Fraunhofer IWM
3D printed insole
With a combination of different structures in an insole, localized rigidity is digitally adjustable.
A group of researchers are working to digitalise the manufacturing of shoe insoles for patients with diabetes using 3D printers.
In the past, these insoles were hand-made by orthopaedic shoemakers. But the Fraunhofer Institutes for Mechanics of Materials IWM and Environmental, Safety and Energy Technology UMSICHT researchers are hoping to advance this process thanks to new software and 3D technology. Specialist shoemakers will not only be able to produce more cost-effectively insoles, but also means the mechanical properties can be assessed scientifically and more effectively.
The end result should mean greater comfort for diabetes sufferers whose nerve endings in their feet are atrophied. This means the person can not necessarily feel a soreness in the foot, giving rise to pressure points and eventually leads to wounds not healing properly. In some cases, this leads to Charcot Foot, where the bones also begin to weaken and fractures become more common.
A remedy, or at least some relief, can be found in the use of insoles that are very soft in areas of injury. These insoles are often custom-made by orthopaedic shoemakers in a variety of materials.
Up to now, it has been virtually impossible to assess the success of insoles scientifically because each insole is unique. It is in the interest of health insurance companies to have the process of manufacturing insoles digitalised to allow the collection of scientific data.
LAUF, a German acronym for laser-assisted construction of customised footwear, refers to a project funded by Germany’s Federal Ministry of Education and Research. The team of researchers is collaborating with industry partners on the process of digitalisation.
Fraunhofer IWM
3D printed shoe insole
3D structures made of TPU for insoles. These structures were designed using CAD, and their properties were simulated and compared with experiments.
“Digital foot mapping is already common practice,” said IWM scientist Dr Tobias Ziegler. “Using newly developed software, the orthopaedic shoemaker can design an insole for an individual patient and can print out the result on a 3D printer.”
This process will satisfy health insurances companies, as the mechanical properties of each insole can be sufficiently assessed., as well as reducing manufacturing cost. Within around two years, this software may be available to orthopaedic technicians throughout IETEC, a member of the project.
Covestro and Lehamn & Voss & Co laid the foundations for the 3D printing of insoles some years ago. These industry partners were the first to develop a soft material for 3D printing in the form of thermoplastic polyurethane (TPU). Working with UMSICHT experts, they are now developing other types of TPU that are expected to be even more suitable for use in orthopaedic insoles.
Meanwhile, IWM scientists have been optimising the three-dimensional structures required of TPU when used for insoles. How soft or rigid insoles are depends on the material and the way it is shaped.
