In this paper, the design, analysis and fabrication of a micromachined piezoelectric endoscopic tactile sensor to determine the properties of tissues in minimally invasive surgery is presented. The viscoelastic Kelvin model is employed for tissue characterization. A closed form expression is derived to express the relationship between the force ratio, compliance and the equivalent viscous damping of the tissue. The designed sensor uses a PVDF film as its sensing element. The sensor consists of rigid and compliant elements which are mounted on the tip of an endoscopic surgical grasper tool. The relative force between adjacent parts of the contact object is used to measure the viscoelastic properties experimentally.

Purpose -The purpose of this paper is to present the design, analysis, fabrication, and assembly of four tooth annular microfabricated tactile sensors integrated with the upper and lower jaws of an endoscopic surgical grasper tool, in order to determine the properties and particularly the compliance of the biological tissues during minimally invasive surgery. Design/methodology/approach -A viscoelastic Kelvin model is employed for tissue characterization. A comprehensive closed form and finite element analysis has been carried out to express the relationship between the force ratio, compliance, and the equivalent viscous damping of the tissue. The designed sensor uses a polyvinyledene fluoride film as its sensing element. The sensor consists of arrays of rigid and compliant elements which are mounted on the tip of an endoscopic surgical grasper tool. Relative force between adjacent parts of the contact object is used to measure the viscoelastic properties. Findings -The tactile sensor is able to characterize different viscoelastic properties of tissues. The experiments validate analytical and finite elements results. Practical implications -The sensor is designed to integrate with the actual endoscopic tools to measure the softness of tissues. Originality/value -A novel sensor-tissue model is presented to characterize the variety of biological tissues.