The joint research project “InMIDoor” by the Institute for Circular Economy of Bio:Polymers at Hof University of Applied Sciences (ibp), KKT-Norsystec and Roos GmbH has developed an innovative approach for vehicle doors. Instead of installing many individual parts such as switches, levers and complex electronics, the new interior door panel offers all the controls in a single, flexible surface. The result: a lightweight, sustainable and intuitive solution.
Our aim was to combine functionality, sustainability and design in a single component. The technology developed makes it possible to integrate touch functions into flexible, bio-based plastics – this combination is unique to date.”
Prof. Dr. Thomas Meins
Research for the mobility of the future
This was to be achieved by developing a new type of injection molding process that enables the integration of capacitive control elements into three-dimensionally shaped plastic surfaces. The aim is to replace traditional mechanical switches in favor of flat, robust and attractive surfaces. The technology is based on so-called mechatronic integrated devices (MIDs), which combine electrical and mechanical functions in a single plastic component.
Sustainable materials and innovative pastes
Together with its partners, Hof University of Applied Sciences developed a conductive print paste structure and carried out various tests with pastes based on silver, copper and graphite particles. These were applied to polypropylene films using a screen printing process, the films were formed using a high-pressure forming process and then back-injected with natural fiber-reinforced biopolymers. The result was an environmentally friendly and functional interior cladding. The researchers tested various combinations of film, adhesion promoter and conductive ink in order to optimize adhesion and electrical conductivity.
Polypropylene is increasingly being used in automotive engineering because it is lightweight, sustainable and versatile. It reduces the weight of vehicles, lowers CO₂ emissions and is also a cost-efficient material that is easy to recycle.
The challenge was to create a conductive print paste structure that can be strongly deformed without losing its electrical function. The interaction of particle material, screen printing and drying parameters was crucial.”
Christian Roos, Managing Director of Roos GmbH
From laboratory to application
In several forming and injection tests, a demonstrator component was finally created – an armrest with an integrated heating function and capacitive touch surfaces. The result: a functional, lightweight and resource-saving component that could set new standards for vehicle interior architecture.
“The door of the future reacts to touch instead of the push of a button. And it is made of materials that significantly reduce our consumption of resources.”
Frank Schollmayer, KKT-Norsystec;
“With InMIDoor, we are demonstrating how scientific findings can be transferred directly into industrial practice,” emphasizes Prof. Dr. Meins. “This results in innovations that are not only technically but also ecologically convincing.”
Future prospects
The innovative manufacturing technology, which combines injection moulding, film integration and capacitive operating functions, is revolutionizing the production of state-of-the-art components with a wide range of applications in industries such as aviation, rail, medical technology and automotive. The focus is on the advanced manufacturing process: Precise injection molding, combined with sustainable carrier materials such as natural fiber-reinforced polypropylene, enables the production of complex, durable and environmentally friendly components. The integration of films and capacitive operating elements creates smooth, easy-to-clean surfaces that meet the highest hygiene and design standards. This process is characterized by high resource efficiency, promotes the use of recyclable components and significantly reduces the ecological footprint. With a predicted market potential of up to 6.5 million euros per year in series production, this technology underlines its role as a pioneering solution.
Funding
The “InMIDoor” project was funded as part of the ZIM program of the Federal Ministry for Economic Affairs and Climate Protection and ran from June 2022 to May 2025.
