A remote palpation instrument for laparoscopic surgery: design and performance.

This paper describes the design and performance of a prototype remote palpation instrument with tactile feedback for laparoscopic surgery. Psychophysical experiments aiming at comparing palpation with and without tactile feedback are also described. The remote palpation instrument is designed to provide the surgeon with information about size and contact force distribution. The instrument consists of a tactile sensor and a tactile display, both of which are small enough to fit onto a conventional laparoscopic grasper. Static tests showed that hardness, size and shape were successfully rendered by the tactile display. Dynamic testing showed that the bandwidth is suboptimal, but at low frequencies the output from the remote palpation instrument is useful. For the psychophysical testing, nine subjects were asked to discriminate hardness and size of objects with and without tactile feedback. The results indicated that the instrument with tactile feedback can be helpful for hardness discrimination, although the difference between the two instruments was not statistically significant for neither hardness nor size. Comparisons with earlier, similar experiments showed that the quality of the grasper and size of the forceps affected the results, indicating that there is a great potential for improving laparoscopic graspers in general.