Implementation and testing of a framework for neuroprostheses and bioelectronic medicine

The development of prosthetic devices increasingly focuses on approaches which allow amputees to control them in a physiological way. A great problem of actual most promising prostheses, myoelectric prostheses, is the absence of sensory feedback, so patients perceive the prosthetic device not as a part of themselves. Different types of electrodes have been proposed to directly interface with the peripheral nervous system at different degrees of invasiveness (i.e Cuff,TIME, tLife). The purpose is restoring motor and sensory activities, in amputees or patients with different kind of neurological injuries. In this work, a system which combines stimulation, recording and elaboration functionalities has been implemented . After the stimulation of peripheral nerves, the EMG signal that comes from muscular contraction elicited is recorded and elaborated in real-time. For the realization of the system, a Tucker Davis Technology (TDT)’s Neurophysiology Workstation has been utilized, which includes: the RZ5D BioAmp Processor, a multi-channel stimulator (IZ2), and a multichannel amplifier (PZ5). These devices are controlled, based on processes that have been configurated through circuit blocks developed in RP Visual Design Tool. The software that manages the hardware devices communicates with a Graphical User Interface developed in Matlab® through which the user can control the stimulation properties and visualize results in real-time. The recorded EMG signals were elaborated and transferred to Matlab® for further processing. The system has been tested in four experimental sessions held on pigs, where hook, cuff and transversal, intrafascicular electrodes have been utilized to stimulate the sciatic nerve. We successfully showed that the system provides information about the level of activation of each of target muscle in respect of the charge injected and about the selectivity of stimulation of intraneural electrodes. The implemented system allows the real-time elaboration of signals and it is customizable according to the applications by simply varying the hardware configuration and the signal processing chain. This platform provides a solid base for everybody who wants to perform experiments related to the characterization of neural electrode selectivity. The system can also integrate the recording of electroneurographic signal so that it can be utilized also in bioelectronic medicine applications that extrapolate information from the peripheral nervous system.