1,720,956 research outputs found
Low-power lab-on-CMOS ISFET arrays for low-cost portable biomedical applications
No full textLa integració de sensors en tecnologia CMOS ha transformat el camp de la detecció química i biològica, permetent una elevada densitat d'integració i uns costos de producció reduïts. En particular, els transistors d'efecte camp sensibles a ions (ISFET, per les seves sigles en anglès) han guanyat interès gràcies a la seva versatilitat i a la seva integració directa en processos CMOS estàndard. Quan s'integren en matrius a gran escala, el seu rendiment es veu millorat en permetre la detecció iònica paral·lela i en temps real, cosa que ha impulsat una revolució en aplicacions biomèdiques com el seqüenciament d'ADN.
Simultàniament, els sistemes lab-on-chip (LoC) han emergit com a plataformes integrades compactes amb capacitat per anàlisis bioquímiques complexes en un sol xip. Aquestes plataformes empenyen els límits de la miniaturització, i resulten avantatjoses respecte als sistemes de laboratori tradicionals en reduir els costos i el temps d’anàlisi. Quan aquests sistemes LoC es construeixen amb tecnologies CMOS, les seves capacitats de detecció poden veure’s notablement millorades, evolucionant cap a plataformes lab-on-CMOS.
Aquesta tesi doctoral explora la integració de matrius d'ISFETs CMOS en plataformes lab-on-CMOS per tal d’assolir sistemes de detecció bioquímica compactes, altament integrats i intel·ligents, combinant la detecció iònica en temps real de les matrius d'ISFETs CMOS amb la miniaturització i el baix cost d’integració de les plataformes lab-on-CMOS.
Es proposa una nova arquitectura de píxel ISFET que aborda les limitacions conegudes dels ISFETs alhora que proporciona una conversió analògic-a-digital dins del mateix píxel. Aquesta arquitectura de píxel ISFET digital s’ha implementat en un procés CMOS comercial de 65\,nm de baix consum mitjançant una matriu de 88 i una altra de 1616 ISFETs, i s’ha validat tant a nivell elèctric com electroquímic. A més, es demostra la millora de la sensibilitat al pH i la reducció de la deriva electroquímica en ISFETs CMOS mitjançant un postprocessat amb deposició de capes atòmiques (ALD) d’HfO\textsubscript{2}.
Es demostren dues metodologies de fabricació per a la integració i encapsulat lab-on-CMOS mitjançant la integració d’estructures microfluídiques amb les matrius d'ISFETs CMOS fabricades de 65\,nm. Aquestes metodologies de fabricació, simples i fiables, són compatibles amb aplicacions biomèdiques de baix cost, i s’han desenvolupat amb l’objectiu de satisfer dues necessitats diferents: (i) la integració i encapsulat de xips CMOS d’escala mil·limètrica en estructures microfluídiques d’escala centimètrica, i (ii) la integració directa de microfluídica sobre el xip.
Les plataformes lab-on-CMOS desenvolupades s’exploren en tres aplicacions biomèdiques. En primer lloc, s’exploten les capacitats de miniaturització per produir una sonda multi-iònica sense elèctrode de referència, capaç de fer mesures en volums inferiors a 1\,mL. La segona aplicació aprofita l’alta densitat d’integració de les matrius d'ISFETs CMOS per permetre immunoassaigs digitals compactes i de baix cost per a la detecció de biomarcadors. Finalment, la tercera aplicació utilitza estratègies de disseny de circuits neuromòrfics per mitigar les no-idealitats dels ISFETs, permetent una detecció espaitemporal contínua de la dinàmica iònica per comprendre processos bioquímics i fisiològics.La integración de sensores en tecnología CMOS ha transformado el campo de la detección química y biológica al permitir una alta densidad de integración y bajos costes de producción. En particular, los transistores de efecto de campo sensibles a iones (ISFETs, por sus siglas en inglés) han ganado interés debido a su versatilidad y a su integración directa en procesos CMOS estándar. Cuando se integran en matrices a gran escala, su rendimiento se ve mejorado al permitir la detección paralela y en tiempo real de iones, lo que ha supuesto una revolución en aplicaciones biomédicas como la secuenciación de ADN.
Paralelamente, los sistemas lab-on-chip (LoC) han surgido como plataformas integradas compactas capaces de realizar análisis bioquímicos complejos en un solo chip. Estas plataformas amplían los límites de la miniaturización, resultando ventajosas frente a los sistemas tradicionales de laboratorio al reducir los costes y el tiempo de análisis. Cuando estos sistemas LoC se construyen sobre circuitos integrados CMOS, sus capacidades de detección pueden mejorarse considerablemente, evolucionando hacia plataformas lab-on-CMOS.
Esta tesis doctoral explora la integración de matrices de ISFETs CMOS en plataformas lab-on-CMOS para desarrollar sistemas de detección bioquímica compactos, altamente integrados e inteligentes, combinando la detección iónica en tiempo real de las matrices de ISFETs CMOS con la miniaturización y los bajos costes de integración de las plataformas lab-on-CMOS.
Se propone una nueva arquitectura de píxel ISFET que aborda limitaciones conocidas de los ISFETs y proporciona conversión analógica-digital en el propio píxel. Esta arquitectura digital de píxel ISFET se ha implementado en un proceso CMOS comercial de 65 nm de bajo consumo mediante matrices de 88 y 1616 ISFETs, y se han validado tanto a nivel eléctrico como electroquímico. Además, se demuestra la mejora de la sensibilidad al pH y la reducción de la deriva electroquímica en ISFETs CMOS mediante un postprocesado con deposición de capas atómicas (ALD) de HfO\textsubscript{2}.
Se presentan dos metodologías de fabricación para la integración y encapsulado lab-on-CMOS, integrando estructuras microfluídicas con las matrices de ISFETs CMOS fabricadas en 65\,nm. Estos métodos de fabricación, simples y fiables, son compatibles con aplicaciones biomédicas de bajo coste y han sido desarrollados para satisfacer dos necesidades distintas: (i) la integración y encapsulado de chips CMOS de escala milimétrica en estructuras microfluídicas de escala centimétrica, y (ii) la integración directa de microfluídica sobre el chip.
Las plataformas lab-on-CMOS desarrolladas se exploran en tres aplicaciones biomédicas. En primer lugar, se explotan las capacidades de miniaturización para producir una sonda multiiónica sin electrodo de referencia, capaz de realizar mediciones en volúmenes inferiores a 1\,mL. La segunda aplicación aprovecha la alta densidad de integración de las matrices de ISFETs CMOS para habilitar inmunoensayos digitales compactos y de bajo coste para la detección de biomarcadores. Finalmente, la tercera aplicación emplea estrategias de diseño de circuitos neuromórficos para mitigar las no idealidades de los ISFETs, permitiendo una detección espaciotemporal continua de la dinámica iónica, con el fin de comprender procesos bioquímicos y fisiológicos.The integration of sensors in CMOS technology has transformed the field of chemical and biological sensing by enabling high integration density and low production costs. In particular, Ion-Sensitive Field-Effect Transistors (ISFETs) have gained interest due to their versatility and direct integration into standard CMOS processes. When integrated in large-scale arrays, their performance is enhanced by enabling parallel real-time ion detection, which has induced a revolution in biomedical applications such as DNA sequencing.
Simultaneously, lab-on-chip (LoC) systems have emerged as compact integrated platforms capable of performing complex biochemical analyses on a single chip. These platforms push the boundaries of miniaturization, proving advantageous over traditional benchtop systems by greatly reducing costs and analysis time. When these LoC systems are built around CMOS integrated circuits, their sensing capabilities can be greatly enhanced, evolving into lab-on-CMOS platforms.
This PhD thesis explores the integration of CMOS ISFET arrays into lab-on-CMOS platforms to realize compact, highly integrated, and intelligent biochemical sensing systems by combining the real-time ion sensing of CMOS ISFET arrays with the miniaturization and low integration costs of lab-on-CMOS platforms.
A novel ISFET pixel architecture is proposed addressing known limitations of ISFETs while providing in-pixel analog-to-digital conversion. This digital ISFET pixel architecture is implemented in a commercial low-power 65-nm CMOS process through an 88 and a 1616 ISFET array, and validated both at electrical and electrochemical level. In addition, the enhancement of pH sensitivity and reduction of electrochemical drift is demonstrated on CMOS ISFETs by post-processing them with a HfO\textsubscript{2} atomic layer deposition.
Two fabrication methodologies for lab-on-CMOS integration and packaging are demonstrated by integrating microfluidic structures with the fabricated 65-nm CMOS ISFET arrays. These simple and reliable fabrication methods are compatible with cost-effective biomedical applications, and have been developed targeting two distinct needs: (i) integration and packaging of mm-scale CMOS chips into cm-scale microfluidic structures, and (ii) direct on-chip integration of microfluidics.
The developed lab-on-CMOS platforms are explored in three biomedical applications. First, the miniaturization capabilities of such platforms are exploited to produce a reference-electrode-free multi-ionic probe capable of sub-mL volume measurements. The second application leverages the high integration density of CMOS ISFET arrays to enable compact and low-cost digital immunoassays for biomarker detection. Finally, the latter exploits neuromorphic circuit design strategies to mitigate ISFET non-idealities, allowing uninterrupted spatiotemporal detection of ion dynamics for understanding biochemical and physiological processes.Universitat Autònoma de Barcelona. Programa de Doctorat en Enginyeria Electrònica i de Telecomunicaci
Ultra-low-power compressive-readout integrated circuit design for smart and wearable biosensing
Get PDFThis work presents the design of an ultra-low-power compressive-readout integrated circuit (IC)
for amperometric electrochemical sensors. The application-specific integrated circuit (ASIC) has
been designed in the frame of a project that aims to develop non-invasive integrated wearable
platforms for monitoring the sweat of athletes in real time. The ASIC, which will be part of
the sensing platforms, must be able to measure full scale currents in the order of µA with
resolutions in the order of nA, while consuming a µW-range power in order to provide the
wearable platform with enough energy autonomy. Moreover, the ASIC must include a digital
communication interface for a reliable data transmission.
The amperometric sensor frontend, designed following a full-custom analog IC design methodology, has been realized with a 3-quantization-level asynchronous delta-sigma (∆Σ) modulator
topology. The inclusion of the sensor in the ∆Σ loop has resulted in a compact architecture.
The digital communication backend, designed following a semi-custom digital IC design flow,
has been developed by adapting a serial communication protocol and modifying it to allow
an asynchronous communication of data, which results in an increase of the power efficiency.
To conclude the work, these two blocks have been integrated in a 0.18-µm complementary
metal-oxide-semiconductor (CMOS) technology
Ultra-low-power compressive-readout integrated circuit design for smart and wearable biosensing
Get PDFThis work presents the design of an ultra-low-power compressive-readout integrated circuit (IC)
for amperometric electrochemical sensors. The application-specific integrated circuit (ASIC) has
been designed in the frame of a project that aims to develop non-invasive integrated wearable
platforms for monitoring the sweat of athletes in real time. The ASIC, which will be part of
the sensing platforms, must be able to measure full scale currents in the order of µA with
resolutions in the order of nA, while consuming a µW-range power in order to provide the
wearable platform with enough energy autonomy. Moreover, the ASIC must include a digital
communication interface for a reliable data transmission.
The amperometric sensor frontend, designed following a full-custom analog IC design methodology, has been realized with a 3-quantization-level asynchronous delta-sigma (∆Σ) modulator
topology. The inclusion of the sensor in the ∆Σ loop has resulted in a compact architecture.
The digital communication backend, designed following a semi-custom digital IC design flow,
has been developed by adapting a serial communication protocol and modifying it to allow
an asynchronous communication of data, which results in an increase of the power efficiency.
To conclude the work, these two blocks have been integrated in a 0.18-µm complementary
metal-oxide-semiconductor (CMOS) technology
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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