Development of an Hexapod BioMicroRobot with Nafion-Pt IPMC microlegs

This paper presents an artificial locomotion servo-system for an insect like hexapod BioMicroRobot (BMR). This servo-system, programmed with VHDL code, will act as a driver in a RISC architecture microcontroller to reproduce insect tripod walking. An overview of the robot control system, in accordance with the insect displacement principle, is demonstrated with timing parameters. A control algorithm of the six legs driving the robot in any direction versus Pulse Width Modulation (PWM) is reviewed. BMR microlegs are built with cylindrical Nafion-Pt Ionomeric Polymer-Metal Composite (IPMC) that have 2.5 degrees of freedom. Specific fabrication process for one leg is exposed. Dynamic behavior and microleg characteristics have been measured in deionized water using a laser vibrometer. BMR current consumption is an important parameter evaluated for each leg. Hardware test bench to acquired measurement is presented. The purpose of this design is to control a BMR for biomedical goals like implantation in human body. Experimental results on the proposed legs are conclusive for this type of bioinspired BMR

Laser-micromachined under-water micro gripper using ionic conducting polymer film (ICPF).

Kwok, Yiu-fai.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.Includes bibliographical references (leaves 87-89).Abstracts in English and Chinese.ABSTRACT --- p.IACKNOWLEDGMENTS --- p.IITABLE OF CONTENT --- p.IIILIST OF FIGURES --- p.VChapter 1 --- INTRODUCTION --- p.1Chapter 1.1 --- Background --- p.1Chapter 1.2 --- Motivation of this project --- p.1Chapter 1.3 --- Organization --- p.2Chapter 2 --- LITERATURE SURVEY --- p.3Chapter 2.1 --- Ionic Conducting Polymer Film (ICPF) --- p.3Chapter 2.2 --- Electroactive Polymer (EAP) --- p.4Chapter 2.3 --- Micro Active Guide Wire Catheter System --- p.5Chapter 2.4 --- Space Application - Dust Wiper --- p.6Chapter 2.5 --- Micro gripper --- p.8Chapter 2.6 --- Summary of literature survey --- p.14Chapter 3 --- METAL-POLYMER COMPOSITIONS --- p.15Chapter 3.1 --- Introduction --- p.15Chapter 3.2 --- Perfluorosulfonic acid polymer (Nafion) --- p.15Chapter 3.3 --- Working principle of ICPF --- p.19Chapter 3.4 --- Different types of composition --- p.21Chapter 3.4.1 --- Chromium-Gold-polymer composite --- p.23Chapter 3.4.2 --- Platinum-Gold-polymer composite --- p.25Chapter 3.4.3 --- Silver-polymer composite --- p.27Chapter 3.4.4 --- Silver/Copper-gold polymer composite --- p.27Chapter 3.4.5 --- Gold-polymer composite --- p.28Chapter 4 --- ICPF FABRICATION --- p.30Chapter 4.1 --- Introduction --- p.30Chapter 4.2 --- ICPF fabrication process --- p.31Chapter 4.3 --- Surface pre-treatment --- p.33Chapter 4.4 --- Gold thin film deposition (Evaporation) --- p.34Chapter 4.4.1. --- Filament evaporation --- p.35Chapter 4.4.2 --- Electronic-beam evaporation --- p.39Chapter 4.4.3 --- Structural analysis of evaporation --- p.40Chapter 4.5 --- Chemical electroplating --- p.42Chapter 4.5.1. --- Deposition rate calibration --- p.44Chapter 5 --- DESIGN AND PACKAGE --- p.46Chapter 6 --- LASER MICROMACHINING --- p.49Chapter 6.1 --- Introduction to Laser micromachining --- p.49Chapter 6.2 --- C02 laser --- p.50Chapter 6.3 --- Nd:YAG Laser --- p.51Chapter 6.4 --- Laser micromachining of ICPF actuator --- p.52Chapter 7 --- EXPERIMENTAL RESULTS AND ANALYSIS --- p.61Chapter 7.1 --- Introduction --- p.61Chapter 7.2 --- Measurement setup --- p.62Chapter 7.3 --- Width test --- p.68Chapter 7.4 --- Length test --- p.73Chapter 7.5 --- Voltage test --- p.76Chapter 8 --- MICRO GRIPPER ACTUATION --- p.79Chapter 8.1 --- Development of micro gripper --- p.79Chapter 8.2 --- Micro gripper --- p.80Chapter 9 --- CONCLUSION --- p.82Chapter 10 --- APPENDIX --- p.83Chapter 10.1 --- Procedures in using E-beam evaporator --- p.83Chapter 10.2 --- Procedures in using Thermo couple evaporator --- p.85Chapter 11 --- REFERENCE --- p.8

METHODOLOGY FOR RESEARCH AND DEVELOPMENT OF NOVEL MEDICAL DEVICES FOR MINIMALLY INVASIVE INTERVENTIONS

The design of innovative medical device requires extensive and hard efforts to reach good results in terms of safety, efficacy and cost effectiveness. First of all the idea has to be set and a wide search of state of the art, both technological and academic, has to be developed. Then the materials, manufacturing processes and design constraints have to be understood. In this work three examples of innovative surgical devices for minimally invasive surgery and assistance have been presented. The Muneretto Beam catheter is a new device for atrial defibrillation. Starting from a catheter produced by Estech company for the treatment of atrial fibrillation by ablating cardiac tissue during surgery, a system for the magnetic guidance of the same has been implemented. Thanks to finite element analysis of various configurations of magnets and to several in vitro tests, a final configuration which allows a good balance between the sliding of the catheter on the tissues and the magnetic interaction and adhesion to tissues has been found. Further attention has been taken to the development of the cover and the right configuration and method of use of the device. The VideoDrain system is a new catheter for the monitoring of post-operative wound. After critical surgical procedures it is necessary to monitor the status of the surgical wound for avoiding second look surgical interventions. Therefore a new balloon catheter for allowing the vision of the abdominal cavity has been produced. Several in vitro and in vivo trials have been conducted and the device is at the pre-industrial stage. The FloSeal GI cath. is a new device for the gastrointestinal release of an haemostatic substance of the Baxter company: the Floseal thrombin matrix. It consists in a balloon catheter suited for the use in the lower and upper gastrointestinal tract in the occurrence of bleedings during endoscopic procedures. This device has been CE labelled and is now on the market. All the devices described in this work come from ideas of surgeons leader in innovation in the field of minimally invasive interventions. Their collaboration has been fundamental for the several phases of design and tests of the devices. This Ph.D. thesis is divided into five chapters. In the Introduction chapter the process of research and development of innovative MDs for minimally invasive surgery has been illustrated. The second chapter shows the efforts done to find a working configuration for the Muneretto Beam catheter and the subsequent first prototypes developed. The progress in the design of VideoDrain has been explained in the third chapter; the whole process goes from the idea to the animal test on prototypes and a preliminary risk analysis. The development of the Floseal GI Catheter is depicted in the fourth chapter; all the details of the materials used and tests done to ensure a CE mark have been reported. Finally, in the Conclusion chapter I have reported some lessons learned from the work in the field of MDs, as a student, researcher and engineer at close contact with the world of surgery and minimally invasive technologies. Some papers about a preliminary research activity in the field of minimally invasive surgery and robotic interventions have been also enclosed. These works have been very useful to start the understanding of the complex and amazing world of MIS

Dynamic modeling of soft continuum manipulators using lie group variational integration

This paper presents the derivation and experimental validation of algorithms for modeling and estimation of soft continuum manipulators using Lie group variational integration. Existing approaches are generally limited to static and quasi-static analyses, and are not sufficiently validated for dynamic motion. However, in several applications, models need to consider the dynamical behavior of the continuum manipulators. The proposed modeling and estimation formulation is obtained from a discrete variational principle, and therefore grants outstanding conservation properties to the continuum mechanical model. The main contribution of this article is the experimental validation of the dynamic model of soft continuum manipulators, including external torques and forces (e.g., generated by magnetic fields, friction, and the gravity), by carrying out different experiments with metal rods and polymer-based soft rods. To consider dissipative forces in the validation process, distributed estimation filters are proposed. The experimental and numerical tests also illustrate the algorithm's performance on a magnetically-actuated soft continuum manipulator. The model demonstrates good agreement with dynamic experiments in estimating the tip position of a Polydimethylsiloxane (PDMS) rod. The experimental results show an average absolute error and maximum error in tip position estimation of 0.13 mm and 0.58 mm, respectively, for a manipulator length of 60.55 mm

Fast catheter segmentation and tracking based on x-ray fluoroscopic and echocardiographic modalities for catheter-based cardiac minimally invasive interventions

X-ray fluoroscopy and echocardiography imaging (ultrasound, US) are two imaging modalities that are widely used in cardiac catheterization. For these modalities, a fast, accurate and stable algorithm for the detection and tracking of catheters is required to allow clinicians to observe the catheter location in real-time. Currently X-ray fluoroscopy is routinely used as the standard modality in catheter ablation interventions. However, it lacks the ability to visualize soft tissue and uses harmful radiation. US does not have these limitations but often contains acoustic artifacts and has a small field of view. These make the detection and tracking of the catheter in US very challenging. The first contribution in this thesis is a framework which combines Kalman filter and discrete optimization for multiple catheter segmentation and tracking in X-ray images. Kalman filter is used to identify the whole catheter from a single point detected on the catheter in the first frame of a sequence of x-ray images. An energy-based formulation is developed that can be used to track the catheters in the following frames. We also propose a discrete optimization for minimizing the energy function in each frame of the X-ray image sequence. Our approach is robust to tangential motion of the catheter and combines the tubular and salient feature measurements into a single robust and efficient framework. The second contribution is an algorithm for catheter extraction in 3D ultrasound images based on (a) the registration between the X-ray and ultrasound images and (b) the segmentation of the catheter in X-ray images. The search space for the catheter extraction in the ultrasound images is constrained to lie on or close to a curved surface in the ultrasound volume. The curved surface corresponds to the back-projection of the extracted catheter from the X-ray image to the ultrasound volume. Blob-like features are detected in the US images and organized in a graphical model. The extracted catheter is modelled as the optimal path in this graphical model. Both contributions allow the use of ultrasound imaging for the improved visualization of soft tissue. However, X-ray imaging is still required for each ultrasound frame and the amount of X-ray exposure has not been reduced. The final contribution in this thesis is a system that can track the catheter in ultrasound volumes automatically without the need for X-ray imaging during the tracking. Instead X-ray imaging is only required for the system initialization and for recovery from tracking failures. This allows a significant reduction in the amount of X-ray exposure for patient and clinicians.Open Acces

Design, Development and Force Control of a Tendon-driven Steerable Catheter with a Learning-based Approach

In this research, a learning-based force control schema for tendon-driven steerable catheters with the application in robot-assisted tissue ablation procedures was proposed and validated. To this end, initially a displacement-based model for estimating the contact force between the catheter and tissue was developed. Afterward, a tendon-driven catheter was designed and developed. Next, a software-hardware-integrated robotic system for controlling and monitoring the pose of the catheter was designed and developed. Also, a force control schema was developed based on the developed contact force model as a priori knowledge. Furthermore, the position control of the tip of the catheter was performed using a learning-based inverse kinematic approach. By combining the position control and the contact model, the force control schema was developed and validated. Validation studies were performed on phantom tissue as well as excised porcine tissue. Results of the validation studies showed that the proposed displacement-based model was 91.5% accurate in contact force prediction. Also, the system was capable of following a set of desired trajectories with an average root-mean-square error of less than 5%. Further validation studies revealed that the system could fairly generate desired static and dynamic force profiles on the phantom tissue. In summary, the proposed force control system did not necessitate the utilization of force sensors and could fairly contribute in automatizing the ablation task for robotic tissue ablation procedures

Study of applications of bio-space technology to patient monitoring systems Final report

Investigation of application of NASA developed technology to cardiovascular and pulmonary patient monitoring to improve availability of data for medical diagnosi

Study of applications of bio-space technology to patient monitoring systems Progress report

Patient monitoring system design and equipment specifications with physiological response display device and warning syste

Vascular Malformations of the Central Nervous System

Vascular malformations of the central nervous system are important pathologies that could present with abrupt onset hemorrhage resulting in devastating neurological deficits. Current knowledge of their biology and natural history is increasing. Diagnostic modalities help clinicians to better evaluate the individual cases, and to decide the best treatment options. Treatment alternatives are various and all treatment options should be evaluated before choosing the final therapeutic modality. The purpose of this book is to review the current knowledge about vascular malformations of the central nervous system and to evaluate the treatment alternatives

The ganglionated plexus: The upstream triggers of atrial fibrillation

The ganglionated plexuses (GP) are dense epicardial nerves that are implicated in atrial fibrillation (AF). They can be functionally located from the endocardium using high frequency stimulation (HFS) which can locate distinct GP that trigger atrial ectopy/AF (ET-GP) or atrioventricular (AV) dissociating (AVD-GP). Our aim was to map and understand the histological, anatomical and functional properties of the different types of GP and ablate them with or without pulmonary vein isolation (PVI) in patients with AF. We hypothesised that ablating these specific GP sites is feasible, and prevents AF. Firstly, to investigate this, we mapped for AVD-GP and ET-GP using HFS in the left atrium of patients with AF. An automated process was used to merge and transform all patient maps onto one reference left atrial shell. A probability density function was applied at each tested site, including GP and negative HFS response sites, to create a probability distribution atlas of AVD-GP and ET-GP. There were distinct anatomical regions according to each GP sub-type, and ET-GP had preponderance to the PV ostia, roof, and mid-anterior wall. These are the areas that would usually be targeted with circumferential PVI. Therefore, a prospective, randomised, controlled study was performed (GANGLIA-AF) which assessed ET-GP ablation without PVI and PVI alone in patients with paroxysmal AF. Patients were followed-up for 12 months with multiple 48hr Holter monitors. The primary endpoint was any documented atrial arrhythmia >30s, and the secondary endpoints included complications and redo ablations. This showed that there was no statistically significant difference in AF prevention between the two arms, however the GP ablation arm required less ablation on average than the PVI arm. We also performed a smaller pilot study of redo AF ablation patients, assessing for feasibility and safety of GP ablation in addition to redo PVI. The same follow-up and endpoint criteria were used as in the GANGLIA-AF study. Some patients had permanent PVI, and non-PV triggers of AF were identifiable with HFS. We also developed a custom-built high frequency stimulator (Tau-20) that was used to identify ectopy-triggering (ET) sites in Langendorff-perfused porcine hearts. We were able to replicate the HFS responses used in the clinical setting in the porcine atria. Transmural cross-sectional dissections were taken from ET and non-ET sites, and the tissues were stained for parasympathetic and sympathetic nerves using immunohistochemistry methods. This showed that the mean density of nerves was greater in ET sites compare to non-ET sites. The Tau-20 has been successfully trialled in humans in the clinical setting, and with further improvements, it may replace the old Grass S88 stimulator for future GP ablation cases. In conclusion, ET-GP are upstream triggers of AF that can be ablated without PVI to prevent paroxysmal AF. GP ablation can be achieved with less RF energy than PVI implying a more specific technique on mechanistic grounds. The cross-over rate and clinical outcomes for GP ablation needs further improvement but GANGLIA-AF provides evidence that GP ablation may be an alternative or an adjunct technique to PVI. In addition, our ex-vivo evidence of increased nerve density at ET sites may account for the differential functional response of ET-GP stimulation in the clinical setting.Open Acces