An experimental study on the mechanics and control of SMA-actuated bioinspired needle.

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.

Design and evaluation of shape memory alloy-actuated active needle using finite element analysis and deflection tracking control in soft tissues.

BACKGROUND: Conventional 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. METHODS: An 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. RESULTS: The 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. CONCLUSIONS: The 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.

Assessment of tissue damage from mosquito-inspired surgical needle.

INTRODUCTION: Many percutaneous procedures utilize surgical needles to extract tissue samples in biopsy or to apply specific cancer treatments. A design of mosquito-inspired surgical needles was proposed to improve the efficacy of these procedures by reducing the needle insertion force and the resulting tissue damage. The focus of this study is to assess tissue damage caused by the insertion of a mosquito-inspired needle into soft tissues. MATERIAL AND METHODS: In this work, the geometric features and the dynamic stinging (insertion) mechanism of mosquito proboscis were mimicked for the design of 3D-manufactured bioinspired needle prototypes. A specially designed test setup was developed to measure the insertion force in bovine liver tissue. The histology assessment based on hematoxylin and eosin staining and image analysis was conducted to determine the bovine liver tissue damage. RESULTS: It was observed that the insertion force can be reduced by up to 39% and the bovine liver tissue damage was decreased by 27% using the mosquito-inspired needles when compared with using the standard needles. CONCLUSION: The findings from this study suggested that the bioinspired needle design has great potential to advance surgical needles for more effective and less invasive percutaneous procedures.