Using ORMOCER®s as casting material for a 3D shape sensor based on Fiber Bragg gratings

In robot assisted minimally invasive surgery, flexible instruments are a highly interesting research topic, as they promise more flexibility and new possibilities for surgical interventions. Shape sensors are needed in order to retrieve information about the geometry and especially the tip position of the instrument. Those shape sensors are usually based on Fiber Bragg Gratings. In contrast to other research groups, which e.g. use nitinol wires as a core for their fibers, we follow the approach of casting the fibers in soft materials. For our latest prototype, a special ORMOCER® material has been used, which is an inorganic-organic hybridpolymer with adjustable properties. The fabrication of the sensor is described in detail. The reproducibility of the wavelength measurements has been validated for several shapes, proving the reasonableness of our approach.