Stretchable optical fibre sensor for soft surgical robot shape reconstruction

Abstract

Soft robotics presents several advantages in the field of minimally invasive surgery. However, existing methods have not fully addressed problems related to soft robot shape sensing due to the complex motion of soft robots and the stretchable nature of the soft materials employed. This study demonstrates the shape sensing of a soft robot with a helically embedded stretchable fibre Bragg grating (FBG)-based optical fibre sensor. Unlike straight FBG embedding configurations, this unique helical configuration prevents sensor dislocation, supports material stretchability, and facilitates shape detection for various soft-robot movements. The proposed soft-robot design principle and FBG sensor are analysed and their fabrication process, which includes an FBG-written optical fibre sensor, is described. Bending experiments are conducted with the soft robot, the wavelengths of FBG sensors at different bending and telescopic movement states are obtained, and the soft-robot shape is reconstructed. Experimental results demonstrate that the maximum error between FBG sensing and the actual bending state is less than 2.5%, validating the feasibility and effectiveness of the proposed helical stretchable FBG sensing method for the shape measurement of soft robots. These results indicate the potential and applicability of this shape-sensing approach in biomedical research.

Fiber-optic-based force and shape sensing in surgical robots: a review

“…This research validates the feasibility of FBG-based shape sensor in soft robots. Also the linear and spiral arrangements of optic fibers were used to measure the shape of soft surgical actuator (He et al, 2018(He et al, , 2021. A novel robot made of magnetic materials without electricity was proposed by Kim et al (2019), which can be shaped quickly and planned to be used in vascular intervention.…”

Sensing of Continuum Robots: A Review

“…By implementing multiple sensors in the catheter robot, the shape of the robot is obtained. Another implementation of FBG sensors was also shown in [ 58 ]. The sensor was helically wrapped and incorporated in the design of a pneumatically controlled soft manipulator.…”

Sensing in Soft Robotics

“…Interestingly, the stretching of the elastomer causes localized illumination of the EL layer, providing a visual cue for the location of the deformation of the robot, which is useful in the design optimization of soft actuators. Xu’s group fabricated a soft surgical robot 124 with FBG-based optical fiber embedded in a spiral fashion, as shown in Figure 6 e. The helical configuration prevented the dislocation of sensors during actuation and supported material stretchability in contrast to mounting in a linear fashion. The FBG optical fiber sensed the bending movement within a 2.5% error.…”

“…(e) Soft surgical robot with helically embedded fiber Bragg grating based optical fiber. Reproduced with permission from ref ( 124 ). Copyright 2021 The Authors under Creative Commons Attribution 4.0 International License, published by Optica Applicata.…”