Sviluppo di un plantare per riabilitazione funzionale basata sulla stimolazione con vibrazione meccanica = Devolopment of an insole for functional rehabilitation based on stimulation carried out through mechanical vibrations

Living beings interact with the external environment through specific receptors, collecting different information and processing appropriate responses. As a matter of fact, damage to information transmission and control mechanisms, due to neuropathy, stroke, or Parkinson's disease, can cause both motor and sensory disturbances. Since the foot is the first and the only direct contact between the human body and the outside world, interest in the role of sensory feedback, generated by the stimulation of mechano-receptors, in the regulation of motor activity and step kinematics, is constantly increasing. The application of mechanical stimuli, as to avoid them from causing resonance in the patient, produces greater coordination of synergistic muscles, an increase in the motor units recruited, and improves the vibratory perception threshold (VPT). Therefore, The Energy Department of the Politecnico di Torino, in collaboration with AZIENDA O.N. "SS. ANTONIO E BIAGIO E C. ARRIGO" of Alessandria, has designed a prototype of plantar receptor stimulation using a vibrating insole capable of providing stress in a range of 60-200 Hz. Although the treatments reported in the literature involve the use of fixed frequencies, numerous studies suggest setting the value individually, since the VPT is different for each individual and a different muscular response is observed when the frequency varies. The idea, therefore, is to maximize the effectiveness of the treatment by defining a feedback system to choose the correct stimulation frequency. Insofar, several scientific studies have demonstrated that by monitoring muscular activity through surface electromyography this objective can be easily achieved. The thesis work hereby presented is divided into parts, each regarding different steps involved in the procedure. The first part focuses on the analysis of the innervation system of the lower limbs and the understanding of mechanisms of sensory and motor impulses integration. The research is based on solid scientific evidence justifying the choice of muscular activity as feedback for the selection of the optimal frequency. The following part is centered on the acquisition system for the EMG. The physiological sources of disturbance, which interfere with a correct interpretation of the data, were thoroughly examined and a careful analysis of the characteristics of the instrumentation was carried out, identifying the most critical aspects. Moreover, the technical specifications of the conditioning and signal conversion blocks were defined, evaluating the measurement errors occurred due to the limits of the electronics and to the sources of noise which are typical of biopotential acquisition. Finally, justified design solutions were proposed and evaluated according to the purpose of the investigation, following the main guidelines, and an overview of electromyographs on the market with the identified requirements was provided. The thesis work defines, therefore, the basis on which to proceed with the completion of the plantar stimulation system. It is possible, in addition, to conduct an experiment at the AZIENDA O.N. "SS. ANTONIO E BIAGIO E C. ARRIGO", coordinated by Dr. Marco Polverelli, which will make it possible to confirm and quantitatively assess the safety and efficacy of the system. Eventual changes to the characteristics of the acquisition system will be made possible, in case of severe criticalities which did not emerge during the design phase.