Researchers are paving the way for the design of bionic limbs that feel natural to users. They demonstrate the connection between hand movement patterns and motoneuron control patterns. The study, published in Science Robotics, also reports the application of these findings to a soft prosthetic hand, which was successfully tested by individuals with physical impairments.

The research study sees the collaboration of two research teams, one at Istituto Italiano di Tecnologia (Italian Institute of Technology) in Genova, Italy, led by Antonio Bicchi, and Imperial College London, UK led by Dario Farina. It is the outcome of the project “Natural BionicS” whose goal is to move beyond the model of current prosthetic limbs, which are often abandoned by patients because they do not respond in a “natural” way to their movement and control needs.

For the central nervous system to recognize the bionic limb as “natural,” it is essential for the prosthesis to interact with the environment in the same way a real limb would. For this reason, researchers believe that the prostheses should be designed based on the theory of sensorimotor synergies and soft robotics technologies, first proposed by Antonio Bicchi’s group at IIT, such as the Soft-Hand robotic hand.

Recent technological advances have opened new possibilities for the development of assistive and medical tools, including prosthetic limbs. While these limbs used to be hard objects with the same shape as limbs, prosthetics are now softer and look more realistic, with some also integrating robotic components that considerably broaden their functions.

Despite these developments, most commercially available robotic limbs cannot be easily and intuitively controlled by users. This significantly limits their effectiveness and the extent to which they can improve people’s quality of life.

Researchers at the Italian Institute of Technology (IIT) and Imperial College London recently developed a new soft prosthetic hand that could be easier for users to control. This system, presented in a Science Robotics paper, leverages a new control approach that integrates the coordination patterns of multiple fingers (i.e., postural synergies) with the decoding of the activity of motoneurons in people’s spinal column.