Experimental and finite element analysis of an endoscopic tooth-like tactile sensor

This paper reports on the finite element analysis and experimental study of a prototype PVDF endoscopic tooth-like tactile sensor capable of measuring compliance of a contact object. Present days endoscopic graspers are designed tooth-like in order to grasp slippery tissues. However they are not equipped with tactile sensors to measure the compliance of tissue. The tactile sensor consists of rigid and compliant cylindrical elements. Determination of the compliance of the sensed objects is based on the relative deformation of contact object/tissue on the compliant and rigid element of the sensor. The polyvinylidene fluoride (PVDF) film sandwiched between rigid cylinder and plate and also between the two base plates has been used to measure the force applied on the rigid element and the total force applied on the sensor, respectively. Using the finite element method, the rigid and compliant elements are modeled as solid and elastic foundations, respectively. The data obtained for the force variation are plotted for the various modulus of elasticity of the sensed object. An array of the sensors was also designed in two different configurations depending on the method of measuring the total force. In one configuration, the total force is measured on the sensed object using common base plates and in the other configuration it is measured using different base plates arrangement. It has been shown that good agreement exists between the finite element results and experimental values. The sensor exhibits high force sensitivity and good linearity. Further, an array of these sensors could be miniaturized to integrate with commercial endoscope.