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 Brought to light – chromobodies reveal changes in endogenous protein concentration in living cells
21.09.2018 | NMI Naturwissenschaftliches und Medizinisches Institut an der Universität Tübingen

nachricht A one-way street for salt
21.09.2018 | Julius-Maximilians-Universität Würzburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists present new observations to understand the phase transition in quantum chromodynamics

The building blocks of matter in our universe were formed in the first 10 microseconds of its existence, according to the currently accepted scientific picture. After the Big Bang about 13.7 billion years ago, matter consisted mainly of quarks and gluons, two types of elementary particles whose interactions are governed by quantum chromodynamics (QCD), the theory of strong interaction. In the early universe, these particles moved (nearly) freely in a quark-gluon plasma.

This is a joint press release of University Muenster and Heidelberg as well as the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt.

Then, in a phase transition, they combined and formed hadrons, among them the building blocks of atomic nuclei, protons and neutrons. In the current issue of...

Im Focus: Patented nanostructure for solar cells: Rough optics, smooth surface

Thin-film solar cells made of crystalline silicon are inexpensive and achieve efficiencies of a good 14 percent. However, they could do even better if their shiny surfaces reflected less light. A team led by Prof. Christiane Becker from the Helmholtz-Zentrum Berlin (HZB) has now patented a sophisticated new solution to this problem.

"It is not enough simply to bring more light into the cell," says Christiane Becker. Such surface structures can even ultimately reduce the efficiency by...

Im Focus: New soft coral species discovered in Panama

A study in the journal Bulletin of Marine Science describes a new, blood-red species of octocoral found in Panama. The species in the genus Thesea was discovered in the threatened low-light reef environment on Hannibal Bank, 60 kilometers off mainland Pacific Panama, by researchers at the Smithsonian Tropical Research Institute in Panama (STRI) and the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) at the University of Costa Rica.

Scientists established the new species, Thesea dalioi, by comparing its physical traits, such as branch thickness and the bright red colony color, with the...

Im Focus: New devices based on rust could reduce excess heat in computers

Physicists explore long-distance information transmission in antiferromagnetic iron oxide

Scientists have succeeded in observing the first long-distance transfer of information in a magnetic group of materials known as antiferromagnets.

Im Focus: Finding Nemo's genes

An international team of researchers has mapped Nemo's genome

An international team of researchers has mapped Nemo's genome, providing the research community with an invaluable resource to decode the response of fish to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

"Boston calling": TU Berlin and the Weizenbaum Institute organize a conference in USA

21.09.2018 | Event News

One of the world’s most prominent strategic forums for global health held in Berlin in October 2018

03.09.2018 | Event News

4th Intelligent Materials - European Symposium on Intelligent Materials

27.08.2018 | Event News

 
Latest News

Astrophysicists measure precise rotation pattern of sun-like stars for the first time

21.09.2018 | Physics and Astronomy

Brought to light – chromobodies reveal changes in endogenous protein concentration in living cells

21.09.2018 | Life Sciences

"Boston calling": TU Berlin and the Weizenbaum Institute organize a conference in USA

21.09.2018 | Event News

VideoLinks
Science & Research
Overview of more VideoLinks >>>