Welcome back to our exploration of cutting-edge research made possible, in part, by the precision and flexibility of the Sharebot Snowwhite SLS 3D printing technology. Today, we are featuring the study ‘Design and fabrication of a modular ergonomic saddle for rehabilitation cycling through a combined additive manufacturing approach.‘ This research highlights how the Snowwhite’s open-system capabilities allow scientists to move beyond standard manufacturing, enabling the development of complex, patient-specific lattice structures in TPU. To begin, we will provide a straightforward explanation of how the researchers optimized these materials and the main results they uncovered. Following this accessible overview, we will share the original abstract and relevant citations for a more in-depth look at the data.

Research Summary: A Modular Saddle for Rehabilitation

This study focuses on creating a high-tech, customizable bike saddle specifically designed for patients in physical rehabilitation. Traditional saddles can be uncomfortable or lack the specific support needed for medical recovery, so the researchers turned to 3D printing to create a “hybrid” solution.

The Design Approach

The researchers used a two-part modular design to balance strength and comfort:

  1. The Base: Made of stainless steel using Laser Powder Bed Fusion (LPBF) to provide a rigid, reusable foundation.

  2. The Cover: This is where the SLS technology shines. The researchers needed a material that was flexible yet durable, eventually choosing TPU (Thermoplastic Polyurethane) over Polypropylene (PP).

    Production cycle for modular saddle

Why SLS was Critical for Research

The study used SLS to create complex “Gyroid Lattice” structures. These are porous, sponge-like internal patterns that allow the saddle to be soft in some areas and firm in others. By using a research-grade SLS printer, they were able to test different cell sizes and wall thicknesses to find the “sweet spot” for patient comfort.

The Testing Process

  • Material Screening: They used thermal analysis to prove TPU was easier to process and better at absorbing energy.

  • Durability: They “tortured” the printed TPU covers with 10,000 compression cycles to ensure they wouldn’t lose their shape during long-term use.

  • Computer Modeling: They used Finite Element Method (FEM) simulations to predict how the saddle would deform under a rider’s weight.

The Discovery: What did they find?

The researchers successfully proved that modular additive manufacturing is both technically and economically viable for medical equipment.

The specific “Breakthrough” findings were:

  • The Optimal Geometry: They identified that a gyroid lattice with an 8 mm cell size and 0.3 mm wall thickness provided the perfect balance—it was flexible enough for comfort but stable enough not to break or permanently deform.

  • Economic Sustainability: Because the expensive metal base is standardized and reusable, only the 3D-printed TPU cover needs to be customized for each patient. This significantly lowers the cost of personalized medical gear.

  • Functional Success: The final prototype was not just a lab experiment; it was successfully mounted and tested on a real cycle ergometer, proving it works in the real world.

Development of an Ergonomic Additively Manufactured Modular Saddle for Rehabilitation Cycling

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1 Institute of Polymers, Composites and Biomaterials (IPCB), National Research Council (CNR), Via Gaetano Previati, 1/E, 23900 Lecco, Italy
2 Institute of Condensed Matter Chemistry and Technologies for Energy (ICMATE), National Research Council (CNR), Via Gaetano Previati, 1/E, 23900 Lecco, Italy
3 Institute of Intelligent Industrial Technologies and Systems for Advanced Manufacturing (STIIMA), National Research Council (CNR), Via Gaetano Previati, 1/E, 23900 Lecco, Italy
4 Institute of Polymers, Composites and Biomaterials (IPCB), National Research Council (CNR), P.le E Fermi 1, 80055 Portici, Italy

Abstract

This work reports the design, fabrication, and validation of a modular ergonomic saddle for rehabilitation cycling, developed through a combined additive manufacturing approach. The saddle consists of a metallic support produced by Laser Powder Bed Fusion (LPBF) in AISI 316L stainless steel and a polymeric ergonomic covering fabricated via Selective Laser Sintering (SLS) using thermoplastic polyurethane (TPU). A preliminary material screening between TPU and polypropylene (PP) was conducted, with TPU selected for its superior elastic response, energy dissipation, and more favourable SLS processability, as confirmed by thermal analyses. A series of gyroid lattice configurations with varying cell sizes and wall thicknesses were designed and mechanically tested. Cyclic testing under both stress- and displacement-controlled conditions demonstrated that the configuration with 8 mm cell size and 0.3 mm wall thickness provided the best balance between compliance and stability, showing minimal permanent deformation after 10,000 cycles and stable force response under repeated displacements. Finite Element Method (FEM) simulations, parameterized using experimentally derived elastic and density data, correlated well with the mechanical results, correlated with the mechanical results, supporting comparative stiffness evaluation. Moreover, a cost model focused on the customizable TPU component confirmed the economic viability of the modular approach, where the metallic base remains a reusable standard. Finally, the modular saddle was fabricated and successfully mounted on a cycle ergometer, demonstrating functional feasibility.