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Positioning and stabilizing a catheter at the required location inside a vessel or the heart is a complicated task in interventional cardiology. In this review we provide a structured classification of catheter stabilization mechanisms to systematically assess their challenges during cardiac interventions. Commercially available, patented, and experimental prototypes of catheters were classified with respect to their stabilizing mechanisms. Subsequently, the classification was used to define requirements for future cardiac catheters and persisting challenges in catheter stabilization. The classification showed that there are two main stabilization mechanisms: surface-based and volume-based. Surface-based mechanisms apply attachment through surface anchoring, while volume-based mechanisms make use of locking through shape or force against the vessel or cardiac wall. The classification provides insight into existing catheter stabilization mechanisms and can possibly be used as a tool for future design of catheter stabilization mechanisms to keep the catheter at a specific location during an intervention. Additionally, insight into the requirements and challenges for catheter stabilization inside the heart and vasculature can lead to the development of more dedicated systems in the future, allowing for intervention- and patient-specific instrument manipulation.

The fields of Minimally Invasive Surgery (MIS) and Natural Orifices Transluminal Endoscopic Surgery (NOTES) strive to reduce the level of invasiveness by entering the body through smaller incisions and natural orifices. Hyper-redundant snake-like instruments can help in this pursuit of reducing invasiveness. Such instruments can pass along multi-curved pathways through the body without any support or guidance from its anatomical environment. In this way, the width of the surgical pathway and thus the invasiveness of the procedure can be reduced significantly. This is referred to as Follow-the-Leader (FTL) motion. Generally, surgical instruments intended for FTL-motion are robotic systems that require medical grade actuators, sensors, and controllers, driving up costs and increasing their footprint in the operation room. Our goal was to discard the need for these elements and develop a non-robotic instrument capable of FTL-motion along pre-determined paths. A proof of concept prototype called MemoFlex II was developed, consisting of a cable-driven hyper-redundant shaft that is controlled via four physical tracks. The MemoFlex II was able to perform 3D FTL-motion along pre-determined paths. Among other things, this study reports on a O8 mm shaft containing seven segments and 14 degrees of freedom (DOFs) following several multi-curved paths with an average maximal footprint between 11.0 and 17.1 mm.

Goal Additive manufacturing, also known as 3D printing, has begun to play a significant role in the field of medical devices. This review aims to provide a comprehensive overview and classification of additively manufactured medical instruments for diagnostics and surgery by identifying medical and technical aspects. Methods A scientific literature search on additively manufactured medical instruments was conducted using the Scopus database. Results We categorized the relevant articles (71) by considering the novelty of each proposed instrument and its clinical application. Then, we analyzed the relevant articles by examining the reasons behind choosing additive manufacturing technology to produce instruments for diagnostics and surgery. Possible customization (27%) and Cost-effectiveness (23%) were the main reasons expressed. Technical specifications of the additive manufacturing technology and the material used were also analyzed, and a tendency of using material extrusion technology (35% of the applications) and polymeric materials (86% of the applications) was shown. Conclusions Additive manufacturing is opening the door to a new approach in the production of medical devices, which allows the complexity of their designs to be pushed to the extreme. However, we found that technical limitations need to be tackled and important aspects such as sterilization or debris contamination are still not considered to be relevant factors during the design and fabrication process. Keeping in mind the challenges of such a new field, additive manufacturing technology can be considered as a great opportunity to provide easy access to healthcare in developing countries as well as an important step toward patient-specific medicine.

Additive Manufacturing (AM) or 3D printing has enabled the production of increasingly complex parts that are difficult to produce with conventional manufacturing methods. Its additive nature has made it possible to create interlocking parts in a single production step. This creates opportunities for new ways of designing and producing mechanisms, which do not need to be assembled after production, called non-assembly mechanisms. Non-assembly mechanisms are different from traditional mechanisms, since they show an unprecedented integration between geometry, material and structure. In this review, by means of a systematic literature search the current state-of-the-art of non-assembly mechanisms is reviewed and analyzed based on the challenges encountered in their design and production. The found examples were categorized according to types of mechanism that have similar production considerations. Per category is discussed what the challenges and opportunities are for the design of non-assembly mechanisms. This review aims to provide a helpful overview of best-practice examples that can be used as inspiration for further development of innovative non-assembly mechanisms.

For pathway surgery, that is, minimally invasive procedures carried out transluminally or through instrument-created pathways, handheld maneuverable instruments are being developed. As the accompanying control interfaces of such instruments have not been optimized for intuitive manipulation, we investigated the effect of control mode (1DoF or 2DoF), and control device (joystick or handgrip) on human performance in a navigation task. The experiments were conducted using the Endo-PaC (Endoscopic-Path Controller), a simulator that emulates the shaft and handle of a maneuverable instrument, combined with custom-developed software animating pathway surgical scenarios. Participants were asked to guide a virtual instrument without collisions toward a target located at the end of a virtual curved tunnel. The performance was assessed in terms of task completion time, path length traveled by the virtual instrument, motion smoothness, collision metrics, subjective workload, and personal preference. The results indicate that 2DoF control leads to faster task completion and fewer collisions with the tunnel wall combined with a strong subjective preference compared with 1DoF control. Handgrip control appeared to be more intuitive to master than joystick control. However, the participants experienced greater physical demand and had longer path lengths with handgrip than joystick control.

Little is known about static friction of stainless-steel wire ropes ('cables') in contact with soft rubbers, an interface of potential importance for rigidifiable medical instruments. Although friction theories imply that the size and profile of the cables affect static friction, there are no confirmative data for stainless-steel cable-rubber contacts. Static friction was measured between five cable types (0.18, 0.27 and 0.45. mm diameter, twisted in 1×7, 1×19, or 7×7 strands) and latex, nitrile, and silicone rubber. Mean static friction coefficients of the cables ranged over 0.27-0.31, 0.25-0.27, and 0.44-0.53 for nitrile, silicone, and latex, respectively. Overall, the cable type had little effect on static friction. For all cables, friction was twice as high for latex as for nitrile rubber, which had slightly higher friction than silicone rubber. The higher static friction for nitrile compared to silicone rubber despite silicone rubber being significantly softer could be caused by the high polar surface free energy of nitrile rubber. Common friction theories were valuable in predicting the effect of cable profiles and rubber properties on static friction but should not be applied without considering interaction effects. Static friction seems to be a minor factor when selecting cables for practical applications involving cable-rubber contacts. © 2014 Elsevier B.V.

The Russian Segment of the International Space Station will be equipped with a 10 m long anthropomorphic space manipulator with six degrees of freedom. The robot is called the European Robot Arm, or ERA. Its hand, or end-effector, contains a camera which will be used for fine positioning of the end-effector, in order to grasp an object. At the Delft University of Technology, a human– machine interface for manual control of the ERA is being developed. The control device is a Spaceball controller, which is used to control the spatial end-effector velocity. This article describes four control methods that transform the Spaceball movements into movements in the end-effector camera picture. The control methods are compared by means of human–machine experiments. The results are also useful in many other areas of spatial manipulation, like undersea robots, robots in the nuclear industry, and minimally invasive surgery.

Laparoscopic surgery is a minimally invasive surgical technique which is performed by using an endoscopic camera and long and slender instruments that are inserted through small incisions in the patient's abdominal wall. The indirect way of observing and manipulating complicates the surgeon's depth perception and disorders the surgeon's eye-hand coordination . This paper describes a concept of an endoscope positioning system that compensates misorientations between the surgeon's hand movements and the movements on the monitor by using a 90 ° endoscope. Movement parallax is realized by means of an endoscope positioning robot which is controlled by the surgeon's head movements.

A space manipulator is a lightweight robotic arm mounted on a space station or a spacecraft. If the manipulator is manually controlled from a remote site (teleoperation), the pictures from cameras in the neighbourhood of the manipulator are the only aids the human operator can use. Besides, manipulator dynamics and the possible presence of time delays in the control loop also complicate manual control. In space manipulator positioning tasks, the manipulator hand (the end-effector) has to be positioned accurately in front of a known (physical) target. This paper evaluates four control methods to position a space manipulator by hand with a force activated input device with six Degrees-of-freedom. With two of these methods, forward and downward end-effector control, the operator controls the movements of the end-effector (‘forward’ resp. ‘downward’ refer to the direction in which the input device must be pushed to let the end-effector move forward in the camera picture shown on the interface console in the remote control room). With the two other methods, the target is the controlled object. The results of man-machine experiments clarify that subjects by far prefer end-effector control above target control. Furthermore, subjects prefer controlling the end-effector in downward mode instead of in forward mode.

Currently, the space manipulator ERA (European Robot Arm) is being developed in Europe. It will be used on the international space station Alpha. When the ERA is controlled in manual control, its movements are monitored with camera’s, like the end-effector camera, which is used for positioning the ’hand’ of the manipulator. At the Delft University of Technology in the Netherlands, research is done on the development of a manmachine interface for the ERA. Herewith, the movements of the manipulator are animated on a graphical workstation. The input device is a 6 degrees of freedom Spaceball controller, which is used to control the velocity of the end-effector. In this paper, the development of a novel graphical display is discussed, that improves the spatial observability of the end-effector camera picture. In this display, the spatial information is presented by means of intersections between 3-dimensional graphical objects. Also, a control method is described, that transforms the movements of the Spaceball into movements in the end-effector camera picture. Finally, some results of man-machine experiments with the display and the control method are given.