Children missing an upper limb face a wide range of issues. Besides the difficulties adult prosthetic users face, such as unsatisfactory function, comfort, and appearance, children also have to deal with the challenges associated with growth. The goal of this thesis was to design an appealing solution for these growing children with an upper limb deficiency. With the specific focus on accommodating the physical dimension changes, as well as their ever-changing tastes and preferences. To find solutions for these issues, a design process was started. Ideas were generated, which were narrowed down into 3 concepts, before the winning concept was further developed into the final design. Crucial aspects of the final design were then validated before finally the thesis work in its entirety was evaluated. The end result of the design process is the Frequently Replaceable Hand concept (FR Hand). Instead of replacing a prosthetic arm every 18 months, the arm is replaced every few months. This allows the arm to always be the right size and keep up with the changing demands of the growing user. For the concept to work, the prosthetic replacement process needs to become significantly easier, cheaper, and faster. In order to achieve this, two main parts were developed. First, a natural looking body-powered hand, which is 3D printed using a combination of flexible and rigid parts. The hand can be quickly and easily assembled without using any tools or fasteners. The 3D CAD (Computer Aided Design) model behind the FR Hand is designed from the ground up to be scalable. The hand’s dimensions are driven by 7 main independent variables.
Second, a Graphical User Interface (GUI) is developed. This allows the user or their family to generate a perfectly fitting prosthetic hand, without requiring any modeling experience or help from a professional. The resulting 3D model can then be sent to any 3D printing service to be printed and shipped to the user.
Some of the most significant aspects of the FR Hand were validated. The durability of the flexible hinges was tested by cycling the hand 300,000 times, none of the hinges failed. The scalability of the CAD model was tested by generating 1320 hands based on randomized dimensions derived from an anthropometric database, the program was able to generate 96% of the hands without any errors. The hand prototype weighs 99 grams, has an actuation force of 14 Newton and a single finger can handle a tensile load of 157 Newton. The FR hand costs under €6 in material costs and can be delivered to the user for less than €100. In conclusion, the FR Hand is a functional prosthetic hand system that is aesthetically pleasing, always the right size and keeps up with the user’s preferences, which were the goals at the start of this project. Currently, the scalable forearm and socket interface to accompany the FR Hand are missing. Overall, the FR Hand is not ready yet to be deployed in the real world, more development and testing need to be conducted before this is a viable option for growing children missing an upper limb.