Design and Fabrication of Piezoelectric-based Tactile Sensor for Detecting Compliance

Present day endoscopic graspers are designed to be tooth-like in order to grasp slippery tissues. They are not, however, able to measure tissue tactile properties such as force and softness. This paper reports on proof of a conceptual and innovative design of an endoscopic piezoelectric tactile sensor. The sensor is capable of measuring the total applied force on the sensed object, as well as the compliance of the tissue/sensed object. Detecting the sensed objects compliance is based on the relative deformation of contact object/tissue on the rigid and compliant elements. One polyvinylidene fluoride (PVDF) film is placed between the rigid cylinder and the plate which measures the force applied on the rigid element. Another PVDF film is sandwiched between the two base plates measuring the total force applied on the sensor. The compliance of the sensed object is measured by recording the PVDF films response under different load sets. The data obtained for the force variation are plotted against the modulus of elasticity of the sensed object. Finite element modeling was used for comparison with the experimental data. The results show that the experimental and the FE approach agree with each other with a reasonable band.