Mar 21
Bio-mimicry Designs — Lessons inside the Ocean
2002… Prof. Anthony Brennan looked awestruck standing in front of the rows of submarines and ships docked at the Pearl Harbour. He was carefully examining the submerged portions which were fouled heavily by algae.
The barnacles — in the Capt. Haddock’s language, “Billions of Blue Blistering Barnacles” — were spread around the water-contact regions of the beasts.
“Dr. Brennan, how to prevent the hull fouling?” — was the challenge put forward to the material science professor of the University of Florida.
The team jumped the gun with traditional approaches such as changing the materials and applying special coatings, but all in vain. Millions of dollars were spent on various materials and complex chemicals. Are fouling harmful to hulls?
Of course yes! The Navel architects and designers burn the midnight oil to design hydrodynamic bodies for a smooth drag free sails. The submerged portions of the ships are so smoothly curved that the water flows around them without creating any turbulence or causing resistance. The design task is not simple as said.
Engineers use Computational Fluid Dynamics (CFD) to check if their designs are efficient enough to cruise against the water (/air) resistance. The simulations may run for hours and days crunching numbers and equations if the designs are complex. If they make any changes in the designs then they have to repeat the task.
Our friend barnacles simply spoil all their efforts in due course of time. As a result, the ships consume extra fuel worth of ~$ 500,000,000 a year in US alone.
This is the main reason why Dr. Brennan was brought here!
After his several futile efforts , the professor saw the problem from the different perspective. His posed a radical question, “Is there any slow moving sea animal that is not fouled?”
They found almost all the big sea creatures — from the large whales to the big fishes — having fouls around their body, except one — the Shark. The team immediately focused their attention towards its skin and analysed for chemical properties first. They synthesized them and found nothing worked.
Next they shifted their focus to the surface of the micro-riblets. Bingo…!
The distinct diamond texture of the shark skin, not its chemicals, prevents the fouling. The algae have no holds on the surface due to its geometry and “choose to stay away”. Dr. Brennan then synthetically fabricated the textured-surfaces and reduced green algae settlements by 85% compared to smooth surfaces. He then founded a startup Sharklet and has been testing with different micro-patterns of Sharklet since then.
He also observed that the amount of bacteria in the micro-riblets is much less than the other parts of the shark. He, in an interview, said, “Sharklet has shown to be effective against many Gram-negative and Gram-positive bacterial strains, including clinical isolates, in different media and flow conditions, e.g. Staphylococcus aureus, MRSA, VRE, and E. coli.”
His startup is now making sticker-like films containing diamond shaped micro-patterns of width about 1/5 of a human hair. It is said to have reduced the amount of bacteria on a surface by 90% — 99% depending on the type of the micro-organisms.
Sharklet can be stuck on at bacteria-prone places such as door handles, backpacks, suitcases or mats. Please note that the distinct micro-pattern textures do not kill the bacteria rather keep them away.
Happy Bio-mimicry Technologies…!
