The interest in tiny wireless applications raises the demand for an integrated reference oscillator with the same performance as the macroscopic quartz crystal reference oscillators. The main challenge of the thesis is to prove that it is possible to build a MEMS based oscillator that approaches the accuracy level of existing quartz crystal oscillators. The MEMS resonator samples which Philips provides are measured and an equivalent electrical model is designed for them. This model is used in the simulations of the Pierce oscillator and the transresistance amplifier oscillator that are evaluated in this thesis. Finally the Pierce oscillator is implemented in the A BCD2 process and manufactured at Philips Semiconductors in Nijmegen, The Netherlands. A test board, for measuring the Pierce oscillator together with a MEMS resonator or a quartz crystal resonator, is built. The Pierce oscillator is then measured with a quartz crystal resonator. In order to simulate the higher series resistance of the MEMS resonators a resistor is put in series with the quartz crystal. The Pierce oscillator is working with a series resistance of 1 kΩ. With higher series resistance the Pierce oscillator stops working. In circuit simulations the Pierce oscillator is working with a series resistance of about 5 kΩ in the MEMS resonator model. To be sure whether the Pierce oscillator has enough gain for the MEMS resonators, it needs to be measured with them. Temperature variations in the MEMS resonators need to be handled and the phase noise performance of the oscillator must be improved, in order for the MEMS based reference oscillator to be a successful replacement for the quartz crystal reference oscillator.

The detection of volatile organic compounds in liquid is of interest for applications in public health, workplace safety and environmental monitoring. Traditionally, water samples were taken and analyzed in the laboratory using classical laboratory instrumentation. Current trends target real-time measurements using e.g. chemical microsensors built with microfabrication technologies. Among these, mass-sensitive chemical sensors, based on cantilever beams or surface acoustic devices, have shown substantial promise in gas-phase applications. In a liquid environment, the resonant microstructures typically suffer from high damping, which negatively affects the sensor resolution. In this work, a novel disk-type resonator developed at Georgia Tech was investigated as chemical microsensor for liquid-phase applications. The micromachined resonator vibrates in a rotational in-plane mode shape, reducing damping in a liquid environment. As part of the present research, a measurement setup with a custom-made flow cell for liquid-phase chemical measurements and a coating system to locally deposit polymer sensitive films onto the resonators were developed. To improve the film adhesion on the resonator surface in liquid, physical and chemical binding techniques were developed and tested on wafer samples. Polymers such as poly(4-vinylpyrrolidone), poly(ethylene-co-propylene) and poly(styrene-co-butadiene) were deposited using the custom-designed coating system onto the disk-type resonators. Liquid-phase measurements using tetrachloroethylene as the chemical analyte were performed. The experimental results are discussed, sources of problems are identified and recommendations for future research are made.

The classical structure of an Opto-Electronic Oscillator (OEO) is based on a long fiber loop acting as a delay line and leading to the high spectral purity, or very low phase noise, of the oscillator. Such an OEO has been developed in SATIE/LPQM laboratory at ENS Cachan, operating at 8 GHz frequency. However, this system has some main disadvantages such as a bulky size, the difficulty to control temperature and a wide range of peaks among which it is difficult to select only one mode. In order to eliminate these disadvantages, high quality factor optical resonator can be used instead of the optical fiber loop. In this thesis, two resonator structures are produced and investigated. Microspheres are fabricated based on optical single mode fiber. Whispering gallery modes of these resonators are characterized by tapered fiber -resonator coupling. The experimental results show that the quality factor of the microsphere is up to 106 and FSR depends on the diameter of the resonator. A microsphere with a diameter of 300 µm, presents a FSR of 0.2 nm corresponding to a frequency of 25 GHz. However, for an OEO system which should work at 8 GHz, microsphere with a smaller FSR or with diameter of some millimeters should be fabricated- that is really difficult to obtain. Another add/drop racetrack resonator is designed and investigated. Optical experimental behavior of racetrack is characterized via fiber micro-lens coupling. The transmission spectrum shows resonance dips with average quality factor of 105 and a small FSR of 0.050 ± 0.003 nm (actually corresponding to 6 GHz) for a scanning wavelength range from 1534 nm to 1610 nm. The most promising features of the racetrack resonator are its high quality factor, and its free spectral range, which give it the high suitability for being used in the OEO system. Nevertheless the coupling with fiber lens leads to high losses and it is not possible to fulfill the oscillation conditions. Future work should be conducted for improving the coupling and for controlling the resonance dips position in agreement with the wavelength of the laser used in the OEO.

Microwave filters play key roles in controlling the frequency response at specific locations of any communications, radar, or test system. Microwave resonators provide the frequency selective building blocks necessary for filter design. Reconfigurable/ tunable microwave resonators have facilitated the design of tunable filters. Recently, MEMS based tuning mechanisms developed widely tunable resonators maintaining high Q; however, limit in the number of reconfiguration states. This thesis proposes a fluidic-reconfigurable Xband SIW resonator capable of continuous tunability across the reconfiguration range. A dielectric post of fluidic dispersions with variable material properties embedded in a two inductive post static SIW resonator defines the tuning mechanism. The development of an analytical closed-form expression for the resonant frequency and Q across reconfiguration, a circuit model, and full-wave simulation predicts the tunable performance with estimated material properties of the fluidic dispersion. Measured data on an initial tunable SIW resonator design showed good reconfiguration performance but more losses than expected which could potentially be explained from the discovery of a major design error not associated with the resonator itself. A second tunable SIW resonator designed and fabricated proves the material properties of the fluidic dispersions contain more losses than estimated and hinder the resonators performance. By comparing simulated and measured data new estimates for the material properties of the fluidic dispersion are proposed which agree with trends in recent literature. Low-loss fluidic dispersions will enable a significant performance increase in the current tunable SIW resonator. Two low-cost material measurement systems are designed to expedite research efforts in finding low-loss microwave fluidics. Both systems accurately compute dielectric constant but not loss tangents. The initial systems provide necessary first steps in the design of future highly accurate material measurement systems.

Microwave near-field probes (MNPs) confine evanescent fields to regions that are substantially smaller than the wavelength at the operation frequency. Such probes are able to resolve subwavelength features, thus providing resolution much higher than the classical Abb?? limit. These abilities of MNPs are primarily due to the evanescent nature of the field generated at the tip of the probes. In the past, MNPs with ultra-high resolution were designed by tapering a resonant opening to provide high field concentration and high sensitivity. The limitations of these MNPs were subject to low surface roughness and practical realization challenges due to their geometrical features and vibration control constraints. Metamaterials with their ability to enhance evanescent fields, lead to the speculation that they could potentially increase the sensitivity of near-field probe. Periodically arranged metamaterial unit elements such as split-ring-resonators (SRRs) can create negative permeability media. Placing such material layer in the proximity of a probe leads to enhancement of the evanescent waves. Guided by this remarkable feature of metamaterials, I proposed an MNP consisting of a wire loop concentric with a single SRR. The evanescent field behavior of the probe is analyzed using Fourier analysis revealing substantial enhancement of the evanescent field consistent with metamaterial theory predictions. The resolution of the probe is studied to especially determine its ability for sub-surface detection of media buried in biological tissues. The underlying physics governing the probe is analyzed. Variations of the probe are developed by placement of lumped impedance loads. To further increase the field confinement to smaller region, a miniaturized probe design is proposed. This new probe consists of two printed loops whose resonance is tunable by a capacitor loaded in the inner loop. The sensing region is decreased from ??/20 to ??/55, where ?? is the wavelength of the probe???s unloaded frequency. The magnetic-sensitive nature of the new probe makes it suitable for sensing localized magnetostatic surface resonance (LMSR) occurring in electrically very small particles. Therefore, I proposed a sensing methodology for detecting localized magnetostatic surface (LMS) resonant particles. In this methodology, an LMS resonant sphere is placed concentrically with the loops. A circuit model is developed to predict the performance of the probe in the presence of a magnetic sphere having Lorentz dispersion. Full-wave simulations are carried out to verify the circuit model predictions, and preliminary experimental results are demonstrated. The Lorentzian fit in this work implies that the physical nature of LMSR may originate from spin movement of charged particle whose contribution to effective permeability may be analogous to that of bound electron movement to effective permittivity in electrostatic resonance. Detection of LMSR can have strong impact on marker-based sensing applications in biomedicine and bioengineering.

The diploma project deals with the numerical modeling, implementation and measurement of dielectric dipoles excited by a coaxial probe. Attention was turned to shape optimization of dipoles from the viewpoint of ultra wideband parameters in the band group 6. (“Bandgroup 6“). Two antennas exhibiting the best parameters were fabricated. Results of measurements were compared with simulation results. Simulations and measurements were in agreement. For the simulations, we use program CST Microwave Studio.

Acoustic resonators, such as the Helmholtz and quarter-wave resonator, can be used to attenuate unwanted noise in an enclosed space. Classical formulations can be used to approximate resonator performance for a given resonator configuration, but may lack sufficient accuracy for some applications. This research aims to improve the analytical characterization of resonators to provide better correlation to experimental results. Using higher-order approximations and proper end corrections, more accuracy can be obtained in calculating the impedance and resonance frequency of a single resonator, which will then carry over into the overall configuration of the model. The impedance of a system of resonators in parallel is also considered, where the effects of acoustic coupling can be observed. Resonators with complex, non-ideal geometries are explored for applications where space is limited. The effects of tapers and toroidal curves are considered using impedance translation methods. These theoretical predictions are found to compare favorably with empirical data. Coupling between an enclosure and resonator system is explored experimentally. The effects of resonator placement, damping, and relative cavity and enclosure volume are considered. These data are used to design and test a resonator system with 10 dB of attenuation over a bandwidth of 10 Hz.

This thesis is about the design of a biosensor system for detection of multiple cancer biomarkers. Accurate diagnosis and prognosis of cancer requires early detection. Equally important, though, is the measurement of biomarker-velocity and detection of multiple biomarkers. Early detection requires highly sensitive biosensors capable of detection at very low concentrations of target molecules. Biomarker-velocity can be measured by monitoring concentration of target molecule over a period of time. This requires a system which is very easy to use, fast, flexible, inexpensive and portable, thus enabling its ubiquitous presence at the point of care. For detection of multiplexed biomarkers, biosensors which easily lend to array configuration are required. Conventional techniques do not fulfill either all or some aspects of the requirements listed above. In this work, we present the design of a biosensor system, keeping in view the desired features described above, to achieve the ultimate goal of enabling ubiquitous presence of biosensor at the point of care. We focus on acoustic transducer based biosensors. The two fundamental components of design in an acoustic biosensor are the design of an acoustic transducer and the design of a novel electrical interface for the transducer. For transducer design, we introduce and present the design of a single structure, GHz range, multi-mode acoustic resonator. We present this as a suitable transducer for liquid phase biosensors, which is the preferred medium for sensing of cancer biomarkers. We explore the underlying physics and do experimental and theoretical characterization of this device. The transducer needs to be functionalized with a chemically sensitive layer which performs the molecular recognition of cancer biomarkers. We present the experimental exploration of a reversible and oriented immobilization based Histidine-Ni(2+) interaction which used NTA as the chelator for anchoring onto the device. Then we discuss the microfluidic design to enable liquid phase operation. We used SU-8 polymer barriers for liquid containment and addressed the challenges of making it compatible with ZnO based devices. An electrical interface is needed to excite and extract the sensor response. We have presented here a novel method to measure and track a resonator's response and extract its characteristic parameters. This method measures the wideband frequency response of the resonator with a much simpler setup as compared to conventional methods. We have proposed and demonstrated the use of a white noise signal as a viable signal for broadband excitation of resonator-based sensing platforms. We have also established, shown through simulation and prototype measurements, the feasibility of the proposed method. The accuracy and speed of the system can be further greatly improved by FFT-based digital implementation of the spectral analysis system. We have presented an example hardware implementation of FFT-based signal analyzer, and have discussed the hardware resources required for actual implementation in a chip form. Lastly we discuss the measurement protocol and sensor results for head and neck cancer and prostate cancer biomarkers. These results demonstrate the usability of the proposed sensor system for detection of cancer biomarkers.

This theis deals with the general overview of the piezoelectric theory, focused both on the mathematical description and on the attributes of piezoelectric materials. It further focuses on the description of piezoelectric resonators with a more detailed explantation of their equivalent scheme and measurement methods of its single elements. The practical part of the thesis rests on the proposal of a measurement apparatus which will serve to measuring the equivalent circuit piezoelectric resonator elements. The realization of the apparatus and its functionality testing are described. In the experimental part of the thesis, the measured rates are processed and levels of the electric equivalent circuit elements of the used piesoelectric resonator for the basic and the two higher closest resonance frequency are set. The measured results are compiled into a standard measurement protocol. This thesis should place basics to the growing laboratory. It should also be a source of necessary theoretical and practical information for this lab.

<p>The objective of this thesis is to evaluate a generic process for fabrication and characterization of the Superconductive coplanar waveguide (CPW) resonators. Superconductive CPW resonators with various lengths and shapes are designed to investigate their electrical and magnetic properties as well as resonance properties and sensitivities. In the first part of thesis, two different models are introduced in order to estimate the nonlinear kinetic inductance of a superconducting CPW resonator. The first model is based on Bean critical-state model and the second one is based on current dependence of London penetration depth. The existence of a shift in resonant frequency  of Superconductive CPW resonator caused by a non-linear kinetic inductance is also shown experimentally. Simulations were carried out to estimate the nonlinear kinetic inductance due to the self- induced magnetic field penetration.</p><p>The rest of the thesis is concerned with development of very smooth Aluminum (Al) thin films with RMS (Root Mean Square) roughness 1~nm and CAD (Computer Aid Design) of superconductive CPW resonators. Experimental investigation of a generic fabrication technique for superconductive CPW resonator is carried out. Many resonators are fabricated with different design parameters, such as centerline or gap width, film thickness and gap capacitors length. The fabrication process is described in detail. Electron Beam Lithography is used to fabricate Nb and Al CPW resonators which are coupled to outer conductors via gap capacitors. We have fabricated GHz frequency CPW resonators with quality factors, Q up 5X10^5.</p>