3-DOF Force-Sensing Motorized Micro-Forceps for Robot-Assisted Vitreoretinal Surgery

Abstract

In vitreoretinal surgery, membrane peeling is a prototypical task where a layer of fibrous tissue is delaminated off the retina with a micro-forceps by applying very fine forces that are mostly imperceptible to the surgeon. Previously we developed sensitized ophthalmic surgery tools based on fiber Bragg grating (FBG) strain sensors, which were shown to precisely detect forces at the instrument’s tip in two degrees of freedom perpendicular to the tool axis. This paper presents a new design that employs an additional sensor to capture also the tensile force along the tool axis. The grasping functionality is provided via a compact motorized unit. To compute forces, we investigate two distinct fitting methods: a linear regression and a nonlinear fitting based on second-order Bernstein polynomials. We carry out experiments to test the repeatability of sensor outputs, calibrate the sensor and validate its performance. Results demonstrate sensor wavelength repeatability within 2 pm. Although the linear method provides sufficient accuracy in measuring transverse forces, in the axial direction it produces a root mean square (rms) error over 3 mN even for a confined magnitude and direction of forces. On the other hand, the nonlinear method provides a more consistent and accurate measurement of both the transverse and axial forces for the entire force range (0–25 mN). Validation including random samples shows that our tool with the nonlinear force computation method can predict 3-D forces with an rms error under 0.15 mN in the transverse plane and within 2 mN accuracy in the axial direction.

Safe tissue manipulation in retinal microsurgery via motorized instruments with force sensing

“…Recently, this concept was extended to provide also the axial force sensing via an axial FBG in the center of the tool shaft (Fig. 1b) [7]. …”

“…To firmly hold the tissue in membrane peeling, our micro-forceps tools [6,7] work based on a grasping mechanism actuated by a motor inside the tool body (Fig. 1a).…”

“…To provide the surgeon with real-time physiological information and assist maneuvers during retinal surgery, various force-sensing instruments have been developed based on FBG sensors. Some of these tools were motorized, which led to independently actuated modular tools and enabled their use in combination with robotic systems for precise manipulation without hand tremor [6,7]. …”

Research on the accuracy of three‐dimensional localization and navigation in robot‐assisted spine surgery

“…It usually used optical tracking devices to locate the relative position of the surgical instrument and the patient. The virtual space was established with the three‐dimensional visualization technology . The surgical path was planned by the doctor, and the surgical tools were operated by the robot to realize the high‐precision surgical positioning.…”

Real-Time Sclera Force Feedback for Enabling Safe Robot-Assisted Vitreoretinal Surgery

“…Smits et al developed a force and distance sensing needle utilizing Fiber Bragg grating (FBG) strain sensors and Optical Coherence Tomography (OCT) [8]. Also, our team developed a family of force-sensing tools based on FGB strain sensors [9], [10]. A novel eye surgery tool was developed by He et al, which is able to simultaneously measure the sclera force, tool tip force and the length of the tool inside the eye (insertion depth, Fig.…”