Future technology
Artificial hand comes to life

If a European research team has their way it won’t be long before the sci-fi bionic man becomes reality.

The research team is currently developing a highly dexterous, bioinspired artificial hand and sensory system that could provide patients with active feeling.

Funded by the Future and Emerging Technologies initiative of the IST programme, the Cyberhand project aims to hard-wire a mechanical hand into the nervous system, allowing sensory feedback from the hand to reach the brain, and instructions to come from the brain to control the hand, at least in part.

The research team is coordinated by Professor Paolo Dario with Professor Maria Chiara Carrozza leading the development of the hand. The project united researchers from Germany, Spain, Italy and Denmark. To date the project has made several significant achievements. The project has a complete, fully sensitised five-fingered hand.

The Cyberhand prototype has 16 Degrees of Freedom made possible by the work of six tiny motors. Each of the five fingers is articulated and has one motor dedicated to its joint flexing for autonomous control. It features that miracle of evolution, the opposable thumb, so the device can perform different grasping actions.
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Other significant achievements include: the design, implementation and assessment of different types of neural interfaces in order to develop the bi-directional link between the peripheral nervous system and the prosthesis; the implementation of an integrated electronic system able to be connected to the neural interfaces and thus to be implanted together with the electrodes in the amputee’s residual limb; the development of the software for the control of the hand using electroneurographic signals from LIFE (Longitudinal IntraFascicular Electrodes).

In addition to traditional wire LIFEs, used to connect the hand to the nervous system, a new type of electrode has been developed to improve performance and make them less invasive in humans: the Thin Film LIFE (tfLIFE). Taking inspiration from the real hand, where a muscle pulls a tendon inside a synovial sheath, Cyberhand's finger cables run through a Teflon sheath pulled by a DC motor. So the proximal, medial and distal phalanges are all driven by the same tendon. This approach is called underactuation as there are more Degrees of Freedom than Degrees of Movement (motors); it means the prosthesis has a self-adaptive grasp.

Dr Lucia Beccai, project manager, explained: “This is a fundamental feature of the Cyberhand prosthesis because only a limited number of control signals are available for user’s voluntary control.” Importantly, it also means less user effort is required to control the hand during daylong use. Dr Beccai told Middle East Health, the hand uses two types of senses.

The Cyberhand prototype integrates a proprioceptive artificial sensory system, in order to integrate the ability to sense both the hand position and movement, and an exteroceptive artificial sensory system, in order to sense the tactile stimuli originating from the environment when the hand grasps and manipulates objects. The link between the hand and the nervous system is achieved by using electrodes – neural interfaces – able to record neural signals (to extract voluntary commands to control the prosthesis) and to stimulate nerve fibres, in particular, afferent nerves to deliver sensory feedback.

The electrodes will be connected to an electronic processing unit and a telemetry system that connects them to the sensorised prosthesis,” explained Dr Beccai. It is expected that it could take five to eight years before the device has cleared all the tests necessary to prove its safety, usability and robustness.

For more information about the Cyberhand project and the consortium involved visit: www.cyberhand.org

                                  
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