Project

Medical Robotics

Goal: Continuum medical robots, deformable robotic phantoms, biomedical systems modeling, medical robotics control and automation

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Project log

S.M.Hadi Sadati
added a research item
The concept of continuum and soft robotics has opened new abilities that were previously unachievable by rigid robotics alone, such as squeezing, growing, and morphing to their environments. As an example, Concentric Tube Robots (CTR) are continuum robots made of a series of pre-curved, elastic tubes where each tube can individually be rotated, as well as extended and recalled; interactions between each tube allows for turns and twists, giving control over the length and configuration of the robot. CTRs can assist in minimally invasive surgery (MIS) to access difficult to reach areas, due to the intricate human anatomy, with advantages including single-site entry and their malleable nature [1]. However, utilizing CTRs, and continuum robots in general, are not without their own challenges. Due to the complex nature of a continuum structure, fast and accurate simulations are still in development and require specific skills to operate. These simulations are not usually accurate due to the complex behaviours of the materials used and their deformable nature. SOFA (Simulation Open Framework Architecture) was introduced as an open-source platform to address some of the challenges with real-time physics-based simulation of interaction with deformable tissue in medical applications and later for modelling soft robots. More specifically, a BeamAdapter plugin2 was developed based on interpolation of a continuous geometry over multiple consecutive Timoshenko beam segments to address the simulation challenges of neurovascular interventions using interleaved catheters and guidewires [2]. The BeamAdapter plugin has been also utilized for interactive planning of coil embolization in brain aneurysms [3] and interactive training system for interventional electrocardiology procedures [4]. We have recently developed a Reduced-Order dynamic model for CTRs based on the shape interpolation of the robot backbone and showcased its real-time performance, correct estimation of the path-dependent motions and snapping instances, accurate simulations of stable and post-snapping motions in an experimental comparative study [5]. In this paper, we outline the process and the code on how a CTR model can be implemented into an example scene provided as a part of the SOFA-framework ‘BeamAdapter’ plugin [2].
S.M.Hadi Sadati
added 3 research items
The direct relationship between early-stage breast cancer detection and survival rates has created the need for a simple, fast and cheap method to detect breast cancer at its earliest stages. Endoscopic evaluation of the mammary ducts known as ductoscopy has great potential to detect early breast cancers. Unfortunately, there are technical limitations, most notably lack of steerability and high tissue damage, limiting its practicality. A promising alternative to rigid endoscopy tools is the use of soft robots.
Continuum surgical robots can navigate anatom-ical pathways to reach pathological locations deep inside thehuman body. Their flexibility, however, generally comes with re-duced dexterity at their tip and limited workspace. Building onrecent work on eccentric tube robots, this paper proposes a newcontinuum robot architecture and theoretical framework thatcombines the flexibility of push/pull actuated snake robots andthe dexterity offered by concentric tube robotic end-effectors.We designed and present a prototype system as a proof-of-concept, and developed a tailored quasistatic mechanics-basedmodel that describes the shape and end-effector’s pose for thisnew type robotic architecture. The model can accommodate anarbitrary number of arms placed eccentrically with respect tothe backbone’s neutral axis. Our experiments show that theerror between model and experiment is on average 3.56% ofthe manipulator’s overall length. This is in agreement with stateof the art models of single type continuum architecture.
S.M.Hadi Sadati
added a research item
This paper presents a multi-purpose gripping and incision tool-set to reduce the number of required manipulators for targeted therapeutics delivery in Minimally Invasive Surgery. We have recently proposed the use of multi-arm Concentric Tube Robots (CTR) consisting of an incision, a camera, and a gripper manipulator for deep orbital interventions, with a focus on Optic Nerve Sheath Fenestration (ONSF). The proposed prototype in this research, called Gripe-Needle , is a needle equipped with a sticky suction cup gripper capable of performing both gripping of target tissue and incision tasks in the optic nerve area by exploiting the multi-tube arrangement of a CTR for actuation of the different tool-set units. As a result, there will be no need for an independent gripper arm for an incision task. The CTR innermost tube is equipped with a needle, providing the pathway for drug delivery, and the immediate outer tube is attached to the suction cup, providing the suction pathway. Based on experiments on various materials, we observed that adding a sticky surface with bio-inspired grooves to a normal suction cup gripper has many advantages such as, 1) enhanced adhesion through material stickiness and by air-tightening the contact surface, 2) maintained adhesion despite internal pressure variations, e.g. due to the needle motion, and 3) sliding resistance. Simple Finite Element and theoretical modeling frameworks are proposed, based on which a miniature tool-set is designed to achieve the required gripping forces during ONSF. The final designs were successfully tested for accessing the optic nerve of a realistic eye phantom in a skull eye orbit, robust gripping and incision on units of a plastic bubble wrap sample, and manipulating different tissue types of porcine eye samples.
S.M.Hadi Sadati
added a research item
Continuum robots can traverse anatomical pathways to intervene in regions deep inside the human body. They are able to steer along 3D curves in confined spaces and dexterously handle tissues. Concentric tube robots (CTRs) are continuum robots that comprise a series of precurved elastic tubes that can be translated and rotated with respect to each other to control the shape of the robot and tip pose. CTRs are a rapidly maturing technology that has seen extensive research over the past decade. Today, they are being evaluated as tools for a variety of surgical applications, as they can offer precision and manipulability in tight workspaces. This review provides an exhaustive classification of research on CTRs based on their clinical applications and highlights approaches for modeling, control, design, and sensing. Competing approaches are critically presented, leading to a discussion of future directions to address the limitations of current research and its translation to clinical applications. Expected final online publication date for the Annual Review of Control, Robotics, and Autonomous Systems, Volume 5 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
S.M.Hadi Sadati
added a research item
This letter presents MAMMOBOT, one of the first millimetre-scale steerable soft growing robots for medical applications. MAMMOBOT aims to access the breast through the nipple and navigate the mammary ducts to detect precursors of invasive breast cancers. Addressing limitations of the state-of-the-art, MAMMOBOT maintains a hollow inner lumen throughout its soft body, enabling the passing of instruments such as miniature endoscopes, biopsy needles, and optical probes for in situ histopathology. MAMMOBOT is developed by a novel manufacturing approach entailing dual LDPE sheet adhesion with localised heat treatment. MAMMOBOT's steerability is achieved through a sub-millimetre profiled tendon-driven catheter that passes through its inner lumen. A duty cycle controller governs steering versus growing to achieve navigation in complex environments within a human-in-the-loop framework. Benchtop experimental evaluation demonstrates the robot's capabilities and agreement with a Reduced-Order Mode (ROM) of its dynamics. Finally, experimental evaluation on a bespoke breast phantom developed for the purposes of this project demonstrates the clinical relevance and potential impact of MAMMOBOT.
S.M.Hadi Sadati
added a research item
This paper presents MAMMOBOT, one of the first millimetre-scale steerable soft growing robots for medical applications. MAMMOBOT aims to access the breast through the nipple and navigate the mammary ducts to detect precursors of invasive breast cancers. Addressing limitations of the state-of-the-art, MAMMOBOT maintains a hollow inner lumen throughout its soft body, enabling the passing of instruments such as miniature endoscopes, biopsy needles, and optical probes for in situ histopathology. MAMMOBOT is developed by a novel manufacturing approach entailing dual LDPE sheet adhesion with localised heat treatment. MAMMOBOT's steerability is achieved through a sub-millimetre profiled steerable catheter that passes through its inner lumen. A duty cycle controller governs steering versus growing to achieve navigation in complex environments within a human-in-the-loop framework. Benchtop experimental evaluation demonstrates the robot's capabilities and agreement with a Reduced Order Model (ROM) of its mechanics. Finally, experimental evaluation on a bespoke breast phantom developed for the purposes of this project demonstrates the clinical relevance and potential impact of MAMMOBOT.
S.M.Hadi Sadati
added 4 research items
Continuum and soft robotics showed many applications in medicine from surgery to health care where their compliant nature is advantageous in minimal invasive interaction with organs. Stiffness control is necessary for challenges with soft robots such as minimalistic actuation, less invasive interaction, and precise control and sensing. This paper presents an idea of scale jamming inspired by fish and snake scales to control the stiffness of continuum manipulators by controlling the Coulomb friction force between rigid scales. A low stiffness spring is used as the backbone for a set of round curved scales to maintain an initial helix formation while two thin fishing steel wires are used to control the friction force by tensioning. The effectiveness of the design is showed for simple elongation and bending through mathematical modelling, experiments and in comparison to similar research. The model is tested to control the bending stiffness of a STIFF-FLOP continuum manipulator module designed for surgery.
In this paper, we propose benefiting from load readings at the base of a continuum appendage for real-time forward integration of Cosserat rod model with application in configuration and tip load estimation. The application of this method is successfully tested for stiffness imaging of a soft tissue, using a 3-DOF hydraulically actuated braided continuum appendage. Multiple probing runs with different actuation pressures are used for mapping the tissue surface shape and directional linear stiffness, as well as detecting non-homogeneous regions, e.g. a hard nodule embedded in a soft silicon tissue phantom. Readings from a 6-axis force sensor at the tip is used for comparison and verification. As a result, the tip force is estimated with 0.016-0.037 N (7-20%) mean error in the probing and 0.02-0.1 N (6-12%) in the indentation direction, 0.17 mm (14%) mean error is achieved in estimating the surface profile, and 3.415 [N/m] (10-16%) mean error is observed in evaluating tissue directional stiffness, depending on the appendage actuation. We observed that if the appendage bends against the slider motion (toward the probing direction), it provides better horizontal stiffness estimation and better estimation in the perpendicular direction is achieved when it bends toward the slider motion (against the probing direction). In comparison with a rigid probe, ≈ 10 times smaller stiffness and ≈ 7 times larger mean standard deviation values were observed, suggesting the importance of a probe stiffness in estimation the tissue stiffness.
This paper presents a medical robotic system for deep orbital interventions, with a focus on Optic Nerve Sheath Fenestration (ONSF). ONSF is a currently invasive ophthalmic surgical approach that can reduce potentially blinding elevated hydrostatic intracranial pressure on the optic disc via an incision on the optic nerve. The prototype is a multi-arm system capable of dexterous manipulation and visualization of the optic nerve area, allowing for a minimally invasive approach. Each arm is an independently controlled concentric tube robot collimated by a bespoke guide that is secured on the eye sclera via sutures. In this paper, we consider the robot's end-effector design in order to reach/navigate the optic nerve according to the clinical requirements of ONSF. A prototype of the robot was engineered, and its ability to penetrate the optic nerve was analysed by conducting ex vivo experiments on porcine optic nerves and comparing their stiffness to human ones. The robot was successfully deployed in a custom-made realistic eye phantom. Our simulation studies and experimental results demonstrate that the robot can successfully navigate to the operation site and carry out the intervention.
S.M.Hadi Sadati
added a project goal
Continuum medical robots, deformable robotic phantoms, biomedical systems modeling, medical robotics control and automation