Waterjet Fracture-directed Steerable Needles

Robotic needle steering is a proposed method in the literature for controlling flexible needles through curved paths in the soft tissue. Needle steering is proven to be effective in correction of insertion errors, steering around obstacles to reach the targets unreachable through conventional methods, and reaching to multiple targets from a single insertion.In spite of their many advantages and potential applications, they are limited by a number of factors. First off, they have constant curvatures and the attainable radius of curvature is a function of the needle and soft tissue parameters. Buckling is another issue that happens when the needle goes through structures and tissues that it cannot penetrate. This imposes a large force at the base of the needle and causes it to buckle.The use of the waterjet in medical applications has been developed more recently and it is used for different applications such as soft tissue resection, bone cutting, wound debridement, and surgery. Because of the many advantages that the waterjet provides like selective cutting of the tissue layers in which the tissue layers can cut deliberately by controlling the pressure of the waterjet, it is an appealing technique for surgery instead of knife.From the marriage between conventional steerable needles and the waterjet technology, waterjet steerable needles is born. In this technique, the direction of the fracture is controlled by high velocity waterjet and then the flexible needle follows the fractured path. This process continues until the needle can be steered in the soft tissue. Waterjet steerable needles resemble "drilling" in the sub-millimeter scale which has been proven to have superior advantages to conventional steerable needles.Our results showed that cutting the tissue with the waterjet can eliminate the cutting force and thus reduces the force at the base of the needle resulting in reduced buckling. Moreover, waterjet steerable needles showed the possibility of smaller radius of curvature with reduced tissue damage. Waterjet steerable needles promise tissue-agnostic steering in which the needle can be chosen to have a low bending stiffness (because the waterjet does the cutting) to obtain super small radii of curvature

Waterjet fracture-directed steerable needles

The focus of this proposal is on the new classes of steerable needles namely fracture-directed steerable needles, and two approaches to achieve this that are tube and stylet method, and water-jet method. Steerable needles hold the promise of improving the accuracy of both therapies and biopsies as they are able to steer to a target location around obstructions, correct for disturbances, and account for movement of internal organs. However, their ability to make late- insertion corrections has always been limited by the lower bound on the attainable radius of curvature. Stylet and tube fracture-directed steerable needles involve a new class of steerable needle insertion where the objective is to first control the direction of tissue fracture with an inner stylet and later follow with the hollow needle. This method is shown to be able to achieve radius of curvature as low as 6.9 mm across a range of tissue stiffnesses and the radius of curvature is controllable from the lower bound up to a near infinite radius of curvature based on the stylet/needle step size. The approach of ”fracture-directed” steerable needles indicates the promise of the technique for providing a tissue-agnostic method of achieving high steerability that can account for variability in tissues during a typical procedure and achieve radii of curvature unattainable through current bevel-tipped techniques. Water-jet technology has been used extensively for decades industrially for many applications including mining, plastic, metal, stone, wood, and produce cutting. The use of water-jet in medical applications has been developed more recently and it is used for different applications such as soft tissue resection, bone cutting, wound debridement, and surgery. Water-jet fracture-directed steerable needles is a new application of water-jet technology in the medical field that harnesses the advantages of water-jet technology and steerable needle technology into one. A needle insertion system is designed and built, which has a custom-designed water-jet nozzle attached to a Nitinol needle as its ”needle”. Insertions with and without water-jet into 10%, 15% and 20% Poly (styrene-b-ethylene-co-butylene-b-styrene) triblock copolymer (SEBS) tissue-mimicking simulants are performed and the associated force data are measured using a force sensor at the base of the needle. Preliminary results of force vs. displacement showed that the water-jet reduces the insertion force associated with traditional needles by eliminating tip forces. For preliminary results, custom-designed straight nozzle is used to show the feasibility of water-jet steerable needles, whereas research underway is focused on steerability using steerable nozzles to improve steerability compared to current steerable needle technologies. Depth of cut as a function of fluid velocity is also measured for different volumetric flow rates. Preliminary results show that depth of cut is a linear function of fluid velocity when the width of the water-jet nozzle is sufficiently small and smooth. Research is underway to understand the characteristics of water-jet - tissue interaction, which is an important aspect to be explored to design better devices as well as path planning and control algorithms. To do so, a physics-based model to predict cutting depth, crack dimensions and insertion load on the needle based on parameters such as tissue properties (constitutive response and toughness), nozzle diameter, tip shape of the needle, and volumetric flow rate is the other aim of this proposal that is lacking in the literature. Another aim of the current proposal is using current path planning methods and proposing a control method for the developed water-jet steerable needle. In order to direct steerable needles to specific targets and avoid anatomical obstacles, planning paths through the patient’s anatomy is needed. Path planning of steerable needles is beyond the intuition of human beings because of complex kinematics, effects of tissue deformation, effects of tissue inhomogeneities, and other causes of motion uncertainty. Efficient computational methods for path planning enables using the full potential of steerable needles. Due to nonlinearity of needle steering, estimation and control problems are coupled. Controller-observed pairs are needed to estimate needle orientation. For image-guided control of water-jet needle steering, needle steering models should be used for model-based feedback controllers to steer the needle inside the tissue. Therefore the other aim of this proposal will be developing a controller to control water-jet needle to reach to a specified target

Engineering Solid Mechanics Anthropomorphic mechanical design and Lyapunov-based control of a new shoulder rehabilitation system

Stroke is one of the main causes of disability. It affects millions of people worldwide. One symptom of stroke is disabled arm function. Restoration of arm function is necessary to resuming activities of daily living (ADL). Along with traditional rehabilitation techniques, robot-aided therapy has emerged recently. The control schemes of rehabilitation robots are designed for two reasons. First they are designed for passive rehabilitation in which the robot guides the patient's limb through a predefined path and second for active rehabilitation in which the patient initiates the movement and is partially assisted or resisted by the robotic device. This paper introduces a new robot for shoulder rehabilitation. The Shoulder Rehabilitation System (SRS) has three degrees of freedom (DOFs) for three rotational DOFs of the shoulder but additional translational DOFs of the shoulder are also allowed to avoid discomfort to the patient. A new open circular mechanism is proposed for the third joint that solves the known issues for rehabilitation robots such as long wiring and discomfort associated with closed mechanisms. Lyapunov-based controller with integral action is proposed to guide the robot through a predefined trajectory. Simulation results proved that the proposed controller can track the desired trajectory; reject constant bounded disturbance to the system and is robust due to its nonlinear nature. The proposed controller is designed to be used in passive rehabilitation

Predictive Mathematical, and finite element model for cut depth of waterjet for medical applications

Water-jet has already been used in several industrial applications such as mining, cutting materials, drilling, and cleaning. Recently, this technology has been used in medical applications such as in surgery, dissection of organs, dentistry, bone cutting, and wound debridement. Measuring depth of cut of water-jet is important from medical applications point of view. For example, in surgical applications using water-jet, selective cutting is a must. In other words, water-jet should cut the desired layer and should not go further. For instance, in order for the optimal performance of the Versajet water-jet surgical tool in treating the different depth face and neck burns, the depth of debridement should be controlled

Towards Water-jet Steerable Needles

Water-jet technology has been used extensively for decades industrially for many applications including mining, plastic, metal, stone, wood, and produce cutting. The use of water-jet in medical applications has been developed more recently and it is used for different applications such as soft tissue resection, bone cutting, wound debridement, and surgery. In this paper, a new application of water-jet technology in the medical field is proposed, namely water-jet cutting at the tip of a needle with a long-term goal of steerable needles. A needle insertion system is designed and built, which has a custom-designed water-jet nozzle attached to a Nitinol needle as its ”needle”. Insertions with and without water-jet into 10%, 15% and 20% Poly (styrene-b-ethylene-co-butylene-b- styrene) triblock copolymer (SEBS) tissue-mimicking simulants are performed and the associated force data is measured using a force sensor at the base of the needle. The results of force vs. displacement show that the water-jet reduces the insertion force associated with traditional needles by eliminating tip forces. In this paper, a custom-designed straight nozzle is used to show the feasibility of water-jet steerable needles, whereas future work will focus on steerability using steerable nozzles. Depth of cut as a function of fluid velocity is also measured for different volumetric flow rates. The results show that depth of cut is a linear function of fluid velocity when the width of the water-jet nozzle is sufficiently small and smooth

Water-jet Steerable Needles

Water-jet technology has been used extensively for decades industrially for many applications including mining, plastic, metal, stone, wood, and produce cutting. The use of water-jet in medical applications has been developed more recently and it is used for different applications such as soft tissue resection, bone cutting, wound debridement, and surgery [1]. Decreasing the insertion force is important in medical applications since high insertion forces can complicate reaching the intended target with high accuracy. Research shows that lower insertion force can reduce needle bending and tissue deflection [2]. It can also reduce the pain felt by the patient during procedure [3]. Therefore, researchers have actively researched ways to reduce the insertion forces. Methods proposed in the literature to reduce the insertion forces include changing needle geometry, using smaller needles, and inserting the needle with different insertion speeds and/or vibration.  To the best of our knowledge, this is the first time that water-jet is incorporated into traditional needles and insertion forces are measured

Fracture-Directed Steerable Needles

Steerable needles hold the promise of improving the accuracy of both therapies and biopsies as they are able to steer to a target location around obstructions, correct for disturbances, and account for movement of internal organs. However, their ability to make late-insertion corrections has always been limited by the lower bound on the attainable radius of curvature. This paper presents a new class of steerable needle insertion where the objective is to first control the direction of tissue fracture with an inner stylet and later follow with the hollow needle. This method is shown to be able to achieve radius of curvature as low as 6.9 mm across a range of tissue stiffnesses and the radius of curvature is controllable from the lower bound up to a near infinite radius of curvature based on the stylet/needle step size. The approach of \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\fracture-directed" steerable needles indicates the promise of the technique for providing a tissue-agnostic method of achieving high steerability that can account for variability in tissues during a typical pro- cedure and achieve radii of curvature unattainable through current bevel-tipped techniques. A variety of inner stylet geometries are investigated using tissue phantoms with multiple stiffnesses and discrete-step kinematic models of motion are derived heuristically from the experiments. The key finding presented is that it is the geometry of the stylet and the tuning of the bending stiffnesses of both the stylet and the tube, relative to the stiffness of the tissue, that allow for such small radius of curvature even in very soft tissues

Fracture-Directed Steerable Needles

This paper is accepted and published at Journal of Medical Robotics Research.Steerable needles hold the promise of improving the accuracy of both therapies and biopsies as they are able to steer to a target location around obstructions, correct for disturbances, and account for movement of internal organs. However, their ability to make late-insertion corrections has always been limited by the lower bound on the attainable radius of curvature. This paper presents a new class of steerable needle insertion where the objective is to first control the direction of tissue fracture with an inner stylet and later follow with the hollow needle. This method is shown to be able to achieve radius of curvature as low as 6.9 mm across a range of tissue stiffnesses and the radius of curvature is controllable from the lower bound up to a near infinite radius of curvature based on the stylet/needle step size. The approach of \fracture-directed" steerable needles indicates the promise of the technique for providing a tissue-agnostic method of achieving high steerability that can account for variability in tissues during a typical pro- cedure and achieve radii of curvature unattainable through current bevel-tipped techniques. A variety of inner stylet geometries are investigated using tissue phantoms with multiple stiffnesses and discrete-step kinematic models of motion are derived heuristically from the experiments. The key finding presented is that it is the geometry of the stylet and the tuning of the bending stiffnesses of both the stylet and the tube, relative to the stiffness of the tissue, that allow for such small radius of curvature even in very soft tissues

Duty Cycling of Waterjet Can Improve Steerability and Radius-of-Curvature (ROC) for Waterjet Steerable Needles

The paper entitled "Duty Cycling of Waterjet Can Improve Steerability and Radius-of-Curvature (ROC) for Waterjet Steerable Needles" is accepted to be published in the proceedings of the ISMR 2020- International Symposium on Medical Robotics.Steerable needles are a type of medical devices that can steer around obstacles to reach to a target location and thus can improve the accuracy of medical procedures. Radius-of-Curvature (ROC) is of paramount importance while designing steerable needles and achieving smaller radius and being able to control it is very important in evaluating the efficacy of the steerable needles. In this paper, the idea of a new class of steerable needle technology namely fracture- directed waterjet steerable needles is presented in which the direction of the tissue fracture is controlled by waterjet and then Nitinol tube follows. Needle steering tests are performed on two different stiffnesses of SEBS soft tissue simulants, as well as 10% by weight Knox Gelatin (Kraft Foods Global Inc., IL) as substitutes to real biological tissues. Curvature of the needle is controlled by waterjet duty cycling and it is shown that it can be controlled from about 0 (when waterjet is OFF at all steps) to maximum curvature (when waterjet is ON for all steps). It is concluded that the curvature is a linear function of the duty cycling and that the smallest ROC of the waterjet steerable needle (when waterjet is ON at all steps) is improved in comparison to the smallest ROC of traditional steerable needles in the same tissue phantom