Evaluation of a novel flexible snake robot for endoluminal surgery

Advanced Soft Robotic System for In Situ 3D Bioprinting and Endoscopic Surgery

Three-dimensional (3D) bioprinting technology offers great potential in the treatment of tissue and organ damage. Conventional approaches generally rely on a large form factor desktop bioprinter to create in vitro 3D living constructs before introducing them into the patient's body, which poses several drawbacks such as surface mismatches, structure damage, and high contamination along with tissue injury due to transport and large open-field surgery. In situ bioprinting inside a living body is a potentially transformational solution as the body serves as an excellent bioreactor. This work introduces a multifunctional and flexible in situ 3D bioprinter (F3DB), which features a high degree of freedom soft printing head integrated into a flexible robotic arm to deliver multilayered biomaterials to internal organs/tissues. The device has a master-slave architecture and is operated by a kinematic inversion model and learning-based controllers. The 3D printing capabilities with different patterns, surfaces, and on a colon phantom are also tested with different composite hydrogels and biomaterials. The F3DB capability to perform endoscopic surgery is further demonstrated with fresh porcine tissue. The new system is expected to bridge a gap in the field of in situ bioprinting and support the future development of advanced endoscopic surgical robots.

Research progress and development trend of surgical robot and surgical instrument arm

BACKGROUND

In recent years, surgical robots have become an indispensable part of the medical field. Surgical robots are increasingly being used in the areas of gynaecological surgery, urological surgery, orthopaedic surgery, general surgery and so forth. In this paper, the development of surgical robots in different operations is reviewed and analysed. In the type of master-slave surgical robotic system, the robotic surgical instrument arms were located in the execution terminal of a surgical robot system, as one of the core components, and directly contact with the patient during the operation, which plays an important role in the efficiency and safety of the operation. In clinical, the arm function and design in different systems varies. Furtherly, the current research progress of robotic surgical instrument arms used in different operations is analysed and summarised. Finally, the challenge and trend are concluded.

METHODS

According to the classification of surgical types, the development of surgical robots for laparoscopic surgery, neurosurgery, orthopaedics and microsurgery are analysed and summarised. Then, focusing on the research of robotic surgical instrument arms, according to structure type, the research and application of straight-rod surgical instrument arm, joint surgical instrument arm and continuous surgical instrument arm are analysed respectively.

RESULTS

According to the discussion and summary of the characteristics of the existing surgical robots and instrument arms, it is concluded that they still have a lot of room for development in the future. Therefore, the development trends of the surgical robot and instrument arm are discussed and analysed in the five aspects of structural materials, modularisation, telemedicine, intelligence and human-machine collaboration.

CONCLUSION

Surgical robots have shown the development trend of miniaturisation, intelligence, autonomy and dexterity. Thereby, in the field of science and technology, the research on the next generation of minimally invasive surgical robots will usher in a peak period of development.

The evolution of lower gastrointestinal endoscopy: where are we now?

Lower gastrointestinal endoscopy has evolved over time, fulfilling a widening diagnostic and therapeutic remit. As our understanding of colorectal cancer and its prevention has improved, endoscopy has progressed with improved diagnostic technologies and advancing endoscopic therapies. Despite this, the fundamental design of the endoscope has remained similar since its inception. This review presents the important role lower gastrointestinal endoscopy serves in the prevention of colorectal cancer and the desirable characteristics of the endoscope that would enhance this. A brief history of the endoscope is presented. Current and future robotic endoscopic platforms, which may fulfil these desirable characteristics, are discussed. The incorporation of new technologies from allied scientific disciplines will help the endoscope fulfil its maximum potential in preventing the increasing global burden of colorectal cancer. There are a number of endoscopic platforms under development, which show significant promise.

Wire-driven flexible manipulator with constrained spherical joints for minimally invasive surgery

PURPOSE

One of the main factors that affect the rigidity of flexible robots is the twist deformation because of the external force exerted on the end effector. Another important factor that affects accuracy is the fact that such robots do not have a constant curvature. The conventional kinematic model assumes that the curvature is constant; however, in reality, it is not. To improve the rigidity and accuracy of flexible robots used in minimally invasive surgery via preventing the twist deformation while ensuring a constant curvature, we propose a novel flexible manipulator with ball-constrained spherical (BCS) joints and a spring.

METHODS

The BCS joints are used to prevent the twist deformation in the flexible robot. The joints have two degrees of freedom (DOFs), which limit the rotation about the axial direction. The rotation is limited because the ball that is inserted into a BCS joint can move only along the ball guide. To obtain a constant curvature, springs are installed among the BCS joints. The springs receive the uniform compression force generated among the joints, thus achieving a constant curvature. The proposed BCS joint is designed based on the diameter of the forceps, desired workspace, and desired bending angle.

RESULTS

To evaluate the proposed mechanism, three experiments were performed using a 20-mm-diameter prototype consisting of 13 BCS joints with a two-DOF motion. The experimental results showed that the prototype can realize a constant curvature with a mean error of 0.21°, which can support up to 5 N with no apparent twist deformation.

CONCLUSIONS

We developed a flexible manipulator with BCS joints for minimally invasive surgery. The proposed mechanism is anticipated to help prevent the twist deformation of the robot and realize a constant curvature. Accordingly, it is expected that rigidity is improved to ensure accuracy.

Dual-Gel 4D Printing of Bioinspired Tubes

The distribution of periodic patterns of materials with radial or bilateral symmetry is a universal natural design principle. Among the many biological forms, tubular shapes are a common motif in many organisms, and they are also important for bioimplants and soft robots. However, the simple design principle of strategic placement of 3D printed segments of swelling and nonswelling materials to achieve widely different functionalities is yet to be demonstrated. Here, we report the design, fabrication, and characterization of segmented 3D printed gel tubes composed of an active thermally responsive swelling gel (poly N-isopropylacrylamide) and a passive thermally nonresponsive gel (polyacrylamide). Using finite element simulations and experiments, we report a variety of shape changes including uniaxial elongation, radial expansion, bending, and gripping based on two gels. Actualization and characterization of thermally induced shape changes are of key importance to robotics and biomedical engineering. Our studies present rational approaches to engineer complex parameters with a high level of customization and tunability for additive manufacturing of dynamic gel structures.

Robotics for Advanced Therapeutic Colonoscopy

Although colonoscopy was originally a diagnostic imaging procedure, it has now expanded to include an increasing range of therapeutic interventions. These procedures require precise maneuvers of instruments, execution of force, efficient transmission of force from the operator to the point of application, and sufficient dexterity in the mobilization of endoscopic surgical instruments. The conventional endoscope is not designed to support technically demanding endoscopic procedures. In case of colonoscopy, the tortuous anatomy of the colon makes inserting, moving, and orientating the endoscope difficult. Exerting excessive pressure can cause looping of the endoscope, pain to the patient, and even perforation of the colon. To mitigate the technical constraints, numerous technically enhanced systems have been developed to enable better control of instruments and precise delivery of force in the execution of surgical tasks such as apposing, grasping, traction, counter-traction, and cutting of tissues. Among the recent developments are highly dexterous robotic master and slave systems, computer-assisted or robotically enhanced conventional endoscopes, and autonomously driven locomotion devices that can effortlessly traverse the colon. Developments in endoscopic instrumentations have overcome technical barriers and opened new horizons for further advancements in therapeutic interventions. This review describes examples of some of these systems in the context of their applications to advanced therapeutic colonoscopy.

Design and Evaluation of a Novel Rotatable One-Element Snake Bone for NOTES

The distal head of the natural orifice transluminal endoscopic surgery (NOTES) platform commonly uses the structure of a snake bone, which cannot rotate, and the manufacturing is often time-consuming. A novel rotatable, one-element snake bone for NOTES is proposed. This paper first describes the movement mechanism and actuation. The new structure, which is composed of hinge pairs for bending and track-sled rings for rotation, was designed to reach a 90 deg bending angle and 62 deg rotational angle. The workspace of the snake bone was derived using screw theory and was simulated on matlab. The relationship between the angle and wire displacement was analyzed in detail. The new snake bone system bent and rotated by manipulating control wires that were actuated by DC motors, and its angular movements were measured by motion sensors with an angle error within ±2.6 deg. The snake bone was mounted on a flexible tube, inserted into a colonoscopy model, and navigated by motor actuation to eventually reach the cecum. The experimental results demonstrate the new snake bone's ability to travel through a natural orifice by rotating and bending, which satisfies the mobility requirement for NOTES.

Robust Neuro-Optimal Control of Underactuated Snake Robots With Experience Replay

In this paper, the problem of path following for underactuated snake robots is investigated by using approximate dynamic programming and neural networks (NNs). The lateral undulatory gait of a snake robot is stabilized in a virtual holonomic constraint manifold through a partial feedback linearizing control law. Based on a dynamic compensator and Line-of-Sight guidance law, the path-following problem is transformed to a regulation problem of a nonlinear system with uncertainties. Subsequently, it is solved by an infinite horizon optimal control scheme using a single critic NN. A novel fluctuating learning algorithm is derived to approximate the associated cost function online and relax the initial stabilizing control requirement. The approximate optimal control input is derived by solving a modified Hamilton-Jacobi-Bellman equation. The conventional persistence of excitation condition is relaxed by using experience replay technique. The proposed control scheme ensures that all states of the snake robot are uniformly ultimate bounded which is analyzed by using the Lyapunov approach, and the tracking error asymptotically converges to a residual set. Simulation results are presented to verify the effectiveness of the proposed method.

A Master-Slave control system with workspaces isomerism for teleoperation of a snake robot

Snake robots can be used to assist experts during surgical operations on internal organs via natural orifices. However, real-time control of such robot in Mater Slave (MS) teleoperation is a major challenge. Inverse kinematics solution of snake robots has being a key challenge towards real time control especially if the robot is hyper-redundant. This paper proposes a method that can achieve fast and precise inverse kinematics solution for real time control MS teleoperation. Monte Carlo method is applied to determine possible positions needed to reach a given target point, while best position is chosen based on the optimization algorithm. For workspace isomerism, the proposed method automatically determines appropriate kinematics mapping for the robots. Experimental results show that the method can achieve accurate position tracking in MS teleoperation.

Non-iterative geometric approach for inverse kinematics of redundant lead-module in a radiosurgical snake-like robot

BACKGROUND

Snake-like robot is an emerging form of serial-link manipulator with the morphologic design of biological snakes. The redundant robot can be used to assist medical experts in accessing internal organs with minimal or no invasion. Several snake-like robotic designs have been proposed for minimal invasive surgery, however, the few that were developed are yet to be fully explored for clinical procedures. This is due to lack of capability for full-fledged spatial navigation. In rare cases where such snake-like designs are spatially flexible, there exists no inverse kinematics (IK) solution with both precise control and fast response.

METHODS

In this study, we proposed a non-iterative geometric method for solving IK of lead-module of a snake-like robot designed for therapy or ablation of abdominal tumors. The proposed method is aimed at providing accurate and fast IK solution for given target points in the robot's workspace. n-1 virtual points (VPs) were geometrically computed and set as coordinates of intermediary joints in an n-link module. Suitable joint angles that can place the end-effector at given target points were then computed by vectorizing coordinates of the VPs, in addition to coordinates of the base point, target point, and tip of the first link in its default pose. The proposed method is applied to solve IK of two-link and redundant four-link modules.

RESULTS

Both two-link and four-link modules were simulated with Robotics Toolbox in Matlab 8.3 (R2014a). Implementation result shows that the proposed method can solve IK of the spatially flexible robot with minimal error values. Furthermore, analyses of results from both modules show that the geometric method can reach 99.21 and 88.61% of points in their workspaces, respectively, with an error threshold of 1 mm. The proposed method is non-iterative and has a maximum execution time of 0.009 s.

CONCLUSIONS

This paper focuses on solving IK problem of a spatially flexible robot which is part of a developmental project for abdominal surgery through minimal invasion or natural orifices. The study showed that the proposed geometric method can resolve IK of the snake-like robot with negligible error offset. Evaluation against well-known methods shows that the proposed method can reach several points in the robot's workspace with high accuracy and shorter computational time, simultaneously.

A Novel Intuitively Controlled Articulating Instrument for Reoperative Foregut Surgery: A Case Report

The field of laparoscopic surgery has continued to grow exponentially over the years, prompting new innovative technologies. Despite substantial advancements, standard laparoscopic tools have undergone little design changes and fail to optimize mobility in limited spaces. Advancements in robotics have attempted to address this, allowing for increasing degrees of freedom and articulation of instruments. Even so, this system has proven to be cumbersome with questionable cost-effectiveness. In this study, we present the first use of a solely mechanical intuitively controlled articulating laparoscopic needle driver. The ability to naturally articulate allowed for ease during suturing and knot tying during the critical portions of the operation. The FlexDex surgical instrument demonstrates promise in the field of foregut surgery in addition to other areas of minimally invasive specialties.

Natural Orifice Translumenal Endoscopic Surgery: Review of Its Applications in Bariatric Procedures

This review aims to summarise clinical applications of natural orifice translumenal endoscopic surgery (NOTES) in bariatric surgery. A review of data, until December 2014, was carried out regarding techniques and outcomes of bariatric NOTES procedures. Nine publications were included in the final analysis, with another six papers describing endolumenal procedures included for comparison. All NOTES studies adopted a hybrid procedure. Hybrid NOTES sleeve gastrectomy (hNSG) was described in four humans and two porcine studies. In humans, six subjects (23.1 %) were converted to conventional laparoscopic methods, and one postoperative complication (3.8 %) was reported. Mean excess weight loss was 46.6 % (range 35.2–58.9). Transvaginal-assisted sleeve gastrectomy appears feasible and safe when performed by appropriately trained professionals. However, improvements must be made to overcome current technical limitations.