When it comes to the structural and electronic components of aircraft, they have to be able to stand up to constant mechanical stress and vibrations without cracking, yet they can't just be soft like rubber. And actually, the same thing applies to the outside of our teeth. Given that fact, a University of Michigan team led by Prof. Nicholas Kotov has created synthetic tooth enamel, which may someday be coming to an airplane near you.
When Kotov looked to nature for a stiff-yet-vibration-damping material, he also considered things like bones and shells. He discovered that tooth enamel is unique, however, in that it has the same basic structure ranging from species to species, over a period of millions of years – it's obviously a design that works, and that has worked for some time.
In natural enamel, there are stiff ceramic crystal pillars surrounded by a softer matrix of proteins. This structure is often repeated for several stacked layers, depending on the purpose of the tooth. As the pillars bend under pressure, the energy is dissipated into the surrounding matrix, keeping the pillars from breaking.
Working with Kotov, postdoctoral researcher Bongjun Yeom recreated this structure by first growing zinc oxide nanowires on a chip (taking the place of the pillars), and then adding two liquid polymers that flowed between the wires (to fill in for the proteins). He added numerous coats of the polymers, allowing each one to cure before applying the next.
All told, it took 40 coats to build up a layer of synthetic enamel measuring just one one-thousandth of a millimeter thick. He then repeated the whole process 20 times, stacking additional nanowire/polymer layers one on top of another. The end product reportedly "approached the ability of real tooth enamel to defend itself from damage due to vibrations."
Needless to say, the production process will have to be streamlined and automated before the material reaches widespread use. Ultimately, though, Kota hopes to see it find use in fields such as aerospace and electronics.
Source: University of Michigan
