ISBN 9783843954846

978-3-8439-5484-6, Reihe Medizintechnik

Sohrab Shojaei Khatouni
TacFiber: A Micro-Optomechanical Sensor for Simultaneous Measurement of Axial Forces, Temperature and Curvature in Intracranial Endovascular Minimally Invasive Surgery

241 Seiten, Dissertation Technische Universität Hamburg (2024), Softcover, A5

Zusammenfassung / Abstract

In minimally invasive endovascular surgery haptic feedback is distorted. Hence, surgeons must estimate the tip forces during navigation of instruments. This work is about the systematic development of a micro sensor that can be used to simultaneously measure pressure, temperature and bending in minimally invasive endovascular procedures. This sensor is particularly intended to be used as a guidewire or pusher wire for endovascular treatment of intracranial aneurysms, where inadequately high forces can lead to fatal bleeding. For this, fiber optic FBG sensors, and a unique combination of multiple FBG and FBGFPI where developed. The gratings were inscribed in the core of polyimide and acrylate coated single mode optical fibers with an overall diameter of 155-170 µm and a core diameter of 6.4 - 9.8 µm. For the evaluation and characterization of each sensor generation and its sensors, three measurement setups are built. The optical sensor signal is evaluated by conventional peak shift determination, traditional ML methods, and DL methods. For this, more than 58,000 samples are measured for each second and third generation sensor. In an analysis of the datasets, traditional ML models perform best, with coefficients of determination R^2 ≥ 0.98 for the second generation sensors. For the third generation sensors that contain the combination of FBG and FBGFPI an additional improvement in the pressure prediction error by approx. 30 % was achieved compared with the best sensor of the second generation.All sensors, that have been developed in this work are bio-compatible, can be coated with metals or other sterilizable materials, have no risk of electrical shock, and can safely be subject to high temperatures during steam sterilization. The sensor signal has no interference with strong magnetic fields in MRI, X-rays in CT or, electrical or electromagnetic fields.