PhD Defense – Fouzia Khan

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The defense of the doctoral thesis titled “Fiber Bragg Grating Sensors for Flexible Medical Instruments” by Fouzia Khan was held on Wednesday, 12th of May 2021 at 11:00 CET in the Auditorium, University of Groningen, Broerstraat 5, Groningen. Due to COVID-related audience restrictions, the defense is invite-only and is made available for the public online here.

Fouzia’s doctoral thesis is available here.

Thesis summary:

The main objective of this thesis is to utilize optical sensors called ber Bragg gratings (FBG) to acquire the position and orientation of exible medical instruments such as catheters. These instruments are frequently used in minimally invasive surgeries where small incisions are made to perform the surgery. These minimally invasive surgeries are benecial for patients because there is no large wound therefore the patient experiences less pain, fast recovery, and fewer complications; thus it contributes to lower hospital costs.

The small size of the incision means that during a minimally invasive surgery the instrument cannot be directly seen, thus the position and orientation of the instrument are concealed. This issue is mitigated currently in practice by utilizing imaging like X-rays or laparoscopes (camera with light source); but these solutions have certain drawbacks such as harmful radiation used in X-rays and inability to use laparoscopes for all minimally invasive surgeries. A laparoscope can only be used in cavities that can be illuminated, such as the abdominal cavity or the ventricles in the brain. However, it is not possible to use a light source in a blood vessel or in solid tissues. These limitations motivate research into alternative methods of acquiring position and orientation of a flexible instrument.

This thesis is an outcome of one such research endeavor and it presents techniques of acquiring the position and orientation of a exible instrument based on measurements from FBG sensors. Moreover, a method to estimate the forces at the instrument’s tip from the sensor measurements is also presented. Chapter 2 provides a technique to get the shape of the catheter based on FBG measurements and to get the position of the catheter in 3D space. The technique is further developed in Chapter 3 to acquire the orientation in addition to the position of the catheter tip. Chapter 4 presents a comparison study between two dierent types of multi-core bers that have FBG sensors. One of the ber has straight cores while the other has helical cores. Lastly, Chapter 5 and 6 present two application studies where the rst study utilizes FBG sensors in conjunction with Ultrasound to track a catheter and the second study utilizes the shape of a exible instrument to estimate the force on its tip.

The research in the thesis shows that FBG sensors are eective as position and orientation sensors for exible medical instruments. Thus, FBG sensors can be applied to instruments utilized in minimally invasive surgery where the instrument is not directly visible. Continuing research in this eld will provide insight into the full spectrum of applications of these sensors.


  • Prof. Dr. S. Misra (University of Twente/University Medical Center Groningen, The Netherlands)


  • Prof. Dr. P.C. Jutte (University Medical Center Groningen, The Netherlands)

Assessment Committee

  • Prof. Dr. E.C.J. Consten (University Medical Center Groningen, The Netherlands)
  • Prof. Dr. S. Manohar (University of Twente, The Netherlands)
  • D. J.J. van den Dobbelsteen (Delft University of Technology, The Netherlands)

Opposition Committee

  • Dr. Ir. P.M.A. van Ooijen (University Medical Center Groningen, The Netherlands)
  • Prof. Dr. F. Rodriguez y Baena (Imperial College London, United Kingdom)
  • Prof. Dr. H.L. Offerhaus (University of Twente, The Netherlands)
PhD Defense – Fouzia Khan | Surgical Robotics Lab