Miniature bending manipulator for fetoscopic intrauterine laser therapy to treat twin-to-twin transfusion syndrome

Smart Shape-Memory Polymeric String for the Contraction of Blood Vessels in Fetal Surgery of Sacrococcygeal Teratoma

Shape-memory polymers (SMPs) are promising materials in numerous emerging biomedical applications owing to their unique shape-memory characteristics. However, simultaneous realization of high strength, toughness, stretchability while maintaining high shape fixity (R_f ) and shape recovery ratio (R_r ) remains a challenge that hinders their practical applications. Herein, a novel shape-memory polymeric string (SMP string) that is ultra-stretchable (up to 1570%), strong (up to 345 MPa), tough (up to 237.9 MJ m^-3 ), and highly recoverable (R_f averagely above 99.5%, R_r averagely above 99.1%) through a facile approach fabricated solely by tetra-branched poly(ε-caprolactone) (PCL) is reported. Notably, the shape-memory contraction force (up to 7.97 N) of this SMP string is customizable with the manipulation of their energy storage capacity by adjusting the string thickness and stretchability. In addition, this SMP string displays a controllable shape-memory response time and demonstrates excellent shape-memory-induced contraction effect against both rigid silicone tubes and porcine carotids. This novel SMP string is envisioned to be applied in the contraction of blood vessels and resolves the difficulties in the restriction of blood flow in minimally invasive surgeries such as fetoscopic surgery of sacrococcygeal teratoma (SCT).

Dermatologic and cosmetic procedures in pregnancy

Background:

Materials and Methods:

Results:

Miniature parallel robot with submillimeter positioning accuracy for minimally invasive laser osteotomy

To overcome the physical limitations of mechanical bone cutting in minimally invasive surgery, we are developing a miniature parallel robot that enables positioning of a pulsed laser with an accuracy below 0.25 mm and minimizes the required manipulation space above the target tissue. This paper presents the design, control, device characteristics, functional testing, and performance evaluation of the robot. The performance of the robot was evaluated within the scope of a path-following experiment. The required accuracy for continuous cuts was achieved and reached 0.176 mm on the test bench.

Water-jet outer sheath with braided shape memory polymer tubes for upper gastrointestinal tract screening

BACKGROUND

Flexible endoscopes have become an important tool for the diagnosis and treatment of gastric cancer. However, there are several limitations to the use of endoscopes in rural areas, including their high cost, poor portability, and unstable platform.

METHODS

This paper presents a novel low-cost outer sheath for stomach screening. The sheath uses braided shape memory polymer (SMP) tubes with a water-jet to control the stiffness and bending motion. The insertion part of the prototype is 250 mm long with a maximum outer diameter of 16 mm and incorporates an internal charge-coupled device camera.

RESULTS

We have tested the workspace and stiffness of the outer sheath. The prototype has also been validated with phantom and ex vivo porcine stomach experiments.

CONCLUSIONS

By controlling the water-jet and temperature of the braided SMP tubes, the outer sheath achieves a large workspace and a remarkable variability in stiffness, demonstrating the potential clinical value of the outer sheath system.

Visible forceps manipulator with novel linkage bending mechanism for neurosurgery

In minimally invasive surgery (MIS), especially the neurosurgery, surgeons often suffer from occlusion region problem. Common surgical instruments, like endoscope and corresponding operating tools, are hard to solve it due to their size and rigid mechanical structure. In this paper, we present a visible forceps manipulator with novel linkage bending mechanism, which realizes the flexible bending capability and high output force, as well as the integrated endoscopic function. We present the simplified experiment to evaluate the results of mechanical performance and brain phantom test to evaluate feasibility and usefulness in neurosurgery. Preliminary results show that phantom experiments using the brain phantom verify the feasibility of the novel manipulator.

Endomicroscopy for Computer and Robot Assisted Intervention

Endomicroscopy is a new technique that allows human tissue to be characterized in vivo and in situ, circumventing the need for conventional biopsy and histology. Despite increased application and growing research interests in this area, the clinical application of endomicroscopy, however, is limited by difficulties in ergonomic control, consistent probe-tissue contact, large area surveillance, and retargeting. Recently, advances in high-speed imaging, mosaicing, and robotics have aimed to address these difficulties. The development of robot-assisted devices in particular has shown great promises in extending the clinical potential of endomicroscopy. Issues related to miniaturization, adaptation to tissue deformation, control stability, force and position compensation, cost, and sterility are being pursued by both research and commercial communities. In this review, recent clinical and technical developments in different aspects of computer and robotic assisted endomicroscopy interventions including instrumentation, multiscale integration, and high-speed imaging techniques are presented. We further address emerging trends and new research opportunities toward more widespread clinical acceptance of robotically assisted endomicroscopy technologies.

A Continuum Robot and Control Interface for Surgical Assist in Fetoscopic Interventions

Twin-twin transfusion syndrome requires interventional treatment using a fetoscopically introduced laser to sever the shared blood supply between the fetuses. This is a delicate procedure relying on small instrumentation with limited articulation to guide the laser tip and a narrow field of view to visualize all relevant vascular connections. In this letter, we report on a mechatronic design for a comanipulated instrument that combines concentric tube actuation to a larger manipulator constrained by a remote centre of motion. A stereoscopic camera is mounted at the distal tip and used for imaging. Our mechanism provides enhanced dexterity and stability of the imaging device. We demonstrate that the imaging system can be used for computing geometry and enhancing the view at the operating site. Results using electromagnetic sensors for verification and comparison to visual odometry from the distal sensor show that our system is promising and can be developed further for multiple clinical needs in fetoscopic procedures.

Medical-grade Sterilizable Target for Fluid-immersed Fetoscope Optical Distortion Calibration

We have developed a calibration target for use with fluid-immersed endoscopes within the context of the GIFT-Surg (Guided Instrumentation for Fetal Therapy and Surgery) project. One of the aims of this project is to engineer novel, real-time image processing methods for intra-operative use in the treatment of congenital birth defects, such as spina bifida and the twin-to-twin transfusion syndrome. The developed target allows for the sterility-preserving optical distortion calibration of endoscopes within a few minutes. Good optical distortion calibration and compensation are important for mitigating undesirable effects like radial distortions, which not only hamper accurate imaging using existing endoscopic technology during fetal surgery, but also make acquired images less suitable for potentially very useful image computing applications, like real-time mosaicing. In this paper proposes a novel fabrication method to create an affordable, sterilizable calibration target suitable for use in a clinical setup. This method involves etching a calibration pattern by laser cutting a sandblasted stainless steel sheet. This target was validated using the camera calibration module provided by OpenCV, a state-of-the-art software library popular in the computer vision community.

Current and emerging robotic assisted intervention for Notes

INTRODUCTION

Natural orifices transluminal endoscopic surgery (notes) procedures are limited by a number of factors including closure of the internal entry point, loss of triangulation, and unstable operative platform. Areas covered: In this paper, new technical developments in different aspects of robotic assisted NOTES interventions are reviewed. We further address new research opportunities for more widespread clinical acceptance of robotic assisted NOTES procedures. Expert commentary: The application of robotics in NOTES intervention is still in its infancy. The development of more compact, smart and intuitive robotic NOTES systems holds much promise for the future of NOTES application.

Evaluation of fetal tissue viscoelastic characteristics for robotic fetal surgery

PURPOSE

Minimally invasive fetal surgery is expected to improve therapeutic outcomes, and surgical robots are expected to aid the dexterous manipulation of fragile fetal tissues. Although robots are currently used for surgery on soft tissues, practical information concerning the viscoelastic characteristics of fetal tissues is lacking. Hence, the mechanical properties of fetal tissues should be quantified to design robotic devices that facilitate computer-assisted fetal surgery.

METHODS

Shear creep tests were performed on abdominal wall tissues of rat fetuses, aged 16-20 days, and on the brain, lung, and liver tissues of adult rats. Viscoelastic properties of these tissues were evaluated using a rheometer. Histological sections of fetal rat tissues were stained with hematoxylin and eosin.

RESULTS

The viscoelastic properties of fetal tissues were quantified using models. Fetal tissues displayed 2 distinct phases of fragility, i.e., gelatinous characteristics with a markedly lower viscoelasticity before day 18 than after day 19. Concomitantly, skin morphology matured remarkably after day 19. As judged by the morphology, the gestation age of 19 days in rats corresponds to that of 23 weeks in human fetuses. From our data, we prepared artificial phantoms; phantoms made from 1.0% gelatin showed mechanical properties very similar to those of the fetuses before day 18.

CONCLUSION

We observed unique mechanical characteristics in fetal tissue, a previously unknown target for surgical robots. From the data obtained, we produced phantoms that have similar viscoelastic properties, aiming at designing surgical robots capable of handling early fetuses.