Sustainability meets robotics: Ankle and knee prostheses made of paper-based composites
The first robotic cover of ankle and knee prostheses made from a new environmentally responsible material was presented at the JEC World 2026 event at the Paris Nord Villepinte Exhibition Center, France. The prototypes stem from the collaboration between the Istituto Italiano di Tecnologia (Italian Institute of Technology) and the start-up Alkivio (part of the Novacart Group), which produces a new innovative composite, based on paper, named AlkiPaper.
The ankle and knee prostheses are part of Omnia, a novel lower-limb prosthetic system designed for individuals with transfemoral amputations. The system was developed by the Rehab Technology Lab of the Istituto Italiano di Tecnologia with INAIL (Italian National Institute for Insurance against Accidents at Work), coordinated by Matteo Laffranchi. The lab is responsible for the development of prosthetic and rehabilitation medical devices. The original system comprised a motorized knee (Unico) and a motorized ankle (Armonico). For the JEC World exhibition, researchers replaced the plastic covers of Unico and Armonico with AlkiPaper biocomposites.
The result is a unique prototype that combines advanced health care technology with environmental sustainability.
Armonico features an elastic foot coupled with an innovative screw mechanism that assists amputees during the initial foot strike by reducing heel impact for enhanced comfort and by lifting the toe during each step to prevent tripping. Unlike passive foot prostheses, Armonico actively amplifies the ankle's flexion angle, providing greater stability on sloped surfaces and ensuring more natural movement.
The Unico knee combines hydraulic and electric technologies. The hydraulic system ensures smooth, quiet, and energy-efficient movement during level walking and descending, while the electric system actively assists with demanding tasks such as climbing stairs, steep slopes, and standing up. The prosthesis has a battery lasting a full day under maximum use, supports up to 125 kg, and fits both right and left knees. It is customizable to the user's height and can be software-adjusted to match sedentary or active lifestyles.
AlkiPaper is a family of biocomposites alternative to plastics developed by Alkivio, a start-up company that originated from the joint research laboratory between the IIT Smart Materials group and Novacart. Established as a start-up in 2022, Alkivio (from the ancient Greek meaning "the force of life") produces AlkiPaper in pellet form thanks to a patented technology licensed from Novacart and IIT. The material is designed to be biodegradable, compostable, environmentally sustainable, colorable, and compatible with the major industrial processes used for plastics, such as injection molding, extrusion, thermoforming, 3D printing, and blow molding.
For some grades of AlkiPaper, biodegradability under controlled conditions has been confirmed by accredited laboratories, while industrial composting certification is ongoing. The biocomposites are mainly made from natural components, including paper from virgin cellulose or industrial residues, and are used in rigid and semi-rigid products for packaging, design, agriculture, sports, and electronics.
To make Armonico and Unico more environmentally sustainable, Alkivio formulated and optimized experimental grades of AlkiPaper biocomposites specific for 3D printing to meet the required aesthetic and mechanical performance standards. The Rehab Technology Lab at IIT used AlkiPaper pellets and filaments to manufacture the prosthesis covers. The next steps to further develop the prototypes will involve technical features validation in relevant environments and material compliance assessments for this end-use.
This achievement opens new possibilities for integrating more sustainable materials into future robotics technologies, thereby reducing the environmental impact of both production and end-of-life disposal.
Provided by Italian Institute of Technology
