Comparative study of micromixers for laminar blood mixing

Miniaturization is the trend in analytical chemistry and life science. It has been emerging into the research field of microfluidics in the application of LOC. The application is used for biochemistry analysis and require a rapid mixing in small area. Due to laminar flow (Reynold Number < 1) passive micromixer is the best method in fluids mixing. Passive micromixer also depend on the channel geometry for mixing effectiveness. In this study, four different micromixers were evaluated based on the baseline control Y-micromixer. The micromixers are internal rib micromixer, patterned grooves micromixer, obstruction micromixer and slanted rib micromixer. These micromixer has 1000μm channel length, 150μm inlet length, 90o between inlets ports, width and depth are 40μm each. The fluids used for mixing were blood which has 1.0 × 10-6 kg/μms of viscosity and toluene which has low viscosity than blood (0.664 × 10-9 kg/μms). The fluids used to evaluate the differences in term of their visual performance based image’s standard deviation by plotting the graph and mixing efficiency by calculation. Based on these evaluations, the slanted rib micromixer is the best micromixer design with the highest mixing efficiency of 99.85% at the outlet of the channel

Advanced Circularly Polarised Microstrip Patch Antennas

The thesis describes outcomes of research on advanced circularly polarised antennas. The proposed designs are intended for integration into small mobile devices, therefore low profile and easy manufacturability are key parameters, along with good CP radiation properties. The designs were validated by simulation and measurement, and are also backed by theory and design guidelines. The primary focus is on the development of planar omnidirectional circularly polarised antennas, which are fabricated using multilayer PCB techniques and thus are lightweight and cost-efficient. Unlike in classical microstrip patch antenna designs, the groundplane of the proposed antenna was substantially reduced. This helps to achieve an omnidirectional circular polarisation pattern and miniaturize the antenna, however at the cost of increased feed circuit complexity. The basic design, its advantages and disadvantages are discussed in Section 3. In the next step, the omnidirectional circularly polarised antenna was extended with additional, advanced features. A miniaturized version is investigated, which offers a 20% footprint reduction by folding parts of the patch underneath itself. Further miniaturization is possible by increasing the dielectric constant of the substrate. A method to adjust the omnidirectional circularly polarised antenna performance by trimming four lumped capacitors is also investigated. Manufacturing inaccuracy in large scale production may cause some of the units to radiate outside of the desired frequencies. By integrating four trimmed capacitors into the antenna it can be precisely tuned to the desired band. Simulated results demonstrate this property by trimming the antenna between GPS L1 band (centre frequency at 1.575 GHz) and Galileo/Beidou-2 E2 band (1.561 GHz). Furthermore, a dual-band omnidirectional circularly polarised antenna is presented, which employs slots and capacitor loading to steer the current path of the first and second resonant mode. The design offers a small frequency ratio of 1.182. The methods to obtain a planar omnidirectional circularly polarised antenna have been further advanced to propose a reconfigurable antenna. The beam reconfiguration is capable of rotating it dipole-like radiation pattern around an axis, thus allowing reception or transmission from any spherical angle. The switching method is simple and does not require any semiconductor devices. Finally, a dual circularly polarised antenna is presented, which achieves dual-polarisation by employing even and odd modes in a coplanar waveguide. This technique allows greater flexibility and size reduction of the feed network, as two signals can be transmitted by a single multi-mode transmission line. Simulated results demonstrate this property by trimming the antenna between GPS L1 band (centre frequency at 1.575 GHz) and Galileo/Beidou-2 E2 band (1.561 GHz). Furthermore, a dual-band omnidirectional circularly polarised antenna is presented, which employs slots and capacitor loading to steer the current path of the first and second resonant mode. The design offers a small frequency ratio of 1.182. The methods to obtain a planar omnidirectional circularly polarised antenna have been further advanced to propose a reconfigurable antenna. The beam reconfiguration is capable of rotating it dipole-like radiation pattern around an axis, thus allowing reception or transmission from any spherical angle. The switching method is simple and does not require any semiconductor devices. Finally, a dual circularly polarised antenna is presented, which achieves dual-polarisation by employing even and odd modes in a coplanar waveguide. This technique allows greater flexibility and size reduction of the feed network, as two signals can be transmitted by a single multi-mode transmission line

Antenna Design for 5G and Beyond

With the rapid evolution of the wireless communications, fifth-generation (5G) communication has received much attention from both academia and industry, with many reported efforts and research outputs and significant improvements in different aspects, such as data rate speed and resolution, mobility, latency, etc. In some countries, the commercialization of 5G communication has already started as well as initial research of beyond technologies such as 6G.MIMO technology with multiple antennas is a promising technology to obtain the requirements of 5G/6G communications. It can significantly enhance the system capacity and resist multipath fading, and has become a hot spot in the field of wireless communications. This technology is a key component and probably the most established to truly reach the promised transfer data rates of future communication systems. In MIMO systems, multiple antennas are deployed at both the transmitter and receiver sides. The greater number of antennas can make the system more resistant to intentional jamming and interference. Massive MIMO with an especially high number of antennas can reduce energy consumption by targeting signals to individual users utilizing beamforming.Apart from sub-6 GHz frequency bands, 5G/6G devices are also expected to cover millimeter-wave (mmWave) and terahertz (THz) spectra. However, moving to higher bands will bring new challenges and will certainly require careful consideration of the antenna design for smart devices. Compact antennas arranged as conformal, planar, and linear arrays can be employed at different portions of base stations and user equipment to form phased arrays with high gain and directional radiation beams. The objective of this Special Issue is to cover all aspects of antenna designs used in existing or future wireless communication systems. The aim is to highlight recent advances, current trends, and possible future developments of 5G/6G antennas

Clustering Inverse Beamforming and multi-domain acoustic imaging approaches for vehicles NVH

Il rumore percepito all’interno della cabina di un veicolo è un aspetto molto rilevante nella valutazione della sua qualità complessiva. Metodi sperimentali di acoustic imaging, quali beamforming e olografia acustica, sono usati per identificare le principali sorgenti che contribuiscono alla rumorosità percepita all’interno del veicolo. L’obiettivo della tesi proposta è di fornire strumenti per effettuare dettagliate analisi quantitative tramite tali tecniche, ad oggi relegate alle fasi di studio preliminare, proponendo un approccio modulare che si avvale di analisi dei fenomeni vibro-acustici nel dominio della frequenza, del tempo e dell’angolo di rotazione degli elementi rotanti tipicamente presenti in un veicolo. Ciò permette di ridurre tempi e costi della progettazione, garantendo, al contempo, una maggiore qualità del pacchetto vibro-acustico. L’innovativo paradigma proposto prevede l’uso combinato di algoritmi di pre- e post- processing con tecniche inverse di acoustic imaging per lo studio di rilevanti problematiche quali l’identificazione di sorgenti sonore esterne o interne all’abitacolo e del rumore prodotto da dispositivi rotanti. Principale elemento innovativo della tesi è la tecnica denominata Clustering Inverse Beamforming. Essa si basa su un approccio statistico che permette di incrementare l’accuratezza (range dinamico, localizzazione e quantificazione) di una immagine acustica tramite la combinazione di soluzioni, del medesimo problema inverso, ottenute considerando diversi sotto-campioni dell’informazione sperimentale disponibile, variando, in questo modo, in maniera casuale la sua formulazione matematica. Tale procedimento garantisce la ricostruzione nel dominio della frequenza e del tempo delle sorgenti sonore identificate. Un metodo innovativo è stato inoltre proposto per la ricostruzione, ove necessario, di sorgenti sonore nel dominio dell’angolo. I metodi proposti sono stati supportati da argomentazioni teoriche e validazioni sperimentali su scala accademica e industriale.The interior sound perceived in vehicle cabins is a very important attribute for the user. Experimental acoustic imaging methods such as beamforming and Near-field Acoustic Holography are used in vehicles noise and vibration studies because they are capable of identifying the noise sources contributing to the overall noise perceived inside the cabin. However these techniques are often relegated to the troubleshooting phase, thus requiring additional experiments for more detailed NVH analyses. It is therefore desirable that such methods evolve towards more refined solutions capable of providing a larger and more detailed information. This thesis proposes a modular and multi-domain approach involving direct and inverse acoustic imaging techniques for providing quantitative and accurate results in frequency, time and angle domain, thus targeting three relevant types of problems in vehicles NVH: identification of exterior sources affecting interior noise, interior noise source identification, analysis of noise sources produced by rotating machines. The core finding of this thesis is represented by a novel inverse acoustic imaging method named Clustering Inverse Beamforming (CIB). The method grounds on a statistical processing based on an Equivalent Source Method formulation. In this way, an accurate localization, a reliable ranking of the identified sources in frequency domain and their separation into uncorrelated phenomena is obtained. CIB is also exploited in this work for allowing the reconstruction of the time evolution of the sources sought. Finally a methodology for decomposing the acoustic image of the sound field generated by a rotating machine as a function of the angular evolution of the machine shaft is proposed. This set of findings aims at contributing to the advent of a new paradigm of acoustic imaging applications in vehicles NVH, supporting all the stages of the vehicle design with time-saving and cost-efficient experimental techniques. The proposed innovative approaches are validated on several simulated and real experiments

Applications of Antenna Technology in Sensors

During the past few decades, information technologies have been evolving at a tremendous rate, causing profound changes to our world and to our ways of living. Emerging applications have opened u[ new routes and set new trends for antenna sensors. With the advent of the Internet of Things (IoT), the adaptation of antenna technologies for sensor and sensing applications has become more important. Now, the antennas must be reconfigurable, flexible, low profile, and low-cost, for applications from airborne and vehicles, to machine-to-machine, IoT, 5G, etc. This reprint aims to introduce and treat a series of advanced and emerging topics in the field of antenna sensors

Electromagnetic Waves

This volume is based on the contributions of several authors in electromagnetic waves propagations. Several issues are considered. The contents of most of the chapters are highlighting non classic presentation of wave propagation and interaction with matters. This volume bridges the gap between physics and engineering in these issues. Each chapter keeps the author notation that the reader should be aware of as he reads from chapter to the other

Antenna Design for 5G and Beyond

This book is a reprint of the Special Issue Antenna Design for 5G and Beyond that was published in Sensors

Integration of Antennas and Solar Cells for Autonomous Communication Systems

Solar energy is becoming an attractive alternative for powering autonomous communication systems. These devices often involve the use of separate photovoltaics and antennas, which demand a compromise in the utilization of the limited space available. This thesis deals with the design, analysis, fabrication and validation of different techniques for the integration of antennas and solar cells in a single multifunctional device. Four different photovoltaic technologies are considered within this work, namely, polycrystalline silicon (poly-Si), monocrystalline (mono-Si) emitter-wrap-through (EWT) rear contact solar cells, amorphous silicon (a-Si) thin film on glass substrate, and bifacial solar cells. The use of a poly-Si solar cell was investigated as ground plane for a microstrip patch antenna as well as reflector for a half-wave dipole antenna. Looking forward to further minimize the shade of the solar element on the solar cell and to increase the smart appearance, a film that is both transparent and conductive, the AgHT-4, was evaluated as an antenna radiating element for the integration with an a-Si thin film photovoltaic module on glass substrate. A different approach involves the use of EWT solar cells as a folded dipole for integration with solar concentration. The solar cells in this structure are used both for power generation and as radiating element, and a parabolic trough is employed as well with a double function as solar concentrator for the PV cells as well as reflector for the folded dipole antenna. Numerical simulation results obtained with CST Microwave Studio were validated experimentally with the construction of the corresponding prototypes. The performance of these prototypes is thoroughly evaluated in an anechoic chamber. The approaches proposed in this work for integration of antennas and PV technology will help to reduce the marginal cost of renewable energy, improving its economic viability due to the possibility of an integrated production and easier maintenance. It also reduces the need for cable deployment and leads to compact reliable systems with decreased exposure to natural disasters and vandalism

Embedded antenna technology in smart polymeric composite structures

One of the fastest-growing uses of sheet moulding compound (SMC) material is in the area of manufacturing of vehicle body components for both structural and non-structural applications. This trend is accelerating, driven by original equipment manufacturers (OEM) and their need for lighter and more fuel-efficient vehicles. In addition, over the last 20 years, the number of entertainment and communication systems in vehicles has also been expanding. The aim of this research is the development of a single wideband antenna that is capable of receiving all of the major services of interest. Taking this approach one step further and embedding such an antenna in a polymeric composite vehicle body panel would combine the benefits of reduced coefficient of drag, lower vehicle weight, reduced assembly complexity and shorter assembly time. These benefits would manifest themselves in the form of lower overall design and manufacturing vehicle cost for the OEMs and lower fuel consumption for customers. This thesis will deal with the development of such an antenna and the challenges faced in embedding it in a polymeric composite vehicle panel to such an extent that it becomes a seamless part of the vehicle body. This application required the development of a detailed understanding of the following three areas. Firstly, understanding of the interactions and effects of SMC material and automotive paint on antenna signal quality and performance through experiments and electromagnetic modelling (EM). Secondly, the development of the manufacturing process and material used to embed the antenna and its impact on the physical properties of the antenna through rheological testing, analytical modelling and experimentation. Lastly, the development of a wideband antenna capable of receiving pre-determined signals, through EM and field testing. The effects of paint application and presence of SMC resulted in a frequency shift of less than 1%. The experiments correlated well with the analytical model developed for compression moulding which incorporates a novel inclusion of the Maxwell’s model to predict the shear forces in the material flow within a confined space. A modular planar inverted conical antenna (PICA) was developed and optimised for the frequency range 700MHz – 9000MHz, which includes the commercial global positioning system (GPS) frequency. This development was then deployed as an embedded prototype in the deck lid of a test vehicle. Comparison against commercial GPS and mobile phone antennas was undertaken. This field test comparison showed that the developed PICA antenna performed better than the commercial antenna by up to 17%, especially in spaces devoid of multi-path signals