The Hybrid Finger: Combining Nature with Technology into a 3D Printed Finger for a Hand Prosthesis with Minimized Assembly

Access to prosthetics is very limited to many potentialusers, while the need is high. There are two main reasonsfor this that both are related to the production of prosthetics: the lack of skilled people and high costs. Minimizedassembly production using 3D printing could be a solution: no training is required, assembly takes only a shortamount of time and cheap materials can be used. Besides,3D printing is a good method for customization. Therefore, this study proposes a 3D-printed finger for a bodypowered hand prosthesis with minimized assembly. Thedesign approach is the following. First, the human fingeranatomy is studied. Then, a stylized version of the humanfinger is made that includes only the functions required forthe prosthesis. Finally, the design principles of the stylizedfinger are evaluated and structurized. Based on the designprinciples, a finger for a prosthetic hand is designed anda prototype is developed. The prototype is produced withan Ultimaker 3 using a rigid and a flexible material in oneprint. The evaluation of the prototype shows promisingresults. The finger is suitable for a hand prosthesis thatcan perform an adaptive power grip and a pinch grip. Themass of the finger is 17 grams, which makes the fingercomfortable to wear. An actuation force of only 16 N isrequired to fully bend the finger. Minimized assembly andcheap production are achieved: only four assembly stepsare required and the material costs are only 1.68 eurosper finger. In conclusion, the prototype shows a promisingstep in the direction of a hand prosthesis that is affordable,functional, body-powered, and has minimized assemblyMechanical Engineerin