Real-time feedback of absorbed dose at a point within a patient can help with radiological quality assurance and innovation. Two radiochromic materials from GafChromic MD-55 and EBT films have been investigated for applicability in real-time in vivo dosimetry of ionizing radiation. Both films were able to produce a real-time measurement of optical density from a small volume, allowing positioning onto a tip of an optical fibre in the future. The increase in optical density was linear with absorbed dose for MD-55, and non-linear for EBT. The non-linearity of EBT is associated with its increased sensitivity to ionizing radiation compared to MD-55, thus reaching optical saturation at a much lower dose. The radiochromic material in EBT film was also shown to polymerize and stabilize faster, decreasing dose rate dependence in real-time measurements in comparison to MD-55. The response of the two media was tested over 75 kVp – 18 MV range of x-ray beams. The optical density measured for EBT was constant within 3% throughout the entire range, while MD-55 exhibited a nearly 40% decrease at low energies. Both materials were also shown to be temperature sensitive, with the change in optical density generally decreasing when the temperature increased from ~22°C to ~37°C. This was accompanied by a shift in the peak absorbance wavelength. It was illustrated that some of this decrease can be corrected for by tracking the peak position and then multiplying the optical density by a correction factor based on the predicted temperature. Overall, the radiochromic material in GafChromic EBT film was found to be a better candidate for in vivo real-time dosimetry than the material in GafChromic MD-55. A novel mathematical model was proposed linking absorbance to physical parameters and processes of the radiochromic materials. The absorbance at every wavelength in the spectrum was represented as a sum of absorbances from multiple absorbers, where absorbance is characterized by its absorption coefficient, initiation constant, and polymerization constant. Preliminary fits of this model to experimental data assuming two absorbers suggested that there is a trade-off between EBT’s greater sensitivity and its dose linearity characteristics. This was confirmed by experimental results.

Real-time feedback of absorbed dose at a point within a patient can help with radiological quality assurance and innovation. Two radiochromic materials from GafChromic MD-55 and EBT films have been investigated for applicability in real-time in vivo dosimetry of ionizing radiation. Both films were able to produce a real-time measurement of optical density from a small volume, allowing positioning onto a tip of an optical fibre in the future. The increase in optical density was linear with absorbed dose for MD-55, and non-linear for EBT. The non-linearity of EBT is associated with its increased sensitivity to ionizing radiation compared to MD-55, thus reaching optical saturation at a much lower dose. The radiochromic material in EBT film was also shown to polymerize and stabilize faster, decreasing dose rate dependence in real-time measurements in comparison to MD-55. The response of the two media was tested over 75 kVp – 18 MV range of x-ray beams. The optical density measured for EBT was constant within 3% throughout the entire range, while MD-55 exhibited a nearly 40% decrease at low energies. Both materials were also shown to be temperature sensitive, with the change in optical density generally decreasing when the temperature increased from ~22°C to ~37°C. This was accompanied by a shift in the peak absorbance wavelength. It was illustrated that some of this decrease can be corrected for by tracking the peak position and then multiplying the optical density by a correction factor based on the predicted temperature. Overall, the radiochromic material in GafChromic EBT film was found to be a better candidate for in vivo real-time dosimetry than the material in GafChromic MD-55. A novel mathematical model was proposed linking absorbance to physical parameters and processes of the radiochromic materials. The absorbance at every wavelength in the spectrum was represented as a sum of absorbances from multiple absorbers, where absorbance is characterized by its absorption coefficient, initiation constant, and polymerization constant. Preliminary fits of this model to experimental data assuming two absorbers suggested that there is a trade-off between EBT’s greater sensitivity and its dose linearity characteristics. This was confirmed by experimental results.

Micromachined accelerometers have found large attention in recent years due to their low-cost and small size. There are extensive studies with different approaches to implement accelerometers with increased performance for a number of military and industrial applications, such as guidance control of missiles, active suspension control in automobiles, and various consumer electronics devices. This thesis reports the development of various capacitive micromachined accelerometers and various integrated CMOS readout circuits that can be hybrid-connected to accelerometers to implement low-cost accelerometer systems. Various micromachined accelerometer prototypes are designed and optimized with the finite element (FEM) simulation program, COVENTORWARE, considering a simple 3-mask surface micromachining process, where electroplated nickel is used as the structural layer. There are 8 different accelerometer prototypes with a total of 65 different structures that are fabricated and tested. These accelerometer structures occupy areas ranging from 0.2 mm2 to 0.9 mm2 and provide sensitivities in the range of 1-69 fF/g. Various capacitive readout circuits for micromachined accelerometers are designed and fabricated using the AMS 0.8 &micro / m n-well CMOS process, including a single-ended and a fully-differential switched-capacitor readout circuits that can operate in both open-loop and close-loop. Using the same process, a buffer circuit with 2.26fF input capacitance is also implemented to be used with micromachined gyroscopes. A single-ended readout circuit is hybrid connected to a fabricated accelerometer to implement an open-loop accelerometer system, which occupies an area less than 1 cm2 and weighs less than 5 gr. The system operation is verified with various tests, which show that the system has a voltage sensitivity of 15.7 mV/g, a nonlinearity of 0.29 %, a noise floor of 487 Hz &micro / g , and a bias instability of 13.9 mg, while dissipating less than 20 mW power from a 5 V supply. The system presented in this research is the first accelerometer system developed in Turkey, and this research is a part of the study to implement a national inertial measurement unit composed of low-cost micromachined accelerometers and gyroscopes.

Despite the increasing number of electrochemical and photoelectrochemical biosensors reported in the research literature, few have achieved success outside of a laboratory setting. This can partly be attributed to accessibility issues with commercially available readout instruments. Consequently, low-cost and portable readout instruments have been developed by researchers, but these devices fail to address other key compatibility and accessibility challenges. Much like the commercial systems, these devices are not natively compatible with multiplexed signal assays consisting of two or more working electrodes, cannot control optical excitation sources for photoelectrochemical biosensing, nor can they interface with auxiliary instruments such as heaters and electromagnets. To this end, we have developed a low-cost smartphone-operated electrochemical and photoelectrochemical readout system for point-of-care biosensing. Our readout system can perform standard voltammetric techniques and is capable of synchronously controlling an optical excitation source to support photoelectrochemical biosensing. This device is compatible with standard three-electrode assays as well as dual signal assays with two working electrodes. We have also created a portable sample heater that can be controlled by this readout system to facilitate on-site sample heating and have also integrated a portable electromagnet to perform away-from-lab magnetic manipulation. / Thesis / Master of Applied Science (MASc) / Early and prompt detection of disease biomarkers is crucial in order to develop effective disease management strategies. Unfortunately, many gold-standard diagnostic techniques for infectious diseases, cancers, heart diseases, among other conditions prove to be time-consuming, costly, and reliant on trained professionals in a laboratory setting. Electrochemical and photoelectrochemical detection are two sensing modalities that show promising potential for point-of-care applications, as they are easily miniaturized, inexpensive, and can be used to detect both the presence of and the amount of analyte present. However, up until now, these sensing modalities have mostly been confined to research settings. To expedite the commercialization of such sensors and to facilitate their translation to point-of-care diagnostics, we have developed a low-cost smartphone-operated electrochemical and photoelectrochemical readout system. Through the integration of peripheral instruments including a sample heater, electromagnet, and optical excitation source, this system is compatible with a number of different biosensors.

This thesis presents the development of CMOS readout electronics for microbolometer type infrared detector arrays. A low power output buffering architecture and a new bias correction digital-to-analog converter (DAC) structure for resistive microbolometer readouts is developed / and a 384x288 resistive microbolometer FPA readout for 35 &micro / m pixel pitch is designed and fabricated in a standard 0.6 &micro / m CMOS process. A 4-layer PCB is also prepared in order to form an imaging system together with the FPA after detector fabrication. The low power output buffering architecture employs a new buffering scheme that reduces the capacitive load and hence, the power dissipation of the readout channels. Furthermore, a special type operational amplifier with digitally controllable output current capability is designed in order to use the power more efficiently. With the combination of these two methods, the power dissipation of the output buffering structure of a 384x288 microbolometer FPA with 35 &micro / m pixel pitch operating at 50 fps with two output channels can be decreased to 8.96% of its initial value. The new bias correction DAC structure is designed to overcome the power dissipation and noise problems of the previous designs at METU. The structure is composed of two resistive ladder DAC stages, which are capable of providing multiple outputs. This feature of the resistive ladders reduces the overall area and power dissipation of the structure and enables the implementation of a dedicated DAC for each readout channel. As a result, the need for the sampling operation required in the previous designs is eliminated. Elimination of sampling prevents the concentration of the noise into the baseband, and therefore, allows most of the noise to be filtered out by integration. A 384x288 resistive microbolometer FPA readout with 35 &amp / #956 / m pixel pitch is designed and fabricated in a standard 0.6 &amp / #956 / m CMOS process. The fabricated chip occupies an area of 17.84 mm x 16.23 mm, and needs 32 pads for normal operation. The readout employs the low power output buffering architecture and the new bias correction DAC structure / therefore, it has significantly low power dissipation when compared to the previous designs at METU. A 4-layer imaging PCB is also designed for the FPA, and initial tests are performed with the same PCB. Results of the performed tests verify the proper operation of the readout. The rms output noise of the imaging system and the power dissipation of the readout when operating at a speed of 50 fps is measured as 1.76 mV and 236.9 mW, respectively.

Today's state-of-the-art rate vibratory gyroscopes use a large proof mass that vibrates at a low resonance frequency (3-30 kHz), a condition that creates a performance tradeoff in which the gyroscope can either offer large bandwidth or high resolution, but not both. This tradeoff led to the development of the capacitive bulk acoustic wave (BAW) silicon disk gyroscope, a new class of micromachined rate vibratory gyroscopes operating in the frequency range of 1-10MHz with high device bandwidth and shock/vibration tolerance. By scaling the frequency, BAW gyroscopes can provide low mechanical noise without sacrificing the high bandwidth performance needed for most commercial applications. The drive loop of the BAW gyroscope can also be exploited as a timing device that can be integrated in existing commercial systems to provide competitive clock performance to the state-of-the-art using less area and power. This dissertation discusses the design and implementation of a CMOS ASIC architecture that interfaces with a high-Q, wide-bandwidth BAW gyroscope and the challenges associated with optimizing the noise performance to achieve navigation-grade levels of sensitivity as the frequency is scaled into the MHz regime. Mathematical models are derived to describe the operation of the sensor and are used to generate equivalent electrical circuit models of the gyroscope. A design strategy is then outlined for the ASIC to optimize the drive loop and sense channel for power and noise, and steps toward reducing this noise as the system is pushed to navigation-grade performance are presented that maintain optimum system power consumption. After analyzing the BAW gyroscope and identifying a strategy for developing the drive and sense interface circuitry, a complete fully-differential ASIC is designed in 0.18μm CMOS to interface with a bulk acoustic wave (BAW) disk gyroscope. As an oscillator, the gyroscope provides an uncompensated clock signal at ~9.64 MHz with a temperature sensitivity of -27 ppm/°C and phase noise of -104 dBc at 1 kHz from carrier. When the complete ASIC is interfaced with the gyroscope, the sensor shows a measured rate sensitivity of 1.15 mV/o/s with an open-loop bandwidth of 280 Hz and a bias instability of 0.095 o/s, suitable for the rate-grade performance commonly required for commercial and consumer electronics applications. The system is recorded to have a total power of 1.6 mW and a total area of 0.64 mm2. Following the design of the interface ASIC, this dissertation investigates in further detail the requirements for designing and optimizing charge pumps for capacitive MEMS devices. Basic charge pump design is outlined, followed by an overview of techniques that can be used to generate larger polarization voltages from the ASIC. Lastly, an alternate measurement technique for measuring the rotation rate of the gyroscope is discussed. This technique is based on the phase-shift modulation of the gyroscope output signal when the device is driven with two orthogonal signal inputs and can be easily modified to provide either linear scale factor measurement or a linear calibration curve that can be used to track and adjust the variation of the sensor scale factor over time.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / As part of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP), the Direct Readout Laboratory (DRL) of NASA/GSFC Code 935, is developing the prototype NPP In-Situ Ground System (NISGS). The NISGS supports earth remote sensing, and its functions bridge from all EOS satellites to planning for future NASA and interagency launches. The NISGS solution enables the end user to acquire and process NPP and predecessor instrument data, and provide a means to make these technologies and data products available to the Direct Broadcast Community. This document describes the NISGS model, methodology, and system architecture.

No description available.

ALICE is one of four major experiments of particle accelerator LHC installed in the European laboratory CERN. The management committee of the LHC accelerator has just approved a program update for this experiment. Among the upgrades planned for the coming years of the ALICE experiment is to improve the resolution and tracking efficiency maintaining the excellent particles identification ability, and to increase the read-out event rate to 100 KHz. In order to achieve this, it is necessary to update the Time Projection Chamber detector (TPC) and Muon tracking (MCH) detector modifying the read-out electronics, which is not suitable for this migration. To overcome this limitation the design, fabrication and experimental test of new ASIC named SAMPA has been proposed . This ASIC will support both positive and negative polarities, with 32 channels per chip and continuous data readout with smaller power consumption than the previous versions. This work aims to design, fabrication and experimental test of a readout front-end in 130nm CMOS technology with configurable polarity (positive/negative), peaking time and sensitivity. The new SAMPA ASIC can be used in both chambers (TPC and MCH). The proposed front-end is composed of a Charge Sensitive Amplifier (CSA) and a Semi-Gaussian shaper. In order to obtain an ASIC integrating 32 channels per chip, the design of the proposed front-end requires small area and low power consumption, but at the same time requires low noise. In this sense, a new Noise and PSRR (Power Supply Rejection Ratio) improvement technique for the CSA design without power and area impact is proposed in this work. The analysis and equations of the proposed circuit are presented which were verified by electrical simulations and experimental test of a produced chip with 5 channels of the designed front-end. The measured equivalent noise charge was <550e for 30mV/fC of sensitivity at a input capacitance of 18.5pF. The total core area of the front-end was 2300?m × 150?m, and the measured total power consumption was 9.1mW per channel. / ALICE é um dos quatro grandes experimentos do acelerador de partículas LHC (Large Hadron Collider) instalado no laboratório europeu CERN. Um programa de atualizações desse experimento acaba de ser aprovado pelo comitê gestor do acelerador LHC. Dentro das atualizações planejadas para os próximos anos do experimento ALICE, está melhorar a resolução e eficiência de rastreamento de partículas produzidas em colisões entre íons pesados, mantendo a excelente capacidade de identificação de partículas para uma taxa de leitura de eventos significativamente maior da atual. Para se alcançar esse objetivo, entre outras ações, é preciso atualizar os detectores Time Projection Chamber (TPC), modificando a eletrônica de leitura de eventos, a qual não é adequada para esta migração. Para superar esta limitação tem sido proposto o projeto, simulação, fabricação, teste experimental e validação de um ASIC protótipo de aquisição de sinais e de processamento digital chamado SAMPA, que possa ser usado na eletrônica de detecção dos sinais no cátodo do TPC, que suporte polaridades negativas de tensão de entrada e leitura continua de dados, com 32 canais por chip, com menor consumo de potência comparado com a versão anterior do chip. Este trabalho tem como objetivo o projeto, fabricação, e teste experimental de um readout front-end em tecnologia CMOS 130nm, com polaridade configurable (positiva/ negativa), peaking time e sensibilidade, de forma que o novo SAMPA ASIC possa ser usada em ambos detectores. Para obter um ASIC integrando 32 canais por chip, o projeto do front-end proposto precisa ter baixa área e baixo consumo de potência, mas ao mesmo tempo requer baixo ruido. Neste sentido, uma nova técnica para melhorar a especificação de ruido e o PSRR (Power Supply Rejection Ratio) sem impacto no consumo de área e potência é proposta neste trabalho. A análise e as equações do circuito proposto são apresentadas as quais foram validadas por simulação e teste experimental de um circuito integrado com 5 canais do front-end projetado. O Equivalent Noise Charge medido foi <550e para uma capacitance do detector de 18.5pF. A área total do front-end foi de 2300?m × 150?m, e o consumo total de potencia medido foi de 9.1mW por canal.

Le travail présenté dans ce manuscrit a été effectué au sein de l’équipe de microélectronique de l’Institut de Recherche sur les lois Fondamentales de l’Univers (IRFU) du CEA. Il s’inscrit dans le contexte de la spectro-imagerie X et gamma pour la recherche en Astrophysique. Dans ce domaine, les futures expériences embarquées à bords de satellites nécessiteront des instruments d’imagerie à très hautes résolutions spatiales et énergétiques.La résolution spectrale d’une gamma-camera est dégradée par l’imperfection du détecteur lors de l’interaction photon-matière lui-même et par le bruit électronique. Si on ne peut réduire l’imprécision de conversion photon-charge du détecteur, on peut minimiser le bruit apporté par l’électronique de lecture. L’objectif de cette thèse est la conception d’une électronique intégrée de lecture de détecteur semi-conducteurs CdTe pixélisés pour gamma-caméra(s) compacte(s) et aboutable(s) sur 4 côtés à résolution spatiale « Fano limitée ». Les objectifs principaux de ce circuit intégré sont: un très bas bruit pour la mesure d’énergie des rayons-X, une très basse consommation, et une taille de canal de détection adaptée au pas des pixels CdTe. Pour concevoir une telle électronique, chaque paramètre contribuant au bruit doit être optimisé. L’hybridation entre l’électronique de lecture et le détecteur est également un paramètre clef qui fait généralement la résolution finale de l’instrument : en imposant une géométrie matricielle à l’ASIC adaptée au pas de 300 µm des pixels de CdTe, on peut espérer, réduire d’un facteur 10 la capacité parasite amenée par la connexion détecteur-électronique et améliorer d’autant le bruit électronique tout en conservant une densité de puissance constante. Une bonne connaissance des propriétés du détecteur nous permet alors d’extraire ses paramètres électroniques clefs pour concevoir l’architecture électronique de conversion et de filtrage optimale. Dans le cadre de cette thèse j’ai conçu deux circuits intégrés en technologies CMOS XFAB 0.18 µm. Le premier, Caterpylar, est destiné à caractériser cette nouvelle technologie, y compris en radiation, identifier un étage d’entrée pour le pixel adapté au détecteur, et valider par la mesure les résultats théoriques établis sur deux architectures de filtrage, semi gaussien et « Multi-Correlated Double Sampling » (MCDS), approchant l’efficacité du filtrage optimal et adaptées aux applications finales. Le deuxième circuit, D2R1, est un système complet, constitué de 256 canaux de lecture de détecteur CdTe, organisés dans une matrice de 16×16 pixels. Chaque canal comprend un préamplificateur de charge adapté à des pixels de 300 μm×300 μm, un opérateur de filtrage de type MCDS de profondeur programmable, d’un discriminateur auto-déclenché à bas seuil de détection programmable par canal. L’ASIC a été caractérisé sans détecteur et est en voie d’être hybridé à une matrice de CdTe très prochainement. Les résultats de caractérisations de la puce nue, en particulier en terme de produit puissance × bruit, sont excellents. La consommation de la puce est de 315 µW/ canal, la charge équivalente de bruit mesurée sur tous les canaux est de 29 électrons rms. Ces résultats valident le choix d’intégration d’un filtrage de type MCDS, qui est, à notre connaissance une première mondiale pour la lecture de détecteurs CdTe. Par ailleurs, ils nous permettent d’envisager d’excellentes résolutions spectrales de l’ensemble détecteur+ASIC, de l’ordre de 600 eV FWHM à 60 keV. / The work presented in this thesis is part of a project where a new instrument is developed: a camera for hard X-rays imaging spectroscopy. It is dedicated to fundamental research for observations in astrophysics, at wavelengths which can only be observed using space-borne instruments. In this domain the spectroscopic accuracy as well as the imaging details are of high importance. This work has been realized at CEA/IRFU (Institut de Recherche sur les lois Fondamentales de l’Univers), which has a long-standing and successful experience in instruments for high energy physics and space physics instrumentation. The objective of this thesis is the design of the readout electronics for a pixelated CdTe detector, suitable for a stacked assembly. The principal parameters of this integrated circuit are a very low noise for reaching a good accuracy in X-ray energy measurement, very low power consumption, a critical parameter in space-borne applications, and a small dead area for the full system combining the detector and the readout electronics. In this work I have studied the limits of these three parameters in order to optimize the circuit.In terms of the spectral resolution, two categories of noise had to be distinguished to determine the final performance. The first is the Fano noise limit. related to detector interaction statistics, which cannot be eliminated. The second is the electronic noise, also unavoidable; however it can be minimized through optimization of the detection chain. Within the detector, establishing a small pixel pitch of 300 μm reduces the input capacitance and the dark current. This limits the effects of the electronic noise. Also in order to limit the input capacitance the future camera is designed as a stacked assembly of the detector with the readout ASIC. This allows to reach extremely good input parameters seen by the readout electronics: a capacitance in range of 0.3 pF - 1 pF and a dark current below 5 pA.In the frame of this thesis I have designed two ASICs. The first one, Caterpylar, is a testchip, which enables the characterization of differently dimensioned CSA circuits to choose the most suitable one for the final application. It is optimized for readout of the target CdTe detector with 300 μm pixel pitch and the corresponding input parameters. With this circuit I have also analyzed possible filtering methods, in particular the semi-Gaussian shaping and the Multi-Correlated Double Sampling (MCDS). Their comparison is preceded by the theoretical analysis of these shapers. The second ASIC D2R1 is a complete readout circuit, containing 256 channels to readout CdTe detector with the same number of pixels, arranged in 16×16 array. Each channel fits into a layout area of 300 μm × 300 μm. It is based on the MCDS processing with self-triggering capabilities. The mean electronic noise measured over all channels is 29 electrons rms when characterized without the detector. The corresponding power consumption is 315 μW⁄channel. With these results the future measurements with the detector give prospects for reaching an FWHM spectral resolution in the order of 600 eV at 60 keV.