The beauty of nature

I love how nature has sussed out so much of our science and engineering problems already, thus leading to many interdisciplinary research teams coming together to take their cues from it.

Inspiration from nature isn’t new, just think barbed wire, a design based on the thorny Osage orange tree. Or, if you want a less literal example think of the iconic Eiffel Tower which is said to have used “a series of wrought iron braces and studs to reproduce the structure of the femur“.

Thorns on the Osage orange tree. Photo by Forest & Kim Starr

Here are a few bio-inspired research pieces that I’ve seen, been impressed by, or just liked the sound of, and wanted to share.

SPF Hippo sweat anyone?

The thought of lathering yourself with hippo sweat may be off-putting to most but thanks to research from Christopher Viney, University of California at UC Merced, and Yoko Saikawa, Keio University in Japan, hippos may actually hold the secret to a future multi-purpose sun protection.

Photo by Joaquim Alves Gaspar

Since 2004, Professor Viney has been researching into the properties that allow hippos to escape sunburn as they roam around in the hot sun all day. His research revealed that the sweat is made up of two liquid crystalline structures: banded and non-banded. When viewed under a light  microscope it was revealed that the banded structures were “characterized by concentric dark rings” which were the answer for their sun blocking capability. The periodic rings are set a specific distance apart, allowing them to scatter light rays, thus shielding the hippo from the damaging UV rays. The non-banded structures have also proved valuable, as their coarse microstructure allows them to break down the viscosity of the sweat so it can easily spread over the hippo’s body.

Not only has hippo sweat shown to be an effective sunblock but Professor Saikawa and her team have shown the red pigment hippos secrete absorbs UV light thus behaving as an effective sunscreen. The benefits of the sweat doesn’t stop there either, it has demonstrated effective insect repellant and antiseptic properties too.

“Pulse of the Planet” interviewed Professor Viney soon after his publication. You can listen to the clip here.

Spiders bio-glue

Okay, so I’ve already known about the amazing strength of spiders silk for a while now…

…but have you ever thought about its stickiness? I hadn’t until I stumbled upon this article on the National Science Foundation website, “Scientists Untangle Spider Web Stickiness

Using orb-weaving spiders, Ali Dhinojwala, University of Akron in Ohio has been studying just how they make their “glue” stick.

When flies land on the web they stick to tiny beads of “glue” – these beads are  three times thinner in diameter than a human hair and made of a protein which is bonded to sugars (called a glycoprotein). This glycoprotein is entangled and cross-linked forming the bead. Professor Dhinojwala and his team showed that it was the elastic property of the “glue” – which allowed it to stretch and stretch just like silly putty – that resulted in its stickiness.

More research still needs to be carried out to understand fully how this mechanical stickiness works and how it can be incorporated into synthetic designs. But just think, we could have a future where we use spider “glue” to adhere wrapping paper, or even better, medical teams could use the water-proof property spiders glue has shown to have when suturing internal wounds.

Spider webs aren’t the only area researchers have looked to for bio-inspired adhesives: think geckos, mussels, sandcastle worms, and the old classic velcro.

Sun powers hornets

Recently there has been quite a lot of coverage on a study that reveals how oriental hornets harness solar energy – probably the most immature research on this blog post as there still needs to be more work to back this theory.

Marian Plotkin, Tel-Aviv University lead the study which had been instigated after it had been observed that Oriental hornets show peak activity in the noon –  “two orders of magnitude greater than the
number of those emerging in the morning or evening hours”. A pattern of activity much different to wasps whose peak activity was in the early morning. It had also been observed that a pigment in the hornet’s cuticle ( which forms the exoskeleton) could “absorb part of the solar radiation“.  Therefore, Dr Plotkin wanted to find out if some form of solar energy harvesting was taking place which resulted in peak hornet activity during peak sun activity.

So what did they find? Plotkin found that although the brown and yellow parts of the hornet are composed differently they both rely on unique exo- and endo-skeletal structures and pigments to allow sun-light that hits their surface to be channelled and absorbed effectively.

Both the brown and yellow areas demonstrated some ability to prevent reflection when light hit the cuticle, helping them collect the light so it could reach the pigments – melanin and xanthopterin. The grooves and sheet-like structures in the brown areas enhanced its ability to do this as it was able to trap the light more effectively and channel it in different directions.  Not only were the hornets shown to collect and trap light well but xanthopterin, which gives rise to the yellow colour is thought to be the light harvesting molecule, able to convert light energy into electrical energy.

Though this study has shed light into how hornets may harness the sun’s energy, the researchers still don’t know how the hornets use this electricity. But if researchers are on the right path with this theory then it may be of great help in future developments of innovative solar technologies.

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