Experimental Investigation of the Vibro-impact Capsule System

Dr. Yang Liu would like to acknowledge the financial support for the Small Research Grant (31841) by the Carnegie Trust for the Universities of Scotland. This work is also partially supported by the National Natural Science Foundation of China (Grant Nos. 11672257 and 11402224), the Natural Science Foundation of Jiangsu Province of China (Grant No. BK20161314).Peer reviewedPublisher PD

A Review of Locomotion Systems for Capsule Endoscopy

Wireless capsule endoscopy for gastrointestinal (GI) tract is a modern technology that has the potential to replace conventional endoscopy techniques. Capsule endoscopy is a pill-shaped device embedded with a camera, a coin battery, and a data transfer. Without a locomotion system, this capsule endoscopy can only passively travel inside the GI tract via natural peristalsis, thus causing several disadvantages such as inability to control and stop, and risk of capsule retention. Therefore, a locomotion system needs to be added to optimize the current capsule endoscopy. This review summarizes the state-of-the-art locomotion methods along with the desired locomotion features such as size, speed, power, and temperature and compares the properties of different methods. In addition, properties and motility mechanisms of the GI tract are described. The main purpose of this review is to understand the features of GI tract and diverse locomotion methods in order to create a future capsule endoscopy compatible with GI tract properties

스키 진동과 마찰력 사이의 상관관계 해석

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2017. 2. 김도년.Friction in icy condition is a complicate phenomenon usually consisting of three representative regimes: boundary, mixed and hydrodynamic regime. 10 Various factors may affect the friction in these regimes including the thickness of water film, the amount of frictional heat, velocity and apparent contact area. In ski jump, ski plates vibrate when gliding on an icy slop, which may have an influence on the gliding performance as they can alter these factors related to friction. Here, we present our effort to investigate the effect of vibration on friction numerically using a combined friction model applied to a jump ski. A pressure-dependent friction model is first derived from experimental data measured in small test specimen, which is well agreed with a theoretical model. Then, we construct a numerical, finite element model for a jumping ski such that it shows the same flexural stiffness as characterized experimentally. Finally, we explore how vibration affects the friction by performing simulations with various amplitudes and frequencies of vibration applied.1. Introduction 1 2. Method 4 2.1 Finite element model for jump ski 5 2.2 Definition of skier and ski boots 10 2.3 Definition of in-run track 12 2.4 Friction mechanism in icy condition 18 2.5 Parameter study for theoretical friction model in icy condition 21 2.6 Definition of external vibration 25 3. Results and Discussion 26 3.1 Static analysis 27 3.2 Dynamic analysis 30 3.2.1 Time integration method 30 3.2.2 Contact & Friction metnod in FEM 33 3.2.3 Simulation setup 36 3.2.4 Relationship between vibration mode and friction force 38 4. Conclusion 45 References 47 Abstract in Korean 52Maste

Self-propelled capsule endoscopy for small-bowel examination: proof-of-concept and model verification

This is the author accepted manuscript. The final version is available on open access from Elsevier via the DOI in this recordThis paper reports an experimental study of a vibro-impact self-propulsion technique applying for small-bowel endoscopy by using a mesoscale capsule prototype, which is 56.9 mm in length and 19.4 mm indiameter. Based on nonsmooth multibody dynamics, a mathematical model is developed for studying the dynamical characteristics of the prototype. Numerical and experimental results are compared to validate the efficacy of the proposed model as well as the feasibility of the technique under various frictional environment. By using the model, we can reveal some hidden dynamics of the prototype and optimise its progression speed and energy efficiency. Based on our calculations, by adopting this technique, the standard-sized capsule, which is 26 mm in length and 11 mm in diameter, can achieve the maximum average speeds of 8.49 mm/s for forward progression and 4.9 mm/s for backward progression, offering the potential for a ‘live’ and controllable small-bowel examinationEngineering and Physical Sciences Research Council (EPSRC

Optimization of the vibro-impact capsule system.

Optimization of the vibro-impact capsule system for the best progression is considered in this paper focusing on the choice of the excitation parameters and the shape of the capsule. Firstly, the fastest and the most efficient progressions are obtained through experimental investigations on a novel test bed. Control parameters, the amplitude and the frequency of harmonic excitation, and one of the system parameter, namely the stiffness ratio, are optimized. The experimental results confirm that the control parameters for the fastest progression are not the same as those for the most efficient progression from the energy consumption point of view. Therefore, the capsule system can be controlled either in a speedy mode or in an energy-saving mode depending on the operational requirements. In the second part of the paper, optimization of the capsule shape is studied using computational fluid dynamics (CFD) simulations. Here the aim of achieving the best progression is addressed through minimizing the drag and the lift forces acting on a stationary capsule positioned in the pipe within a fluid flow. The CFD results indicate that both drag and lift forces are dependent on capsule and arc lengths, and finally, an optimized shape of the capsule is obtained

Intracorporeal anchoring and guiding system with permanent magnet force modulation

Magnetic manipulation of objects within the body is a growing field of research since the second half of the last century. Therapeutic and diagnostic capabilities offered by such technology are extended with the clinical need to make procedures less invasive and traumatic for the patients. Ophthalmologists were among the first to explore magnetic manipulation for removing iron fragments from the interior of the eye. Subsequently, the intubation devices were developed for extracting foreign objects from the body. The first case of magnetic guidance is an intravascular catheter magnetically guided by large external magnets in the 1950s. Half a century later, magnetic actuation of medical devices has led to many developments growing in complexity, such as wireless endoscopic capsule for exploring the gastrointestinal tract; intraocular microrobots of sub-millimitric size per- forming delicate tasks; internal magnetic laparoscopic instruments magnetically coupled through the abdominal wall without the need of additional incisions; or enormous systems for remote magnetic steering of catheters in cardiovascular or neurological procedures. Technically, magnetic guidance requires variable, reshapable or steerable magnetic fields and therefore is generally associated with large magnetic arrangements of coils or perma- nent magnets surrounding the patient; while magnetic anchoring is achievable by external permanent magnets of adequate size placed or dragged manually on the surface of the body. In this thesis work, we propose a novel type of magnetic guidance. Instead of having the guiding part external to the body, we propose to perform the guidance locally, on- site, by having the guiding part within the body in close vicinity of the element to be guided. Although the separation distance between the guiding and guided member is decreased, the required magnetic field to be generated is still significant with regards to the size of the system. Moreover, the magnetic attractions force should be adjusted in order to provide a robust guidance over variable and dynamic anatomical conditions. Electromagnets are an ideal solution by their ability to control the strength, polarity and shape of the generated magnetic field. However, obtaining a substantial magnetic field strength becomes challenging in the millimetric scale. Rare-earth magnets produce strong magnetic fields and become interesting when size is limited. But, they produce a constant field and the resulting attractive forces are strongly depending on the distance, which can be a safety issue. To overcome these hurdles, we present a proof-of-concept of intracorporeal force mod- ulation with steerable permanent magnets. We demonstrate through several examples that the magnetic forces applied to the guided element can be modulated by combining permanent magnets together or with other ferromagnetic materials. A first prototype of force modulator is produced, characterized and tested in vitro. We analyze the behavior of this “magnetotractive” system of guidance through two operating modes, namely passive and active guidance modes. While the passive guidance mode uses static magnetic fields, the active guidance mode allows the variation of the magnetic field during the guidance. Operating at static magnetic field implies that the coupling force within the system depends on the tissue thickness and irregularities. As the coupling force decreases approximately as the square of the distance, levels of coupling force could rapidly change during the guidance. Therefore, having the capability of adjusting the coupling force provides flexibility of the method. We demonstrate that active control can be achieved by a combination of several movable permanent magnets. This provides smoother guidance and superior robustness in comparison with the passive mode. On the guided element, we empirically identify the parameters representing the most significant effect on friction during the guidance. These findings could be very helpful in the design of magnetic guidance systems. Finally, we show that magnetic attractive forces applied on the guided element could be adjusted with permanent magnet arrangements. This solution not only offers larger amplitude of force with regards to its size, but the range of modulation is significant in comparison with electromagnets. In addition, we demonstrate in vitro that intracorporeal magnetic guidance with steerable permanent magnets is feasible over variable and irregular tissue thickness. Therefore, this novel type of guidance has the potential to facilitate for example the treatment of cardiac arrhythmias

A continuum robotic platform for endoscopic non-contact laser surgery: design, control, and preclinical evaluation

The application of laser technologies in surgical interventions has been accepted in the clinical domain due to their atraumatic properties. In addition to manual application of fibre-guided lasers with tissue contact, non-contact transoral laser microsurgery (TLM) of laryngeal tumours has been prevailed in ENT surgery. However, TLM requires many years of surgical training for tumour resection in order to preserve the function of adjacent organs and thus preserve the patient’s quality of life. The positioning of the microscopic laser applicator outside the patient can also impede a direct line-of-sight to the target area due to anatomical variability and limit the working space. Further clinical challenges include positioning the laser focus on the tissue surface, imaging, planning and performing laser ablation, and motion of the target area during surgery. This dissertation aims to address the limitations of TLM through robotic approaches and intraoperative assistance. Although a trend towards minimally invasive surgery is apparent, no highly integrated platform for endoscopic delivery of focused laser radiation is available to date. Likewise, there are no known devices that incorporate scene information from endoscopic imaging into ablation planning and execution. For focusing of the laser beam close to the target tissue, this work first presents miniaturised focusing optics that can be integrated into endoscopic systems. Experimental trials characterise the optical properties and the ablation performance. A robotic platform is realised for manipulation of the focusing optics. This is based on a variable-length continuum manipulator. The latter enables movements of the endoscopic end effector in five degrees of freedom with a mechatronic actuation unit. The kinematic modelling and control of the robot are integrated into a modular framework that is evaluated experimentally. The manipulation of focused laser radiation also requires precise adjustment of the focal position on the tissue. For this purpose, visual, haptic and visual-haptic assistance functions are presented. These support the operator during teleoperation to set an optimal working distance. Advantages of visual-haptic assistance are demonstrated in a user study. The system performance and usability of the overall robotic system are assessed in an additional user study. Analogous to a clinical scenario, the subjects follow predefined target patterns with a laser spot. The mean positioning accuracy of the spot is 0.5 mm. Finally, methods of image-guided robot control are introduced to automate laser ablation. Experiments confirm a positive effect of proposed automation concepts on non-contact laser surgery.Die Anwendung von Lasertechnologien in chirurgischen Interventionen hat sich aufgrund der atraumatischen Eigenschaften in der Klinik etabliert. Neben manueller Applikation von fasergeführten Lasern mit Gewebekontakt hat sich die kontaktfreie transorale Lasermikrochirurgie (TLM) von Tumoren des Larynx in der HNO-Chirurgie durchgesetzt. Die TLM erfordert zur Tumorresektion jedoch ein langjähriges chirurgisches Training, um die Funktion der angrenzenden Organe zu sichern und damit die Lebensqualität der Patienten zu erhalten. Die Positionierung des mikroskopis chen Laserapplikators außerhalb des Patienten kann zudem die direkte Sicht auf das Zielgebiet durch anatomische Variabilität erschweren und den Arbeitsraum einschränken. Weitere klinische Herausforderungen betreffen die Positionierung des Laserfokus auf der Gewebeoberfläche, die Bildgebung, die Planung und Ausführung der Laserablation sowie intraoperative Bewegungen des Zielgebietes. Die vorliegende Dissertation zielt darauf ab, die Limitierungen der TLM durch robotische Ansätze und intraoperative Assistenz zu adressieren. Obwohl ein Trend zur minimal invasiven Chirurgie besteht, sind bislang keine hochintegrierten Plattformen für die endoskopische Applikation fokussierter Laserstrahlung verfügbar. Ebenfalls sind keine Systeme bekannt, die Szeneninformationen aus der endoskopischen Bildgebung in die Ablationsplanung und -ausführung einbeziehen. Für eine situsnahe Fokussierung des Laserstrahls wird in dieser Arbeit zunächst eine miniaturisierte Fokussieroptik zur Integration in endoskopische Systeme vorgestellt. Experimentelle Versuche charakterisieren die optischen Eigenschaften und das Ablationsverhalten. Zur Manipulation der Fokussieroptik wird eine robotische Plattform realisiert. Diese basiert auf einem längenveränderlichen Kontinuumsmanipulator. Letzterer ermöglicht in Kombination mit einer mechatronischen Aktuierungseinheit Bewegungen des Endoskopkopfes in fünf Freiheitsgraden. Die kinematische Modellierung und Regelung des Systems werden in ein modulares Framework eingebunden und evaluiert. Die Manipulation fokussierter Laserstrahlung erfordert zudem eine präzise Anpassung der Fokuslage auf das Gewebe. Dafür werden visuelle, haptische und visuell haptische Assistenzfunktionen eingeführt. Diese unterstützen den Anwender bei Teleoperation zur Einstellung eines optimalen Arbeitsabstandes. In einer Anwenderstudie werden Vorteile der visuell-haptischen Assistenz nachgewiesen. Die Systemperformanz und Gebrauchstauglichkeit des robotischen Gesamtsystems werden in einer weiteren Anwenderstudie untersucht. Analog zu einem klinischen Einsatz verfolgen die Probanden mit einem Laserspot vorgegebene Sollpfade. Die mittlere Positioniergenauigkeit des Spots beträgt dabei 0,5 mm. Zur Automatisierung der Ablation werden abschließend Methoden der bildgestützten Regelung vorgestellt. Experimente bestätigen einen positiven Effekt der Automationskonzepte für die kontaktfreie Laserchirurgie

Wireless capsule endoscope for targeted drug delivery

The diagnosis and treatment of pathologies of the gastrointestinal (GI) tract are performed routinely by gastroenterologists using endoscopes and colonoscopes, however the small intestinal tract is beyond the reach of these conventional systems. Attempts have been made to access the small intestines with wireless capsule endoscopes (WCE). These pill-sized cameras take pictures of the intestinal wall and then relay them back for evaluation. This practice enables the detection and diagnosis of pathologies of the GI tract such as Crohn's disease, small intestinal tumours such as lymphoma and small intestinal cancer. The problems with these systems are that they have limited diagnostic capabilities and they do not offer the ability to perform therapy to the affected areas leaving only the options of administering large quantities of drugs or surgical intervention. To address the issue of administering therapy in the small intestinal tract this thesis presents an active swallowable microrobotic platform which has novel functionality enabling the microrobot to treat pathologies through a targeted drug delivery system. This thesis first reviews the state-of-the-art in WCE through the evaluation of current and past literature. A review of current practises such as flexible sigmoidoscopy, virtual colonoscopy and wireless capsule endoscopy are presented. The following sections review the state-of-the-art in methods of resisting peristalsis, drug targeting systems and drug delivery. A review of actuators is presented, in the context of WCE, with a view to evaluate their acceptability in adding functionality to current WCEs. The thesis presents a novel biologically-inspired holding mechanism which overcomes the issue of resisting natural peristalsis in the GI tract. An analysis of the two components of peristaltic force, circumferential and longitudinal peristaltic contractions, are presented to ensure correct functionality of the holding mechanism. A detailed analysis of the motorised method employed to deploy the expanding mechanism is described and a 5:1 scale prototype is presented which characterises the gearbox and validates the holding mechanism. The functionality of WCE is further extended by the inclusion of a novel targeting mechanism capable of delivering a metered dose of medication to a target site of interest in the GI tract. A solution to the problem of positioning a needle within a 360 degree envelope, operating the needle and safely retracting the needle in the GI tract is discussed. A comprehensive analysis of the mechanism to manoeuvre the needle is presented and validation of the mechanism is demonstrated through the evaluation of scale prototypes. Finally a drug delivery system is presented which can expel a 1 ml dose of medication, stored onboard the capsule, into the subcutaneous tissue of the GI tract wall. An analysis of the force required to expel the medication in a set period of time is presented and the design and analysis of a variable pitch conical compression spring which will be used to deliver the medication is discussed. A thermo mechanical trigger mechanism is presented which will be employed to release the compressed conical spring. Experimental results using 1:1 scale prototype parts validate the performance of the mechanisms.Open Acces

Zur Beeinflussung reibungsbehafteter Systeme mithilfe überlagerter Schwingungen

Die Beeinflussung reibungsbehafteter Systeme mithilfe überlagerter Schwingungen ist seit vielen Jahren Gegenstand der Forschung. Infolge überlagerter Schwingungen können sich geglättete Reibkennlinien ergeben, so dass die ursprünglich nicht-glatten Eigenschaften trockener Reibung unterdrückt werden. Im Rahmen der vorliegenden Arbeit werden die Ergebnisse der in der Literatur etablierten Modellierung ergänzt und im Hinblick auf nachgiebige Kontakte und experimentelle Ergebnisse erweitert

Book of Abstracts 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and 3rd Conference on Imaging and Visualization

In this edition, the two events will run together as a single conference, highlighting the strong connection with the Taylor & Francis journals: Computer Methods in Biomechanics and Biomedical Engineering (John Middleton and Christopher Jacobs, Eds.) and Computer Methods in Biomechanics and Biomedical Engineering: Imaging and Visualization (JoãoManuel R.S. Tavares, Ed.). The conference has become a major international meeting on computational biomechanics, imaging andvisualization. In this edition, the main program includes 212 presentations. In addition, sixteen renowned researchers will give plenary keynotes, addressing current challenges in computational biomechanics and biomedical imaging. In Lisbon, for the first time, a session dedicated to award the winner of the Best Paper in CMBBE Journal will take place. We believe that CMBBE2018 will have a strong impact on the development of computational biomechanics and biomedical imaging and visualization, identifying emerging areas of research and promoting the collaboration and networking between participants. This impact is evidenced through the well-known research groups, commercial companies and scientific organizations, who continue to support and sponsor the CMBBE meeting series. In fact, the conference is enriched with five workshops on specific scientific topics and commercial software.info:eu-repo/semantics/draf