Tag Archives: cobalt

Nanoparticles from tattoo inks circulate through your body

English: Tattoo of Hand of Fatima,. Model: Casini. Date: 4 July 2017, 18:13:41. Source : Own work. Author: Stephencdickson.

For those who like their news in video format, there’s this Canadian Broadcasting Corporation (CBC) news item broadcast on Sep. 11, 2017 (after the commercials),

For those who like text and more detail, scientists at the European Synchrotron Radiation Facility (ESRF) have produced a study of the (at the nanoparticle scale) inks in tattoos. From a Sept. 12, 2017 news item on phys.org,

The elements that make up the ink in tattoos travel inside the body in micro and nanoparticle forms and reach the lymph nodes, according to a study published in Scientific Reports on 12 September [2017] by scientists from Germany and the ESRF, the European Synchrotron, Grenoble (France). It is the first time researchers have found analytical evidence of the transport of organic and inorganic pigments and toxic element impurities as well as in depth characterization of the pigments ex vivo in tattooed tissues. Two ESRF beamlines were crucial in this breakthrough.

A Sept. 12, 2017 ESRF press release (also on EurkeAlert), which originated the news item, explains further,

The reality is that little is known about the potential impurities in the colour mixture applied to the skin. Most tattoo inks contain organic pigments, but also include preservatives and contaminants like nickel, chromium, manganese or cobalt. Besides carbon black, the second most common ingredient used in tattoo inks is titanium dioxide (TiO2), a white pigment usually applied to create certain shades when mixed with colorants. Delayed healing, along with skin elevation and itching, are often associated with white tattoos, and by consequence with the use of TiO2. TiO2 is also commonly used in food additives, sun screens and paints. Scientists from the ESRF, the German Federal Institute for Risk Assessment, Ludwig-Maximilians University, and the Physikalisch-Technische Bundesanstalt have managed to get a very clear picture on the location of titanium dioxide once it gets in the tissue. This work was done on the ESRF beamlines ID21 and ID16B.

drawing tattookinetics.jpg

Translocation of tattoo particles from skin to lymph nodes. Upon injection of tattoo inks, particles can be either passively transported via blood and lymph fluids or phagocytized by immune cells and subsequently deposited in regional lymph nodes. After healing, particles are present in the dermis and in the sinusoids of the draining lymph nodes. Credits: C. Seim.

The hazards that potentially derive from tattoos were, until now, only investigated by chemical analysis of the inks and their degradation products in vitro. “We already knew that pigments from tattoos would travel to the lymph nodes because of visual evidence: the lymph nodes become tinted with the colour of the tattoo. It is the response of the body to clean the site of entrance of the tattoo. What we didn’t know is that they do it in a nano form, which implies that they may not have the same behaviour as the particles at a micro level. And that is the problem: we don’t know how nanoparticles react”, explains Bernhard Hesse, one of the two first authors of the study (together with Ines Schreiver, from the German Federal Institute for Risk Assessment) and ESRF visiting scientist.

titaniumdistribution.jpg

Particle mapping and size distribution of different tattoo pigment elements.  a, d) Ti and the Br containing pigment phthalocyanine green 36 are located next to each other. b, e) Log scale mappings of Ti, Br and Fe in the same areas as displayed in a) and d) reveal primary particle sizes of different pigment species. c, f) Magnifications of the indicated areas in b) and e), respectively. Credits: C. Seim.

X-ray fluorescence measurements on ID21 allowed the team to locate titanium dioxide at the micro and nano range in the skin and the lymphatic environment. They found a broad range of particles with up to several micrometres in size in human skin, but only smaller (nano) particles transported to the lymph nodes. This can lead to the chronic enlargement of the lymph nodes and lifelong exposure. Scientists also used the technique of Fourier transform infrared spectroscopy to assess biomolecular changes in the tissues in the proximity of the tattoo particles.

ESRF16_Tattoo-1low.jpg

Ines Schreiver doing experiments on ID16B with Julie Villanova. Credits: B. Hesse.

Altogether the scientists report strong evidence for both migration and long-term deposition of toxic elements and tattoo pigments as well as for conformational alterations of biomolecules that are sometimes linked to cutaneous adversities upon tattooing.

Then next step for the team is to inspect further samples of patients with adverse effects in their tattoos in order to find links with chemical and structural properties of the pigments used to create these tattoos.

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

Synchrotron-based ν-XRF mapping and μ-FTIR microscopy enable to look into the fate and effects of tattoo pigments in human skin by Ines Schreiver, Bernhard Hesse, Christian Seim, Hiram Castillo-Michel, Julie Villanova, Peter Laux, Nadine Dreiack, Randolf Penning, Remi Tucoulou, Marine Cotte, & Andreas Luch. Scientific Reports 7, Article number: 11395 (2017) doi:10.1038/s41598-017-11721-z Published online: 12 September 2017

This paper is open access.

Refining metals more sustainably

We don’t just extract and refine metals from the earth, increasingly, we extract and refine them from consumer goods. Researchers from McGill University (Montréal, Québec, Canada) have devised a ‘greener’ technique to do this. From a June 7, 2017 McGill University news release (received via email and also on EurekAlert),

A team of chemists in Canada has developed a way to process metals without using toxic solvents and reagents.

The system, which also consumes far less energy than conventional techniques, could greatly shrink the environmental impact of producing metals from raw materials or from post-consumer electronics.

“At a time when natural deposits of metals are on the decline, there is a great deal of interest in improving the efficiency of metal refinement and recycling, but few disruptive technologies are being put forth,” says Jean-Philip Lumb, an associate professor in McGill University’s Department of Chemistry. “That’s what makes our advance so important.”

The discovery stems from a collaboration between Lumb and Tomislav Friscic at McGill in Montreal, and Kim Baines of Western University in London, Ont. In an article published recently in Science Advances, the researchers outline an approach that uses organic molecules, instead of chlorine and hydrochloric acid, to help purify germanium, a metal used widely in electronic devices. Laboratory experiments by the researchers have shown that the same technique can be used with other metals, including zinc, copper, manganese and cobalt.

The research could mark an important milestone for the “green chemistry” movement, which seeks to replace toxic reagents used in conventional industrial manufacturing with more environmentally friendly alternatives. Most advances in this area have involved organic chemistry – the synthesis of carbon-based compounds used in pharmaceuticals and plastics, for example.

“Applications of green chemistry lag far behind in the area of metals,” Lumb says. “Yet metals are just as important for sustainability as any organic compound. For example, electronic devices require numerous metals to function.”

Taking a page from biology

There is no single ore rich in germanium, so it is generally obtained from mining operations as a minor component in a mixture with many other materials. Through a series of processes, that blend of matter can be reduced to germanium and zinc.

“Currently, in order to isolate germanium from zinc, it’s a pretty nasty process,” Baines explains. The new approach developed by the McGill and Western chemists “enables you to get germanium from zinc, without those nasty processes.”

To accomplish this, the researchers took a page from biology. Lumb’s lab for years has conducted research into the chemistry of melanin, the molecule in human tissue that gives skin and hair their color. Melanin also has the ability to bind to metals. “We asked the question: ‘Here’s this biomaterial with exquisite function, would it be possible to use it as a blueprint for new, more efficient technologies?'”

The scientists teamed up to synthesize a molecule that mimics some of the qualities of melanin. In particular, this “organic co-factor” acts as a mediator that helps to extract germanium at room temperature, without using solvents.

Next step: industrial scale

The system also taps into Friscic’s expertise in mechanochemistry, an emerging branch of chemistry that relies on mechanical force – rather than solvents and heat – to promote chemical reactions. Milling jars containing stainless-steel balls are shaken at high speeds to help purify the metal.

“This shows how collaborations naturally can lead to sustainability-oriented innovation,” Friscic says. “Combining elegant new chemistry with solvent-free mechanochemical techniques led us to a process that is cleaner by virtue of circumventing chlorine-based processing, but also eliminates the generation of toxic solvent waste”

The next step in developing the technology will be to show that it can be deployed economically on industrial scales, for a range of metals.

“There’s a tremendous amount of work that needs to be done to get from where we are now to where we need to go,” Lumb says. “But the platform works on many different kinds of metals and metal oxides, and we think that it could become a technology adopted by industry. We are looking for stakeholders with whom we can partner to move this technology forward.”

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

A chlorine-free protocol for processing germanium by Martin Glavinovic, Michael Krause, Linju Yang, John A. McLeod, Lijia Liu, Kim M. Baines, Tomislav Friščić, and Jean-Philip Lumb. Science Advances 05 May 2017: Vol. 3, no. 5, e1700149 DOI: 10.1126/sciadv.1700149

This paper is open access.

ETA June 9, 2017 at 1700 hours PDT: I have to give them marks for creativity. Here’s the image being used to illustrate the work,

Caption: Strategy for reducing the environmental impact of a refining process: replace hazardous chemicals with more benign and recyclable compounds. Credit: Michael J. Krause (Western University)

Vitamin-driven lithium-ion battery from the University of Toronto

It seems vitamins aren’t just good for health, they’re also good for batteries. My Aug. 2, 2016 post on vitamins and batteries focused on work from Harvard, this time the work is from the University of Toronto (Canada). From an Aug. 3, 2016 news item on ScienceDaily,

A team of University of Toronto chemists has created a battery that stores energy in a biologically derived unit, paving the way for cheaper consumer electronics that are easier on the environment.

The battery is similar to many commercially-available high-energy lithium-ion batteries with one important difference. It uses flavin from vitamin B2 as the cathode: the part that stores the electricity that is released when connected to a device.

“We’ve been looking to nature for a while to find complex molecules for use in a number of consumer electronics applications,” says Dwight Seferos, an associate professor in U of T’s Department of Chemistry and Canada Research Chair in Polymer Nanotechnology.

“When you take something made by nature that is already complex, you end up spending less time making new material,” says Seferos.

An Aug. 2, 2016 University of Toronto news release (also on EurekAlert) by Peter McMahon, which originated the news item, explains further,

To understand the discovery, it’s important to know that modern batteries contain three basic parts:

  • a positive terminal – the metal part that touches devices to power them – connected to a cathode inside the battery casing
  • a negative terminal connected to an anode inside the battery casing
  • an electrolyte solution, in which ions can travel between the cathode and anode electrodes

When a battery is connected to a phone, iPod, camera or other device that requires power, electrons flow from the anode – the negatively charged electrode of the device supplying current – out to the device, then into the cathode and ions migrate through the electrolyte solution to balance the charge. When connected to a charger, this process happens in reverse.

The reaction in the anode creates electrons and the reaction in the cathode absorbs them when discharging. The net product is electricity. The battery will continue to produce electricity until one or both of the electrodes run out of the substance necessary for the reactions to occur.

Organic chemistry is kind of like Lego

While bio-derived battery parts have been created previously, this is the first one that uses bio-derived polymers – long-chain molecules – for one of the electrodes, essentially allowing battery energy to be stored in a vitamin-created plastic, instead of costlier, harder to process, and more environmentally-harmful metals such as cobalt.

“Getting the right material evolved over time and definitely took some test reactions,” says paper co-author and doctoral student Tyler Schon. “In a lot of ways, it looked like this could have failed. It definitely took a lot of perseverance.”

Schon, Seferos and colleagues happened upon the material while testing a variety of long-chain polymers – specifically pendant group polymers: the molecules attached to a ‘backbone’ chain of a long molecule.

“Organic chemistry is kind of like Lego,” he says. “You put things together in a certain order, but some things that look like they’ll fit together on paper don’t in reality. We tried a few approaches and the fifth one worked,” says Seferos.

Building a better power pack

The team created the material from vitamin B2 that originates in genetically-modified fungi using a semi-synthetic process to prepare the polymer by linking two flavin units to a long-chain molecule backbone.

This allows for a green battery with high capacity and high voltage – something increasingly important as the ‘Internet of Things’ continues to link us together more and more through our battery-powered portable devices.

“It’s a pretty safe, natural compound,” Seferos adds. “If you wanted to, you could actually eat the source material it comes from.”

B2’s ability to be reduced and oxidized makes its well-suited for a lithium ion battery.

“B2 can accept up to two electrons at a time,” says Seferos. “This makes it easy to take multiple charges and have a high capacity compared to a lot of other available molecules.”

A step to greener electronics

“It’s been a lot of trial-and-error,” says Schon. “Now we’re looking to design new variants that can be recharged again and again.”

While the current prototype is on the scale of a hearing aid battery, the team hopes their breakthrough could lay the groundwork for powerful, thin, flexible, and even transparent metal-free batteries that could support the next wave of consumer electronics.

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

Bio-Derived Polymers for Sustainable Lithium-Ion Batteries by Tyler B. Schon, Andrew J. Tilley, Colin R. Bridges, Mark B. Miltenburg, and Dwight S. Seferos. Advanced Functional Materials DOI: 10.1002/adfm.201602114 Version of Record online: 14 JUL 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Ultimate discovery tool?

For anyone familiar with the US nanomedicine scene, Chad Mirkin’s appearance in this announcement from Northwestern University isn’t much of a surprise.  From a June 23, 2016 news item on ScienceDaily,

The discovery power of the gene chip is coming to nanotechnology. A Northwestern University research team is developing a tool to rapidly test millions and perhaps even billions or more different nanoparticles at one time to zero in on the best particle for a specific use.

When materials are miniaturized, their properties—optical, structural, electrical, mechanical and chemical—change, offering new possibilities. But determining what nanoparticle size and composition are best for a given application, such as catalysts, biodiagnostic labels, pharmaceuticals and electronic devices, is a daunting task.

“As scientists, we’ve only just begun to investigate what materials can be made on the nanoscale,” said Northwestern’s Chad A. Mirkin, a world leader in nanotechnology research and its application, who led the study. “Screening a million potentially useful nanoparticles, for example, could take several lifetimes. Once optimized, our tool will enable researchers to pick the winner much faster than conventional methods. We have the ultimate discovery tool.”

A June 23, 2016 Northwestern University news release (also on EurekAlert), which originated the news item, describes the work in more detail,

Using a Northwestern technique that deposits materials on a surface, Mirkin and his team figured out how to make combinatorial libraries of nanoparticles in a very controlled way. (A combinatorial library is a collection of systematically varied structures encoded at specific sites on a surface.) Their study will be published June 24 by the journal Science.

The nanoparticle libraries are much like a gene chip, Mirkin says, where thousands of different spots of DNA are used to identify the presence of a disease or toxin. Thousands of reactions can be done simultaneously, providing results in just a few hours. Similarly, Mirkin and his team’s libraries will enable scientists to rapidly make and screen millions to billions of nanoparticles of different compositions and sizes for desirable physical and chemical properties.

“The ability to make libraries of nanoparticles will open a new field of nanocombinatorics, where size — on a scale that matters — and composition become tunable parameters,” Mirkin said. “This is a powerful approach to discovery science.”

“I liken our combinatorial nanopatterning approach to providing a broad palette of bold colors to an artist who previously had been working with a handful of dull and pale black, white and grey pastels,” said co-author Vinayak P. Dravid, the Abraham Harris Professor of Materials Science and Engineering in the McCormick School of Engineering.

Using five metallic elements — gold, silver, cobalt, copper and nickel — Mirkin and his team developed an array of unique structures by varying every elemental combination. In previous work, the researchers had shown that particle diameter also can be varied deliberately on the 1- to 100-nanometer length scale.

Some of the compositions can be found in nature, but more than half of them have never existed before on Earth. And when pictured using high-powered imaging techniques, the nanoparticles appear like an array of colorful Easter eggs, each compositional element contributing to the palette.

To build the combinatorial libraries, Mirkin and his team used Dip-Pen Nanolithography, a technique developed at Northwestern in 1999, to deposit onto a surface individual polymer “dots,” each loaded with different metal salts of interest. The researchers then heated the polymer dots, reducing the salts to metal atoms and forming a single nanoparticle. The size of the polymer dot can be varied to change the size of the final nanoparticle.

This control of both size and composition of nanoparticles is very important, Mirkin stressed. Having demonstrated control, the researchers used the tool to systematically generate a library of 31 nanostructures using the five different metals.

To help analyze the complex elemental compositions and size/shape of the nanoparticles down to the sub-nanometer scale, the team turned to Dravid, Mirkin’s longtime friend and collaborator. Dravid, founding director of Northwestern’s NUANCE Center, contributed his expertise and the advanced electron microscopes of NUANCE to spatially map the compositional trajectories of the combinatorial nanoparticles.

Now, scientists can begin to study these nanoparticles as well as build other useful combinatorial libraries consisting of billions of structures that subtly differ in size and composition. These structures may become the next materials that power fuel cells, efficiently harvest solar energy and convert it into useful fuels, and catalyze reactions that take low-value feedstocks from the petroleum industry and turn them into high-value products useful in the chemical and pharmaceutical industries.

Here’s a diagram illustrating the work,

 Caption: A combinatorial library of polyelemental nanoparticles was developed using Dip-Pen Nanolithography. This novel nanoparticle library opens up a new field of nanocombinatorics for rapid screening of nanomaterials for a multitude of properties. Credit: Peng-Cheng Chen/James Hedrick

Caption: A combinatorial library of polyelemental nanoparticles was developed using Dip-Pen Nanolithography. This novel nanoparticle library opens up a new field of nanocombinatorics for rapid screening of nanomaterials for a multitude of properties. Credit: Peng-Cheng Chen/James Hedrick

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

Polyelemental nanoparticle libraries by Peng-Cheng Chen, Xiaolong Liu, James L. Hedrick, Zhuang Xie, Shunzhi Wang, Qing-Yuan Lin, Mark C. Hersam, Vinayak P. Dravid, Chad A. Mirkin. Science  24 Jun 2016: Vol. 352, Issue 6293, pp. 1565-1569 DOI: 10.1126/science.aaf8402

This paper is behind a paywall.

Split some water molecules and save solar and wind (energy) for a future day

Professor Ted Sargent’s research team at the University of Toronto has a developed a new technique for saving the energy harvested by sun and wind farms according to a March 28, 2016 news item on Nanotechnology Now,

We can’t control when the wind blows and when the sun shines, so finding efficient ways to store energy from alternative sources remains an urgent research problem. Now, a group of researchers led by Professor Ted Sargent at the University of Toronto’s Faculty of Applied Science & Engineering may have a solution inspired by nature.

The team has designed the most efficient catalyst for storing energy in chemical form, by splitting water into hydrogen and oxygen, just like plants do during photosynthesis. Oxygen is released harmlessly into the atmosphere, and hydrogen, as H2, can be converted back into energy using hydrogen fuel cells.

Discovering a better way of storing energy from solar and wind farms is “one of the grand challenges in this field,” Ted Sargent says (photo above by Megan Rosenbloom via flickr) Courtesy: University of Toronto

Discovering a better way of storing energy from solar and wind farms is “one of the grand challenges in this field,” Ted Sargent says (photo above by Megan Rosenbloom via flickr) Courtesy: University of Toronto

A March 24, 2016 University of Toronto news release by Marit Mitchell, which originated the news item, expands on the theme,

“Today on a solar farm or a wind farm, storage is typically provided with batteries. But batteries are expensive, and can typically only store a fixed amount of energy,” says Sargent. “That’s why discovering a more efficient and highly scalable means of storing energy generated by renewables is one of the grand challenges in this field.”

You may have seen the popular high-school science demonstration where the teacher splits water into its component elements, hydrogen and oxygen, by running electricity through it. Today this requires so much electrical input that it’s impractical to store energy this way — too great proportion of the energy generated is lost in the process of storing it.

This new catalyst facilitates the oxygen-evolution portion of the chemical reaction, making the conversion from H2O into O2 and H2 more energy-efficient than ever before. The intrinsic efficiency of the new catalyst material is over three times more efficient than the best state-of-the-art catalyst.

Details are offered in the news release,

The new catalyst is made of abundant and low-cost metals tungsten, iron and cobalt, which are much less expensive than state-of-the-art catalysts based on precious metals. It showed no signs of degradation over more than 500 hours of continuous activity, unlike other efficient but short-lived catalysts. …

“With the aid of theoretical predictions, we became convinced that including tungsten could lead to a better oxygen-evolving catalyst. Unfortunately, prior work did not show how to mix tungsten homogeneously with the active metals such as iron and cobalt,” says one of the study’s lead authors, Dr. Bo Zhang … .

“We invented a new way to distribute the catalyst homogenously in a gel, and as a result built a device that works incredibly efficiently and robustly.”

This research united engineers, chemists, materials scientists, mathematicians, physicists, and computer scientists across three countries. A chief partner in this joint theoretical-experimental studies was a leading team of theorists at Stanford University and SLAC National Accelerator Laboratory under the leadership of Dr. Aleksandra Vojvodic. The international collaboration included researchers at East China University of Science & Technology, Tianjin University, Brookhaven National Laboratory, Canadian Light Source and the Beijing Synchrotron Radiation Facility.

“The team developed a new materials synthesis strategy to mix multiple metals homogeneously — thereby overcoming the propensity of multi-metal mixtures to separate into distinct phases,” said Jeffrey C. Grossman, the Morton and Claire Goulder and Family Professor in Environmental Systems at Massachusetts Institute of Technology. “This work impressively highlights the power of tightly coupled computational materials science with advanced experimental techniques, and sets a high bar for such a combined approach. It opens new avenues to speed progress in efficient materials for energy conversion and storage.”

“This work demonstrates the utility of using theory to guide the development of improved water-oxidation catalysts for further advances in the field of solar fuels,” said Gary Brudvig, a professor in the Department of Chemistry at Yale University and director of the Yale Energy Sciences Institute.

“The intensive research by the Sargent group in the University of Toronto led to the discovery of oxy-hydroxide materials that exhibit electrochemically induced oxygen evolution at the lowest overpotential and show no degradation,” said University Professor Gabor A. Somorjai of the University of California, Berkeley, a leader in this field. “The authors should be complimented on the combined experimental and theoretical studies that led to this very important finding.”

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

Homogeneously dispersed, multimetal oxygen-evolving catalysts by Bo Zhang, Xueli Zheng, Oleksandr Voznyy, Riccardo Comin, Michal Bajdich, Max García-Melchor, Lili Han, Jixian Xu, Min Liu, Lirong Zheng, F. Pelayo García de Arquer, Cao Thang Dinh, Fengjia Fan, Mingjian Yuan, Emre Yassitepe, Ning Chen, Tom Regier, Pengfei Liu, Yuhang Li, Phil De Luna, Alyf Janmohamed, Huolin L. Xin, Huagui Yang, Aleksandra Vojvodic, Edward H. Sargent. Science  24 Mar 2016: DOI: 10.1126/science.aaf1525

This paper is behind a paywall.

Carbon nanotubes sense spoiled food

CNT_FoodSpolage

Courtesy: MIT (Massachusetts Institute of Technology)

I love this .gif; it says a lot without a word. However for details, you need words and here’s what an April 15, 2015 news item on Nanowerk has to say about the research illustrated by the .gif,

MIT [Massachusetts Institute of Technology] chemists have devised an inexpensive, portable sensor that can detect gases emitted by rotting meat, allowing consumers to determine whether the meat in their grocery store or refrigerator is safe to eat.

The sensor, which consists of chemically modified carbon nanotubes, could be deployed in “smart packaging” that would offer much more accurate safety information than the expiration date on the package, says Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT.

An April 14, 2015 MIT news release (also on EurekAlert), which originated the news item, offers more from Dr. Swager,

It could also cut down on food waste, he adds. “People are constantly throwing things out that probably aren’t bad,” says Swager, who is the senior author of a paper describing the new sensor this week in the journal Angewandte Chemie.

This latest study is builds on previous work at Swager’s lab (Note: Links have been removed),

The sensor is similar to other carbon nanotube devices that Swager’s lab has developed in recent years, including one that detects the ripeness of fruit. All of these devices work on the same principle: Carbon nanotubes can be chemically modified so that their ability to carry an electric current changes in the presence of a particular gas.

In this case, the researchers modified the carbon nanotubes with metal-containing compounds called metalloporphyrins, which contain a central metal atom bound to several nitrogen-containing rings. Hemoglobin, which carries oxygen in the blood, is a metalloporphyrin with iron as the central atom.

For this sensor, the researchers used a metalloporphyrin with cobalt at its center. Metalloporphyrins are very good at binding to nitrogen-containing compounds called amines. Of particular interest to the researchers were the so-called biogenic amines, such as putrescine and cadaverine, which are produced by decaying meat.

When the cobalt-containing porphyrin binds to any of these amines, it increases the electrical resistance of the carbon nanotube, which can be easily measured.

“We use these porphyrins to fabricate a very simple device where we apply a potential across the device and then monitor the current. When the device encounters amines, which are markers of decaying meat, the current of the device will become lower,” Liu says.

In this study, the researchers tested the sensor on four types of meat: pork, chicken, cod, and salmon. They found that when refrigerated, all four types stayed fresh over four days. Left unrefrigerated, the samples all decayed, but at varying rates.

There are other sensors that can detect the signs of decaying meat, but they are usually large and expensive instruments that require expertise to operate. “The advantage we have is these are the cheapest, smallest, easiest-to-manufacture sensors,” Swager says.

“There are several potential advantages in having an inexpensive sensor for measuring, in real time, the freshness of meat and fish products, including preventing foodborne illness, increasing overall customer satisfaction, and reducing food waste at grocery stores and in consumers’ homes,” says Roberto Forloni, a senior science fellow at Sealed Air, a major supplier of food packaging, who was not part of the research team.

The new device also requires very little power and could be incorporated into a wireless platform Swager’s lab recently developed that allows a regular smartphone to read output from carbon nanotube sensors such as this one.

The funding sources are interesting, as I am appreciating with increasing frequency these days (from the news release),

The researchers have filed for a patent on the technology and hope to license it for commercial development. The research was funded by the National Science Foundation and the Army Research Office through MIT’s Institute for Soldier Nanotechnologies.

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

Single-Walled Carbon Nanotube/Metalloporphyrin Composites for the Chemiresistive Detection of Amines and Meat Spoilage by Sophie F. Liu, Alexander R. Petty, Dr. Graham T. Sazama, and Timothy M. Swager. Angewandte Chemie International Edition DOI: 10.1002/anie.201501434 Article first published online: 13 APR 2015

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This article is behind a paywall.

There are other posts here about the quest to create food sensors including this Sept. 26, 2013 piece which features a critique (by another blogger) about trying to create food sensors that may be more expensive than the item they are protecting, a problem Swager claims to have overcome in an April 17, 2015 article by Ben Schiller for Fast Company (Note: Links have been removed),

Swager has set up a company to commercialize the technology and he expects to do the first demonstrations to interested clients this summer. The first applications are likely to be for food workers working with meat and fish, but there’s no reason why consumers shouldn’t get their own devices in due time.

There are efforts to create visual clues for food status. But Swager says his method is better because it doesn’t rely on perception: it produces hard data that can be logged and tracked. And it also has potential to be very cheap.

“The resistance method is a game-changer because it’s two to three orders of magnitude cheaper than other technology. It’s hard to imagine doing this cheaper,” he says.