This Tiny Sponge is Probably Set to Change The World

By Anupum Pant

Background

Things absorbing water from the air is nothing new. Hygroscopic substances – or substances which have ability to attract and hold water molecules from the surrounding environment – have always been around. Coffee powder for instance is one great example – leave the dry coffee powder in the open and it will turn into a mushy matter within hours. Thanks to the moisture present in the air that it absorbs.

Hygroscopy in Nature

In the nature too, hygroscopy – the ability to extract water from thin air – has some peculiar functions. One fantastic example is the seed of the needle-and-Thread grass. This seed, with the help of a hygroscopic awn attached to it, can twist and untwist the screw like structure by releasing and absorbing moisture from the air. This way, it is able to dig its way into the ground. But that’s just one of the many examples of how hygroscopy is all around us. Here’s another one…

Thorny devil – an Australian lizard – lives in the arid scrubland and desert that covers most of central Australia. It has a hard time finding water in this dry place. So, blessed by the evolutionary forces of nature, the lizard has developed tiny hygroscopic channels between the spines on its back. These channels, working in tandem with a capillary action mechanism, are able to draw water from the air. Then their precise design makes the water move into the mouth of the lizard. Fascinating!

Other Ways

Although not exactly using hygroscopy, the Namib desert beetle, also does something similar – drawing water from thin air. Unlike the hygroscopic grooves of the thorny devil’s back, the desert dwelling beetle has developed some patterns on its hard wings which help it in drawing water from the air. These patterns include an array of  hydrophobic and hydrophilic materials which are able to trap water from the foggy morning air and are able to channel it to the beetle’s mouth.

The Nanotube Sponge Mat

This particular beetle’s hard wings with magical patterns on it, intrigued a couple of researchers. They took cue from this natural material and were able to create an artificial mat which could absorb water from the air.

nanotube sponge

Although we do have commercial Atmospheric Water Generators (AWG) which can harvest water from the air and supply drinking water, the sad thing is that these things run on electricity. This new mat that was fabricated recently, using an array of carbon nano tubes sandwiched between hydrophilic and hydrophobic layers, doesn’t need any electricity to extract water.

This mat they’ve fabricated is smaller than your thumbnail, but it still works, and is able to extract about 1/4th of it’s weigh in water within a few hours. The researchers are working on it to make it more efficient. [more information] [Original Paper]

A couple of years back a US based startup, NBD Nano, was inclined on developing a water bottle based on the same Namib desert beetle principle. The much touted water bottle, they said, would be able to fill itself! I’m not sure where their project is headed today, but an auto-filling water bottle sure would be a product just too cool to not own by every kid at school!

Needless to say, it would probably make a huge difference by lowering greatly the number of people who don’t find clean drinking water every day – Just for the record, about 1/7th of the world population didn’t have access to clean water today.

Revolutionary – A Simple Yet Much Stronger Artificial Muscle

By Anupum Pant

Background

Some things are just too simple to be noticed by most adults, rather a child would notice it better. Scientists are the ones who manage to hone their ability to  look at things like a child would see it – Children of course are the best scientists. That is what makes scientists different from most other people. And that is what helps them make elegant discoveries, like the one we are seeing here today.

Now, this may seem like a useless thing to some, but in reality the simple fishing line muscle is a huge step towards creating affordable personal robots, exoskeletons and a host of other earth changing devices. I can’t stop thinking how massive this simple thing could end up being.

The Discovery

A team of researchers at the University of Texas at Dallas, did exactly that. In a simple nylon fishing line, these researchers saw something that everyone till date has failed to notice. They noticed that, by twisting a nylon line into a coil (and heat treating), they could turn it into an artificial muscle. Later it was learnt that a simple artificial muscle made in this manner is about 100 times stronger than a human muscle and can go through millions of cycles without failing.

It’s actually so simple to do that you could make an artificial muscle in your own home. In fact, it works with a variety of other kinds of materials too, but better stick to the tested fishing line for now.

All you need to do is to hold one end of a long fishing line and start twisting the other end (a hand mixer could come in handy here). At some point the line reaches a point where it can’t twist any more, and then it starts getting coiled into a telephone wire kind of a spring. Now it can be heated in an oven (carefully, without melting) and cooled to lock it in this coil shape. There, you’ve got your own artificial muscle.

Working

Unlike what you think it would do when heated, the coil actually contracts and can lift a good amount of weight. An array of such artificial muscle fibres could lift a much heavier weight. as shown in the video below.

At first I found it confusing. It was hard for me to understand, what physics goes inside that makes the coil contract as a whole when it is heated. From the words of a wise scienitist, I found that it works like a chinese finger trap (and then I had to look what this piece of origami was). Whatever the coil does is absolutely elegant. It’s almost impossible for me to explain in words how it works. You might have to watch the video below…

The catch is that the nylon muscles made in this manner are very inefficient, but that can be worked upon.

Lycurgus Cup – An Ancient Nanotech Marvel

By Anupum Pant

The concepts of modern nanotechnology must have been first seeded in the year 1959 by the renowned physicist Richard Feynman, but Romans were already doing it back in 300 AD (around 290-325 AD). About 1700 years back, utilizing the principles of Nanotechnology, Roman engineers had crafted a magnificent chalice – Lycurgus Cup (picture). Like the Prince Rupert’s drop, this is another glass marvel you should know about.

Side note: You can listen to the legendary lecture by Dr. Feynman on YouTube – There’s Plenty of Room at the Bottom, where he discusses the “possibility of synthesis via direct manipulation of atoms”, or Nanotechnology.

Lycurgus cup description

The Lycurgus cup was probably the first ever optical artificial [meta]material – Ruby Glass – engineered to have properties that may not be found in nature. Its unusual optical properties are something that makes it stand out.

Normally, the cup appears green, but if it is illuminated from the inside or lit up using a light placed behind it, it glows ruby-red; hence the name, ruby glass. This kind of glass is known as a Dichroic glass. Dichroic  literally means ”two colored” and is derived from the Greek words ”di” for two, and ”chroma” for color; in this case, the colors green and red.

The technology behind this cup baffled scientists for around 40 years (from 1950s to 1990s). It was only in 1990s that they figured out how it really worked. The goblet has been preserved well, and is presently at display in the British Museum.

Dichroic glass

Dichroic glasses do not use paints, dyes, or any coloring agents for the color. They are made using fine coatings on glass. The coatings themselves do not have a color, but rather they bend light to reflect colors like a prism does, to make rainbows.

These colors are visible due to the presence of very minute amounts of finely ground gold and silver particles in it. Romans could have included these powders unknowingly as contaminants or might have added them on purpose to achieve the very effect, we’ll never know.

Inspired by an age-old technology

NASA, in the 1950s, used a similar technology to fabricate a kind of glass that could selectively reflect light wavelengths. They achieved this by depositing a thin-film of metal on the glass.

With innumerable combinations of oxides, glass colors and patterns available, the possibilities to utilize this phenomenon for various useful purposes are endless.
The unusual properties of this cup have also inspired material scientists to create concepts for an invisibility cloak using modern nanofabrication technology. [Source]

I want to study interesting materials like these

If you think the Lycurgus cup, Wolverine’s claws and Aerogels (If you haven’t heard about it, you must definitely check this out!) are awesome. You can make a career in researching materials like these by making a foray into Materials Science and Engineering. Most good universities offer a course in it. It is a budding field, growing at a rapid pace, replete with real-world challenging conundrums waiting to be resolved.