Precise thumb movement with lubrication-free lead screw technology in bionic hand prosthesis

• What was needed: high helix lead screw with lead screw nut for precise adjustment of the thumb position
• Requirements: long service life, high efficiency, low weight, 100 % lubrication- and maintenance-free, cost-effective
• Industry: Medical technology, mobility and rehab
• Success for the customer: With the current solution, the costs are optimised in relation to the function of the hand prosthesis.

The biggest challenge in the development of hand prostheses is the finger mechanisms. The aim is to achieve the most accurate possible reproduction of the movement ranges that match or come very close to human anatomical capabilities. In addition, an attempt was made to define the values for gripping force as closely as possible to the challenges of everyday patient life.

The thumb is the strongest finger of the hand and its correct position is crucial to enable certain grips that are necessary for everyday use. When the thumb is positioned correctly, the patient can grip or lift better. This is particularly important for activities such as holding cutlery or opening doors. When adjusting the finger position, it is important to ensure that the thumb can make small, precise movements that correspond to its vertical axis. This should enable finer control and accuracy when handling objects.

The designers at Aether Biomedical were looking for the right linear technology to optimise the thumb's movement mechanism.

The dryspin® steep thread in combination with the lead screw nut aus iglidur® W300 offers the patient the ability to safely perform precise movements to change the position of the thumb. This is of immense importance for accuracy and control in everyday activities.

The steep thread and lead screw nut operate quietly, which increases patient comfort. In addition, the coordinated components ensure smooth movement without the patient having to exert any additional force. For example, objects weighing up to 35 kg can be lifted. The prosthesis helps the patient to stand up from a seated position, thus ensuring additional stability and safety. The patient can be 100% confident that the movements will be reliable and without unexpected disruptions. dryspin® lead screw technology requires no external lubrication or maintenance. From both the designer's and the patient's point of view, these are important plus points in terms of functionality and user-friendliness.