A haptic probe for soft tissue abnormality identification during minimally invasive surgery

This paper proposes a novel haptic probe for the identification of tissue properties during minimally invasive surgery (MIS). The purpose of such a device is to compensate a surgeon for a portion of the loss of haptic and tactile feedback experienced during robotic-assisted MIS. A prototype for validating the concept in an ex-vivo setting was developed and used to characterize two different testing modalities - rolling tissue indentation and uniaxial tissue indentation. A MIS compatible design (capable of passing through 10 mm hole) is also presented. The key feature of the wheeled device is the ability to measure the tool-tissue interaction force as well as the rolling indentation depth concurrently. The purpose of the rolling indentation is to generate a mechanical image which can indicate tissue abnormalities, such as tumors, which are difficult to isolate under static testing conditions. After locating the abnormal region, the uniaxial indentation is subsequently conducted on the region of interests for detailed investigation. Experiments on a silicone phantom show that the developed prototype is capable of rapidly locating embedded hard nodules within the silicone model. Moreover by performing static additional uniaxial indentation, the device can be used to identify the parameters of the tissue viscoelastic constitutive equation.