology, the researchers are currently developing more precisely calibrated chips and conducting field tests with government partners for applications in quality assurance and contaminant identification.

"If you want to detect forgeries," says Burgess, "you can tune your sensor to be acutely sensitive to one specific formulation, and then anything that's different stands out, regardless of the composition."

One immediate application would allow authorities to verify the fuel grade of gasoline right at the pump. Burgess also envisions creating a chip that tests bootleg liquor for toxic levels of methanol.

The W-Ink technology would additionally be useful for identifying chemical spills very quickly. A W-Ink chip that was calibrated to recognize a range of toxic substances could be used to determine, on the spot, whether the spill required special treatment.

"A device like this is not going to rival the selectivity of GC-MS [gas chromatography–mass spectrometry]," remarks co-principal investigatorJoanna Aizenberg, the Amy Smith Berylson Professor of Materials Science at SEAS and a core faculty member of the Wyss Institute.

"But the point is that if you want something in the field that requires no power, is easy to use, and gives you an instant result, then the W-Ink may be what you need."

Aizenberg is also the Susan S. and Kenneth L. Wallach Professor at the Radcliffe Institute for Advanced Study; Professor of Chemistry and Chemical Biology at Harvard; and Co-Director of the Kavli Institute for Bionano Science and Technology at Harvard.

Burgess, Mishchenko, Hatton, Lonèar, and Aizenberg were joined on the paper by co-author Mathias Kolle, a postdoctoral researcher in Aizenberg's lab.

The "W-Ink" research was supported by grants from: the Air Force Office of Scientific Research; the Natural Sciences and Engineering Research Council of Canada; and the U.S. Department of Homeland Security (DHS), administered by the Oak Ridge Institute for Science and Education, through an interagency agreement between the U.S. Department of Energy and DHS.

Electron microscopy was performed at Harvard's Center for Nanoscale Systems, part of the National Nanotechnology Infrastructure Network, which is supported by the National Science Foundation.

Caroline Perry | EurekAlert!
Further information:
http://www.harvard.edu

More articles from Life Sciences:

nachricht What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Robot on demand: Mobile machining of aircraft components with high precision

06.12.2016 | Power and Electrical Engineering

A new dead zone in the Indian Ocean could impact future marine nutrient balance

06.12.2016 | Earth Sciences

Significantly more productivity in USP lasers

06.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>