Shape Sensor Using Magnetic Induction with Frequency Sweeping for Medical Catheters
Shape sensors are important for safer and more dexterous manipulation of the medical catheters. Among the electromagnetic based shape sensors, a voice coil shape sensor measures the variation of a mutual inductance between the coils placed along the tube due to the bending of the tube. Owing to the design flexibility of a voice coil, it offers the small size without the external magnetic field generator outside patient body. This paper presents an improved voice coil shape sensor in terms of modeling and measurement. Analytic model that incorporates the bending of an exciter coils is used to improve the accuracy of the sensor and band-pass filter is applied to simplify the measurements. Bending angle from sensors placed in multiple locations can be measured through a single channel from frequency sweep input. The simulation and experimental results verify the improvement and demonstrate that the sensor system can reconstruct a shape of a catheter placed through larynx.