Investigation of Energetic Processes During Needle Penetration into Soft Solids
Needle insertion is a crucial component of many biomedical operations such as neurosurgery, brachytherapy cancer treatment, and minimally invasive surgeries. During such clinical procedures, accurate needle deployment is vital for accurate diagnosis and effective treatment, which are achieving growing importance in modern medicine. The inaccuracies of needle placement or target tracking can be reduced by using a robotic-assisted system that steers the needle towards the target region. Such use of a robotic system requires knowledge of the needle-tissue interaction mechanism, which can be obtained through experimental examinations in combination with numerical analysis. Therefore, numerical modeling is an ideal complement to experimental observation, which could be very useful for surgical training and navigation; for example, experienced physicians are already taking advantage of these developments by using simulators to plan surgical procedures and improve the design of surgical tools. The 3 -dimensional ( 3 D) finite element (FE) model, inspired by previous works where 2 D numerical analyses are implemented, has been developed and serves a critical role in this thesis while capturing key characteristics of the needle insertion process. We also introduce an efficient method for coupling physically relevant soft material properties with the FE model, which is easy to use without defining any user subroutines. Comparing the computational results with the experimental results revealed that the 3D cohesive zone model (CZM) and contact formulations to the cutting and insertion problem effectively predicted and simulated the penetration process. We further demonstrate a theoretical model based on the energy approach, which might suggest further insight into the mechanism of the needle insertion problem.