Design, Modeling and Simulation of a Micro Tactile Sensor for Soft Tissue Stiffness Measurement with Three Tips Configuration

Artificial tactile feedback systems is now emerging as an essential part in laparoscopic surgeries. This paper presents a new structure for a micro tactile sensor, whose output does not depend on the applied pushing distance or the contact angle with the tissue. The sensor structure is based on using three silicon cantilevers in one plane, acting as three springs with different stiffness, which are protected by square PDMS diaphragms. A detailed design has been executed to achieve high sensitivity and linearity. A finite element simulation was implemented to validate the design and sensor performance. Different values have been assigned to the tissue Young's modulus (up to 1 MPa) covering different organisms. The results show that the sensor can differentiate between different types of tissues based on their modulus of elasticity. The sensor output was demonstrated to be independent of neither the pushing distance nor the contact angle up to (±3 degree). The error of the mean value of output due to the inclination angle did not exceed 3.5%.