A Piezoelectric Tactile Sensor and Human-inspired Tactile Exploration Strategy for Lump Palpation in Tele-operative Robotic Minimally Invasive Surgery

A piezoelectric tactile sensor is proposed in this paper featuring small size suitable for minimally invasive surgery (MIS), simple structure with only one transducer for both actuation and sensing, and easy instrumentation requiring only electrical impedance measurement. Its validity and sensing performance are confirmed with simulations. In addition, the sensor together with a model of soft tissue with embedded lump are used to generate stiffness maps in various scenarios, which facilitate the construction of a virtual lump palpation system together with a vibrotactile feedback device and a visual tracking system. Subsequent experimental studies reveal that human palpation strategies have influence on the lump detection performance. The "Scanning" strategy leads to better performance in lump localization and size discrimination ratio, whereas the "Edge following" strategy achieves better performance in shape discrimination. Therefore, a combination of different palpation strategies is suggested which may help achieve the best performance in all aspects of the lump palpation task, and finally forms a human-inspired lump palpation solution that contributes to the robot-assisted MIS.