This thesis presents a systematic characterisation of relatively simple to increasingly complex phosphate based glass (PBG) systems. Resorbable PBG can potentially be applied as fibrous reinforcement for resorbable polymers such as polY(Ecaprolactone) for biomedical applications. These resorbable composites are of considerable interest since subsequent absorption allows for a gradual transfer of load to the healing bone and avoids the need for secondary surgery. The PBG compositions investigated ranged from binary, ternary to quaternary and quinternary glass systems. The effects of these compositions on their thermal and structural properties were investigated. The studies revealed that the thermal properties such as glass transition and thermal stability (defined as the difference between glass transition and the onset of crystallisation) improved with increasing phosphate content as well as with the incorporation of additional higher valence cations such Ca2+, Fe2+/3+ and Ti3+/4+. It was observed that the addition of Fe2+/ 3+ and Ti3+/4+ had a more profound effect on the thermal properties in comparison to increasing phosphate content. Also of primary interest was investigation into the viscosity properties for these glasses. These studies enabled an alternative route for fibre drawing of PBG which was via the preform drawn method. The viscous properties of these glasses were compared in terms of their fragility index for a viscosity region of log · 1 08 - log 105 .5 Pa s. The quaternary and quinternary compositions investigated were successfully drawn into fibres via the preform drawn method and the measured fragility index was in the range of36.6 to 44.1. It was found that fibres could be drawn witl}in ±10°C of the estimated fibre drawing temperature. In brief, a high fragility index reflected a 'fragile' melt whereas low fragility indexes indicated a 'strong' melt. It is desirable to have a 'strong' melt since it will make the fibre drawing temperature less critical provided that crystallization can be avoided. The fiberisation process (via the preform method) also highlighted the importance of identifying a suitable etching procedure as some of the preforms had undergone surface hydrolysis reaction which made fibre drawing extremely difficult for those specific formulations. The most iii exciting, novel and challenging studies were designing novel hybrid (core/clad) glass preforms and fibres. The idea was to explore the possibility of creating PBG glass fibres with specific ion release profiles via alternate formulations for the both core and clad. The successful co-extrusion and fiberisation of quarternary and quinternary glass systems provided the required proof of concept. The dissolution properties of both bulk glass and fibres were also examined. It was found that Ti containing glasses were more effective in reducing the solubility rate compared to Fe ions. An interesting phenomenon was observed during the dissolution of annealed and non-annealed fibres. It was found that the strength of the annealed glass fibres increased significantly with dissolution time compared to nonannealed fibres. This was attributed to a combination of higher density as well as the peeling away of outer layers from the fibre surfaces. A similar trend was also observed for the Fe clad hybrid glass fibre. The nonexistent peeling effect of the hydrated layer for Ti clad hybrid glass fibres indicated that the Ti fibres were more durable in comparison to the Fe clad hybrid glass fibres. Overall, this work has improved the understanding on the correlation between the thermal properties especially viscosity of phosphate based glasses and fiberisation process via the preform drawn method. iv

Glutamate has been described as one of the most important markers during many neurological problems, including brain injury, hypoxia and ischaemia amongst others.

No description available.

Ochratoxin A is a contaminant in wine and known to be immunosuppressive and possibly carcinogenic. Therefore, the development of a rapid and sensitive method for field analysis is required for risk assessment and management. The work presented in this thesis reports the construction of a sensor platform capable of fulfilling these requirements. As a sensor platform, screen-printed thick film electrodes and microelectrodes on a silicone support were investigated for sensor development. As biological recognition elements, an antibody specifically binding ochratoxin A and a peptide receptor that was designed using computational modelling were examined. A disposable immunosensor for ochratoxin A was developed based on screen-printing technology. An indirect competitive immunoassay format was used on bare screen printed gold electrode (SPGE). The performance of this sensor was compared to carboxmethylated dextran (CMD) modified SPGE. Detection was performed by chronoamperometry monitoring the reaction of tetramethylbenzidine and hydrogen peroxide catalysed by horseradish peroxidase. The SPGE-based immunosensor achieved a detection limit of 100 ng L-1 and the CMD-modified SPGE immunosensor 10 ng L-1. The latter has been used for ochratoxin A determination in wine samples and was validated against standard HPLC and a commercial immunoassay test kit. Wine sample analysis involved the sample pre-treatment using immunoaffinity chromatography, electrochemical wine component characterisation and interference control. The immunosensor format was transferred to a gold microelectrode array based on a silicone support for the purpose of signal sensitivity enhancement and miniaturisation in the prospect of field analysis. Preliminary data showed the characterisation of the microelectrode array immunosensor construction and characterisation. Further optimisation is needed to establish a calibration curve with the required sensitivity. The second part of the work comprised the design of a peptide receptor for ochratoxin A using computational methods by screening de novo designed peptide libraries. An octapeptide (CSIVEDGL) and a 13-peptide (GPAGIDGPAGIRC) were selected for synthesis and affinity characterised for ochratoxin A recognition using a surface plasmon resonance biosensor (BiacoreTM). The peptide receptors showed good sensitivity for ochratoxin A of 10 μg L-1. Preliminary affinity characterisation resulted in KA = 63 mM-1 for the 13-mer peptide and KA = 84 mM-1 for the octapeptide, which appears to be binding with higher strength to ochratoxin A. The affinity values correspond to the binding score (binding energy) calculated by computational modelling. This work shows the potential of designing peptide receptors for small molecules (e.g. ochratoxin A) and suggests their application in affinity sensors for detecting ochratoxin A contamination.

Ion sensitive field effect transistors (ISFETs) have long been used as analogue chemical sensors particularly for biomedical applications. However, there are some applications where a "yes" / "no" type answer regarding pH change is sufficient. For example, in DNA sequencing the question is whether a chain extension reaction took place or not. Detecting this at the sensing point reduces the sensing process to pH change threshold detection. It eliminates the need for analogue to digital conversion and facilitates an all digital sensory system. This thesis presents Novel Floating Gate ISFET based Chemical Inverters that were created with semiconductor based biomedical applications in mind. It starts by allowing two ISFETs to share the same ion sensing membrane and a common floating gate. Arranging them in a simple FG inverter configuration, their switching may be triggered by either the reference voltage or chemical pH change. In order to enhance its input noise immunity, a chemical Schmitt Trigger is presented. Using ISFETs for the detection of minute pH changes have been a challenge. A simple method to locally scale input referred chemical signal at the ISFET's floating gate is presented. It is based on using the ratio of capacitive coupling to the floating gate. The chemical signal is coupled via the passivation capacitance (Cpass) while an electrical input (V2) is coupled via a poly capacitance (C2). V2 sees the chemical signal with a scaling of Cpass/C2, which can be designed. Finally, ISFETs suffer from initial trapped charges that cause mismatch between devices in the same die. A fast matching method is presented here, that can be used to hugely reduce mismatch of arrays of FG devices. It is based on using indirect bidirectional tunnelling. Two tunnelling structures are added to each ISFET's FG, one adds electrons to it while the other removes them. It is possible to match all ISFETs' initial FG voltages to a point where both tunnelling currents reach equilibrium.

Hyperbolic-Sine (Sinh) filters form a subclass of Externally-Linear-Internally-Non-Linear (ELIN) systems. They can handle large-signals in a low power environment under half the capacitor area required by the more popular ELIN Log-domain filters. Their inherent class-AB nature stems from the odd property of the sinh function at the heart of their companding operation. Despite this early realisation, the Sinh filtering paradigm has not attracted the interest it deserves to date probably due to its mathematical and circuit-level complexity. This Thesis presents an overview of the CMOS weak inversion Sinh filtering paradigm and explains how biomedical systems of low- to audio-frequency range could benefit from it. Its dual scope is to: consolidate the theory behind the synthesis and design of high order Sinh continuous–time filters and more importantly to confirm their micro-power consumption and 100+ dB of DR through measured results presented for the first time. Novel high order Sinh topologies are designed by means of a systematic mathematical framework introduced. They employ a recently proposed CMOS Sinh integrator comprising only p-type devices in its translinear loops. The performance of the high order topologies is evaluated both solely and in comparison with their Log domain counterparts. A 5th order Sinh Chebyshev low pass filter is compared head-to-head with a corresponding and also novel Log domain class-AB topology, confirming that Sinh filters constitute a solution of equally high DR (100+ dB) with half the capacitor area at the expense of higher complexity and power consumption. The theoretical findings are validated by means of measured results from an 8th order notch filter for 50/60Hz noise fabricated in a 0.35μm CMOS technology. Measured results confirm a DR of 102dB, a moderate SNR of ~60dB and 74μW power consumption from 2V power supply.

The efficacy of a direct electric current (10μA, 9V) via electrode-conducting carbon impregnated catheters to prevent colonisation of catheters by micro-organisms was investigated. The catheters acting as the anode and the cathode were inserted into a nutrient agar plate inoculated with a lawn of bacteria. There was no zone of inhibition observed around the anode. Organisms susceptible to 10μA at the cathode were Staphylococcus aureus (2 strains), Staphylococcus epidermidis (5 strains), Escherichia coli and Klebsiella pneumoniae (2 strains each), and one strain of the following micro-organisms: Staphylococcus hominis, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans. The mechanisms of the bactericidal activity associated with the cathode were investigated with S. epidermidis and S. aureus. The inhibition zone was created reduced in the presence of catalase. Hydrogen peroxide was produced at the cathode surface under aerobic conditions, but not in the absence of oxygen. A salt-bridge apparatus was used to demonstrate further that hydrogen peroxide was produced at the cathode, and chlorine at the anode. Antibacterial activity was reduced under anaerobic conditions, which is compatible with the role of hydrogen peroxide as a primary bactericidal agent of electricity associated with the cathode. A reduction in chloride ions did not significantly reduce the antibacterial activity. 10μA applied via the catheters did not prevent the initial biofilm growth by the adherent bacteria but reduced the number of bacteria in the biofilm by 2 log order after 24h. The results suggested that 10μA may prevent the colonisation of catheters by both the extra- and intra-luminal routes. The localised production of hydrogen peroxide and chlorine and the intrinsic activity due to electric current may offer a useful method for the eradication of bacteria from catheter surfaces.

No description available.

Adolescents have been identified as users of medical devices who are currently overlooked in the design and development of these products. This research presents a set of studies that investigate the non-clinical user requirements of adolescent medical device users. Interviews with a range of healthcare professionals provided guidance into chronic conditions and devices which are relevant to adolescent populations. Workshops involving healthy adolescents in schools were carried out to elicit adolescent perspectives of current medical device design. The results of this study showed that the range of medical devices presented did not satisfy adolescent user requirements and provided insight into factors which are important to this specific user group. The workshop also identified the acapella® physiotherapy device, used for chest and airway clearance in the treatment of cystic fibrosis, as a suitable case study for further evaluation with real adolescent users. Case study interviews were carried out with adolescents with cystic fibrosis: the users of the acapella®. The interviews identified a range of unmet requirements and expanded on the results from the workshops. In addition to the more general design factors, users of the acapella® highlighted the effect of device use on clinical effectiveness. The data from the workshops and case study interviews was used in a co-design project with an adolescent user of the device. A design specification was interpreted from the data to produce a visual representation of the adolescent requirements. The research has produced two outputs. The first is the development of a prototype tool for eliciting adolescent design priorities for medical devices - The Adolescent Medical Device Assessment Tool (AMDAT) The second deliverable is a set of guidelines which detail the specific requirements and goals of adolescent users of medical devices - Adolescent Medical Device Requirements. This guidance aims to facilitate the consideration of adolescent user requirements in the design and development of new medical devices. The research investigation has contributed new understanding to the fields of human factors and adolescent healthcare. The findings from these studies demonstrate how adolescent populations can be successfully engaged in research tasks. This research investigation has shown that adolescents have specific needs of medical devices and that meeting these needs through user-centred methods may lead to better adherence of use and improved health outcomes.

Στόχος της παρούσας διπλωματικής εργασίας είναι η αναζήτηση, χαρτογράφηση πηγών πληροφόρησης και αναφορών, σχετικά με δυσμενή περιστατικά προερχόμενα από τον ιατροτεχνολογικό εξοπλισμό. Σε πρώτο στάδιο γίνεται περιγραφή των ιατρικών μηχανημάτων και επισημαίνεται η συμβολή τους στην εξελικτική πορεία ίασης των ασθενών. Αναφέρεται επίσης η ισχύουσα Ευρωπαϊκή νομοθεσία στον τομέα των ιατροτεχνολογικών προϊόντων (Medical Devices Directives). Στη συνέχεια, επιχειρείται η αναλυτική περιγραφή ενός συστήματος επαγρύπνησης και η αναγκαιότητα ύπαρξης του συστήματος αυτού στον τομέα της Υγείας. . Ως μέρος της εργασίας, παρουσιάζονται επίσης οι σημαντικότεροι κατασκευαστές ιατρικών μηχανημάτων, καθώς και οι κυριότεροι Οργανισμοί παγκοσμίως, από τους οποίους αντλούνται πληροφορίες σχετικά με δυσμενή περιστατικά τα οποία οφείλονται σε βλάβη, πλημμελή συντήρηση ή κακό χειρισμό ιατρικών μηχανημάτων. Τέλος, δημιουργείται και παρουσιάζεται καταγραφή δεδομένων για τα δυσμενή περιστατικά των ιατρικών μηχανημάτων που συνέβησαν μέσα στο έτος 2013. θα γίνει ανάλυση των αποτελεσμάτων. Τέλος θα ακολουθήσει συζήτηση για την παρούσα κατάσταση στην Ελλάδα. / The goal is to search, mapping and creation reports on adverse incidents that derived from medical equipment. First stage of this thesis is the description of medical equipment and the important role they play in the evolution of healing patients. It also mentions the European legislation concerning medical devices (Medical Devices Directives). We will refer to the main organizations that exist worldwide as the leading manufacturer of medical devices that provide information on the adverse events of medical equipment. Finaly done recording adverse events of medical equipment that occurred in 2013. Will analyze the results. End followed by a discussion on the current situation in Greece.