The Fluidhand 6 is a particularly compact version of the hydraulic hand prosthesis, reduced to the essentials. The index, middle and ring fingers are each moved in the base joint via a flexible bellows drive, the little finger is mechanically coupled to the ring finger, and the middle finger is hydraulically coupled to the ring finger. The thumb is actuated in the basic joint. In this way, the thumb and index finger can be moved separately, while the other fingers move together. The 4 drives are controlled by a 3 valve bank, the miniature pump sucks distilled water from a pressure storage tank to pump it into the drive chambers. The weight of the hand is about 350 g. The aluminum fingers were covered with a PU foam. In the basic joints, all long fingers have an elastically mounted abduction.

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At this stage of development, experiments were carried out with different variants of the fluid hand, with the number of joints and drives as well as the required valves being varied considerably. The aim was to find an optimum between size, anatomical design and weight on the one hand and functionality on the other. Extremely reduced versions with only 4 drives and three valves, such as the Fluidhand 6, were built, which could be designed in this way to be very small, light and anatomical. This version of the Fluidhand is a particularly interesting candidate for a robust prosthesis suitable for everyday use, since the smallest number of hydraulic components was installed here. The systems are very light throughout, but also very complex in terms of the physical effects that occur, such as cavitation or the problem of changing material parameters, especially the elastic drives and connecting hoses in the course of operation, as well as wear and corrosion on the valves and the pump.