Measurement of mechanical properties of eardrum, middle ear exudate and inner ear membranes

Abstract

This paper introduces three sensor instruments for measuring mechanical properties of small organic elements in human ear: sensor instrument for measuring penetrating force of an eardrum, which is 60 μm thick and φ 10 mm in diameter; sensor instrument for measuring tensile strength of an inner ear membrane, which is about 10 μm thick, 0.2 mm wide and 0.5 mm long; and sensor instrument for measuring dynamic viscosity of a middle ear exudate with a volume of 50 μl. These instruments contain force sensing units with parallel plate structure and strain gauges to provide fine resolution, for example, the sensor instrument for measuring tensile strength has a resolution of 1.51×10 −2 mN. Using the instruments on specimen from organic bodies, we measured the tensile strength of a mouse eardrum and round ear membrane from the inner ear; the former was 20 MPa at 0.57 strain and the latter, 5.0 MPa at 1.0 strain.