Science: the first wearable bionic hand that 'feels' objects was successfully tested in Italy

The prosthesis, tested with a Danish left-hand amputee, was able to transmit tactile sensations to his brain and allowed him to manipulate objects with the right strength. LifeHand2 it is the sequel to the homonymous research project which five years ago led to the first prosthesis capable of responding to brain impulses

Rome, 5 February 2014 - An artificial hand grafted onto the amputated arm, capable of moving not only by responding directly to brain impulses, but also capable of transmitting tactile sensations, making the shapes and textures of the objects "feel" in the hand. The experimentation that has made possible this new step towards the definitive implantation of bionic hands is called LifeHand2 and is the result of an international project that sees Italy at the forefront. Doctors and bioengineers from the Catholic University–Policlinico Agostino Gemelli in Rome, from theUniversità Campus Bio-Medico di Roma, of the Scuola Superiore Sant'Anna of Pisa and of the IRCSS San Raffaele of Rome. Two cross-border centers are also part of the research group: theFederale Polytechnic School of Lausanne and the IMTEK Institute of the University of Fribourg. The results of the study, published in the new issue of the journal Science Translational Medicine released today, 5 February 2014, document the extraordinary nature of the result obtained. Among the authors of the study also the current Minister of University and Research, Professor Maria Chiara Carrozza.

It was New Year's Eve 2004 when Dennis Aabo Sorensen, a 36-year-old Danish, had his left hand amputated, destroyed by the explosion of a firecracker. Since then only an aesthetic prosthesis and the commitment to start over with the fortitude that also allowed him to pass the selection psychological tests, up to Rome, to face the experimental phase of LifeHand 2. The communication between Dennis' brain and the artificial hand actually worked thanks to a complex system of impulses between the center and the periphery, between the organism and the artificial limb, which brought science even closer to the reproduction of the natural phenomenon. “Sensory feedback was a wonderful experience for me – says Dennis –. Feeling the different textures of objects again, understanding whether they are hard or soft and feeling how I was holding them was incredible".

A subjective experience confirmed by experimental observation. In fact, in eight days of exercises, Dennis was able to recognize the consistency of hard, intermediate and soft objects in over 78 percent of the holds. Furthermore, in 88 percent of the cases, he correctly defined the dimensions and shapes of objects such as a baseball, a glass or the oval of a tangerine. Not only. He was also able to locate their position with respect to the hand with 97 percent accuracy, managing to dose with precision not too far from that of a natural hand the force to be applied to grasp them.

Experimental data have thus shown that it is possible to restore an effective feedback sensory in the nervous system of an amputee patient, using signals from the sensory fingers of the prosthesis.

Eight hours of surgery to implant the electrodes

The connection point between Dennis' nervous system and the biomechatronic prosthesis were four intraneural electrodes, slightly larger than a hair, implanted in the median and ulnar nerves of his arm. A delicate operation, which lasted more than eight hours, performed on January 26, 2013 at the 'Agostino Gemelli' Polyclinic in Rome by the neurosurgeon, Prof. Eduardo Marcos Fernandez. Developed in the IMTEK Biomedical Microtechnology Laboratory of the University of Freiburg, under the direction of Prof. Thomas Stieglitz, the electrodes were implanted transversally with respect to the nerve fascicles, so as to multiply their possibility of contact with the nerve fibers and consequently their ability to communicate with the central nervous system.

The working group coordinated by Prof. Silvestro Micera, professor of Bioengineering at the BioRobotics Institute of the Sant'Anna School of Advanced Studies in Pisa and at theFederal Polytechnic School of Lausanne, has developed in parallel a series of algorithms capable of transforming the information coming from the artificial hand into a language comprehensible to Dennis' brain. "The patient he managed to modulate the gripping force to be applied to the objects in a very effective way and in real time – he comments il Prof. Silvestro Micera -. He also carried out the exercises blindfolded, managing to recognize the various properties of these objects thanks solely to the continuous transmission of sensory information from the prosthesis to his nervous system. It's the first time something like this has been done".

Use a metaphor, to explain the challenge, the Prof. Paolo Maria Rossini, Clinical manager of the trial at the IRCCS San Raffaele Pisana in Rome and Director of the Institute of Neurology of the Catholic University-Policlinico Gemelli: “We introduced ourselves a bit like the researchers of the first lunar mission: after years of work, you push the button, you launch the spaceship and you can never go back from there”. The trip to the future, however, went well: “We aimed to explore the changes in Dennis' brain organization – continues Rossini – hoping that what happened then occurred: the full control of the feedback coming from the prosthesis by the patient, the preservation of the functionality of what remains of his median and ulnar nerves, the reorganization of the neuroplasticity of his brain in order to allow him an effective robotic hand control”.

New Products LifeHand 2 compared to the 2008 trial

Funded by the European Union and the Italian Ministry of Health, whose lead institution is the IRCCS San Raffaele-Pisana of Rome, LifeHand 2 it is the continuation of a research program that five years ago led to the biomechatronic prosthesis CyberHand – less evolved version of the OpenHand used for this second experiment – ​​to respond for the first time in the world to movement commands transmitted directly from the patient's brain. In 2008, however, the prosthesis could not yet be worn on the human arm, it allowed only three movements (pincer grip, fist closure and little finger movement) to be performed and did not give back any sensation to the person.

Future prospects for the development of prostheses and more

"The trial just ended - explains the Prof. Eugenio Guglielmelli, Director of the Laboratory of Biomedical Robotics and Biomicrosystems ofUniversità Campus Bio-Medico di Roma - allows us to look with confidence at the goal of integrating an ever-increasing number of tactile sensors into this type of prosthesis. The more the complexity of sensations and movements increases, the more important it will be to identify algorithms that distribute in the best possible way the tasks to be assigned to the brain and those that can instead be delegated to the control of the artificial intelligence mounted on board the hand. Our research continues on these aspects”.

However, the use of intraneural stimulation using electrodes does not only concern the development of communication systems between the human body and bionic prostheses. With their application at different levels of invasiveness, which can go as far as implanting these thin filaments directly into the brain, intraneural stimulation has long seen many research groups around the world engaged in the treatment of various pathologies, such as the movement deficits of paraplegic subjects. Frontiers of research united by an increasingly close relationship between the human body and technology.