Researchers develop nanotech gels to monitor food freshness

James Snodgrass

Published: January 3, 2013 6:00 am ET

Related to this story

Topics Packaging, Film & Sheet, Design

HOUSTON (Jan. 3, 11:10 a.m. ET) — In the refrigerator of the future, we won’t be looking for “Use By” or “Best Before” dates. We will be able to tell whether food is fresh, or has turned for the worse, with a quick visual inspection.

In-mold labels made from a photonic gel will change color when exposed to chemicals associated with a foodstuff going off. So we will have an instant visual warning if our food’s gone bad.

This is just one of many applications for a novel, extremely thin color-changing films that have been developed by materials scientists at Rice University and the Massachusetts Institute of Technology. The research has been published in the nanotechnology journal of the American Chemical Society, ACS Nano.

Leading the project is Ned Thomas, dean of Houston-based Rice’s engineering school, and former chair of the department of materials science and engineering at MIT).

Thomas and his team have combined polymers into a self-assembled metamaterial that changes color when exposed to ions dissolved in solution — or ions in the environment at large. The material changes color according to the ions’ ability to penetrate the hydrophilic layers.

The micron-thick material, made from nanoscale layers of hydrophobic (water resisting) polystyrene and hydrophilic (water loving) poly(2-vinyl pyridine) (P2VP), is called a photonic gel. Thinner than a human hair, Thomas believes the photonic gels will be extremely inexpensive to produce.

“We could cover an area the size of a football field with this film for about $100,” Thomas said.

Exposing the films to various solutions, the researchers discovered that they changed color in proportion to the amount of solvent absorbed by the P2VP. From the film’s neutral, clear, state the researchers turned the film blue (using thiocyanate), green (iodine), yellow (nitrate), orange (bromine) and red (chlorine). All these interactions were reversible; the film returned to its transparent state in the absence of contaminants.

The change in color is caused by expansion of the P2VP layers. Different thicknesses of layers within the film change the way that light is refracted through the film. Thomas suggests that these changes can be exploited in such a way as to make gels that are “tuned” to react in specific ways.

Thomas said: “These days in photonics, people are thinking about light as though it were water. That is, you can put it in these tiny pipes. You can turn light around corners that are very sharp. You can put it where you want it, keep it from where you don’t want it. The plumbing of light has been much easier than in the past, due to photonics, and in photonic crystals, due to band gaps.”

Other potential applications for the technology include security (instant, visual testing for drugs, explosives or biological contaminants) or as an alternative technology to e-ink or thin film transistor displays.


Comments

Researchers develop nanotech gels to monitor food freshness

James Snodgrass

Published: January 3, 2013 6:00 am ET

Post Your Comments


Back to story


More stories

Image

Windmöller & Hölscher looking to continued growth in China

July 21, 2014 3:40 pm ET

With 2013 global sales of 600 million euros, China has grown into an important export market for Windmöller & Hölscher KG, second only to the United...    More

Image

Grocery store chain says bag recycling up by 10 percent

July 21, 2014 2:54 pm ET

Kroger Co., with more than 2,600 stores in 34 states and sales nearing $100 billion, saw plastic bag recycling increase by 10 percent last year.    More

Image

New startup uses film for a 'virtual venetian blind' in smart windows

July 21, 2014 12:50 pm ET

Flexible ITO Solutions, which goes by FITOS, has an informal development agreement with a smart window manufacturer that could use the technology to...    More

Image

Huhtamäki to evaluate its films business

July 21, 2014 9:52 am ET

Finland-based plastics packaging group, Huhtamäki Oyj, has announced that it is evaluating its options regarding its films business, due to its...    More

Image

Portugal's Gepack setting up PET packaging facility in Arizona

July 18, 2014 3:32 pm ET

Gepack, a maker of PET bottles in Portugal, is setting up new a manufacturing facility in Arizona.    More

Market Reports

Injection Molders Market Report & Ranking 2014

This special package contains our 132-page 2014 Market Report on the Injection Molding segment and our exclusive 2014 RANKINGS database of 500+ Injection Molders for a discounted package price.

Learn more

Plastics Recycling Market Review & Outlook 2014

This special report from Plastics News examines the North American plastics recycling industry and provides insight into indicators that impact market viability, including Resin pricing trends for virgin and recycled market material and historical Resin production trends for post- consumer and industrial waste.

Learn more

Shale Gas Market - Analysis of North American Region

This report highlights the impact of shale-based natural gas on the North American plastics market and features an in-depth analysis of production trends in the United States during 2013 and a forecast for 2014 and beyond.

Learn more

Upcoming Plastics News Events

September 10, 2014 - September 12, 2014Plastics Caps & Closures 2014

February 4, 2015 - February 6, 2015Plastics News Executive Forum 2015

More Events