BIOINSPIRED SURGICAL NEEDLE INSERTION MECHANICS IN SOFT TISSUES FOR PERCUTANEOUS PROCEDURES

Abstract

Needles are commonly used to reach target locations inside of the human body for various medical interventions such as drug delivery, biopsy, and brachytherapy cancer treatment. The success of these procedures is highly dependent on whether the needle tip reaches the target. One of the most significant contributors to the target accuracy is the needle insertion force that causes needle-tip deflection, tissue deformation, and tissue damage. Recently there has been tremendous interest in the medical community to develop innovative surgical needles using biologically-inspired designs. It is well known that insects such as honeybee and mosquito steer their stingers effortlessly to a specific target and release their venom in a certain path through the skin with minimal force. These unique traits inspire this dissertation work to develop bioinspired needles and to study the insertion mechanics of these needles for reducing the insertion force, needle-tip deflection, tissue deformation, and tissue damage. In this work, the insertion mechanics of honeybee-inspired needles with applied vibration in polyvinyl chloride (PVC) tissue phantom and chicken breast tissues was first investigated. It was observed that the insertion force was decreased by 43% and the needle tip deflection was minimized by 47% using honeybee-inspired needles. Furthermore, the insertion mechanics of mosquito-inspired needles in PVC tissue phantom and bovine liver tissues were studied. Design parameters such as maxilla design on the needle body, labrum-tip, vibration, and insertion velocity were considered. It was found that the insertion force was reduced by 60% in PVC tissues and 39% in bovine liver tissues using mosquito-inspired needles. To validate the developed bioinspired needle prototypes, a size scale study was performed using insertion test in a PVC tissue phantom. It was confirmed that the insertion force was decreased by 38% using different needle sizes. An analytical LuGre friction model was used to explain the insertion mechanics and to confirm the experimental results. Lastly, to investigate the effect of the insertion force reduction, the tissue deformation and the tissue damage studies were performed. Using a novel magnetic sensing system, it was observed that the tissue deformation caused by mosquito-inspired needles was decreased by 48%. A histological study was performed to quantify the tissue damage in bovine liver tissues. It was observed that the tissue damage of mosquito-inspired needles was reduced by 27% compared to standard needles. In conclusion, this dissertation study shows that applying bioinspired needle designs and vibration during insertion into tissues reduces the insertion force, the needle-tip deflection, the tissue deformation, and the tissue damage. The outcome of this study will benefit medical communities to advance the bioinspired needles for vibration-assisted clinical procedures.