Characterization of Statical Properties of Rat's Whisker System

This contribution describes mechanical properties of the whisker system of rats. The motivation for the work was to achieve a better understanding of the functionality of this remarkable sense organ by defining structure-function-correlations. Special features of the different types of whisker are interpreted in terms of their morphological background, e.g., object recognition and texture discrimination. The whiskers are found to be conical in shape. Theoretical considerations of rod types reveal certain advantages of conically shaped rods over cylindrical rods. There is a difference in deformation, with the higher values applying to conical rods. Whiskers have a very flexible tip which is sensitive to very small forces. Uniaxial bending tests using actual whiskers were performed to characterize the static parameters. From experimental data obtained, the spring constant, the Young's modulus and the flexural stiffness are calculated. Young's modulus is one standard parameter for the characterization of materials. It was found that this can be regarded as constant along the whiskers with an average value of 7.36 GPa. Flexural stiffness was found to depend on the hair diameter and decrease from base to tip. The short vibrissae exhibit the lowest flexural stiffness, which means they are sensitive to very small forces. The experimental results obtained might well be used as a basis for the optimization or the construction of bioinspired technical sensor systems.