We have our feet to thank for walking, standing, running and so many other activities. They take the weight of the entire body day in, day out, so they are often overworked.
It has been calculated that in the Western World, every human being, during an 80-year lifetime, walks on average around 174.000 kilometers. That is about half the distance between the Earth and the Moon.
Most of that is covered encased in shoes, so research is underway in the laboratories of Geox in Montebelluna near Venice to keep your feet dry, and comfortable.
Along with scientists at Venice and Padua University, and the Jozef Stafan Institute in Ljubljana, Slovenia they have been studying a special micro-porous membrane. Once applied inside a shoe, it uses physics to do its job.
Everything starts with the study of anatomy and physiology of the foot, and in particular the mechanism of heat exchange between the feet and the external environment. When muscles in the feet contract, they produce heat, which must be dissipated.
“In contrast to other parts of the body, the foot doesn’t have very many heat generating organs; those are in the rest of the body. So really the foot is like a radiator. The heat must come to the foot, like to the hands, and we must lose this heat to the environment by the sweating or evaporation, and also by heat-loss from the skin,” says Environmental Physiologist Igor B. Mekjavic of the Josef Stafan Institute.
The membrane allows the dissipation of water vapor molecules caused by sweating, but is a barrier to external humidity and keeps the foot dry.
“The membrane is a micro-porous material, characterized by high permeability and high breathability. Its main characteristic is the pore dimension, as we can see in a microscope picture magnified 12.000 times.
In particular, the dimension of every single pore is 20.000 times smaller than a water molecule, like for example a molecule of rain. But it is 700 times bigger than a molecule of water steam, as a molecule of sweat. This means that you can put the membrane on a pierced sole, as in this case.
This will stop water passing through the porous membrane and getting inside the shoe, while allowing sweat to escape through the sole,” says researcher Marta Toffoletto.
To improve its performance, the membrane undergoes a number of tests. The transpiration test measures the quantity of water vapour passing through the membrane and its condensation on a glass surface.
In a tank bubbles show how air from the lower chamber can cross the membrane If the membrane is waterproof, the lower chamber stays perfectly dry.
Using humidity sensors and thermo cameras it is possible to analyze the performance of the membrane on a person while they are walking.
“The objective of our research is to study the breathability of these materials, in terms of mechanical resistance and duration. We started the research many years ago, and while we are making progress there is a long way to go,” says researcher at the University of Venice Marco Ganzina.
Applying technology to the shoe seems long overdue, and it is not stopping here.
“Smart wear is another very interesting area. That means putting sensors into clothing and footwear, which provide people with feedback and knowledge about the status of the body and the feet. If we have children who are incapable of telling us that they are cold or hot, or the elderly, then this data, maybe conveyed to a Smartphone, or i-pad or whatever, will allow us to monitor their well-being. In this case, you’d be sure the feet were at an optimal temperature,” says Mekjavic.
A lot more research is still needed until we can get our hands on the so-called shoes of the future, and give our feet a break.
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