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Compostable wood foam replaces plastic in shoe insoles

Published: 18.6.2024

Aalto University students develop prototype of durable wood-based insole – Finnish shoe company starts testing material on users this autumn

insole at pdp gala — The insoles were on display at the Aalto University PDP gala. Image: Adela Navratilova / Aalto University

Students at Aalto University have developed a wood-based material suitable for shoe insoles. A particular advantage of the new type of insole is its ability to withstand repetitive loading, which has previously been a challenge in foam-like biomaterials.

The material was created in a product development project course (PDP), where a team of students, with the support of researchers, aimed to develop a polyurethane-like biofoam for the textile industry. The team, made up of engineering and art and design students, worked together for nine months. A patent has been applied for in Finland for the new type of insole.

‘The sample insoles we developed are made through a heat press die process and they nicely take the shape of the mold. We have performed extensive testing of the insoles with users and taken their feedback on how they feel about this material’, says project manager, mechanical engineering student Taha Qureshi.

In the insoles' layered construction, a hard, biodegradable material forms a thin mesh inside a soft filling material. The hard material protects the soft from excessive pressure, while the soft material protects the hard from damage caused by flexing. The result is an insole that feels soft and supple against the skin.

The innovation builds on fundamental research on foams at the Aalto University Department of Applied Physics, which in recent years has focused on replacing plastics with wood-based materials. A major advantage of such materials is their closed-cell structure, which makes them strong and heat-insulating.

The students managed to solve one of the basic weaknesses of such materials.

‘The real challenge with foam-like biomaterials is the repetitive loading’, says Research Fellow Juha Koivisto, sponsor of the project. ‘It’s much easier to create strong and lightweight materials than ones that endure cyclic loading with elastic and soft response. The insole the students have created really feels like its oil-based polyurethane alternative’.

Hoping to bring insoles to consumers in just over a year

The plan is to start piloting the soles in the autumn with the Finnish shoe brand VIBAe. Kalle Gummerus, a founding member of the company, says the hope is to have shoes with the new sole material on sale in just over a year.

Gummerus came across the foam research at Aalto University through a press release a few years ago when he was looking for an environmentally friendly material for VIBAe insoles.

’The polyurethane we use today is the only non-ecological part of our shoes. There was simply no environmentally friendly alternative with the same properties. After reading about Aalto University's materials research, I contacted the researchers and as a result we started a collaboration to develop their wood foam to make it more suitable for shoes, i.e. moisture resistant and elastic. Now we have reached the point where we can start testing the insoles on users in the autumn’.

The students will continue their research at least through the summer, while investors are sought for the project. The researchers also see wider potential for the material.

‘The insole is the perfect proof-of-concept for market entry in a textile industry due to the extreme loading conditions insoles experience in use. If the material fills the needs of the insole, it will fill the needs of any other textile’, states Koivisto.

The project follows on from the earlier FoamWood project and its spin-off company Woamy Oy. The aim of the student project was to add functionality to the bio-foam developed by Woamy, originally designed as a packaging material to replace styrofoam. The advantage of this material over styrofoam is that it is compostable and consists entirely of wood-based raw materials without harmful chemicals or microplastics.

The new insole was tested at the Aalto University PDP Gala in May, where it received a lot of positive attention. The Product Development Project (PDP) course allows students to work in multidisciplinary teams on real business challenges. For more than 25 years, the highly popular course has brought together business, engineering and design students with partners from a range of disciplines, from large companies to start-ups. The course's pedagogy is based on problem-based learning, and some of the most valuable learning experiences include working in a multidisciplinary team, as well as producing prototypes to be presented at the gala. This year, 16 teams participated, with projects ranging from microplastic filters to sprayable building materials.

Contact:

Juha Koivisto
Research fellow
[email protected]
0504419 233

Taha Qureshi
041 7236 512
Project manager, student
[email protected]

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