Anthropomorphic prosthetic finger with actuation and elastic return by cable with adjustable pre-tensioning. Possibility of under-implementation with preservation of the adaptability and differentiality of closure.

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The advanced prosthetics was valued as $1.42 billion in FY 2018 and is forecasted to grow with a CAGR of 10.31% in the period of 2019-2024 and is estimated to be valued $2.55 billion in FY 2024.


The problem consists in the creation of prosthetic fingers capable of generating a grip of objects as natural as possible and close to the behavior of human fingers. The main need is therefore that of designing a finger adaptable to the object with which it comes into contact, and characterized by a certain number of degrees of freedom, which guarantees a wide range of movement both in the implemented phases and in those of passive movement. A further problem is the possibility to easily choose and vary the trajectories and closing sequences of the finger, in order to choose how the finger will close and with what grasping speed / grasping. Another problem is the reliability of the finger system, able to withstand the opening and closing cycles for the entire life of the device in the hands of the user.

Additional but necessary features are the overall robustness of parts and mechanism, lightness and the possibility of aesthetic customization of the parts.

The existing under-implemented prosthetic fingers, currently on the market, involve the use of mechanisms constructed by means of rigid rods hinged together, incorporated into the body of the phalanges. With the use of this type of mechanism, both the flexion of the phalanges and the extension of the same are implemented by means of leverage. This is positive for the duration of the mechanism but limits the adaptability of the device when gripping objects (highly disabling feature).

Current Technology Limits

  • Current existing solutions typically present different critical issues such as:
  • Typically only one degree of freedom (dof) is implemented for each finger, drastically limiting the overall movement to a very different grip than that of the human hand. The only solutions which have a movement comprising more than one dof per finger typically couple the overall movement by means of rigid levers. The resulting movement in this case turns out to be again different from the real hand which moves the individual phalanges independently
  • Poor strength due to the presence of rigid levers
  • Difficult to maintain
  • Anthropometric proportions not respected (especially in solutions that foresee more than one dof

Killer Application

The current invention is intended for a prosthetic type application. It can find application in the field of humanoid robotics

Our Technology and Solution

Prosthetic finger for an upper limb prosthesis solution in which at least one hand and / or partial hand prosthesis is provided.

Prosthetic finger with an anthropomorphic shape, designed with two transmission cables: the first to operate and close the finger, and the second to allow its extension, once the drive cable stops to apply its torque to the two joints. The first cable can be connected to an electric motor, placed inside a prosthetic hand, while the second cable is connected to an internal elastic component, such as a spring. This type of actuation allows the adaptive movement of the two joints, and consequently of the entire finger.


  • Closure adaptability combined with the possibility of under-implementation in a complete hand system
  • Variability / sequentiality of closure of the phalanges and combination of trajectories
  • Independence of passive springback
  • Springback adjustment
  • Long-term reliability
  • System modularity
  • Problem of anthropometric dimensions solved
  • Mechanical performance issue resolved
  • Strongly emphasized lightness
  • High energy density elastic recall in reduced dimensions
  • Simplicity of the system
    Low economic impact.
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