Accurate and efficient fiber optical shape sensor for MRI compatible minimally invasive instruments

Van Der Heiden, M. S.; Henken, K.R.; Cheng, L.K.; Van Den Bosch, B. G.; Van Den Braber, R.; Dankelman, J.; van den Dobbelsteen, J.

Accurate and efficient fiber optical shape sensor for MRI compatible minimally invasive instruments

Conference paper (2012)

Authors

M. S. Van Der Heiden TNO Utrecht

K.R. Henken Medical Instruments & Bio-Inspired Technology - Mechanical, Maritime and Materials Engineering

L.K. Cheng TNO Utrecht

B. G. Van Den Bosch TNO Utrecht

R. Van Den Braber TNO

J. Dankelman Medical Instruments & Bio-Inspired Technology - Mechanical, Maritime and Materials Engineering

J. van den Dobbelsteen Medical Instruments & Bio-Inspired Technology - Mechanical, Maritime and Materials Engineering

Research Group

Medical Instruments & Bio-Inspired Technology (Mechanical, Maritime and Materials Engineering) (TU Delft)

Deformation Monte Carlo simulation Calibration procedure MRI compatible Error analysis FBG based optical shape sensor Flexible instruments Submicro-strain accuracy

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Published Date

2012

Language

English

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Faculty

Mechanical, Maritime and Materials Engineering

Department

Biomechanical Engineering

Research Group

Medical Instruments & Bio-Inspired Technology

Abstract

Background: The mechanical properties of small minimally invasive instruments are limited and thus must be treated as flexible instruments. Proper functional behavior of these instruments can be significantly enhanced when the instrument is equipped with a shape sensor to track the path of the flexible instrument. MRI compatible instruments, and thus the corresponding paths, are long in particular. Therefore, the accuracy of the tip position is stringent. Approach: We have developed and realized a thin Fiber Bragg Grating (FBG) based fiber optical shape sensor. The main advantages of this fiber optical sensor are its minimum dimensions, the intrinsic MRI compatibility, and the ability of sensing deformation with submicro-strain accuracy. The shape sensor consists of three fibers, each equipped with multiple FBG's, which are integrated physically by gluing and can be positioned inside an flexible instrument. In this study a critical component analysis and numerical error analysis were performed. To improve performance, a calibration procedure was developed for the shape sensor. Results and Conclusion: With current state of the art interrogators it is possible to measure a local deformation with a triplet of FBG sensor very accurately. At high radii of curvature, the accuracy is dominated by the interrogator, whereas at low radii of curvature, the position of the fibers is leading. The results show that position error of a single segment of the shape sensor (outer diameter of 220 μm, a segment length of 23.5 mm and a minimum bending radius of 30 mm) could be measured with accuracies (3σ) of 100 μm for low radius of curvature upto 8 μm for high radii of curvature.