Design and modeling of an endoscopic piezoelectric tactile sensor

The paper presents a proof-of-concept design of a tactile sensor capable of measuring compliance of a contact tissue/sensed object. 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 its compliance. The sensor consists of a rigid and compliant cylindrical element. Determination of the compliance of sensed objects is based on the ratio of force experienced by the rigid cylinder to the total force applied to the sensor. To obtain this force ratio, a circular PVDF film is sandwiched between rigid cylinder and plate to measure the force applied on the rigid element and a rectangular PVDF film is sandwiched between the two base plates to measure the total force applied on the sensor. The detailed design of the senor was performed using finite element analysis. A prototype was fabricated and tested and it has been shown that good agreement exists between the finite element results and experimental values. The proposed sensor exhibits high force sensitivity and good linearity and offers the potential for future miniaturization in order to be integrated with the commercial endoscope graspers used in minimally invasive surgery.