Extrude it Like Nature

Nature is a better 3D printer than we are. Whereas our version laboriously lays down separate thin layers, nature can extrude complex 3D structures like a bird’s feather or a butterfly’s optically tuned wingscale in a continuous process.

There is no reason that such continuous fabrication should be beyond human ken and, indeed, a paper by Tumbles ton et al in Science (20 March 2015) describes just such continuous 3D printing. The technique uses continuous liquid phase stereolithography with a “dead zone” in which controlled oxygen inhibition prevents the resin curing in that region. The location of the dead zones is of course specified by a computer programme in the usual way. Feature resolution is below 100 micrometres and objects that would take hours by layered 3D take minutes with the new technique.

This work is truly exciting: a great breakthrough in our morphological abilities but what is strange about the paper is that the techniques  origin in nature – biomimetics, in other words – is never mentioned. Odd, because a high proportion of published papers these days include the word “biomimetic” in the title. It is a buzz word.

One technique of continuous printing produces gyroid patterns and this makes the omission of the biomimetic angle even stranger because the gyroid is one of the ways that butterfly wingscales are formed.

There have been many other examples  of independent discvery of phenomena by nature and Homo sapiens (structural colour for instance was discovered without reference to those butterfly wing scales). Biomimeticians need to up their game: there is still plenty of low hanging fruit.

The story of the butterfly wing gyroids appears in my and Tom Grimsey’s Nanoscience: Giants of the Infinitesimal.