LAUSR

Multilayer electroactive polymer films actuate a small hand-held device to display tool tip forces during MR-guided interventions. The display produces localized skin stretch at the tips of the index finger and thumb. Tests confirm that the device does not significantly affect MR imaging and produces detectable stimuli in response to forces measured by a biopsy needle instrumented with fiber Bragg grating sensors. Tests with human subjects explored robotic and teleoperated paradigms to detect when the needle contacted a silicone membrane. The membrane was embedded in a tissue phantom that approximated the properties of porcine liver. In the robotic paradigm, naive users detected membranes with a 98.9  percent success rate as the needle was driven at fixed speed. In the teleoperated paradigm, users with experience in needle-based procedures controlled the needle insertion and detected membranes embedded in tissue phantoms with a 98.1  percent success rate; some experienced users detected membranes with very light contact forces, but there was greater subject-to-subject variation.