Polyimide sensing layer for bending shape measurement in soft surgical manipulators

This paper proposes a polyimide sensing layer based on Fiber Bragg Gratings (FBGs) for bending curvature measurement in soft surgical manipulators. An optical fiber with FBG sensors is embedded into a piece of polyimide thin film to form a flexible sensing system. The polyimide sensing layer is integrated into a soft manipulator model as the smart strain limited layer, which can serve as a key component of the soft pneumatic actuator to realize the bending shape control of the soft surgical manipulators. The calibration of the FBG sensors are conducted. The bending curvatures of a soft manipulator model at different deformed shapes are calculated based on the measured Bragg wavelength shift values, and the relative geometrical shapes of the soft manipulator are reconstructed using the measured curvatures and the interpolation and curve fitting functions. The maximum error between the sensing measurement values and the actual bending curvatures is less than 2.1%. The effectiveness of the polyimide sensing layer for bending shape measurement in soft surgical manipulators is verified.