Microfabricated Instruments for Fetal Cardiac Surgery: Experiments on Haptic Tissue Recognition

This paper describes the performance of a microfabricated gripper, equipped with semiconductor strain gauges as force sensors, and teleoperated via a PHANTOM haptic interface. The main objective is to demonstrate that the force sensed by the gripper, when rendered to the user by means of a haptic interface, can provide a feeling of tissue stiffness that allows the user to successfully discriminate among different tissue types during the most delicate operations of minimally invasive surgery, such as in fetal cardiac surgery. Experiments aimed to prove the usefulness of this approach have been carried out: the system allowed unskilled operators to qualitatively discriminate pieces of pulmonary valve and endocardium (excited from fetal lamb). Haptic response models were created from the measured data and additional experiments were carried out off-line on a PHANTOM interface. User trials on the simulated tissue demonstrate the excellent discrimination capability of the system.