Air-cushion force-sensitive probe for soft tissue investigation during minimally invasive surgery

Purpose: We propose a novel air-cushion force-sensitive indentation probe for rapidly locating abnormalities within soft tissues during minimally invasive surgery (MIS). Method: This system comprises a spherical-tipped optical-based force-sensing device that employs an air-cushion technique to conduct continuous rolling indentation over the surface of soft tissues. The device combines rapid acquisition of tissue resistance forces with high manoeuvrability. To determine the stiffness variation, the interaction forces acquired during rolling indentation can be integrated to generate spatio-mechanical stiffness images that can be used for tissue diagnosis. Results: Rolling indentation tests on the probe were carried out on excised porcine liver. The results demonstrate that the probe can be used to acquire force signals for constructing mechanical images, reliably indicating areas of variable stiffness. Conclusions: This probe could be used to characterize the force tissue deflection profile of soft tissues during minimally invasive surgery providing surgeons with enhanced haptic feedback.