Analysis of strain transfer characteristics of no-substrate and thin diameter sensor

Abstract

Fiber Bragg grating (FBG) is a promising technology for shape detection in medical surgery robots. Conventional optical fiber is prone to fracture due to bending and torsion, so it needs fiber encapsulation before use. However, the encapsulating materials and bonding materials bring strain transfer loss. For correcting error and improving measurement precision, the thin diameter no-substrate sensor suitable for laryngeal surgery robot detection was proposed to establish the model. The four-layer composite structure of FBG shape sensor, including adhesive layer, fiber optic layer, coating layer and adhesive layer, was established. The theoretical model of strain transmissibility of fiber optic coating was proposed, and the effects of elastic modulus of adhesive, length of adhesive layer and diameter of encapsulation on static strain transfer were analyzed. The correctness of theoretical prediction was verified by finite element numerical analysis. The research results revealed the influence law of strain transmissibility of non-substrate sensor, offered theoretical model for strain analysis, and provided important basis for improving shape perception accuracy of medical devices. The strain transfer rate is introduced into shape reconstruction, and the accuracy of end positioning is improved from 2.71% to 2.45%.