Flexible tactile sensor attached to laparoscope for mechanical characteristics of soft materials and tissues

Detection of the mechanical characteristic of tissues is useful to distinguish the difference between a cancerous lump and healthy tissues for minimally invasive surgery (MIS). In this study, a novel miniaturized tactile sensor is designed to attach to laparoscope for differentiating soft tissues from animals. The flexible tactile sensor consists of two patterned flexible print circuit (FPC) sandwiching a polymer piezoelectric film (PVDF) and a small steel ball embedded in a soft material (PDMS) on the FPC surface. Due to the stiffness difference between steel ball and PDMS material, the uneven stress distribution on piezoelectric film can be induced and varied with contact objects. Therefore, the mechanical characteristics of contact object can be differentiated by the ratio of voltage outputs between the inner and outer electrodes on the piezoelectric film. As experimental results, the voltage ratio increases with the Young´s Modulus for the commercial elastomeric materials. In addition, five soft tissues of animals also can be differentiated by the tactile sensor attached to a laparoscope.