1,092 research outputs found

    MEMS-Based Endomicroscopes for High Resolution in vivo Imaging

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    Intravital microscopy is an emerging methodology for performing real time imaging in live animals. This technology is playing a greater role in the study of cellular and molecular biology because in vitro systems cannot adequately recapitulate the microenvironment of living tissues and systems. Conventional intravital microscopes use large, bulky objectives that require wide surgical exposure to image internal organs and result in terminal experiments. If these instruments can be reduced sufficiently in size, biological phenomena can be observed in a longitudinal fashion without animal sacrifice. The epithelium is a thin layer of tissue in hollow organs, and is the origin of many types of human diseases. In vivo assessment of biomarkers expressed in the epithelium in animal models can provide valuable information of disease development and drug efficacy. The overall goal of this work is to develop miniature imaging instruments capable of visualizing the epithelium in live animals with subcellular resolution. The dissertation is divided into four projects, where each contains an imaging system developed for small animal imaging. These systems are all designed using laser beam scanning technology with tiny mirrors developed with microelectromechanical systems (MEMS) technology. By using these miniature scanners, we are able to develop endomicroscopes small enough for hollow organs in small animals. The performance of these systems has been demonstrated by imaging either excised tissue or colon of live mice. The final version of the instrument can collect horizontal/oblique plane images in the mouse colon in real time (>10 frames/sec) with sub-micron resolution (<1 um), deep tissue penetration (~200 um) and large field of view (700 x 500 um). A novel side-viewing architecture with distal MEMS scanning was developed to create clear and stable image in the mouse colon. With the use of the instrument, it is convenient to pinpoint location of interest and create a map of the colon using image mosaicking. Multispectral fluorescence images can by collected at excitation wavelength ranging from 445 nm to 780 nm. The instruments have been used to 1) validate specific binding of a cancer targeting agent in the mouse colon and 2) study the tumor development in a mouse model with endogenous fluorescence protein expression. We use these studies to show that we have developed an enabling technology which will allow biologist to perform longitudinal imaging in animal models with subcellular resolution.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/136954/2/dxy_1.pd

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

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    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

    New approaches in ortho-surgical treatments with stimulate & innovative technology

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    The aim of this study is to show the effectiveness of laser technology for the exposure of the palatally impacted canines, using a CO2 laser device (Smart US20D®, DEKA - Florence, Italy) and Diodi Laser device (Raffaello, DMT, Lissone, Italy, 980nm +645nm), which can stimulate the spontaneous eruption of the canine, without orthodontic traction application. Moreover, the purpose of this study is to monitor the movement of the impacted tooth after exposure with laser approach with digital technologies. Another aspect of this study is focused on the differences between digital monitoring through scanner and conventional monitoring which is based exclusively on the clinical evaluation of the photos and the study of the plaster casts. The final experimental sample was constituted of 18 patients, 9 females and 9 males; of these 8 patients showed a bilateral inclusion and 10 a mono-lateral inclusion of the canine, for a total of 26 canines. To demonstrate the validity of the technique applied to the study group, a CONTROL GROUP, which included 9 patients with unilateral and bilateral palatally impacted canines (in total 13 canines), treated by a traditional surgical-orthodontic approach, was observed. This experimental project was conducted in order to evaluate the effectiveness of laser surgery as an alternative approach to conventional surgical-orthodontic treatment. After laser exposure, no orthodontics treatment was initiated until the impacted tooth had erupted sufficiently into the palate and the autonomous eruption capacity was assessed. The spontaneous eruption was quantified by measuring the millimeter distance between the cusp of the canine one week after surgery (released from the overlying mucous and bone tissues) and the cusp of the same after 16 weeks from laser surgery. Of the 26 canines under study all of them performed a movement between 2,72 mm and 7,04 mm (mean value: 5,01 mm). Therefore, we can state that, at the end of the evaluation period of 16 weeks, a significant teeth movement was observed. Furthermore, the exposure of part of the dental crown, allowed, in all cases treated, to apply a bracket or a button to align the tooth in the dental arch. Our data suggests that the response of the dental element to the bio-stimulant action of the laser, applied to expose their crown, can be considered effective. Of the values obtained, the ones most distanced from the mean value were considered (the highest values 6,9 and 7,04 and the minimum values 2,72 and 3,12) and the type of inclusion of treated canines to which they refer was evaluated. The four values correspond to canines in bone inclusion; in particular, the millimetric value 7,04 corresponds to a deep inclusion canine. Therefore, from what emerges from our study, no significant correlation was found between the extent of spontaneous eruption (in mm) and the type of inclusion. A further purpose of this study was the evaluation of the possible different action between the CO2 laser (wavelength: 10600 nm; power: 4.5 Watts) used in super-pulsed emission mode (that no have bio-stimulation capacity) and the diode laser (wavelength: 980 nm + 645 nm; power: 4 Watts) used in continuous wave emission mode. Comparing the millimeters of eruption of the canines treated with the two different types of lasers and applying the Student’s T-Test, we found a super-imposable value. Moreover, the study groups (group A and group B) and the control group were compared in terms of mean eruption time, respectively spontaneous or forced by means of a Crozat orthodontic device, activated monthly to allow the displacement of the canines .I n the control group the duration of the orthodontic traction is, on average, 10 months. In the study groups the canine eruption was spontaneous and occurred in an average period of 4 months. It can be stated that, although a forced orthodontic traction was applied in the control group to allow tooth eruption, the eruption times in the study groups were significantly lower. The results obtained indicate the effectiveness of the new approach proposed by us, although performed on a small sample of patients. The results are significant from different points of view. The advantages found in this study are numerous. The main advantages of digital monitoring are the possibility of evaluating parameters that cannot be evaluated analogically and of making measurements of distances normally calculated on plaster casts with compass and rubber with the respective errors. Other advantages are represented by the reduction of work time, due to the abolishing of the need to request plaster casts to the dental technician. Which also means the reduction of the costs of the laboratory and it also means less costs for the patients. By eliminating the steps of the analogue impressions and of the plaster casts, the details are certainly represented with more precision and accuracy and there is a minimum error accumulated. This digital workflow that is created is also managed entirely by a single person, which represents a further saving of time. Moreover, we have clinical advantages, that are the less discomfort of the patient who does not tolerate the classic impressions in alginate and of the orthodontist, and the reduction of the chair time. The application of the digital technologies in the monitoring helps the orthodontist to make clinical decisions supported on measurable data and not just on clinical experience. The our ortho-surgical protocol with the use of different technologies set off to a new concept of work in dentistry, in particular, in the cases characterized by impacted teeth or cases that expect an orthodontic and surgical approach. Finally, a not indifferent aspect consists in the reduce of treatment time, which is an advantage for both the orthodontist and the patient. It is consequence of the reduction of the steps and work-time, and it is due to the real monitoring that can be performed on the patient

    Orthognathic surgical simulation of Class III patients using 3-D cone beam CT images

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    Objective: Our aim is to determine if virtual surgery performed on 3-D cone beam CT models correctly simulated the actual surgical outcome of Class III orthognathic surgical patients. Methods: All data was acquired from the UNC orthognathic surgery stability studies. We created segmentations of the maxillofacial hard tissues of twenty class III patients. We performed virtual surgeries on cone beam CT images using the CranioMaxilloFacial Application software. Results: The virtual surgical models were superimposed on the models of the actual surgical outcomes. The virtual surgery accurately recreated all surgical movements. Surgery residents showed greater variability in lateral ramus positioning than attending faculty. Conclusions: Our methodology demonstrated valid recreation of the subjects' craniofacial skeleton. It allows the surgeon to better predict surgical outcomes. Future validation of occlusal and soft tissue components would be valuable. Virtual surgical training for surgical residents could be beneficial. Supported by NIDCR DE 005215 and the SA

    X-ray based machine vision system for distal locking of intramedullary nails

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    In surgical procedures for femoral shaft fracture treatment, current techniques for locking the distal end of intramedullary nails, using two screws, rely heavily on the use of two-dimensional X-ray images to guide three-dimensional bone drilling processes. Therefore, a large number of X-ray images are required, as the surgeon uses his/her skills and experience to locate the distal hole axes on the intramedullary nail. The long-term effects of X-ray radiation and their relation to different types of cancer still remain uncertain. Therefore, there is a need to develop a surgical technique that can limit the use of X-rays during the distal locking procedure. A Robotic-Assisted Orthopaedic Surgery System has been developed at Loughborough University named Loughborough Orthopaedic Assistant System (LOAS) to assist orthopaedic surgeons during distal-locking of intramedullary nails. It uses a calibration frame and a C-arm X-ray unit. The system simplifies the current approach as it uses only two near-orthogonal X-ray images to determine the drilling trajectory of the distal-locking holes, thereby considerably reducing irradiation to both the surgeon and patient. The LOAS differs from existing computer-assisted orthopaedic surgery systems, as it eliminates the need for optical tracking equipment which tends to clutter the operating theatre environment and requires care in maintaining the line of sight. Additionally use of optical tracking equipment makes such systems an expensive method for surgical guidance in distal-locking of intramedullary nails. This study is specifically concerned with the improvements of the existing system. [Continues.

    Process Improvement Through Reverse Engineering

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    It has become increasingly important to become able to generate 3d shapes in commercial application using rapid prototyping technologies. In many cases shapes are taken from real world objects that do not have existing computer model. Creating an accurate model for these objects by hand is extremely time consuming and difficult. Therefore 3D scanner is used to capture the objects shape and create a high resolution model of the object. To able to reverse engineer we essentially have to reverse the design decisions. Following the transformation approach we can use the transformation of forward engineering methodology and apply them backwards. ZPrinter 310 plus has been used for producing 3D model directly from CAD model. ZP R 130 powder and ZB binder provided by Zcorporation were used to prepare the physical object. The variation of strength and hardness with respect to built direction is shown. Loctite 406, when added along with above powder and binder shows improvement in properties of the prototype

    Concept and Design of a Hand-held Mobile Robot System for Craniotomy

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    This work demonstrates a highly intuitive robot for Surgical Craniotomy Procedures. Utilising a wheeled hand-held robot, to navigate the Craniotomy Drill over a patient\u27s skull, the system does not remove the surgeons from the procedure, but supports them during this critical phase of the operation

    Doctor of Philosophy

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    dissertationPrecise optical neural stimulation is an essential element in the use of optogenetics to elicit predictable neural action potentials within the brain, but accessing specific neocortical layers, light scattering, columniation, and ease of tissue damage pose unique challenges to the device engineer. This dissertation presents the design, simulation, microfabrication, and characterization of the Utah Optrode Array (UOA) for precise neural tissue targeting through three main objectives: 1. Maskless wafer-level microfabrication of optical penetrating neural arrays out of soda- lime glass: Utah Optrode Array. 2. Utah Optrode Array customization using stereotactic brain atlases and 3D CAD modeling for optogenetic neocortical interrogation in small rodents and nonhuman primates. 3. Single optrode characterization of the UOA for neocortical illumination. Maskless microfabrication techniques were used to create 169 individual 9 × 9 arrays 3.85 mm × 3.85 mm with 1.1 mm long optrodes from a single two inch glass wafer. The 9 × 9 UOA was too large for precise targeting of the upper layers of the cortex in smaller animals such as mice, so an array customization method was developed using Solidworks and off-the-shelf brain atlases to create 8 × 6 arrays 3.45 mm × 2.45 mm with 400 μm long optrodes. Stereotactic atlases were imported into Solidworks, splined, and lofted together to create a single 3D CAD model of a specific region of interest in the brain. Chronic and acute brain trauma showed excellent results for the 8 × 6 arrays in C57BL/6 wild-type mice (Mus musculus) and macaque monkey (Macaca fascicularis). Simulation, characterization, and radiometric testing of a single optrode of the 9 × 9 array was necessary to prove the ability to transmit light directly to specific tissue. Zemax optical design software was used to predict the light transmission capabilities, and then these results were compared to actual bench-top results. Insertion loss was both predicted and measured to be 3.7 dB. Power budgeting showed 9% of the light was lost at the interfaces of the UOA's backplane and tip in air, and 48% was lost through back-scattering, leaving 43% transmitting through the optrode with no measurable taper loss. Scanning electron microscopy showed small amounts of devitrification of the glass, and atomic force microscopy showed average surface roughness to be 13.5 nm and a root mean square roughness of 20.6 nm. The output beam was profiled in fluorescein dye with a total divergence angle of 63◦ with a cross over distance to adjacent beams at 255 μm

    The Design of Artificial Metacarpophalangeal Joints

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    Artificial finger joints have been developed for the past 30 years, and a number of these prostheses has been applied in medical practice
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