Microfabricated instrument for haptic tissue recognition in fetal cardiac surgery

To keep a minimal level of invasiveness, some of the most delicate interventions of minimally invasive surgery, such as fetal cardiac surgeries, have to be carried out without direct vision, which makes tissue recognition extremely difficult. In this paper we investigate whether the haptic sense can be used instead. We describe a micro-fabricated gripper, equipped with semiconductor strain gauges as force sensors, and teleoperated via a haptic interface. We demonstrate that the force sensed by the gripper and rendered to the user through the haptic interface can provide a feeling of tissue stiffness that allows the user to successfully discriminate among two different tissue types. Experiments show that the system allowed unskilled operators to qualitatively discriminate tiny tissue samples excited from the heart of a fetal lamb. Haptic response models were created from the strain gauges response during grasping and additional experiments were carried out off-line on the haptic interface, to avoid tissue decay. User trials on the simulated tissues demonstrate that discrimination is possible with high statistical significance