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

This paper proposes a novel concept of developing an air-cushion force-sensitive indentation probe for rapidly locating abnormalities within soft tissue organs during minimally invasive surgery (MIS). This system comprises a sphere-tip optical-based force sensing device which employs a novel air-cushion technique to conduct continuous rolling indentation over the surface of soft tissue, such as internal organs. The concept and prototype described in the paper combines rapid acquisition of tissue resistant force with high maneuverability. The experimental results demonstrate that the probe has a good sensitivity to stiffness variation in viscoelastic materials, such as biological soft tissues. To visualize the stiffness variation across the tissue surface, the interaction forces acquired during rolling indentation can be integrated to generate spatio-mechanical stiffness images which can be used for tissue diagnosis. The laboratory experiments were conducted in a controlled environment using a soft-tissue substitute made of silicone with hard nodules embedded beneath the surface as well as porcine liver samples which prove the feasibility of the proposed concept. Results are presented.