Integrated Circuits for Medical Ultrasound Applications: Imaging and Beyond

Medical ultrasound has become a crucial part of modern society and continues to play a vital role in the diagnosis and treatment of illnesses. Over the past decades, the develop- ment of medical ultrasound has seen extraordinary progress as a result of the tremendous research advances in microelectronics, transducer technology and signal processing algorithms. How- ever, medical ultrasound still faces many challenges including power-efficient driving of transducers, low-noise recording of ultrasound echoes, effective beamforming in a non-linear, high- attenuation medium (human tissues) and reduced overall form factor. This paper provides a comprehensive review of the design of integrated circuits for medical ultrasound applications. The most important and ubiquitous modules in a medical ultrasound system are addressed, i) transducer driving circuit, ii) low- noise amplifier, iii) beamforming circuit and iv) analog-digital converter. Within each ultrasound module, some representative research highlights are described followed by a comparison of the state-of-the-art. This paper concludes with a discussion and recommendations for future research directions

Digital CMOS ISFET architectures and algorithmic methods for point-of-care diagnostics

Over the past decade, the surge of infectious diseases outbreaks across the globe is redefining how healthcare is provided and delivered to patients, with a clear trend towards distributed diagnosis at the Point-of-Care (PoC). In this context, Ion-Sensitive Field Effect Transistors (ISFETs) fabricated on standard CMOS technology have emerged as a promising solution to achieve a precise, deliverable and inexpensive platform that could be deployed worldwide to provide a rapid diagnosis of infectious diseases. This thesis presents advancements for the future of ISFET-based PoC diagnostic platforms, proposing and implementing a set of hardware and software methodologies to overcome its main challenges and enhance its sensing capabilities. The first part of this thesis focuses on novel hardware architectures that enable direct integration with computational capabilities while providing pixel programmability and adaptability required to overcome pressing challenges on ISFET-based PoC platforms. This section explores oscillator-based ISFET architectures, a set of sensing front-ends that encodes the chemical information on the duty cycle of a PWM signal. Two initial architectures are proposed and fabricated in AMS 0.35um, confirming multiple degrees of programmability and potential for multi-sensing. One of these architectures is optimised to create a dual-sensing pixel capable of sensing both temperature and chemical information on the same spatial point while modulating this information simultaneously on a single waveform. This dual-sensing capability, verified in silico using TSMC 0.18um process, is vital for DNA-based diagnosis where protocols such as LAMP or PCR require precise thermal control. The COVID-19 pandemic highlighted the need for a deliverable diagnosis that perform nucleic acid amplification tests at the PoC, requiring minimal footprint by integrating sensing and computational capabilities. In response to this challenge, a paradigm shift is proposed, advocating for integrating all elements of the portable diagnostic platform under a single piece of silicon, realising a ``Diagnosis-on-a-Chip". This approach is enabled by a novel Digital ISFET Pixel that integrates both ADC and memory with sensing elements on each pixel, enhancing its parallelism. Furthermore, this architecture removes the need for external instrumentation or memories and facilitates its integration with computational capabilities on-chip, such as the proposed ARM Cortex M3 system. These computational capabilities need to be complemented with software methods that enable sensing enhancement and new applications using ISFET arrays. The second part of this thesis is devoted to these methods. Leveraging the programmability capabilities available on oscillator-based architectures, various digital signal processing algorithms are implemented to overcome the most urgent ISFET non-idealities, such as trapped charge, drift and chemical noise. These methods enable fast trapped charge cancellation and enhanced dynamic range through real-time drift compensation, achieving over 36 hours of continuous monitoring without pixel saturation. Furthermore, the recent development of data-driven models and software methods open a wide range of opportunities for ISFET sensing and beyond. In the last section of this thesis, two examples of these opportunities are explored: the optimisation of image compression algorithms on chemical images generated by an ultra-high frame-rate ISFET array; and a proposed paradigm shift on surface Electromyography (sEMG) signals, moving from data-harvesting to information-focused sensing. These examples represent an initial step forward on a journey towards a new generation of miniaturised, precise and efficient sensors for PoC diagnostics.Open Acces

Technical Design Report for the PANDA Micro Vertex Detector

This document illustrates the technical layout and the expected performance of the Micro Vertex Detector (MVD) of the PANDA experiment. The MVD will detect charged particles as close as possible to the interaction zone. Design criteria and the optimisation process as well as the technical solutions chosen are discussed and the results of this process are subjected to extensive Monte Carlo physics studies. The route towards realisation of the detector is outlined

Novel MRI Technologies for Structural and Functional Imaging of Tissues with Ultra-short T₂ Values

Conventional MRI has several limitations such as long scan durations, motion artifacts, very loud acoustic noise, signal loss due to short relaxation times, and RF induced heating of electrically conducting objects. The goals of this work are to evaluate and improve the state-of-the-art methods for MRI of tissue with short T₂, to prove the feasibility of in vivo Concurrent Excitation and Acquisition, and to introduce simultaneous electroglottography measurement during functional lung MRI

Tinnitus – psychiatric comorbidity and treatment using transcranial magnetic stimulation (TMS)

Tinnitus is the perception of sound in the absence of any external noise. It severely impairs the quality of life in 1-2% of people. Tinnitus is frequently associated with depression, anxiety, and insomnia. The exact pathophysiology of tinnitus is still unclear. No curative therapy exists for chronic tinnitus, and treatment focuses on symptomatic relief. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulation technique that is used for treating depression and neuropathic pain. The evidence of its efficacy for chronic tinnitus is still inconclusive, and the optimal treatment protocols are thus still obscure. This thesis aimed to further evaluate the use of rTMS for chronic tinnitus and investigate the psychiatric comorbidity of tinnitus patients. The first (open pilot) study utilized electric field (E-field) navigated rTMS for very severe chronic tinnitus with promising results. In the second (randomized placebo-controlled) study, the effects of 1-Hz E-field rTMS targeted according to the tinnitus pitch to the left auditory cortex were analyzed. Despite the significant improvements in tinnitus, active rTMS was not superior to the placebo, possibly due to large placebo-effect and wide inter-individual variation in treatment efficacy. The third study on parallel groups compared the effects of neuronavigated rTMS to nonnavigated rTMS (based on the 10-20 EEG localization system). Both groups benefitted from the treatment, but the method of coil localization was not a critical factor for treatment outcome. In the fourth study, current and lifetime DSM-IV diagnoses of Axis I (psychiatric disorders) and Axis II (personality disorders) were assessed in tinnitus patients using structured clinical interviews (SCID-I and -II). Tinnitus patients were prone to episodes of major depression, and they often had obsessive-compulsive personality features. Psychiatric disorders in this study seemed to be comorbid or predisposing conditions rather than the consequences of tinnitus.Tinnitus – psykiatrinen sairastavuus ja hoito transkraniaalisella magneettistimulaatiolla (TMS) Tinnituksen ääniaistimus syntyy ilman ulkoista äänilähdettä. Se heikentää vakavasti elämänlaatua 1-2%:lla ihmisistä. Tinnitus yhdistetään usein masennukseen, ahdistukseen ja unettomuuteen. Tinnituksen tarkka syntymekanismi on vielä epäselvä. Pitkäaikaiselle tinnitukselle ei ole parantavaa hoitoa, vaan hoidossa keskitytään oireiden lievittämiseen. Transkraniaalinen magneettistimulaatio sarjapulssein (rTMS) on kajoamaton aivojen toimintaa muokkaava menetelmä, jota käytetään masennuksen ja hermoperäisen kivun hoidossa. Sen teho pitkäaikaiseen tinnitukseen on vielä epävarmaa ja optimaaliset hoitoprotokollat ovat selvittämättä. Tämän väitöskirjan tavoitteena oli arvioida rTMS:n käyttöä pitkäaikaisen tinnituksen hoidossa ja lisäksi tutkia tinnituspotilaiden psykiatrista sairastavuutta. Ensimmäisessä osatyössä (avoin pilotti) käytettiin sähkökenttäohjattua (E-field) navigoivaa rTMS:a pitkäaikaiseen, erittäin vaikeaan tinnitukseen lupaavin tuloksin. Toisessa osatyössä (satunnaistettu lumekontrolloitu) arvioitiin tinnitusäänen korkeuden mukaan vasemmalle kuuloaivokuorelle suunnatun 1- Hz:n sähkökentän mukaan navigoidun rTMS:n vaikutuksia. Vaikka tinnitus helpottui merkittävästi, ei aktiivi-rTMS ollut lumehoitoa parempi, mahdollisesti johtuen suuresta lumevaikutuksesta ja laajasta yksilöiden välisestä vaihtelusta hoidon tehossa. Kolmannessa osatyössä verrattiin rinnakkaisryhmien välillä neuronavigoidun rTMS:n ja sokko rTMS:n (10-20 EEG-systeemiin perustuva paikannus) vaikutuksia. Molemmat ryhmät hyötyivät hoidosta, eikä kelan paikannusmenetelmä ollut ratkaiseva tekijä hoidon lopputuloksen kannalta. Neljännessä osatyössä nykyiset ja elämänaikaiset akselin I (psykiatriset häiriöt) ja akselin II (persoonallisuushäiriöt) DSM-IV diagnoosit määritettiin tinnituspotilailta käyttäen strukturoituja psykiatrisia haastatteluja (SCID-I ja -II). Tinnituspotilaat olivat alttiita vakaville masennusjaksoille ja heillä oli usein vaativan persoonallisuuden piirteitä. Psykiatriset häiriöt vaikuttivat olevan ennemmin samanaikaisia tai altistavia tiloja kuin tinnituksen seurauksena ilmaantuneita häiriöitä

Voyager Spacecraft Phase B, Task D. Annex to Volume 4 - Spacecraft Electrical Subsystems Definition Final Report

Systems analysis and tradeoff data on electrical subsystems for recommended Voyager spacecraft configuratio

Mechanical systems readiness assessment and performance monitoring study

The problem of mechanical devices which lack the real-time readiness assessment and performance monitoring capability required for future space missions is studied. The results of a test program to establish the feasibility of implementing structure borne acoustics, a nondestructive test technique, are described. The program included the monitoring of operational acoustic signatures of five separate mechanical components, each possessing distinct sound characteristics. Acoustic signatures were established for normal operation of each component. Critical failure modes were then inserted into the test components, and faulted acoustic signatures obtained. Predominant features of the sound signature were related back to operational events occurring within the components both for normal and failure mode operations. All of these steps can be automated. The structure borne acoustics technique lends itself to reducing checkout time, simplifying maintenance procedures, and reducing manual involvement in the checkout, operation, maintenance, and fault diagnosis of mechanical systems

Real-Time Fault Diagnosis of Permanent Magnet Synchronous Motor and Drive System

Permanent Magnet Synchronous Motors (PMSMs) have gained massive popularity in industrial applications such as electric vehicles, robotic systems, and offshore industries due to their merits of efficiency, power density, and controllability. PMSMs working in such applications are constantly exposed to electrical, thermal, and mechanical stresses, resulting in different faults such as electrical, mechanical, and magnetic faults. These faults may lead to efficiency reduction, excessive heat, and even catastrophic system breakdown if not diagnosed in time. Therefore, developing methods for real-time condition monitoring and detection of faults at early stages can substantially lower maintenance costs, downtime of the system, and productivity loss. In this dissertation, condition monitoring and detection of the three most common faults in PMSMs and drive systems, namely inter-turn short circuit, demagnetization, and sensor faults are studied. First, modeling and detection of inter-turn short circuit fault is investigated by proposing one FEM-based model, and one analytical model. In these two models, efforts are made to extract either fault indicators or adjustments for being used in combination with more complex detection methods. Subsequently, a systematic fault diagnosis of PMSM and drive system containing multiple faults based on structural analysis is presented. After implementing structural analysis and obtaining the redundant part of the PMSM and drive system, several sequential residuals are designed and implemented based on the fault terms that appear in each of the redundant sets to detect and isolate the studied faults which are applied at different time intervals. Finally, real-time detection of faults in PMSMs and drive systems by using a powerful statistical signal-processing detector such as generalized likelihood ratio test is investigated. By using generalized likelihood ratio test, a threshold was obtained based on choosing the probability of a false alarm and the probability of detection for each detector based on which decision was made to indicate the presence of the studied faults. To improve the detection and recovery delay time, a recursive cumulative GLRT with an adaptive threshold algorithm is implemented. As a result, a more processed fault indicator is achieved by this recursive algorithm that is compared to an arbitrary threshold, and a decision is made in real-time performance. The experimental results show that the statistical detector is able to efficiently detect all the unexpected faults in the presence of unknown noise and without experiencing any false alarm, proving the effectiveness of this diagnostic approach.publishedVersio

UTB/TSC Legacy Degree Programs and Courses 2014 – 2015

https://scholarworks.utrgv.edu/brownsvillelegacycatalogs/1030/thumbnail.jp

Development and validation of the thermal diagnostics instrumentation in lisa pathfinder

This thesis focuses on the issues related to the thermal diagnostics aboard the space mission LISA Pathfinder (LPF). LPF is a technological mission devoted to put to test critical subsystems for the LISA mission. LISA will be the first space born gravitational wave (GW) observatory with the main objective of detecting GWs. GWs are ripples of the space-time geometry caused by acceleration of masses in an asymmetric way. Their detection requires put test masses (TMs) in an almost perfect inertial frame (or free fall).Non-inertial forces perturbing the TMs must be less than 6 fN/sqrt(Hz) in the frequency range of 0.1 mHz to 0.1 Hz and the noise in the measurement between the TMs (separated by 5 Gm) must be of 40 pm/sqrt(Hz) in the same band. To reduce the risks of a direct launch of LISA, ESA has decided to first launch LPF to put all the LISA technologies to test.The payload of LPF, the LISA Technology Package (LTP), contains two TMs placed in two cylinders inside a single spacecraft (SC) and an interferometric system that measures the relative distance between them. The SC isolates the TMs from the external disturbances but internal stray forces will still perturb the TMs. Their levels must be bounded not to challenge the free fall accuracy. One of these disturbances is temperature fluctuations and the aspects related to their measurement are the leitmotif of this thesis.In chapter 1 we have presented how temperature fluctuations couple into the key subsystems of the LTP to degrade their performance. The foreseen effects are radiation pressure, radiometer effect, temperature coefficient of optical components, etc. Onground estimations conclude that the temperature stability in the LTP must be less than 100 microK/sqrt(Hz) in the frequency range of 1 mHz to 30 mHz (LTP band). Since temperature fluctuations are an important issue in LPF and in LISA, a thermal diagnostic subsystem is needed aboard both missions.The task of the thermal diagnostics in the LTP is twofold: on the one hand, temperature fluctuations in different subsystems must be measured with noise levels of 10 microK/sqrt(Hz) in the LTP band. On the other hand, a set of heaters will generate heat pulses that in conjunction with temperature measurements will be used to estimate the actual coupling between temperature and systems performance. These actions will provide information on the behaviour of the system and will permit to identify the fraction of noise in the system coming from temperature issues. The main function of LPF, as precursor mission of LISA, is the understanding of all the noise sources in the system. This will provide clues to the final leap from LPF sensitivity to LISA one.The main investigations carried out during this thesis can be split into three main categories: (i) the design and validation of the LTP temperature measurement subsystem (TMS); (ii) the extension of the system to the LISA requirements; and (iii) the analysis of the in-flight thermal experiments in the LTP. The thesis is organised as follows: in chapter 2 we describe the designed electronics and the temperature sensors chosen. Aspects related to the coupling of the TMS with other subsystems nearby are discussed in chapter 3. Chapter 4 focuses on the design of the testbed needed for the validation of the TMS. Two different testbeds are described: one for the LTP measurement bandwidth (MBW) and another one for the LISA MBW, 0.1 mHz. In chapter 5 we present the results of the test campaigns: the prototype, the engineering model and the flight model systems were put to test. The results of the investigations in the LISA band are also shown. Chapter 6 contains investigations in view of LISA requirements to reduce excess noise at very low frequency and to reduce the floor noise of the measurement. Chapter 7 focuses on the thermal experiment on-board LPF: a set of thermal excitations are proposed to extract information of the thermal behaviour of the key subsystems of the LTP