Design and Implementation of Electromagnetic Actuation System to Actuate Micro/NanoRobots in Viscous Environment

The navigation of Micro/Nanorobots (MNRs) with the ability to track a selected trajectory accurately holds significant promise for different applications in biomedicine, providing methods for diagnoses and treatments inside the human body. The critical challenge is ensuring that the required power can be generated within the MNR. Furthermore, ensuring that it is feasible for the robot to travel inside the human body with the necessary power availability. Currently, MNRs are widely driven either by exogenous power sources (light energy, magnetic fields, electric fields, acoustics fields, etc.) or by endogenous energy sources, such as chemical interaction energy. Various driving techniques have been established, including piezoelectric as a driving source, thermal driving, electro-osmotic force driven by biological bacteria, and micro-motors powered by chemical fuel. These driving techniques have some restrictions, mainly when used in biomedicine. External magnetic fields are another potential power source of MNRs. Magnetic fields can permeate deep tissues and be safe for human organisms. As a result, magnetic fields’ magnetic forces and moments can be applied to MNRs without affecting biological fluids and tissues. Due to their features and characteristics of magnetic fields in generating high power, they are naturally suited to control the electromagnetically actuated MNRs in inaccessible locations due to their ability to go through tiny spaces. From the literature, it can be inferred from the available range of actuation technologies that magnetic actuation performs better than other technologies in terms of controllability, speed, flexibility of the working environment, and far less harm may cause to people. Also, electromagnetic actuation systems may come in various configurations that offer many degrees of freedom, different working mediums, and controllability schemes. Although this is a promising field of research, further simulation studies, and analysis, new smart materials, and the development and building of new real systems physically, and testing the concepts under development from different aspects and application requirements are required to determine whether these systems could be implemented in natural clinical settings on the human body. Also, to understand the latest development in MNRs and the actuation techniques with the associated technologies. Also, there is a need to conduct studies and comparisons to conclude the main research achievements in the field, highlight the critical challenges waiting for answers, and develop new research directions to solve and improve the performance. Therefore, this thesis aims to model and analyze, simulate, design, develop, and implement (with complete hardware and software integration) an electromagnetic actuation (EMA) system to actuate MNRs in the sixdimensional (6D) motion space inside a relatively large region of interest (ROI). The second stage is a simulation; simulation and finite element analysis were conducted. COMSOL multi-physics software is used to analyze the performance of different coils and coil pairs for Helmholtz and Maxwell coil configurations and electromagnetic actuation systems. This leads to the following.: • Finite element analysis (FEA) demonstrates that the Helmholtz coils generate a uniform and consistent magnetic field within a targeted ROI, and the Maxwell coils generate a uniform magnetic gradient. • The possibility to combine Helmholtz and Maxwell coils in different space dimensions. With the ability to actuate an MNR in a 6D space: 3D as a position and 3D as orientation. • Different electromagnetic system configurations are proposed, and their effectiveness in guiding an MNR inside a mimicked blood vessel environment was assessed. • Three pairs of Helmholtz coils and three pairs of coils of Maxwell coils are combined to actuate different size MNRs inside a mimicked blood vessel environment and in 6D. Based on the modeling results, a magnetic actuation system prototype that can control different sizes MNRs was conceived. A closed-loop control algorithm was proposed, and motion analysis of the MNR was conducted and discussed for both position and orientation. Improved EMA location tracking along a chosen trajectory was achieved using a PID-based closed-loop control approach with the best possible parameters. Through the model and analysis stage, the developed system was simulated and tested using open- and closed-loop circumstances. Finally, the closedloop controlled system was concluded and simulated to verify the ability of the proposed EMA to actuate an MN under different trajectory tracking examples with different dimensionality and for different sizes of MNRs. The last stage is developing the experimental setup by manufacturing the coils and their base in-house. Drivers and power supplies are selected according to the specifications that actuate the coils to generate the required magnetic field. Three digital microscopes were integrated with the electromagnetic actuation system to deliver visual feedback aiming to track in real-time the location of the MNR in the 6D high viscous fluidic environment, which leads to enabling closed-loop control. The closed-loop control algorithm is developed to facilitate MNR trajectory tracking and minimize the error accordingly. Accordingly, different tests were carried out to check the uniformity of the magnetic field generated from the coils. Also, a test was done for the digital microscope to check that it was calibrated and it works correctly. Experimental tests were conducted in 1D, 2D plane, and 3D trajectories with two different MNR sizes. The results show the ability of the proposed EMA system to actuate the two different sizes with a tracking error of 20-45 µm depending on the axis and the size of the MNR. The experiments show the ability of the developed EMA system to hold the MNR at any point within the 3D fluidic environment while overcoming the gravity effects. A comparison was made between the results achieved (in simulation and physical experiments) and the results deduced from the literature. The comparison shows that the thesis’s outcomes regarding the error and MNR size used are significant, with better performance relative to the MNR size and value of the error

Electromigration in solder joints: Towards better understanding using real-time visuals

With the increasing demands and consequent miniaturization of electronic devices, electromigration is posing a challenge to the reliability not only of integrated circuits but also of the electronic packages. A methodology is reported that allows for quasi-continuous in-situ optical microscopic imaging of a cross-sectioned solder joint (sample) during testing for electromigration. This methodology is complemented with another approach that estimates the local temperature increase from Joule heating of the sample which allows for an appropriate temperature selection for the EM test to understand the contribution of failures from Joule heating. A SAC305 solder joint in a flip configuration was encapsulated in epoxy and cross-sectioned. Current stressing was applied to producing electromigration, with a theoretical current density in the range of (1.02 - 2.29) × 10⁴ A/cm². In-situ optical microscopic imaging and resistance measurements were performed simultaneously until an open circuit was observed. A crack and void started to form in an example experiment, and their evolution was recorded using the real-time imaging. The void and the crack continued growing until the end of current stressing. The void area at the cross-section grew to 1500 μm² while the crack grew to a length of 110 μm. After 330 h, the experiment was stopped as an open circuit occurred, which was preceded by a 10% rise of the resistance, indicating failure due to electromigration. During the end of the test, the test vehicle temperature increased by 20 °C as a result of increased Joule heating due to the loss in cross-sectional area of the solder joint. The location of the void did not agree with the expected current crowding location at the solder joint corner. It was inferred that the formation of cracks due to internal stresses prompted the formation of the void at that location that resulted in the open circuit, demonstrating the interconnection between the various failure mechanisms caused by EM. Microstructural changes were also monitored after the open circuit and were possibly due to the thermal stress occurring once the sample cooled down. Hillock formation and additional cracks were observed 30 min after the open circuit. The results highlight the unique capacity of real-time imaging to support more detailed electromigration research in solder joints by tracing the source of specific failure events. Additionally, cross-sectioning of samples for real-time visuals decreases the cross-sectional area and increases the current density, allowing for accelerated EM testing. Thus, the use of real-time visuals allows for accelerated tests which is helpful for studying EM under varying test conditions and comparing the reliability of different solder materials through a detailed analysis of the failure times

Design of hybrid power generation systems connected to utility grid and natural gas distribution network: a new contribution

Hybrid power generation system (HPGS) is an active research area, which is in need of a continuous improvement. It represents the best solution for the most complex problems facing the world in the last decades. These problems are known as the shortage of energy, or lack of electricity, which logically are the results of the continuous increasing demand. Therefore, the researchers do their best to overcome all expected roadblocks facing the development, where the most applicable solutions to solve these problems are introduced. In this paper, the HPGS includes; wind turbine (WT), photovoltaic (PV), storage battery (SB), gas turbine (GT), and utility grid (UG). The GT of this system is fueled directly from the natural gas distribution network considering all operational conditions of it, which may be affected by fueling the natural gas for the GT. So, the natural gas distribution network is becoming an important component of the HPGS, and it is included in the HPGS for the first time. Multi meta-heuristic optimization techniques are applied to obtain the components sizing of this system, where cuckoo search algorithm (CSA), firefly algorithm (FA), and flower pollination algorithm (FPA) have been applied. Therefore, this paper introduces a new contribution not only to the new configuration of the HPGS, but also in applying the new optimization techniques as solving tools. The output results are compared to show the effectiveness and the superiority of the applied techniques as well as extract a recommendation for the best solving technique

Effervescent Atomization of Suspensions in a Gaseous Cross Flow

Atomization of liquids (pure liquids and suspensions) plays an important role in numerous industrial fields and applications. One of the main important applications is in thermal spraying processes which is the primary motivation for this study. The main trend in thermal spray processes is to coat with sub-micron and nano sized particles due to the superior performance of fine microstructured coatings. Recently, thermal spraying processes are using the suspension spraying technique. The breakup of a suspension in the atomization process differs from that of a pure liquid by the influence of the suspended particles on the fragmentation kinetics. In suspension spraying process, different types of atomizers are used but clogging problems can occur due to the suspension properties. Effervescent atomizers have shown to be a good alternative to the conventional atomizers to solve clogging issue when liquids with large variety of viscosity and density such as suspensions are atomized. In this study, effervescent atomization of suspensions in a crossflow of air is investigated experimentally. The tests have been performed at different liquid-to-gas momentum flux ratios (q) and different gas to liquid ratios (GLR). Hydrophilic and hydrophobic particles are used in the experiments. Shadowgraphy and image processing have been used in order to capture the penetration height of the spray. New correlations have been developed to predict the spray penetration height of suspensions in case the non-aerated liquid jet (GLR= 0) and for the aerated liquid jet (GLR ≠ 0). Moreover, suspensions properties such as viscosity and surface tension have a crucial effect on the atomization process. Because the atomization process and droplet formation occur in a very short timescale of the order of milliseconds, it is necessary to analyze the rapid change of the affecting suspension properties related to this timescale especially surface tension. Therefore, the time changing (dynamic) surface tension is more appropriate to be analyzed than static surface tension. In this work, the dynamic surface tension of suspensions is investigated using a combined analytical and experimental approach based on the physics governing the oscillation of elliptical jets. The dynamic surface tension of suspensions liquids in the timescale of milliseconds is calculated. The effect of the dynamic surface tension of suspension on its atomization process has been analyzed

Cranioplasty: A New Perspective

AIM: This work aims to present the different indication, benefits, possible complications and methods used for fixation of methyl methacrylate in cranioplasty. Also, 50 cases will be presented demonstrating the different aetiologies of the defects, and the different techniques used for fixation of methyl methacrylate in cranioplasty. METHODS: This investigation included a prospective study to be carried out on 50 patients with cranial defects of different aetiologies, sites and sizes to be operated upon in Cairo University Hospitals starting from August 2016 to April 2017.RESULTS: The principal aims of cranioplasty in this study are to restore aesthetic contour and to provide cerebral protection. However, it has been noted that a great improvement occurs in cerebral blood flow and cerebral perfusion after cranioplasty. CONCLUSION: Ball and socket technique appear to be a simple, safe economic and efficient method for fixation of cranioplasty flap. The high incidence of development of postoperative seroma suggests the necessity of-of a subgaleal drain placement for 48 hours. &nbsp

Management Dilemma of an Infertile Patient with More Than 20 Submucous Fibroids

Background: Submucous fibroids can lead to menorrhgia, infertility, recurrent pregnancy loss, and obstetric complications. The management of multiple submucous fibroids in patients who would like to preserve their reproductive function can be a challenge. The aim of this report is to discuss the management dilemma of a patient who presented with multiple (more than 20) submucous fibroids. Case: The patient was a 33-year-old Caucasian woman who had an initial complaint of menometrorrhagia and secondary infertility, which led to a diagnostic hysteroscopy. Multiple submucosal fibroids were noted; no other etiology for infertility was identified. She subsequently underwent hysteroscopic resection of several fibroids. Postoperative hyterosalpingogram demonstrated intrauterine scarring, unilateral tubal blockage, and several remaining fibroids. She did, however, conceive with intrauterine insemination. Unfortunately, this pregnancy ended in an early spontaneous abortion of twins. After being counseled on her options, including the possibility of needing a surrogate uterus, she elected to have an abdominal resection of the remaining fibroids. During this procedure, several steps were taken to restore the uterine cavity to a normal shape. After allowing her uterus to heal, she achieved pregnancy through in vitro fertilization. At 29 weeks of gestation, she had preterm premature rupture of membranes and, subsequently, had a cesarean section at 34 weeks of gestation. She had a viable 6 pound 1 ounce baby boy. At the time of her cesarean section, only one submucosal fibroid was identified. Conclusion: We present a unique case of multiple sub-mucous fibroids that failed hysteroscopic management and were subsequently treated successfully with hysterotomy, myomectomy, and uterine reconstructive surgery. Based on our experience with this case, we recommend hysterotomy and myomectomy for management of multiple sub-mucous fibroids from the outset. (J GYNECOL SURG 31:274)Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140098/1/gyn.2014.0123.pd

POLYNOMIAL STATIC OUTPUT FEEDBACK H ∞ CONTROL FOR CONTINUOUS-TIME LINEAR SYSTEMS VIA DESCRIPTOR APPROACH

International audienceThis paper deals with the problem of the robust static output feedback H ∞ control (SOFC) for continuous linear systems with polytopic uncertainties. The controller has been gotten by the use of descriptor redundancy. Under this approach a sufficient condition is provided for the existence of a solution to the problem. Thus, the advantage of this method is to obtain more free matrices in the design condition, also the polynomial approach helps to have a less conservative result. In the end, the performance of the method is shown by several examples

Robust H∞ Filters for Uncertain Systems with Finite Frequency Specifications

International audienceThis paper deals with H∞ filtering problem of linear discrete-time uncertain systems with finite frequency input signals. The uncertain parameters are supposed to reside in a polytope. By applying the generalized Kalman–Yakubovich–Popov lemma, polynomially parameter-dependentLyapunov function and some key matrices to eliminate the product terms between the filter parameters and the Lyapunov matrices, an improved condition isobtained for analyzing the H∞performance of the filtering error system. Then sufficient condition in terms of linear matrix inequality is established for designing filters with a guaranteed H∞ filtering performance level. Finally, a numerical examples are used to demonstrate the effectiveness of the proposed method

Traumatic Dural Venous Sinuses Injury

The traumatic dural venous sinus injury is one of the most dangerous complications of TBI, either due to fatal intracranial compressing venous bleeding, or disturbing the intracranial pressure which could be caused by injury to the SSS On the other hand, post traumatic dural sinus thrombosis is considered a rare complication which may lead to hemorrhagic infarction with its serious consequences including epilepsy, neurological deficits, or death. Therefore, knowledge of the appropriate treatment of this kind of head injury is essential