This Tiny Sponge is Probably Set to Change The World

By Anupum Pant


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.

The Hard Boiled Egg Sprinkler Mystery

By Anupum Pant


Cracking an egg to check if it is boiled or not is not a very intelligent way. While many know that spinning an egg can be used to determine whether an egg is a boiled one or not, I’m amazed by the sheer number of people who aren’t still aware of this trick.

Just in case you are one of those who don’t know this, it works like this –  try spinning an egg on a smooth surface. If it spins well and stands up vertically, it is a boiled egg. If it doesn’t spin properly, you can say that it isn’t cooked….as simple as that.

Tip: There’s a way to check if your eggs have gone bad without risking opening it up to take in the nasty stench. [Here]

Boiled Egg Sprinkler Experiment

Now that I’m sure you know about the boiled egg spinning trick I can tell you about this simple experiment you can do at home. Besides dealing with an angry mom, it carries no other risks.

Here’s what you do – Get some milk and pour it on the kitchen counter. Now, boil an egg if you don’t have a boiled one already. Make sure it is hard-boiled by doing the spinning test. Next, spin it on the milk puddle you created on the counter. Nasty mess ensues…

Yes, there sure is a mess afterwards. But something amazing happens when the egg spins on the milk puddle. When it spins, the egg first stands up and then the milk starts rising on the surface of the egg till it reaches the equator and then the milk gets sprinkled at the equator in a very beautiful manner. It’s like a skirt of milk. Different sprinkling effects can be obtained with different spinning speeds.

Until now, no one knew why this happened. The rotating egg would suck up milk like magic and create a fountain of milk. The exact physics part of it wasn’t known until some researchers at Brigham Young University decided to figure out why this happens. I, on the other hand didn’t even know this sprinkling thing could be done. Nice to know.

Turns out, there’s nothing peculiar about milk and eggs that creates this effect. The same thing can be done with an 8-ball or any other ball for that matter. On the other side, it works with other liquids too. For instance, if you use a liquid with a higher viscosity (glycerine and water mix), the rotating ball could create not just sprinkles, but whole sheets of liquid getting flicked off at the equator. Some times if the fluid is viscous enough and the ball is spinning fast enough, sheets spanning several feet can be seen getting flicked off the equator of the spinning balls! It’s like a motor.

Here is an amazing hi-speed video of this happening in the laboratory and the elegant physics behind has been explained too. Watch it here:

After having watched the explanation, I can say one thing for sure: There’d be no sprinkling if this was done on Superfluid Helium because superfluid helium would have no viscosity and it wouldn’t rotate with the ball!

A Book That Filters 4 Years of Drinkable Water

By Anupum Pant

I’ve written a lot about water in the past. No wonder drinking water is such a precious commodity. Still, not many have access to clean water. About a 7th of the whole world’s population don’t have clean water to drink. Every year about 3.4 Million people die out of water borne diseases.

A group of people who go by the name WaterisLife are putting in everything to change that. By working with a group of scientists from Carnegie Mellon and the University of Virginia, they have been able to come up with a novel idea that could change this. They call it the drinkable book. 

Drinkable book is a book full of cards that have been coated with silver nanoparticles. These cards bear the ability to filter dirty water and reduce the count of bacteria in it by about 99.9%. It can kill the bacteria that causes diseases like cholera, typhoid and E. coli., producing drinkable water that is as pure as tap water used in the US. Each page of this book can filter about 30 days of drinkable water. In fact, each page contains the instructions to filter water properly too. The whole book can provide 4 years of potable water. Definitely a boon to the developing countries.