250 research outputs found
Bio-Inspired Flexible Vertebral Drill: The design, manufacturing and evaluation of a prototype
No full textAbstract—Spinal fusion surgery is an operation in which two or more adjacent vertebrae are rigidly connected, with the goal to remedy spinal instability, deformation of the vertebrae, or a herniated intervertebral disc. Vertebrae are conventionally fixated by means of pedicle screws, the downsides of which are accidental cortical wall breaches during drilling and poor holding strength of the screw. The holding strength of the bone anchor may be improved by increasing its contact area with the hard cortical wall of the vertebral body. To accomplish this, a curved hole needs to be made along the inside of the cortical wall. This research presents the design, manufacturing, and testing of a bone drilling device, that is flexible in one plane. To this end, the drill was developed on the basis of the tsetse fly’s proboscis, which is a mechanism that uses a cutting surface with its axis of rotation perpendicular to the drilling direction. Implementing this cutting motion has several advantages over conventional drilling: It facilitates using leaf springs as a flexible transmission, and it is not limited to drilling round holes. A prototype was built and tested on Sawbones closed cell foam, which closely mimics the mechanical properties of the cancellous bone found in human vertebrae. The prototype was capable of effectively cutting through foam with densities up to 10 pounds per cubic foot (PCF) with a feed rate of 50 mm/min. The ability to deflect off and follow a simulated cortical wall was also tested, and proved to be effective up to an insertion angle of 15˚. The bio-inspired drilling device presented in this research opens up new possibilities in the development of flexible drilling for a wide variety of orthopaedic applications.Mechanical Engineering | BioMechanical Desig
Some investigations on redundancy and possible bandwith compression in television transmission
No full textElectrical Engineering, Mathematics and Computer Scienc
Steering and Harvesting Technology for Minimally Invasive Biopsy
No full textContemporary medical imaging technologies, such as computed tomography or magnetic resonance imaging, play a pivotal role in medical diagnosis, allowing for a relatively fast and non-invasive examination of the human body. In the field of cancer surgery they allow for preoperative detection of tumorous tissue and aid the surgical planning. However, only recent developments in the imaging field have introduced the possibility for a real-time non-invasive intraoperative detection of tumorous tissue with sufficient margins for radical tumour resection. These imaging technologies are collectively called optical biopsy and besides providing the real-time visualisation of the tumorous tissue on a large scale, e.g. near-infrared fluorescence, they allow for an instant tumour detection and analysis on a small scale, e.g. differential pathlength spectroscopy, ultimately without the need for any pathological analysis. While the optical biopsy provides an answer to the tumour detection, its subsequent accurate resection, or mechanical biopsy, remains a challenge. This challenge is further aggravated with more demanding applications, such as minimally invasive surgery, as compared to open surgery, and accurate resection of organ exterior as compared to organ interior. Yet, as challenges are here to be solved, the aim of this work is to provide an answer to combining the optical and the mechanical biopsies in an accurate manner with the aim to perform safe minimally invasive resection of small tumours at organ and tissue surfaces. Furthermore, as minimally invasive surgical applications pose various spatial restrictions on tissue manipulation, the second objective of this work is to present a reliable joint construction for the envisioned tissue resection instrument, allowing it to attain a proper orientation to the tissue of interest. As the focus of this thesis is twofold, its chapters are grouped into two parts. The first part of this thesis treats the combination of the optical and the mechanical biopsies in a reliable and an effective manner, showing the development of a resection tip, the opto-mechanical biopsy harvester, for a minimally invasive surgical instrument (Chapters 2-4). The second part of this thesis addresses the issue of steerable joint constructions in the minimally invasive surgical instruments and their reliable controllability in order to provide both flexibility and stability for the accurate tumour detection and resection (Chapters 5-8). With the vision to devise the design of the opto-mechanical biopsy harvester, a review of the state-of-the-art minimally invasive surgical instruments capable of performing the optical and the mechanical biopsies successively and accurately was performed and it is presented in Chapter 2. In addition, the review outlines any and all the minimally invasive surgical devices housing an accessory channel, thus mechanically capable of integrating a fibre optic cable for optical biopsy. As the findings of the aforementioned literature review were rather limited, this gave an opportunity to conceive and develop a novel bio-inspired design of a frontally-acting opto-mechanical biopsy harvester. Its experimental design and prototype are presented in Chapter 3 together with feasibility tests proving the concept. While the instrument steerability was not yet incorporated, the experimental design was created with a great consideration of its ultimate functionality. Chapter 4 concludes the first part of this thesis with a follow-up optimisation of the biopsy harvester’s collapsible resection device, the crown-cutter, bio-inspired by the sea urchin’s chewing organ Aristotle’s lantern and shaped as a crown of numerous pointy teeth. The study researches the impact of tooth quantity and type of their bevel on the induced tissue deformation, penetration forces and proper tooth collapsibility. Similarly to the first part of this thesis, the second part begins with a review article in Chapter 5 of all the mechanical joint constructions used in the state-of-the-art steerable minimally invasive surgical instruments. By clear categorisation, the aim of this review is to help identify a reliably controllable steerable joint ensuring accurate operation of the envisioned instrument’s tip. The fundamental joint classification can also serve as a design aid for other developments in this field. With the vision to develop a stiff and reliably controllable joint for the envisioned biopsy instrument, a novel steerable laparoscopic instrument prototype DragonFlex was developed. As discussed in Chapter 6, its simple, repetitive and symmetrical design incorporates a rolling joint with a special tight cable guidance. Together they maximise the driving cable lifespan, equalise the forces in both cables and enable control of seven instrument degrees of freedom by only seven structural components. Not only is DragonFlex the world’s first almost entirely additive manufactured steerable laparoscopic instrument prototype, but it also sheds new light on the potential of additive manufacturing in the surgical field. The promisingly high bending stiffness of DragonFlex’s rolling joint is evaluated in Chapter 7, which provides an empirical evidence that this joint construction is indeed superior to the state of the art in this respect. As clarified, the insight into achieving high bending stiffness of cable-driven joint constructions lies in the principle of full actuation of each degree of freedom, as opposed to underactuation. In order to perfect DragonFlex’s already stiff rolling joint Chapter 8 illustrates a way to minimise the small degree of remaining cable slack in the original design. As opposed to the common design practice attempting to eliminate the cable slack by a cable tensioning mechanism, this chapter introduces a more fundamental solution applicable to rolling joints in general. On top of minimising the cable slack, this solution removes the need for a cable tensioning mechanism, hence simplifying the overall design and assembly even further. The thesis is concluded with a discussion section in Chapter 9 outlining the combination of the reliable steering and the accurate harvesting technology developed for the purpose of minimally invasive biopsy. This last chapter presents the envisioned design and the real-scale fully functional prototype of the steerable minimally invasive opto-mechanical biopsy harvester composed of a permanent and a disposable section. The fusion of all the presented insights and designs is addressed in a practical manner, especially with regard to the manufacturability and the proposed usage of the final envisioned instrument.BioMechanical EngineeringMechanical, Maritime and Materials Engineerin
The development of a predictive display for space manipulator positioning task
No full textMechanical Maritime and Materials Engineerin
Endoscope
No full textAn endoscope (1) for use in minimally invasive surgery, comprises an inspection tube (2), provided with a light source (8). A lens (3) is positioned on an angularly adjustable lens holder (4) at the distal part of the inspection tube (2). A control organ (5), at the proximal end of the inspection tube (2) is coupled with the lens holder (4) for its adjustment in relation to the inspection tube. The light source (8) is positioned near the distal end at such a distance from the lens holder (4), that silhouettes perceivable by the lens (3) can be formed.Mechanical, Maritime and Materials Engineerin
Apparatus suited for use in a space which is difficulty accessible
No full textThe invention relates to an apparatus suitable for use in a space that is not easily accessible, comprising a distally provided head, which can be equipped with an inspection organ and/or intervention organ, and which is designed to be introduced into a cavitous body, a proximal control member remaining permanently outside the body, and a connecting body extending between the control member and the distal head, wherein the connecting body is designed for being at least partly introduced into the body, and wherein the head is provided with at least one rotatable bypass organ for at least one coupling element, a first end of which at least one coupling element is coupled to a permanently fixed point and a second end is posit ion- variable, and wherein the first and the second ends of the coupling element are located at the side of the control member, wherein the connecting body is not compressible and surrounds the at least one coupling element, acting as guide.Mechanical, Maritime and Materials Engineerin
Instrument comprising a cable or tube provided provided with a propulsion device
No full textThe invention relates to an instrument (1) comprising a cable or tube (3), at a distal end of which a propulsion device (4) is provided for moving the cable or tube in a hollow space, the propulsion device being shaped like a donut lying in a plane at right angles to the longitudinal direction of the cable or tube, wherein the donut-shaped propulsion device is, at least in part, externally delimited by at least one wire gauze (6) that is rotatable about a closed axis of the donut body, which axis lies in the plane of the donut.Mechanical, Maritime and Materials Engineerin
The design of a man-machine interface for a space manipulator
No full textMechanical Maritime and Materials Engineerin
Grip in laparoscopic surgery by means of adhesion: A background information report
No full textMinimally invasive surgery (MIS) is a surgery technique that is carried out through small incisions in the skin with thin, long instruments. In order for the surgeon to see his actions with his instruments, a small camera with a light source (an endoscope) is used to look inside the person that is operated. MIS, also called laparoscopy when carried out in the abdominal cavity, has many advantages compared to traditional surgery such as less operative trauma and reduced hospitalization time. However, there are many disadvantages as well. Especially for the surgeon a lot of aspects of surgery have become more difficult. The instruments that the surgeon uses are small and have tiny forceps in order to fit through the incisions. A problem that occurs with these forceps is that of not having good grip on the slippery tissue. The surgeon tries to prevent this by using a large pinch force and using forceps that are provided with a saw-tooth profile. The consequence however is that due to these two solutions the tissue sometimes gets damaged. Since a lot of research is done nowadays on adhesives that stick to mucus tissue (mucoadhesives), it is interesting to investigate whether it is worthwhile to design and develop a laparoscopic forceps that provides the grip with the tissue by means of such a mucoadhesive so that large pinch forces and profiles are not necessary anymore. This thesis gives background information on this subject by studying chemistry, physics, patent and biological literature. From physical and chemistry information, insight was gained on the working principles of adhesion in general. For using a mucoadhesive on a laparoscopic forceps in order to manipulate the tissue, the adhesion mechanism between forceps and tissue must be temporary. This adhesion mechanism must be strong enough but must have a quick release or deactivation mechanism as well. From a patent research came forward that there is very little done on the area of manipulating tissue by means of an adhesive. The main problem of using an adhesive to create grip with tissue is how to loosen the adhesive again from the tissue. No patent was found that explained a method of loosening the adhesive again, which confirmed that this is the most important problem that has to be solved to come to a good design. In order to investigate methods for undoing adhesion, research in biological literature was done, because temporary adhesion is something that is used by a lot of animals for instance to walk upside down a ceiling. From a number of examples of temporary adhesion mechanisms a number of release mechanisms were found. From the demands that the release mechanism should suffice to be used on a laparoscopic forceps, two interesting release mechanisms came forward. These release mechanisms, peeling and hydration of the mucoadhesive need further investigation. Overall can be concluded that from the background information presented in this thesis it can be recommended to do further research for the design of a laparoscopic forceps that has grip by means of a mucoadhesive. Peeling of the mucoadhesive or hydrating are the most interesting release mechanisms that could be applied in such a forceps.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin
Wasp-inspired needle insertion with low net push force
No full textThis paper outlines the development of a four-part needle prototype inspired by the ovipositor of parasitic wasps. In the wasp ovipositor, three longitudinal segments called valves move reciprocally to gain depth in the substrate. It has been suggested that serrations located along the wasp ovipositor induce a friction difference between moving and anchoring valves that is needed for this reciprocal motion. Such an anchoring mechanism may not be desired in a medical setting, as serrations can induce tissue damage. Our aim was to investigate whether a multipart needle can penetrate tissue phantom material with near-zero net push force while using needle parts devoid of surface gripping textures or serrations. Accordingly, a four-part needle prototype was developed and tested in gelatine substrates. The performance of the prototype was assessed in terms of the degree of slipping of the needle with respect to the gelatine, with less slip implying better performance. Slip decreased with decreasing gelatine concentration and increasing offset between the needle parts. Motion through gelatine was achieved with a maximum push force of 0.035 N. This study indicates the possibility of needle propagation into a substrate with low net push force and without the need of serrations on the needle surface.Accepted Author ManuscriptMedical Instruments & Bio-Inspired Technolog
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