Novel Air-float Tactile Array for Stiffness Characterization in Soft Tissue Palpation

This paper presents a feasibility study of a novel air-float palpation probe for stiffness characterization in soft tissues. The probe is designed to accommodate multiple sensing elements which allow rapid acquisition and averaging of tactile information. Each sensing element has a sphere floating on a thin lubricating film of air. Hence the probe can move over soft tissues in any direction in a near frictionless manner. With the air pressure maintained constant, the displacement of each sensing element is a direct function of the stiffness of the tissue under investigation. The sensor has a tunable force range and the indentation force can be adjusted externally to match tissue limitations. The structure, working principle, a mathematical model for sensor output and the behavior of the tactile sensing system are described.