Possible breakthrough for trail shoes

Why Mud Doesn’t Stick - Dr Yuying Yan
(TZ's comments in italics.)

Earthworms and dung beetles could hold the answer to sticky engineering problems according to Dr Yuying Yan of Nottingham University who is working with Colleagues at Jilin University in China on a Royal Society International Joint Project, to understand how good design from nature can be applied in engineering. (And trail running.)

Dr Yuying Yan, a thermofluid scientist and Senior Lecturer at the University of Nottingham, is interested in biomimetics how we can use the natural solutions that plants and animals have developed throughout evolution to address the problems that scientists and engineers (and trail runners) face today. In particular, he is currently interested in the special anti-adhesion qualities of soil animals such as earthworms or dung beetles which enable them to burrow through moist soil without mud sticking to them, with the hope that these mechanisms could be used to develop longer lasting and more efficient agricultural equipment and stirring blades (and running shoes.)

If you move machinery through moist soil, adhesive forces between the soil and the machinery make the soil stick, causing resistance, increasing energy consumption and reducing the quality of the work (or run.) At the same time however, soil doesn't seem to adhere to some burrowing animals. We are trying to find out why not, explains Dr Yan.

In 2003, Dr Yan was awarded a Royal Society Grant for an International Joint Project to enable collaboration with one of the Chinese pioneers of Biomimetics Professor Luquan Ren from Jilin University. While much experimental study and biomimetic design has been carried out in Jilin University in the course of the last few years, the mechanism of anti adhesion and the potential for design based on this mechanism remained largely unexplored. With the support of the Royal Society's international grant, Dr Yan has visited the laboratory at Jilin University in 2003 and 2004 to work with his collaborators in analyzing experimental data; and Professor Ren and his assistants have in return visited Nottingham. Dr Yan feels that he is making real progress thanks to the collaboration and has now developed techniques to simulate the surface interactions which could provide useful models to help us understand the complex biomimetics problems (like why the mud on the Powerline trail cakes up with 10 friggin pounds of mud per shoe!)

Dr Yan commented: We now have a much better understanding of the mechanism by which an earthworm is capable of anti-soil-adhesion. Earthworms and dung beetles carry bioelectricity of a few millivolts, so when they move in the moist soil, a microscopic electro-osmotic system is formed. This drives the water in the moist soil to the surface of the animal, forming a micro layer of liquid which, along with secretions from the animal, lubricate the surface.

An electro-osmotic system requiring 12 volts of electricity has now been designed at Jilin University to enable this principle to be tested for engineering applications. (Can trail running shoes be far behind?) As a thermofluids scientist, I have spent quite a few years studying the conventional problems of fluid flow and heat transfer in heat exchangers and the process industry; the study of biomimetics has indeed broadened my thinking. Now I am focusing on more of the interactions between the surfaces of biological bodies and their surrounding environment, and thinking about how this can be applied to a wider range of engineering applications. It is really challenging and could have a great impact in the engineering world. (And an even bigger impact to ultra runners.)