An Assistant Professor of Chemical and Environmental Engineering at the University of California is aiming to develop more efficient batteries based on the formation of snail teeth.
David Kisailus uses nature as inspiration for technological advances. He’s been investigating chitons (a type of marine mollusc) because of their radula, a specialised organ containing 70 to 80 parallel rows of teeth. The chitons use this to eat algae off rocks, so that when grinding the rock wears out their teeth, there is always a new layer that can enter the ‘wear zone’.
Kisailus has previously found that these teeth contain magnetite (magnetic iron oxide), the hardest known biomineral on earth, making them useful starting-points for research into impact-resistant materials. In the paper published this week, he set out to determine how the hard, magnetic outer region of these teeth are formed.
He found that this process occurred in distinct stages, involving ferrihydrite (hydrated iron oxide) crystals nucleating on a chitinous organic template. These then undergo a solid-state transformation to become magnetite. These magnetite particles then grow along organic fibres, which creates parallel rods in the mature teeth, giving them their toughness. The amazing thing about this process that that it “occurs at room temperature and under environmentally benign conditions” says Kisailus. Therefore, he hopes to use principles from this biomineralisation process to guide his work into the growth of minerals that are used in solar cells and lithium-ion batteries.
If the crystal size, shape and orientation are controlled in the engineering nanomatierals, he believes this could create more efficient solar cells, that could capture and convert more sunlight into electricity, and more efficient lithium-ion batteries, which would recharge more quickly. As well as improving efficiency of batteries, using the formation of these snail teeth as inspiration would mean engineering nanocrystals could grow at lower temperatures, reducing production costs. And it’s not just batteries that could be based on these principles, materials for car and airplane frames and even development of abrasion resistant clothing could benefit from understanding this process.
This is another example of how nature often has the best solution, and by imitating it we can come up with technological advances that evolution developed thousands of years ago.
Wang, Q., Nemoto, M., Li, D., Weaver, J. C., Weden, B., Stegemeier, J., Bozhilov, K. N., Wood, L. R., Milliron, G. W., Kim, C. S., DiMasi, E. and Kisailus, D. (2013), Phase Transformations and Structural Developments in the Radular Teeth of Cryptochiton Stelleri. Adv. Funct. Mater.. doi: 10.1002/adfm.201202894
