LED light out

All manner of technology is available for use across the food and beverage industries. So one that can help consumers determine whether food left in the fridge is still safe to eat could be a tremendous aid to all inside and outside the trade.

The technology – developed by the University of Melbourne, the Lawrence Berkeley National Laboratory, University of California, Berkeley, and the Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems (TMOS) – centres around a device that could identify a suite of gases, potentially including lethal ones.

Every gas has a different spectral fingerprint, marking the wavelengths it absorbs when a broad part of the electromagnetic spectrum is shone through it. A research team demonstrated the capacity to identify gases such as methane and water vapour with materials small enough that they could be added to smart phones.

“Our new technology bonds a thin layer of black phosphorus crystals to a flexible, plastic-like substrate, allowing it to be bent in ways that cause the black phosphorus to emit light of different wavelengths essentially creating a tuneable infrared LED that allows for the detection of multiple materials,” study author Professor Kenneth Crozier of the University of Melbourne said in a statement.

The attraction of black phosphorus is that it can be induced to release infrared radiation with wavelengths from 2.3-5.5 micrometers (55-130THz) depending on the strain it is placed under. That’s broad enough that most relevant gases’ absorption lines can be detected.

This new black phosphorus technology also requires just one layer allowing the device to be flexible, giving it unique properties when bent.

“The shift in black phosphorus’ emission wavelength with bending is really quite dramatic, enabling the LED to be tuned across the mid-infrared,” said Professor Ali Javey, from the University of California at Berkeley, whose group led the work. “Our IR photo detectors could be integrated into a camera so that we could look at our phone screen and ‘see’ gas leaks or emissions and be able to determine what kind of gas it is,” Professor Crozier said.

Crozier sees abundant applications, from firefighting to plumbing, but a device “ inside a fridge could send a notification that meat is going off,” he said.

The University of Melbourne Professor added that the technology “could fit inside smartphones and become part of everyday use.”

“When pointed at a handbag, it could reveal whether the bag is made of real leather or a cheaper substitute,” said Professor Crozier, who is also the deputy director of TMOS.

It is estimated that a third of the world’s food is wasted, going bad or being consumed by pests between harvest and dinner plate.

A surprising proportion of this waste food goes bad after reaching the consumer. The bacteria responsible release gases that this new sensor could detect, providing a reminder to eat the food before it is too late. The same sensors could give the all-clear to food that might otherwise be thrown out.

It would be naive to think just one technology could solve all ills. Apps that track food inventories are already quite compelling. But, just like the apps, the technology would need to be adaptable to people with a variety of lifestyles, skills, and desires. Tech will save us! Or maybe not. What could be effective in addition to technology, is rallying people around a greater cause of connecting the issue of food waste to other issues such as nutrition.

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Food and Drink Technology