Generating and characterising material of extreme strength from limpet teeth

  • Pal, Bidyut (PI)

Project Details

Description

Limpets are shoreline creatures that live on rocks and use a tongue-like organ called the radula that is coated with teeth to gather algae from tough surfaces. Limpet teeth are uniquely adapted to this role and are now known to be the strongest tested biological material (Barber, Lu, and Pugno 2015). Limpet teeth have two key ingredients. The first is a soft yet elastic scaffold material called chitin. The second is made of crystals of metal iron oxide which provides strength (Runham 1961; Lowenstam 1962). The combination of these two components arranged into tiny microscopic filaments intertwined with crystals generates a ‘composite material’ that is stronger than spider silk, comparable in strength to manmade carbon fibres and yet this material is not brittle (van der Wal 1989; Barber, Lu, and Pugno 2015).

Composite materials are extremely useful and include items we take for granted every day ranging from plywood to fibreglass. Even our own bones are made of a composite material of collagen and calcium, which is one reason why tissue engineering scaffolds and surgical bone implants are often made from composite materials (Kuttappan, Mathew, and Nair 2016). Even spacecraft use low weight, high strength composite materials within their propulsion systems (Schmidt et al. 2004).

As limpet tooth is a uniquely strong yet flexible composite material, our aim so far has been to find methods to reproduce this biomaterial in the laboratory via an interdisciplinary, fully- controlled process that would have potential impacts in many scenarios in manufacturing, engineering and design.

So far, we have sequenced the entire genetic code of the radula so we can understand how limpets grow their own teeth in order to reproduce this process in petri dish. We have also managed to extract specific cells from limpet’s radula and grow these under laboratory conditions so that they deposit iron. We have even been able to take a small piece of limpet tissue and, from that, grow limpet teeth in a petri dish. We have also developed a synthetic approach by making an artificial microfiber-based scaffold from chitin, which can then be coated with iron containing mineral using messengers that are secreted from limpet cells.

To progress to the application stage of project development we need to better understand the mechanical properties of the materials that we have made and compare them directly with actual limpet tooth. We want to do this by exploiting high resolution 3D X-ray scans using world class equipment available at the Zeiss Global Centre. This will be followed by the generation of computer models aiming to predict the mechanical behaviour of our materials. We shall carry out the mechanical testing in the School of Mechanical and Design Engineering (SMDE), at Cartier and Diamond centres, and then compare the predictions of computer models with the results of mechanical testing for both native limpet tooth and lab made limpet tooth material. This will help sustain further development by advancing our project and bring the prospect of every day usable composite limpet tooth material several steps closer.
StatusFinished
Effective start/end date1/08/1831/07/19

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