ANALYSING SKIN SENSITIVITY

Authors

M.Jothi basu (07D436),G.kannan (07D438),K.Mukesh (07D444)

Department of BioMedical Engineering

Guided by E.MALAR,Lecturer,Department of Biomedical engineering

PSG COLLEGE OF TECHNOLOGY,CBE-641004

Abstract

The physiological properties of reception and transmission of tactile and thermal stimuli of man are different in quality and quantity. Tactile stimuli are transmitted by the myelinated A and B fibers which have a diameter between 8and15micro meter with a conduction velocity of 40-70m/s, whereas thermal stimuli are transmitted by the nonmyelinated C fibers which have a diameter between 3 and 4micrometer with a conduction velocity of 0.5 to 2 m/s .The sensation of thermal pain which follows a heat stimulus is slower, less localized, and more persistent than tactile pain .Using external electrodes, one can obtain summated action potentials resulting from the combined action of a great number of neurons. A measurement of this type reflects the entire possible information incident in that region of the body, e.g., the effect of all adequate stimuli like pressure or heat. The temporal amplitude patterns of potentials actually reflect the functioning of the nervous system and depend greatly on the electrical conductance of the skin where the stimulus is applied. Most of the techniques adopted to the quantitative evaluation of peripheral sensory functions suffer various limitations.

Our project aims at development of techniques designed to measure the electric responses to periodic tactile and thermal Stimuli on the skin of the hand. The measurements are made in a screened room using gold-surfaced Electrodes applied on the region of the wrist. These electronic techniques have been adopted because they are suitable in recovering induced periodic action potentials and in eliminating noise, and therefore make it possible to compare different neural functional states of the hand. This method might have a clinical application in plastic surgery of the hand, where the only indication that sensitivity in skin pedicle flaps has been recovered is still often dependent on the subjective judgment of the patient.