Modelagem da Resposta de Mecanorreceptores Táteis SAII com Circuitos MOS

Abstract

Sensory functions have been essential for the survival of living organisms. As a consequence,evolution has adapted the somatosensory system, giving humans a set of mechanoreceptorswhose complementarity allows us to feel a variety of mechanical stimuli such as vibration,stretching and pressure. Currently, several research groups are working to push prosthetics to the state of the art by equipping artificial limbs with touch sensors. However, there is a longdistance between the diversity, density and communication ability of a natural member inrelation to its bionic version. The first step in closing the tactile feedback in the control of the prosthesis is to appropriately modulate the spiking output characteristics for afferent nerves. These efforts can be observed through the increasing number of investigations into the characterization of mechanoreceptor behavior. The circuit design is based on mathematical models of neurons known as Hodgkin-Huxley, Izhikevich and the simplest: the integration and firing model. The potential is formed through the accumulation of charges arising from the current injected into the neural membrane, as the charge is being injected it controls the current through channels. Different types of afferent responses can be used in mechanoreceptors such as FA-I, SA-I, SA-II and FA-II, which represent strength variations. In the implementation of SA-II, the investigations on the behavior of tactile mechanoreceptors for gripping tasks revealed that the force employed in the movement is answered. In order to control the triggering activity of the oscillator, the SA-II modeling can be done from the force, while the others, FA-I, SA-I and FA-II can be constituted from fundamental math calculations as derivatives and integrals. Conceptually the circuit can be understood as a relaxation oscillator that has its capacitor charged and discharged by voltage-controlled current sources, the control voltages representing the mechanical quantities.