‘Super-grippy’ sole developed using a Japanese paper-cutting technique known as kirigami could make shoes better suited to walking on ice
- Kirigami is an origami-like paper art which uses cutting in addition to folding
- US Experts created kirigami sheets that have spikes that pop out when stretched
- In tests, sheets increased friction on ice by 20–35% when attached to shoe soles
A ‘super-grippy’ sole developed using a Japanese paper-cutting technique — known as kirigami — could make shoes better suited to walking on ice, a study has found.
Kirigami is a Japanese art similar to origami, except it makes use of intricate cuts to the paper, rather than relying on folding alone, to create striking 3D art.
Researchers led from the Massachusetts Institute of Technology created a kirigami pattern of concentric circles that folds into spikes when stretched.
Applying this to the soles of shoes, they found it could increase friction when walking on ice by up to 35 per cent — with the potential to help people avoid falls.
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A ‘super-grippy’ sole developed using a Japanese paper-cutting technique — known as kirigami — could make shoes better suited to walking on ice, a study has found
‘We set out to address the challenge of preventing falls — particularly on icy, slippery surfaces — and developed a kirigami-based system that facilitates an increase of friction,’ said paper author and mechanical engineering Giovanni Traverso of MIT.
Kirigami has recently been used by other researchers to develop bandages that adhere more easily to tricky surfaces like knees and other joints, as well as sensors than can be places on the skin of soft robots to help them orient themselves.
In their study, however, Professor Traverso and colleagues used the art to fabricate an intricate pattern of spikes in a sheet of material — either stainless steel or plastic.
When the sheet is attached to the sole of a shoe, this pattern — while remaining flat when the wearer is standing still — exposes its spikes when bent by the motion of walking.
‘The novelty of this type of surface is that we have a shape transition from a 2D flat surface to a 3D geometry with needles that come out,’ said paper author and engineer Sahab Babaee, also of MIT.
‘You can use those elements to control friction, because the sharp needles can pop in and out based on the stretch that you apply.’
As part of their study, the team explored various designs — including repeating spike patterns shaped like curves, squares and triangles — lain out at different sizes and in different arrangements.
Exploring the angle at which the spikes popped out in each design — alongside the friction such could generated on surfaces including ice, wood, vinyl flooring and artificial grass.
The researchers found that all of the designs increased friction — but that the best results were produced by a pattern that involved an arrangement concave curves.
When attached to the soles of shoes worn by volunteers over a special force-measuring plate covered in an inch of ice, the team found hat the kirigami sheet increased friction underfoot by was 20–35 per cent.
Kirigami is a Japanese art similar to origami, except it makes use of intricate cuts to the paper, rather than relying on folding alone, to create striking 3D art, pictured (stock image)
With their initial study complete, the researchers are now exploring different ways to integrate the kirigami surfaces into footwear — which would see the patterns built into soles, or alternatively as an attachable accessory akin to a snow chain.
At the same time, the team are also experimenting with different materials — for example, a rubber-like polymer which features reinforced steel tips — and testing the design on other surfaces, such as in wet or oily working environments.
‘We’re looking at potential routes to commercialise the system, as well as further development of the system through different use cases,’ Professor Traverso said.
The full findings of the study were published in the journal Nature Biomedical Engineering.