A sub-millimetric, 0.25 mN resolution fully integrated fiber-optic force-sensing tool for retinal microsurgery

Abstract

PURPOSE: Retinal microsurgery requires extremely delicate manipulation of retinal tissue where tool-to-tissue interaction forces are usually below the threshold of human perception. Creating a force-sensing surgical instrument that measures the forces directly at the tool tip poses great challenges due to the interactions between the tool shaft and the sclerotomy opening. METHODS: We present the design and analysis of a force measurement device that senses distal forces interior to the sclera using 1-cm long, 160 microm diameter Fiber Bragg Grating (FBG) strain sensors embedded in a 0.5 mm diameter tool shaft. Additionally, we provide an algorithm developed to cancel the influence of environmental temperature fluctuations. RESULTS: The force-sensing prototype measures forces with a resolution of 0.25 mN in 2 DOF while being insensitive to temperature. CONCLUSION: Sub-millinewton resolution force sensors integrated into microsurgical instruments are feasible and have potential applications in both robotic and freehand microsurgery.