Force feedback-based microinstrument for measuring tissue properties and pulse in microsurgery

Miniaturized and "smart" instruments capable of characterizing the mechanical properties of tiny biological tissues are needed for research in biology, physiology and biomechanics, and can find very important clinical applications for diagnostics and minimally invasive surgery (MIS). We are developing a set of robotic microinstruments designed to augment the performance of the surgeon during MIS. These microtools are intended to restore (or even enhance) the finger palpation capabilities that the surgeon exploits to characterize tissue hardness and to measure pulsating vessels in traditional surgery, but that are substantially reduced in MIS. The paper describes the main features and the performance of a prototype miniature robotic instrument consisting of a microfabricated microgripper, instrumented with semiconductor strain-gauges as force sensors. For the (in vitro) experiments reported in the paper, the microgripper is mounted on a workstation and teleoperated. A haptic interface provides force feedback to the operator. We have demonstrated that the system can discriminate tiny skin samples based on their different elastic properties, and feel microvessels based on pulsating fluid flowing through them.