A micromachined piezoelectric tactile sensor for an endoscopic grasper-theory, fabrication and experiments

Present-day commercial endoscopic graspers do not have any built-in sensors, thus, the surgeon does not have the necessary tactile feedback to manipulate the tissue safely. This paper presents the design, fabrication, testing, and experimental results of a micromachined tactile sensor, which can be integrated with the tips of commercial endoscopic graspers. The prototype sensor consists of three layers. The top layer is made of micromachined silicon with a rigid tooth-like structure similar to the present-day endoscopic grasper. The bottom layer is made of flat Plexiglass serving as a substrate. Packaged between the Plexiglass and the silicon is a patterned Polyvinglidene Fluoride (PVDF) film. The proposed sensor exhibits high sensitivity, a large dynamic range, and a high signal-to-noise ratio. Through experimental results, it is shown that the magnitude and position of an applied force can be determined from the magnitude and slope of the output signals from the PVDF sensing elements. Structural analysis is also performed using the finite-element method, and the results are compared with the experimental analysis. The advantages and limitations of this sensor are also reported. A discussion of how the design of the sensor can be integrated with the design of an endoscopic grasper is also presented.