Improvements in electrochemical glucose biosensors

Diabetes is one of the leading causes of death and disability in the world. Even though insulin was discovered in 1920, an intense research on diabetes has been conducted during the last five decades and this is because of the market size. The huge demand is creating the need for the development of new approaches. This project involved the research aimed at better understanding and improvements in performance of glucose biosensors. In general, high surface area electrodes are desired as the high surface area provides more active sites for electrochemical reactions, and hence higher kinetic rate capability. Therefore, the determination of the active electrochemical surface area of the electrode is very important. A study has been conducted to determine the real electrochemical surface area of the Pelikan screen printed electrodes (SPEs) and a method has been optimised and established by Pelikan for the evaluation of their SPEs. Another very important issue that most of the current blood glucose monitoring tests are facing is the haematocrit effect, since the haematocrit differences observed in the blood samples can significantly affect glucose measurements. Therefore a study has been conducted in order to observe the absorption of the blood samples into the working electrode paste according to the haematocrit level. The second part of the study included the characterisation of the novel conjugated polymer made of N-(N, N’ diethyldicarbamoyl ethyl amido ethyl) aniline (NDDEAEA), the optimization of the conditions for the electrochemical polymerization, their application in grafting and finally the development of NDDEAEA based glucose biosensor. The new conducting polymer, acted as a matrix for the biosensor fabrication in this study, possesses macroiniferter properties and is capable of initiation free radical initiated addition polymerisation after formation of the polyaniline (PANI) material while preserving or even enhancing some of the PANI’s electrochemical properties. This material can potentially be used in the construction of novel Pelikan electrodes with enhanced integration functionalities, e.g. grafting non adhesive polymer coatings to assure that the poor performance in sensors as a result of impact of blood components can be mitigated. The final study included the development and optimisation of the reaction conditions for grafting a hyperbranched polymer onto the surface of the multi walled carbon nanotubes (MWCNT), using the A3 and B2 approach (described below). The aim of this work was achieving further increase in the sensitivity of Pelikan sensors.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Pseudo-Random Single Photon Counting for Time-Resolved Optical Measurements

Ph.DDOCTOR OF PHILOSOPH

Redesigning chemical analysis: transducing information from chemical into digital

Aquesta tesi planteja que les xarxes distribuïdes de detecció de substàncies químiques serán eines beneficioses per aconseguir millors resultats de salut com a éssers humans, així com per a guiarnes en el nostre paper autodeterminat con a guardians en l'àmbit ecològic. Tot aixo, des de la perspectiva d’introduir elements de disseny en les eines analítiques. El treball comença amb una introducció a la visió de com els sensors químics s'adapten als contextos més grans de la biologia, la història i la tecnologia. El segon capítol ofereix una base de coneixements sobre els mètodes i principis científics i tecnològics subjacents sobre els quals es basa aquest treball. A continuació, es fa una revisió crítica dels avenços acadèmics cap als sensors electroquímics distribuïts, que divideixen el problema en tres aspectes: rendiment adequat, usabilitat intuïtiva i assequibilitat. Entre aquests, la usabilitat s'identifica com el coll d'ampolla principal en l'adopció generalitzada de sensors químics centrats en l'usuari. Els capítols posteriors ofereixen algunes respostes als reptes, en forma de treball experimental original. Encara que aquest treball es basa en l'electroquímica analítica, s'aborda des d’una metodologia de disseny, amb iteracions d'anàlisi i síntesi incrustades en el procés d'ideació. Les declaracions finals reflexionen sobre el treball com una petita part en una creixent revolució de l'edat de la informació química; com una petita esquerda a la presa que contenia una allau de dades químiques de diagnòstic amb conseqüències imprevisibles, però positives i revolucionàries.Esta tesis postula que las redes distribuidas de detección química serán herramientas beneficiosas para alcanzar mejores resultados de salud como seres humanos, así como para guiarnos en nuestro papel autodeterminado como guardianes en la esfera ecológica. Todo esto desde una perspectiva de introducir elementos de diseño en herramientas analíticas. El trabajo comienza con una introducción a la visión de cómo los sensores químicos se ajustan a los contextos más amplios de la biología, la historia y la tecnología. El segundo capítulo proporciona algunos antecedentes de los métodos y principios científicos y tecnológicos subyacentes en los que se basa este trabajo. Esto es seguido por una revisión crítica de los avances académicos hacia sensores electroquímicos distribuidos, que divide el problema en tres aspectos: rendimiento apropiado, usabilidad intuitiva y asequibilidad. Entre estos, la usabilidad se identifica como el cuello de botella principal en la adopción generalizada de sensores químicos centrados en el usuario. Los siguientes capítulos ofrecen algunas respuestas a los desafíos, en forma de trabajo experimental original. Mientras que este trabajo se arraiga en la electroquímica analítica, se aborda desde una metodología de diseño, con iteraciones de análisis y síntesis integradas en el proceso de ideación. Las declaraciones finales reflejan el trabajo como una pequeña parte en una floreciente revolución de la era de la información química; como una pequeña grieta en la presa que contiene una avalancha de datos químicos de diagnóstico con consecuencias imprevisibles, pero positivas y revolucionarias.This thesis posits that distributed chemical sensing networks will be beneficial tools towards our greater health outcomes as humans, as well as in guiding us in our self-determined role as custodians over the ecological sphere. A perspective of infusing design elements and approaches into analytical tools is shared. The work begins with an introduction presenting a vision of how chemical sensors fit within the greater contexts of biology, history, and technology. The second chapter provides some background to the underlying scientific and technological methods and principles on which this work stands. This is followed by a critical review of the academic advances towards distributed electrochemical sensors, which divides the problem into three aspects of appropriate performance, intuitive usability, and affordability. Amongst these, usability is identified as the principal bottleneck in the widespread adoption of user-centered chemical sensors. The subsequent chapters offer some responses to the challenges, in the form of original experimental work. While rooted in analytical electrochemistry, the work is approached with a design methodology, with iterations of analysis and synthesis embedded in the ideation process. Concluding statements reflect on the work as a small part in a burgeoning revolution of the chemical information age; as a minor crack in the dam holding back a flood of diagnostic chemical data with unforeseeable, yet positive and revolutionary consequences