A team of MIT researchers has designed a breathable workout suit with ventilating flaps that open and close in response to an athlete's body heat and sweat.

The flaps, which range from thumbnail to finger-sized, are lined with live microbial cells that shrink and expand in response to changes in humidity.

The cells act as tiny sensors and actuators, driving the flaps to open when an athlete works up a sweat, and pulling them closed when the body has cooled off.

The researchers have also fashioned a running shoe with an inner layer of similar cell-lined flaps to air out and wick away moisture.

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They say that moisture-sensitive cells require no additional elements to sense and respond to humidity, and the microbial cells they have used are also proven to be safe to touch and even consume.

What's more, with new genetic engineering tools available today, cells can be prepared quickly and in vast quantities to express multiple functions in addition to moisture response.

To demonstrate this, the researchers engineered moisture-sensitive cells to not only pull flaps open but also light up in response to humid conditions.

"We can combine our cells with genetic tools to introduce other functionalities into these living cells," says Dr Wen Wang, a former research scientist in MIT's Media Lab and Department of Chemical Engineering.

"We use fluorescence as an example, and this can let people know you are running in the dark. In the future, we can combine odour-releasing functionalities through genetic engineering.

"So maybe after going to the gym, the shirt can release a nice-smelling odour."

World's thinnest hologram

Scientists have created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday electronics like smartphones, computers and TVs.

Photo / RMIT University
Photo / RMIT University

Interactive 3D holograms are a staple of science fiction - from Star Wars to Avatar - but the challenge for scientists trying to turn them into reality is developing holograms that are thin enough to work with modern electronics.

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Now a pioneering team led by Distinguished Professor Min Gu of Melbourne's RMIT University has designed a nano-hologram that is simple to make, can be seen without 3D goggles and is 1000 times thinner than a human hair.

"Conventional computer-generated holograms are too big for electronic devices but our ultrathin hologram overcomes those size barriers," Gu says.

"Our nano-hologram is also fabricated using a simple and fast direct laser writing system, which makes our design suitable for large-scale uses and mass manufacture.

"Integrating holography into everyday electronics would make screen size irrelevant - a pop-up 3D hologram can display a wealth of data that doesn't neatly fit on a phone or watch.

"From medical diagnostics to education, data storage, defence and cybersecurity, 3D holography has the potential to transform a range of industries, and this research brings that revolution one critical step closer."

Conventional holograms modulate the phase of light to give the illusion of three-dimensional depth.

But to generate enough phase shifts, those holograms need to be at the thickness of optical wavelengths.

The RMIT research team, working with the Beijing Institute of Technology, has broken this thickness limit with a 25-nanometre hologram based on a topological insulator material - a novel quantum material that holds the low refractive index in the surface layer but the ultrahigh refractive index in the bulk.

The topological insulator thin film acts as an intrinsic optical resonant cavity, which can enhance the phase shifts for holographic imaging.

The next step involves developing a rigid thin film that could be laid on to an LCD screen to enable 3D holographic display - something that would mean having to shrink the nano-hologram's pixel size to be at least 10 times smaller.

Crackly crust

An authentic French baguette is one of those key staples that foodies hunt for.

Now scientists have gained new insight into why a crisp crust is a must for the quintessential bread, reporting their findings on how crumb and crust structure affect aroma - and therefore, perceived taste.

The smell of baked bread that's fresh out of the oven is mouthwatering, but the effect of aroma doesn't stop there.

Chewing food also releases molecules that waft in our mouths, interact with olfactory receptors and influence how we perceive what we're eating.

Understanding this dynamic could help food scientists improve the taste of products.

Taking the baguette as an example to explore this possibility, scientists from the American Chemical Society wanted to see how its texture would affect its aroma when chewed.

The researchers had three study participants eat samples of nine baguettes, each with different crumb and crust densities, water content and elasticity.

An analysis of volatile organic compounds that are exhaled through the "nose spaces" of the participants along with their chewing activity showed that firm bread and brittle crust led to more chewing and a greater rate of release of aroma molecules.

The findings could help food scientists create new bread types better tailored to meet consumers' expectations, the researchers say.