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Bevel angle study of flexible hollow needle insertion into biological mimetic soft-gel: Simulation and experimental
Mohamed G Jushiddi1, Rachel M Cahalane2, Michael Byrne3
1Modeling, Simulation and Innovative Characterisation (MOSAIC), Bernal Institute and Department of Physics, University of Limerick, Limerick, Ireland; School of Engineering, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland.
Background:
A thorough understanding of cutting-edge geometry and cutting forces of hollow biopsy needles are required to optimise needle tip design to improve fine needle aspiration procedures.
Objectives:
To incorporate the dynamics of needle motion in a model for flexible hollow bevel tipped needle insertion into a biological mimetic soft-gel using parameters obtained from experimental work. Additionally, the models will be verified against corresponding needle insertion experiments.
Methods:
To verify simulation results, needle deflection and insertion forces were compared with corresponding experimental results acquired with an in-house developed needle insertion mechanical system. Additionally, contact stress distribution on needles from agar gel for various time scales were also studied.
Results:
For the 15°, 30°, 45°, 60° bevel angle needles, and 90° blunt needle, the percentage error in needle deflection of each needle compared to experiments, were 7.3%, 9.9%, 8.6%, 7.8%, and 9.7% respectively. Varying the bevel angle at the needle tip demonstrates that the needle with a lower bevel angle produces the largest deflection, although the insertion force does not vary too much among the tested bevel angles.
Conclusion:
This experimentally verified computer-based simulation model could be used as an alternative tool for better understanding the needle-tissue interaction to optimise needle tip design towards improved biopsy efficiency.
