Modeling and testing of an endoscopic piezoelectric-based tactile sensor

This paper reports on the design and modeling of an endoscopic tooth-like tactile sensor which is capable of measuring compliance of a contact tissue/sensed object. 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. In this work, proof of a conceptual and innovative design of an endoscopic piezoelectric tactile sensor is presented. The main objective of this study is to design and model a piezoelectric sensor 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 and is responsible for the measurement of the force applied on the rigid element. Another PVDF film is sandwiched between the two base plates to measure 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. We used finite element modeling results as a basis of comparison for the experimental data. The agreement between the theoretical predictions and the experimental data is reasonable and within the acceptable range.