Recent advancements in technology have paved the way for the creation of more sophisticated and functional prosthetic limbs. While early prosthetics were rigid and mechanical, today’s prosthetic devices are not only softer and more realistic in appearance, but they also incorporate robotic components that expand their functionality. Despite these innovations, a significant challenge remains: most robotic prosthetics are difficult for users to control intuitively, limiting their practical use and impact on the user’s daily life.
A new development from researchers at the Italian Institute of Technology (IIT) and Imperial College London offers a promising breakthrough. In a recent paper published in Science Robotics, the team introduced a soft prosthetic hand designed to be easier for users to control through a more natural and intuitive connection between the user and the device. This prosthetic uses a novel control approach that integrates postural synergies—the natural coordination patterns of multiple fingers—with the decoding of motoneuron activity from the spinal cord.
“Through our recent paper, we’ve made a step toward establishing a more natural interface between the user and their artificial hand,” explained Antonio Bicchi, a co-author of the study. “We’re creating a neural connection that allows human and artificial intelligence to communicate effectively.” The key innovation is the integration of two elements: the dynamic coordination of the fingers during manual tasks (known as postural synergies) and the decoding of electrical signals from motoneurons, which provide a direct readout of the user’s intentions.
When humans perform manual tasks, their fingers move in coordinated patterns to achieve the desired result. These patterns, called postural synergies, are what the research team has leveraged to make prosthetic control more intuitive. By combining these coordination patterns with the electrical signals from the user’s spinal cord, the system can predict and execute the hand movements the user wants to perform.
The prosthetic hand itself is a blend of soft and rigid materials. “The skin, tendons, and ligaments are made of soft materials, while the bones are constructed from rigid materials,” Bicchi explained. The unique design of the artificial “bones” allows them to roll over one another, instead of pivoting around fixed pins as typical robotic hands do. This allows the prosthetic hand to adapt its shape to grasp different objects—much like a human hand. The result is a hand that exhibits autonomous, intelligent grasping behaviors.
What sets this prosthetic apart from others is not only its ability to pick up objects but also to manipulate them with precision. For example, the hand could not only grip a water bottle but also twist the cap open, using the same kind of dexterity one would expect from a biological hand.
The researchers tested the prosthetic hand with both individuals with intact limbs and those who rely on prosthetics. The results were promising, showing that the hand allowed users to perform complex movements with greater precision and naturalness than with traditional prosthetic hands. The soft prosthetic hand’s ability to grasp and manipulate objects intuitively opens the door to more functional and user-friendly prosthetic solutions.
“We’ve demonstrated that the human grasping phenomenon can be mapped onto two levels of organization,” Bicchi explained. “On one level, there’s the coordination of patterns in the way we use our hands daily. On another, we can decode motoneuron signals from the spinal cord. Our study connects these two levels, making it possible to control the prosthetic hand in a more natural way using the language of motoneuron activity.”
Looking ahead, the control method and design pioneered by this team have the potential to revolutionize not just hand prosthetics but other types of prosthetic limbs as well. The soft prosthetic hand could undergo further refinement and testing in clinical environments, with the ultimate goal of bringing it to the commercial market.
“This is just the beginning,” Bicchi said. “We are continuing to explore how to make the system even more intuitive and adaptable for real-world use, and we hope to see it applied to other prosthetics in the future.”
By bridging the gap between human motor coordination and robotic prosthetic control, this breakthrough could dramatically improve the functionality of prosthetic limbs, offering users greater autonomy and a more natural interaction with the world around them. With further research and development, this soft, bio-inspired prosthetic hand could redefine what is possible in assistive technologies and provide a new level of independence for people who rely on prosthetics.
By Impact Lab
