Shoes that stick and clothes that reveal

What we wear isn’t just about comfort and style when scientists get involved. Function rules fashion.

Two recent innovations include a Swiss fabric that can detect a body’s movements and a friction-boosting material with the potential to give shoes serious grip when needed. One is all high-tech; the other borrows from a traditional art form.

The fabric is actually not just for clothing. Fabien Sorin and Andreas Leber from Ecole Polytechnique Fédérale de Lausanne say a material that can monitor breathing as well as physical gestures might just as easily be used for hospital bed sheets, or to make human interactions with robots more intuitive.

At its heart is a single sensor that can detect different kinds of fabric deformation – such as stretching, pressure and torque – at the same time.

“Our technology works similar to a radar, but it sends out electrical impulses instead of electromagnetic waves,” says Leber. “Our fibre sensors operate like transmission lines for high-frequency communication.

“The system measures the time between when a signal is sent out and when it’s received, and uses that to determine the exact location, type and intensity of deformation.”

Creating the fibres is a complex task involving liquid metal, which serves as the conductor, and an optical fibre fabrication process. The structure is just a few micrometres thick and turns the entire surface of the fabric into a sensor. But it has to be perfect, or it won’t work.

“The trick was to create transmission lines made entirely of flexible materials, using a simple method that can be scaled up easily,” says Sorin. The next step will be to make the technology more portable by shrinking the electronic component.

The research – which is described in a paper in the journal Nature Electronics – drew on a variety of disciplines, including electrical, mechanical and process engineering and materials science.

Engineers at the Massachusetts Institute of Technology in the US created the clever shoe soles, while also continuing the quest to find modern applications for the ancient Japanese art of kirigami (origami with cutting).

Sahab Babaee and colleagues used it to create intricate patterns of spikes in a sheet of plastic or metal that remain flat while a wearer is standing but pop out during the natural movement of walking.

They created and tested several different designs, including repeating patterns of spikes shaped like squares, triangles, or curves. They also measured the friction generated by each design on a variety of surfaces, including ice, wood, vinyl flooring, and artificial turf.

They found that all of the designs boosted friction, with the best results produced by a pattern of concave curves.

When coatings with this design subsequently were applied to a range of footwear for tests with human volunteers, the amount of friction generated was 20-35% percent higher than for shoes alone.

The researchers are now working on determining the best way to incorporate the kirigami surfaces – either embedding them into the soles or creating a separate element that could be attached when needed.

The Royal Institution of Australia has an education resource based on this article. You can access it here.