Abstract
A novel tactile sensor design for stiffness detection of soft tissues is proposed aiming to get output readings uninfluenced of the contact conditions. The sensor principle is based on the concept of applying two springs, with considerably different stiffnesses, to soft tissue for stiffness detection. The sensor consists of two coaxial diaphragms with contact mesa to work as two different springs. The sensor mesas are designed in circular shape to compensate the error caused by the pushing distances between the sensor and the soft tissue. A finite element simulation model is developed to investigate the sensor performance. The results show that the sensor can successfully distinguish between different tissues with close stiffnesses independently of the pushing distance between the sensor and the tissue. Moreover the sensor shows good output linearity when measure different tissue stiffnesses.