Feeling and manipulating objects with the prosthesis

LifeHand 2 aims to experiment the skilful use of an upper limb biomechatronic prosthesis by an amputated patient. An artificial hand capable of directly conversing with the brain via four intraneural electrodes, implanted in the median and ulnar nerves of the patient’s stump. it was a matter of assessing the capability of the prosthesis, equipped with tactile sensors activated on the index and small finger, in sending to the brain information about the shape, consistency and position of different objects. A flow of information which, starting from the prosthesis, had to reach the nerves via neural electrodes and from there the brain. As to the opposite process (communication from brain to the prosthesis) it was a question of demonstrating that the patient, on the basis of his free will or of the sensory feedback, would be able to grasp objects moving naturally and effectively as well as to apply, in real time, the appropriate strength to the grip. LifeHand 2’s goal was to create the first bidirectional control of a biomechatronic upper limb, from the prosthesis to the bran (feelings) and from the brain to the prosthesis (movement intentions).

Bidirectional communication in real time

This bidirectional circuit had to furthermore occur at such a speed as to restore motor and sensory experience in real time without any significant delay (feeling and reaction delays in relation to the patient’s movement intentions).Obtaining this result meant the patient recovering the natural flow of sensations and movements between limb and nervous system, enabling him to use the robotic prosthesis in a very similar way to a human hand, including the ability to rectify any incorrect amount of strength applied during the course of a movement. during the experimentation, OpenHand was employed, the biomechatronic limb prototype developed by ArtsLab of The BioRobotics Institute of Scuola Superiore Sant’Anna of Pisa. While in the LifeHand (2008) experimentation the prosthesis was placed on a surface in the patient’s field of vision, in LifeHand 2 it was directly fitted on the stump of the patient’s arm via a specially madeto-measure socket. 

A new experimentation is expected to take place in about two years.