Dutch designers Suzanne Oude Hengel and Joris de Groot have developed an innovative sneaker crafted entirely from a single material: thermoplastic polyurethane (TPU). Their research-led project, Welded Loop, explores the potential of TPU as a fully recyclable, multi-functional material that can be knitted, 3D printed, and welded—eliminating the need for additional adhesives or mixed-material components.

A Sustainable Alternative to Traditional Footwear
The majority of contemporary shoes are difficult to recycle due to their combination of diverse materials and adhesives. Welded Loop proposes a more sustainable alternative by ensuring that every component—including the knitted upper, the 3D printed sole, and decorative details—is made entirely of TPU. By welding the parts together instead of using glue, the design improves recyclability and streamlines the manufacturing process.

Collaboration and Expertise
The project brings together the expertise of both designers: Oude Hengel, founder of textile design studio Knit in Motion, specializes in knitted materials, while De Groot has extensive experience with high-frequency welding, a precision method for joining plastic components. Their collaborative effort has resulted in a mono-material sneaker that maintains both functionality and aesthetic appeal.

The Manufacturing Process
The process involves only a few key steps. TPU yarns are knitted into a templated textile structure. 3D printed TPU eyelets are welded onto the upper. The material is thermoformed around a mould to create the shoe’s shape. Finally, the upper is welded to the 3D printed TPU sole.

With just three welds, the entire shoe is assembled efficiently while maintaining an intricate and contemporary aesthetic. This streamlined approach reduces waste and simplifies recycling, making the shoes a promising option for circular fashion and sustainable product design.

Expanding Applications of TPU
The Welded Loop project originated when the designers discovered the availability of 100% TPU yarns. Unlike conventional TPU applications, which tend to be airtight and impermeable, knitted TPU introduces breathability and flexibility, expanding its potential uses across various design industries.

Beyond Footwear: Broader Implications
This innovation could inspire applications in product design, industrial textiles, and even architectural materials, where mono-material and seamless manufacturing processes can enhance sustainability. By eliminating adhesives and reducing material complexity, this approach aligns with the growing movement towards circular design.

Future Development and Commercial Potential
The project debuted during Dutch Design Week 2024 at the Something Bigger exhibition in Eindhoven, where the first research phase was presented. Supported by the Creative Industries Fund NL Experiment Grant, the initiative is still in its exploratory stage, with further material experiments planned.

Oude Hengel and de Groot aim to refine their techniques and explore additional applications for mono-material textiles beyond footwear. While they hope to collaborate with commercial partners in the future, their primary goal remains pushing the boundaries of TPU’s capabilities before finalizing a market-ready product.

Source: Dezeen
Photos: Knit in Motion, Joris de Groot