The objective of the GRIP Project is to advance towards the long term research goal of restoring hand functions to persons who lost it, by exploiting recent advances in Information Technologies (IT) and MicroSystems Technologies (MST). A solution to the problem of restoring upper limb functions following trauma or neurological diseases not only is important for a large number of disabled persons in Europe and in the world, but may also represent an attractive opportunity for European industry in the fields of IT, MST and biomedical devices.
In order to achieve the main result of GRIP several preliminary achievements had to be obtained:
1.development of selective cuff electrodes
2.development of an implantable stimulator
3.development of the system for the RF connection between the implant and the external controller
4. development of systems to record the sensory information during grasp
5. test of the cuff electrodes in animal models in order to verify their biocompatibilty and selectivity
6. development of algorithms for the cognitive feedback
7. development and test in animal and human models of the control systems
8. definition of the implantation sites
9. chronic test of the implantable components in animal models
10. implant of the GRIP Final Demonstrator in selected human volunteers and assessment of its efficacy
During the GRIP Project many important results have been achieved on topics 1-8, while the chronic experiments are now in progress. If the results of these experiments will confirm the possibility of implanting the GRIP components in selected human volunteers, the Consortium is ready to carry out the implants in at least two different sites (in Pisa and in Aalborg) where the multidisciplinary team necessary for this kind of activity has been already created. Moreover, a European network of clinical centres interested in implanting the GRIP Final Demonstrator is under definition.
In the past, solutions to the problem of partial or total loss of hand function have been investigated in two separate ways for two different pathologies: by developing more dextrous and "sensate" hand prostheses for the amputee; and by developing instrumentation for Functional Electrical Stimulation (FES) of the residual muscles or nerves through external or implanted electrodes, for persons with intact hand anatomy but partial or total loss of nerve functions. The GRIP Project represents a unified approach to both classes of pathologies and will develop a usable solution to the specific problem of patients with Spinal Cord Injury (SCI). The motivations for an integrated approach to the restoration of hand functionality in amputees and in paralysed persons stems from an important observation: the key factor in both pathologies is the "command interface", that is an interface (implanted or external) which allows the disabled person to control either the prosthesis or some basic functions of the paralysed hand in a simple and natural manner, possibly by "feeling" some sensory information. The strategy of GRIP is to develop a simple version of a "natural" interface, and to assess its effectiveness in a FES system for restoring basic upper limb functions in persons with upper limb paralysis, for example deriving from a lesion of the brachial plexus, using the feedback from artificial sensors. The results from the GRIP Project will provide a practical solution to the needs of a significant fraction of disabled persons (whose situation cannot, at the moment, be alleviated by surgical or by other medical interventions), and will also represent a very important intermediate step towards the more difficult long term goal of developing a "cybernetic" hand prosthesis and a closed-loop FES system using afferent nervous signals from "natural" cutaneous and muscle receptors.
During the GRIP Project we will develop and in vivo test a system including: a) implantable (regeneration-type and cuff-type) neural connectors comprising an array of microelectrodes and able to establish stable electrical contact with nerves; b) implantable signal processing circuits able to process sensory and motor signals and to transmit and receive signals transcutaneously by RF transmission; c) a system for controlling by FES some basic upper limb movements, and specifically grasp, in persons with SCI. The patient will control the FES system through some unimpaired skills (such as voice, the contraction of normal muscles, or the movements of the contralateral shoulder).
The closed-loop control of the stimulator will be implemented by using signals from artificial "skin like" sensors and finger motion sensors incorporated in a glove worn by the disabled. The controller of the FES system will be based on neuro-fuzzy techniques and will incorporate strategies based on results obtained during experiments on cognitive feedback.
Funding SchemeCSC - Cost-sharing contracts
38206 La Laguna
08193 Bellaterra, Barcelona