Haptics for Multi-fingered Palpation

During open surgery, surgeons can perceive the locations of tumors inside soft-tissue organs using their fingers. Palpating an organ, surgeons acquire distributed pressure (tactile) information that can be interpreted as stiffness distribution across the organ -an important aid in detecting buried tumors in otherwise healthy tissue. Previous research has focused on haptic systems to feedback the tactile sensation experienced during palpation to the surgeon during minimally invasive. However, the control complexity and high cost of tactile actuators limits its current application. This paper describes a pneumatic multi-fingered haptic feedback system for robot-assisted minimally invasive surgery. It simulates soft tissue stiffness by changing the pressure of an air balloon and recreates the deformation of fingers as experienced during palpation. The pneumatic haptic feedback actuator is validated by using finite element analysis. The results prove that the interaction stress between the fingertip and the soft tissue as well as the deformation of fingertips during palpation can be recreated by using our pneumatic multi-fingered haptic feedback method.