Towards a Nitinol Actuator for an Active Surgical Needle (original) (raw)
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Studies With SMA Actuated Needle for Steering Within Tissue
Volume 2: Mechanics and Behavior of Active Materials; Integrated System Design and Implementation; Bioinspired Smart Materials and Systems; Energy Harvesting, 2014
Flexible needles that can be steered within soft tissues are a promising approach to precisely reach target locations, thereby can significantly benefit needle based surgical procedures such as brachytherapy and biopsy. Several design approaches have been suggested to increase needle flexibility that include beveltipped needles, kinked needles and flexure-based needles. These needles when inserted into a soft materials takes a curved path. This curved path can be controlled while inserting by rotating the needle at its base. In this work another approach to control the curved path was explored. Here the needle body was attached with a shape memory alloy (SMA) actuator close the needle tip that when actuated bends the needle and thereby leads to a curved path inside soft tissue. A prototype of the SMA actuated needle was developed and the working principle was demonstrated in air, tissue-mimicking gel, and pig liver. Moreover, the effect of actuator wire diameter on the needle behavior were studied.
Behavior and Mechanics of Multifunctional Materials and Composites 2015, 2015
Due to its outstanding properties of Nitinol, known as shape memory and superelasticity, Nitinol wires have been used as actuators in many medical devices. For the medical applications, it is critical to have a consistent strain response of Nitinol wires. This work focuses on studying the effect of parameters such as biased stress, maximum temperature, and wire diameters that influence the strain response of Nitinol wires. Specifically, Nitinol phase transformations were studied from microstructural point of view. The crystal structures of one-way shape memory Nitinol wires of various diameters under different thermomechanical loading conditions were studied using X-Ray Diffraction (XRD) method. The location and intensity of characteristic peaks were determined prior and after the thermomechanical loading cycles. It was observed that Nitinol wires of diameters less than 0.19 mm exhibit unrecovered strain while heated to the range of 70ºC to 80ºC in a thermal cycle, whereas no unrecovered strains were found in larger wires. The observation was supported by the XRD patterns where the formation of R-phase crystal structure was showed in wire diameters less than 0.19 mm at room temperature.
A new design of a Nitinol ring-like wire for suturing in deep surgical field
Materials Science and Engineering: C, 2015
The present work proposes a new suturing procedure based on self-accommodating suture points. Each suture point is made of a commercial NiTi wire hot-shaped in a single loop ring; a standard suture needle is then fixed at one end of the NiTi suture. According to this simple geometry, several NiTi suture stitches have been prepared and tested by tensile test to verify the closing force in comparison to that of commercial sutures. Further experimental tests have also been performed on anatomic samples from animals to verify the handiness of the NiTi suture. Moreover, surface quality of sutures has been carefully investigated via microscopy. Results show that the NiTi suture expresses high stiffness and a good surface quality. In addition, the absence of manual knotting allows for a simple, fast and safe procedure.
Sliding mode control of a shape memory alloy actuated active flexible needle
SUMMARY In medical interventional procedures such as brachytherapy, biopsy and radio-frequency ablation, precise tracking through the preplanned desired trajectory is very essential. This important requirement is critical due to two major reasons: anatomical obstacle avoidance and accurate targeting for avoiding undesired radioactive dose exposure or damage to neighboring tissue and critical organs. Therefore, a precise control of the needling device in the unstructured environment in the presence of external disturbance is required to achieve accurate target reaching in clinical applications. In this paper, a shape memory alloy actuated active flexible needle controlled by an adaptive sliding mode controller is presented. The trajectory tracking performance of the needle is tested while having its actual movement in an artificial tissue phantom by giving various input reference trajectories such as multi-step and sinusoidal. Performance of the adaptive sliding mode controller is compared with that of the proportional, integral and derivative controller and is proved to be the effective method in the presence of the external disturbances. 1. Introduction Needles are one of the most significant minimally invasive tools to intervene diagnostic regions of the human body. In those needle-based therapeutic percutaneous, medical interventional procedures such as biopsy, fluid/blood collection, brachytherapy, radio-frequency-based thermal ablation, cryo-therapy, anesthetic drug delivery, neural stimulation and so on, 1 accurate needle placement is one of the major requirements, as the success of such procedures are dependent on the accuracy of the needle placement. To enhance needle steerability while performing the percutaneous interventions, Webster III et al. 2 have proposed a methodology that entails precurved concentric tubes with stiffness variation. A further approach to execute improved needle steerability with minimal tissue damage and higher curvature, is proposed by Swaney et al., 3 which features a flexure-based kinked needle design. The flexible needle steering techniques are categorized mainly into passive needle steering and active needle steering. The passive needles are the ones which have no actuators and sensors attached to their shaft. Rather, they are mere free bodies either with symmetrical or asymmetrical tip to undergo the reaction force from the tissue environment.
Mechanics of Flexible Needles Robotically Steered through Soft Tissue
The International Journal of Robotics Research, 2010
The tip asymmetry of a bevel-tip needle results in the needle naturally bending when it is inserted into soft tissue. This enables robotic needle steering, which can be used in medical procedures to reach subsurface targets inaccessible by straight-line trajectories. However, accurate path planning and control of needle steering requires models of needle-tissue interaction. Previous kinematic models required empirical observations of each needle and tissue combination in order to fit model parameters. This study describes a mechanics-based model of robotic needle steering, which can be used to predict needle behavior and optimize system design based on fundamental mechanical and geometrical properties of the needle and tissue. We first present an analytical model for the loads developed at the tip, based on the geometry of the bevel edge and material properties of softtissue simulants (gels). We then present a mechanics-based model that calculates the deflection of a bevel-tipped needle inserted through a soft elastic medium. The model design is guided by microscopic observations of needle-gel interactions. The energy-based formulation incorporates tissue-specific parameters, and the geometry and material properties of the needle. Simulation results follow similar trends (deflection and radius of curvature) to those observed in experimental studies of robotic needle insertion.
Design optimization study of a shape memory alloy active needle for biomedical applications
Medical Engineering & Physics, 2015
Majority of cancer interventions today are performed percutaneously using needle-based procedures, i.e. through the skin and soft tissue. The difficulty in most of these procedures is to attain a precise navigation through tissue reaching target locations. To overcome this challenge, active needles have been proposed recently where actuation forces from shape memory alloys (SMAs) are utilized to assist the maneuverability and accuracy of surgical needles. In the first part of this study, actuation capability of SMA wires was studied. The complex response of SMAs was investigated via a MATLAB implementation of the Brinson model and verified via experimental tests. The isothermal stress-strain curves of SMAs were simulated and defined as a material model in finite element analysis (FEA). The FEA was validated experimentally with developed prototypes. In the second part of this study, the active needle design was optimized using genetic algorithm aiming its maximum flexibility. Design parameters influencing the steerability include the needle's diameter, wire diameter, pre-strain and its offset from the needle. A simplified model was presented to decrease the computation time in iterative analyses. Integration of the SMA characteristics with the automated optimization schemes described in this study led to an improved design of the active needle.
A Variable Stiffness Mechanism for Minimally Invasive Surgical Needles
10th Hamlyn Symposium on Medical Robotics 2017, 2017
This year marks the 10 th anniversary of the Hamlyn Symposium on Medical Robotics, which was held at the Royal Geographical Society from 25 th to 28 th June 2017. On this special occasion, we set the theme of this year's symposium as 'The Next 10 Years: Challenges, Innovation and Diffusion of Medical Robotics.' We had the honour of an impressive line-up of leading scientists and engineers in medical robotics, covering intra-operative imaging and sensing, smart surgical instruments, soft and continuum robotics, micro-nano robots, surgical workflow analysis, surgical vision, clinical highlights and first-inhuman studies. This year's Storz-Hopkins lecture was delivered by Professor Joseph Sung,
Simulation and experimental studies of the SMA-activated needle behavior inside the tissue
Active and Passive Smart Structures and Integrated Systems 2015, 2015
Recently, the concept of developing an active steerable needle has gathered a lot of attention as they could potentially result in an improved outcome in various medical percutaneous procedures. Compared to the conventional straight bevel tip needles, active needles can be bent by means of the attached actuation component in order to reach the target locations more accurately. In this study, the movement of the passive needle inside the tissue was investigated using numerical and experimental approaches. A finite element simulation of needle insertion was developed using LSDYNA software to study the maneuverability of the passive needle. The Arbitrary-Eulerian-Lagrangian (ALE) formulation was used to model the interactions between the solid elements of the needle and the fluid elements of the tissue. Also the passive needle insertion tests were performed inside a tissue mimicking phantom. This model was validated for the 150mm of insertion which is similar to the depth in our needle insertion experiments. The model is intended to be based as a framework for modeling the active needle insertion in future.
A Tape Spring Steerable Needle Capable of Sharp Turns
bioRxiv (Cold Spring Harbor Laboratory), 2023
Objective: To make steerable needles more effective, researchers have been trying to minimize turning radius, develop mechanics-based models, and simplify control. This paper introduces a novel cable-driven steerable needle that has a 3mm turning radius based on tape spring mechanics, which sets a new minimum turn radius in stiffness-matched tissue models. Methods: We characterize the turn radius and the forces that affect control and performance and create predictive models to estimate required insertion forces and maximum insertion depth. Finally, we demonstrate the performance of a task outside the capabilities of a conventional needle. Results: Minimal force is required to maintain bends, allowing surrounding tissue to fix them in place, and minimal energy is required to propagate bends, allowing the device to navigate easily through various tissue phantoms. The turn radius of the device is independent of surrounding tissue stiffness, making for simple and precise control. We show that all aspects of performance depend on minimizing the tip cutting force. Under ultrasound guidance, we successfully navigate into and then follow a deep blood vessel model at a steep angle of approach. Conclusion: This design allows the system to accurately control the direction of the device while maintaining a smaller turn radius than other steerable needles, providing the potential to broaden access to challenging targets in patients.
Measurement of temperature and displacement with NiTi actuators under certain electrical conditions
Journal of Measurements in Engineering
In this study, various mechanical behaviors of a shape memory alloy, depending on different thermal and electrical conditions to be used in areas such as biomedical, aerospace and aeronautics. Temperature changes and length change rates under different electrical current values of a shape memory alloy named "nickel titanium", or "nitinol" (NiTi) has been observed. It has been seen that a 0.3 mm diameter wire can generate a force of 25 N while the material extends its linear measurement with a rate of 3.7 mm/s. It is observed that, under diverse constant electrical current values, the displacement and temperature relations of the nickel titanium wire is varying. It has empirically been seen that the nickel titanium alloy actuators are advantageous than their alternatives in terms of the generated strength to weight ratio and shape memory alloy materials can be used as actuators in industrial and biomedical applications.
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