Niell Gorman and Jeff Feng
Commercial prosthetic hands have rapidly advanced in recent years, with new intelligent control systems and lightweight materials. Despite these breakthroughs, many upper-limb amputees cannot afford any type of functional prosthesis or lack insurance coverage that will pay for such a device. 3D printing technology promises to address this gap by allowing functional prosthetic hands to be produced at a low cost. However, current printed hand designs are limited by durability and grip functionality issues. Many of these issues are related to the use of rigid polylactic acid (PLA) plastic material favored for consumer 3D printers, which cannot accurately recreate the soft, compliant nature of the biological human hand. Thermoplastic polyurethane (TPU) filament is an elastic material that can be easily and cost-effectively 3D printed to create more realistic, compliant structures. Knack is an innovative low-cost functional prosthetic hand that uses a hybrid rigid/elastic printing process to increase performance. TPU is used to create simple compliant return springs and soft, grippy touch surfaces for the finger pads and palm. Knack uses a modular design approach, consisting of only 20 parts that snap together without additional hardware or adhesive. Knack achieves simplicity and realism without sacrificing durability, representing a significant advancement to the current market of 3D-printable prosthetic hands.
Niell Gorman and Jeff Feng