We are reporting on a study of the near-field sensitivity and resolution of a metal-dielectric probe (MDP). The propagation of the electromagnetic field across the probe was studied experimentally by means of time-domain terahertz spectroscopy and numerically simulated by CST MicroWave Studio 2008. Several localised areas at the probe end facet were distinguished and showed to be sensitive to the local dielectric properties and local anisotropy of the sample. Contrast and sensitivity measurements were conducted in several configurations of a MDP; the results were confirmed by simulations. The acquired data were analysed by using singular value decomposition that enabled separating independent physical phenomena in the measured datasets and filtering external disturbances out of the signal. Independent components corresponding to the changes in the output terahertz pulse upon varying the probe-sample distance and reflecting the local anisotropy in a ferroelectric barium titanate (BaTiO3) crystal were extracted and identified. The domain structure with characteristic dimensions of about 5 um was resolved during imaging experiments on the ferroelectric BaTiO3 sample, i.e. the resolved structures were ten times smaller than the characteristic dimensions of the end facet of the probe and forty times smaller than...

No description available.

Recent advances in near-field acoustical holography (NAH) have expanded the theory to interior spaces where multiple sources and/or reflections are present. In 1990, Tamura presented the spatial Fourier transform separation method to measure the reflection coefficient at oblique angles using two measurement planes in the wave number domain. This paper adapts the spatial Fourier transform separation method for application in interior NAH. A practical exploration of important experimental parameters is performed, which include the relative amplitudes of primary and disturbing sources, the measurement plane separation distance, and an acceptable noise floor. This technique is successfully applied in a reverberant environment to reconstruct the velocity of a clamped vibrating plate. NAH methods based on the measurement of pressure and particle velocity have led to the ability to reduce the required measurement locations. Other recent advances in NAH have expanded the theory to interior spaces where multiple sources and/or reflections are present. This paper investigates the use of interpolation techniques to reduce the required measurement locations for interior NAH. Specifically, the benefits of a bi-cubic Hermite surface patch interpolation are discussed and compared to other interpolation routines. Although the required inputs for the Hermite interpolation can be measured using a variety of devices, a scanning six-microphone probe in a tetrahedral configuration is suggested. The six microphones are utilized to simultaneously sample pressure on two parallel planes and estimate the pressure gradients on both of these planes. The two interpolated measurement holograms are used to separate the incoming and outgoing waves using the spatial Fourier-transform method. Analytical simulations of simply supported plates are shown as well as experimental results in a reverberation room to characterize the reduction in measurement locations. Depending on the spatial frequency of the hologram, a measurement location reduction of 20–80% was observed.

The project presented in this report is set out to develop a portable electronic system to be used as a medicine pill container. With the functionality to configure up to twelve daily repeated alarms, the purpose of the medicine dosage system is first and foremost to remind the user when they should take their medicine. Secondly, LED lights and user-recorded voice notifications are to be implemented to further aid the user in taking the right medicine each time. The device is also to have a memory log, recording up to one hundred missed dosages, enabling an authorized medicine professional to verify the medicine adherence of the user.Prior to the start of the project, an outline for the functionality and physical appearance of the device was set by the project owner, Victrix AB. This project covers the hardware and software development, as well as the design choices within. The aim is to follow the proposed functionality specification as close as possible, while making justified hardware and software choices considering simplicity, efficiency, power consumption, and availability. By following the specification, the goal is ultimately to increase the medicine adherence for users of the device developed with this thesis.Using qualitative research methods, a valid background study was created, preceding the development of the medicine dosage system. Hardware for a first prototype of the device was then chosen based on the gathered information about existing technologies and related work. With thorough testing and recurrent information exchange with the client, a prototype of the medicine dosage system, based on an Arduino microcontroller, was constructed. The prototype was evaluated to fulfill 92% of the requirements considered as high priority by Victrix. / Projektet som presenteras i denna rapport är tänkt att utveckla ett portabelt elektroniskt system för användning som en medicinsk pillerbehållare. Med funktionaliteten att konfigurera upp till tolv dagligen upprepande alarm är syftet med medicindoseringssystemet först och främst att påminna användaren när de ska ta sin medicin. Lysdioder och användarens egna inspelade röst som notifikationer ska implementeras för att vidare hjälpa användaren att ta rätt medicin vid varje tillfälle. Enheten ska också ha en minneslogg som sparar upp till etthundra missade doseringar, vilket gör det möjligt för auktoriserad sjukvårdspersonal att verifiera användarens följsamhet till medicineringen.En översiktlig beskrivning av funktionaliteten samt det fysiska utseendet av enheten skrevs av projektägaren Victrix AB innan projektet startades. Det som detta projekt täcker är hårdvaruoch mjukvaruutvecklingen, så väl som där tillhörande designval. Projektet siktar på att följa den föreslagna funktionalitetsspecifikationen så nära som möjligt, och samtidigt göra välgrundade val för hårdoch mjukvara med enkelhet, effektivitet, energiförbrukning och tillgänglighet i åtanke. Genom att följa specifikationen är det slutliga målet att frambringa ökad medicinföljsamhet för användare av den med det här projektet utvecklade enheten.Utvecklingen av medicindoseringssystemet föregicks av en befogad bakgrundsstudie utformad genom användningen av kvalitativa forskningsmetoder. Hårdvara att användas för en första prototyp av enheten valdes sedan baserat på den insamlade informationen om existerande teknologier och relaterat arbete. Genom grundliga tester och regelbundet informationsutbyte med kunden konstruerades en prototyp av medicindoseringssystemet baserat på en Arduinomikrokontroller. Prototypen utvärderades att uppfylla 92% av kraven som Victrix ansåg vara av hög prioritet.

Surface Plasmon Polaritons (SPPs) are considered to be attractive components for plasmonics and nanophotonic devices due to their sensitivity to interface changes, and their ability to guide and confine light beyond the diffraction limit. They have been utilized in SPP resonance sensors and near field imaging techniques and, more recently, SPP experiments to monitor and control ultrafast charge carrier and energy relaxation dynamics in thin films. In this thesis, we discuss excitation and propagation properties of ultrafast SPPs on thin extended metal films and SPP waveguide structures. In addition, localized and propagating surface plasmon interactions in functional plasmonic nanostructures will also be addressed. For the excitation studies of ultrafast SPPs, we have done detailed analysis of femtosecond surface plasmon pulse generation under resonant excitation condition using prism coupling technique. Our results show that photon-SPP coupling is a resonant process with a finite spectral bandwidth that causes spectral phase shift and narrowing of the SPP pulse spectrum. Both effects result in temporal pulse broadening and, therefore, set a lower limit on the duration of ultrafast SPP pulses. These findings are necessary for the successful integration of plasmonic components into high-speed SPP circuits and time-resolved SPP sensors. To demonstrate interactions between localized and propagating surface plasmons, we used block-copolymer based self assembly techniques to deposit long range ordered gold nanoparticle arrays onto silver thin films to fabricate composite nanoparticle thin film structures. We demonstrate that these gold nanoparticle arrays interact with SPPs that propagate at the film/nanoparticle interface and therefore, modify the dispersion relation of SPPs and lead to strong field localizations. These results are important and advantageous for plasmonic device applications. For the propagation studies of ultrafast SPPs, we have designed and constructed a home-built femtosecond photon scanning tunneling microscope (fsPSTM) to visualize ultrafast SPPs in photonic devices based on metal nanostructures. Temporal and phase information have been obtained by incorporating the fsPSTM into one arm of a Mach-Zehnder interferometer, allowing heterodyne detection. Understanding plasmon propagation in metal nanostructures is a requirement for implementing such structures into opto-electronic and telecommunication technologies.

Near field imaging using microwave in medical applications has gain much attention recently as various researches show its high ability and accuracy in illuminating object comparing to the well-known screening tools such as Magnetic Resonance Imaging (MRI), digital mammography, ultrasound etc. This has encourage and motivate scientists continue to exploit the potential of microwave imaging so that a better and more powerful sensing tools can be developed. This thesis documents the development of antenna design for microwave imaging application such as breast cancer detection. The application is similar to the concept of Ground Penetrating Radar (GPR) but operating at higher frequency band. In these systems a short pulse is transmitted from an antenna to the medium and the backscattered response is investigated for diagnose. In order to accommodate such a short pulse, a very wideband antenna with a minimal internal reflection is required. Printed monopole and planar metal plate antenna is implemented to achieve the necessary operating wide bandwidth. The development of new compact printed planar metal plate ultra wide bandwidth antenna is presented. A generalized parametric study is carried out using two well-known software packages to achieve optimum antenna performance. The Prototype antennas are tested and analysed experimentally, in which a reasonable agreement was achieved with the simulations. The antennas present an excellent relative wide bandwidth of 67% with acceptable range of power gain between 3.5 to 7 dBi. A new compact size air-dielectric microstrip patch-antenna designs proposed for breast cancer detection are presented. The antennas consist of a radiating patch mounted on two vertical plates, fed by coaxial cable. The antennas show a wide bandwidth that were verified by the simulations and also confirmed experimentally. The prototype antennas show excellent performance in terms the input impedance and radiation performance over the target range bandwidth from 4 GHz to 8 GHz. A mono-static model with a homogeneous dielectric box having similar properties to human tissue is used to study the interaction of the antenna with tissue. The numerical results in terms the matching required of new optimised antennas were promising. An experimental setup of sensor array for early-stage breast-cancer detection is developed. The arrangement of two elements separated by short distance that confined equivalent medium of breast tissues were modelled and implemented. The operation performances due to several orientations of the antennas locations were performed to determine the sensitivity limits with and without small size equivalent cancer cells model. In addition, a resistively loaded bow tie antenna, intended for applications in breast cancer detection, is adaptively modified through modelling and genetic optimisation is presented. The required wideband operating characteristic is achieved through manipulating the resistive loading of the antenna structure, the number of wires, and their angular separation within the equivalent wire assembly. The results show an acceptable impedance bandwidth of 100.75 %, with a VSWR < 2, over the interval from 3.3 GHz to 10.0 GHz. Feasibility studies were made on the antenna sensitivity for operation in a tissue equivalent dielectric medium. The simulated and measured results are all in close agreement.

Near field imaging using microwaves in medical applications is of great current interest for its capability and accuracy in identifying features of interest, in comparison with other known screening tools. Many imaging methods have been developed over the past two decades showing the potential of microwave imaging in medical applications such as early breast cancer detection, analysis of cardiac tissues, soft tissues and bones. Microwave imaging uses non-ionizing ultra wideband (UWB) electromagnetic signals and utilises tissue-dependent dielectric contrast to reconstruct signals and images using radar-based or tomographic imaging techniques. Microwave imaging offers low health risk, low operational cost, ease of use and user-friendliness. This study documents microwave imaging experiments for early breast cancer detection and bone fracture detection using radar approach. An actively tuned UWB patch antenna and a UWB Vivaldi antenna are designed and utilised as sensing elements in the aforementioned applications. Both UWB antennas were developed over a range of frequency spectrum, and then characteristics were tested against their ability for microwave imaging applications by reconstructing the 3D Inversion Algorithm. An experiment was conducted using patch antenna to test the detection of variable sizes of cancer tissues based on a simple phantom consisting of a plastic container with a low dielectric material emulating fatty tissue and high dielectric constant object emulating a tumour, is scanned between 4 to 8 GHz with the patch antenna. A 2-D image of the tumour is constructed using the reflected signal response to visualize the location and size of the tumour. A Vivaldi antenna is designed covering 3.1 to 10.6 GHz. The antenna is tested via simulation for detecting bone fractures of various sizes and 2-D images are generated using reflected pulses to show the size of fracture. The Vivaldi antenna is optimised for early breast cancer detection and detailed simulated study is carried out using different breast phantoms and tumour sizes. Simulations are backed with the experimental investigation with the test setup used for patch antenna. Generated images for simulations and experimental investigation show good agreement, and show the presence of tumour with good location accuracy. Measurements indicate that both prototype microwave sensors are good candidates for tested imaging applications.

Microwave imaging finds numerous applications involving optically obscured targets. One particular area is breast cancer detection, since microwave technology promises fast low-cost image reconstruction without the use of harmful radiation typical of X-ray mammography. However, the success of microwave imaging is hindered by a critical issue, the complex nature of near-field electromagnetic scattering in tissue. To overcome this, specialized image reconstruction algorithms alongside sensitive measurement hardware are required. In this work, real-time near-field microwave imaging algorithms known as quantitative microwave holography and scattered power mapping are explored. They are experimentally demonstrated to identify potential tumor regions in tissue phantoms. Alongside this development, quality control techniques for evaluating microwave hardware are also described. Two new methods for improving the image reconstruction quality are also presented. First, a novel technique, which combines two commonly used mathematical approximations of scattering (the Born and Rytov approximations), is demonstrated yielding improved image reconstructions due to the complimentary nature of the approximations. Second, a range migration algorithm is introduced which enables near-field refocusing of a point-spread function (PSF), which is critical for algorithms that rely on measured PSFs to perform image reconstruction. / Thesis / Doctor of Philosophy (PhD) / Breast cancer remains as one of the highest causes of cancer-related deaths in women in Canada. Though X-ray mammography remains the gold standard for regular breast cancer screening, its use of harmful radiation, painful breast compression, and radiologist dependent evaluation remain as detracting factors for its use. Over the past 40 years, researchers have been exploring the use of microwave technology in place of X-ray mammography. Microwave radiation, used at power levels similar to that of a cellphone, has been demonstrated successfully in simulations of breast scans. However, in experimental evaluations with breast phantoms, the complex scattering path of the radiation through tissue complicates image reconstruction. In this thesis, methods of improving the accuracy of microwave algorithms are explored, alongside new breast phantom structures that replicate well the electrical properties of tissue. The results of this work demonstrate the flexibility of microwave imaging, and the adversities that still need to be overcome for it to begin seeing clinical use.

No description available.

No description available.