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Abstract BackgroundConventional needles lack active mechanisms for large tip deflection to bypass obstacles or guide through a desired trajectory in needle‐based procedures, compromising accuracy and effectiveness. MethodsAn active needle with a shape memory alloy (SMA) actuator was designed and evaluated by demonstrating deflections in tissue‐mimicking gels. Finite element simulation and real‐time needle tip deflection tracking in tissue‐mimicking gels were performed. ResultsThe active needle deflected 50 and 39 mm at 150 mm insertion depth in the liver and prostate mimicking gels, respectively. Reasonable simulation errors of 16.42% and 12.62% in needle deflections and small root mean squared errors of 1.42 and 1.47 mm in deflection tracking were obtained. ConclusionsThe proposed needle produced desirable large tip deflections capable of bypassing obstacles in the insertion path and tracked a preplanned trajectory with minor errors. The finite element study would help optimise needle designs and predict deflections in soft tissues. 

Abstract Reducing the force required during needle insertion is vital to minimize tissue damage in percutaneous procedures. A composite coating of Polydopamine, Polytetrafluoroethylene, and Activated Carbon materials was applied to the needles to address this challenge. The coating reduces needle surface friction, which eventually helps to decrease the insertion force and minimize tissue damage. In this study, measuring the insertion and extraction forces inside a bovine kidney showed that the coated needles decreased the insertion force by 49% and the extraction force by 30%. In addition, a histological analysis was conducted to compare the tissue damage caused by coated and bare needles. The results revealed that coated needles insertion reduced tissue damage by 39.6% compared to bare needles. These findings highlight the potential of this composite coating approach to improve the safety and precision of percutaneous procedures. 

Abstract This study explores the mechanical interactions between surgical needles and soft tissues during procedures like biopsies and brachytherapy. A key challenge is needle tip deflection, which can cause deviation from the intended target. The study aims to develop an analytical model that predicts needle tip deflection during insertion by combining principles from interfacial mechanics and soft tissue deformation. A modified version of the dynamic Euler-Bernoulli beam theory is employed to model needle insertion and predict needle tip deflection. The model’s predictions are then compared to experimental data obtained from needle insertions in real tissues. The research aims to deepen our understanding of needle-tissue interactions and develop a reliable model for predicting needle deflection, ultimately enhancing surgical robots and navigation systems for safer and more precise percutaneous procedures. Pig organs are used as a material data source for a viscoelastic model, simulating needle insertion into kidney-like environments and analyzing organ deformation. The modified Euler-Bernoulli beam theory considers the viscoelastic properties of the tissue. Deflection is then calculated and compared to experimental data, with analytical deflection measurements exhibiting a 5–10% difference compared to experimental results. 

Abstract Active needles obtain more significant tip deflection and improved accuracy over passive needles for percutaneous procedures. However, their ability to navigate through tissues to reach targets depends upon the actuation mechanism, the tip shape, and the surface geometry of the shaft. In this study, we investigate the benefits of changing the surface geometry of the active needle shaft in a) needle tip deflection and b) trajectory tracking during tissue insertion. The modifications in passive needle surface geometry have been proven to reduce friction force, tissue displacement, and tissue damage. This study incorporates the effect of modifying the regular smooth cannula with a mosquito proboscis-inspired design in the active needles. The changes in insertion force, tip deflection, and trajectory tracking control during insertion into a prostate-mimicking phantom are measured. Results show that insertion force is reduced by up to 10.67% in passive bevel-tip needles. In active needles, tip deflection increased by 12.91% at 150mm when the cannula is modified. The bioinspired cannula improved trajectory tracking error in the active needle by 39% while utilizing up to 17.65% lower control duty cycle. Improving tip deflection and tracking control would lead to better patient outcomes and reduced risk of complications during percutaneous procedures. 

Abstract Soft tissue biopsy is a necessary diagnostic and therapeutic procedure, but traditional biopsy needles can cause harm to the patient, including tissue damage, bleeding, and pain. These can compromise the accuracy of the sample and negatively impact the patient’s well-being. Hence, there has been a growing interest in developing bio-inspired surgical needles that are safer, more effective, and more comfortable for the patient. The scorpion-inspired curved tip needle study focuses on analyzing the mechanics of needle-tissue interaction and creating needles that travel through soft tissue with minimum resistance at the tip. An essential aspect of the study is the mechanics and geometry of the needle tip, which plays a crucial role in its performance. The study incorporates structures of curved scorpion’s stinger to balance between penetration and minimal needle-tissue interaction forces. In this study, various parameters of curved tip geometry are explored to decrease the insertion and extraction forces. Tests are initially performed on brain tissue mimicking medical gelatin with Young’s modulus of 2kPa. It is observed that the insertion force with curved tip needles is decreased by up to 21.7%, and the extraction force is decreased by up to 28.2%. This study shows that a scorpion-inspired tip design can minimize insertion and extraction forces, leading to less tissue damage and deformation. Furthermore, the proposed tip design has great potential to improve surgical needles for more effective minimally invasive percutaneous procedures with various applications such as biopsy, brachytherapy, tumor ablation, and drug delivery to the brain. 

Abstract Active needles demonstrate improved accuracy and tip deflection compared to their passive needle counterparts, a crucial advantage in percutaneous procedures. However, the ability of these needles to effectively navigate through tissues is governed by needle-tissue interaction, which depends on the tip shape, the cannula surface geometry, and the needle insertion method. In this research, we evaluated the effect of cannula surface modifications and the application of a vibrational insertion technique on the performance of shape memory alloy (SMA)-actuated active needles. These features were inspired by the mosquito proboscis’ unique design and skin-piercing technique that decreased the needle tissue interaction force, thus enhancing tip deflection and steering accuracy. The bioinspired features, i.e., mosquito-inspired cannula design and vibrational insertion method, in an active needle reduced the insertion force by 26.24% and increased the tip deflection by 37.11% in prostate-mimicking gel. In addition, trajectory tracking error was reduced by 48%, and control effort was reduced by 23.25%, pointing towards improved needle placement accuracy. The research highlights the promising potential of bioinspired SMA-actuated active needles. Better tracking control and increased tip deflection are anticipated, potentially leading to improved patient outcomes and minimized risk of complications during percutaneous procedures. 

Abstract Considerable research efforts have been devoted for studying the interaction between surgical needles and soft tissues which can be used to evaluate the deflection of a bevel-tip needle inside a tissue. The development of an analytical model to predict the steering behavior of the needle during needle-tissue interactions could improve the performance of many percutaneous needle-based procedures. In this study, Euler-Bernoulli beam elastic foundation theory was utilized to model the needle as a cantilever beam moving along its longitudinal axis and undergoing various external loads. The external loads are the result of the interaction between the tissue and the needle during insertion, they can be modeled as a concentrated tissue cutting force acting at the needle bevel, and needle-tissue interaction forces acting along the needle length and tangent to the needle shaft. The accuracy of the analytical predictions offered by the model are verified by comparing them to the experimental data. Due to the assumption of the elastic tissue material, the difference between the analytical model and the experimental results was between 15% to 33%. Current work is ongoing to consider tissue viscoelastic properties to improve the analytical prediction. 

Abstract Active needles obtain more significant tip deflection and improved accuracy over passive needles for percutaneous procedures. However, their ability to navigate through tissues to reach targets depends upon the actuation mechanism, the tip shape, and the surface geometry of the shaft. In this study, we investigate the benefits of changing the surface geometry of the active needle shaft in a) needle tip deflection and b) trajectory tracking during tissue insertion. The modifications in passive needle surface geometry have been proven to reduce friction force, tissue displacement, and tissue damage. This study incorporates the effect of modifying the regular smooth cannula with a mosquito proboscis-inspired design in the active needles. The changes in insertion force, tip deflection, and trajectory tracking control during insertion into a prostate-mimicking phantom are measured. Results show that insertion force is reduced by up to 10.67% in passive bevel-tip needles. In active needles, tip deflection increased by 12.91% at 150mm when the cannula is modified. The bioinspired cannula improved trajectory tracking error in the active needle by 39.00% while utilizing up to 17.65% lower control duty cycle. Improving tip deflection and tracking control would lead to better patient outcomes and reduced risk of complications during percutaneous procedures.