Detailed finite element modelling of deep needle insertions into a soft tissue phantom using a cohesive approach

Abstract

Detailed finite element modelling of needle insertions into soft tissue phantoms encounters difficulties of large deformations, high friction, contact loading and material failure. This paper demonstrates the use of cohesive elements in high-resolution finite element models to overcome some of the issues associated with these factors. Experiments are presented enabling extraction of the strain energy release rate during crack formation. Using data from these experiments, cohesive elements are calibrated and then implemented in models for validation of the needle insertion process. Successful modelling enables direct comparison of finite element and experimental force-displacement plots and energy distributions. Regions of crack creation, relaxation, cutting and full penetration are identified. By closing the loop between experiments and detailed finite element modelling, a methodology is established which will enable design modifications of a soft tissue probe that steers through complex mechanical interactions with the surrounding material.

Indentation and needle insertion properties of the human eye

“…Recent use of finite element analysis with adaptive cohesive crack modelling has provided some further insights into the needle-tissue interaction. 21 This has improved the stress field and soft tissue fracture behaviour around the needle tip, showing much higher stress concentrations and greater tissue/tip contact areas than has been demonstrated before.…”

Toward a Miniaturized Needle Steering System With Path Planning for Obstacle Avoidance

“…Thirdly, a better, more accurate model of steering, which describes the complex relationship between steering offset and curvature by taking into account interaction forces, friction and substrate properties, will be developed. Following on from our first attempt to model tool-tissue interaction forces with finite elements [30], work will also continue on tissue deformation modeling and tracking, online path re-planning and better predictive models of tool tissue interaction and damage initiation. Lastly, research will progress of the identification of suitable materials and manufacturing processes which will aid in the development of a biocompatible, scaled down prototype suitable for clinical use.…”

“…The gelatin phantom was prepared with 6 weight %, as used in previous works [4,5] to mimic in some simplified fashion the stiffness of brain tissue. The approximate Young's modulus for the gelatin phantom used in this work was experimentally found to be 7k Pa [30].…”

Neurosurgery and brain shift: review of the state of the art and main contributions of robotics

“…First, the opening of the dura mater (a membrane that covers and protects the brain) causes large nonlinear deformations due to pressure changes and cerebrospinal fluid loss, [54] and [55]. The surgical procedures of resection, cuts or excision are the second cause [56]. Different authors argue that brain shift is one of the greatest causes of failure in neurosurgical procedures with neuronavigation systems [8] and [57].…”

“…Even more interesting are the approximations that make use of a mathematical-physical model of deformations to predict the displacements of all points of the brain [54] and [55]. But they require a model validation process which is often not easy to carry out due to the difficulty of measuring the actual displacements to check the generated model [56]. On the other hand, the input information for the model is provided by the displacements of the points that are measurable (visible) by optical methods, which produces an important bias in the input data.…”