Durable and wear-resistant bar stock for finger prosthesis

Profile

• What was needed: Reliable plastic bearings in the smallest possible installation space, resilient and aesthetically pleasing
• Manufacturing process: Made from bar stock
• Requirements: Load capacity, reliability in the smallest space, lubrication-free and precision
• Material: iglidur® J
• Industry: Prosthetics
• Success for the customer: A maintenance-free prosthesis solution for everyday use

Problem

Hand prostheses are becoming more flexible, delicate and functional and have become more and more similar to their human model. For people who have to live with the loss of individual fingers or a part of the hand, there has been no satisfactory prosthesis solution. The VINCENT finger closes this gap and opens up new opportunities for those affected. The company VINCENT Systems GmbH manufactures fingers for the everyday movement and thus offers prosthesis users an opportunity for a better existence in everyday life.
A clearance-free and wear-free transmission of forces is of great importance especially in the field of this very precise and sometimes heavily stressed application. The special requirements stem primarily from point loads that are caused by rapid and impulsive or oscillating movements.
A hand prosthesis must also be able to cope in very harsh environments in some cases and remain fully functional in dirty or wet application areas. Finally, a solution had to be found that would work in the smallest of installation spaces and that could be implemented with an aesthetically sophisticated design.

Solution

This prosthesis is an electrically powered finger. The joint at the base of the finger is moved directly via a gear motor, which carries along the middle joint via a flexible connection. All axes involved in this movement are mounted through plastic bushings made of iglidur J. A total of 8 such bearings are integrated in one finger. The control system of the prosthesis works via muscle signals, which are forwarded to a microcontroller. The energy supply is provided by 2 lithium-ion batteries.
The bearings machined from iglidur J bar stock are corrosion-resistant and have a low wear rate. Lubrication-free and maintenance-free properties are also two important criteria for use on the body, which the plastic plain bearings fulfil. In addition, they reduce the transmission of sound of the motor to adjacent joints to avoid complications. However, the bearing solution also fulfils the potential use in dirty or wet application areas with a long service life at the same time.