Flexible Ultrasonic Transducers and Their Performance

Peer reviewed: YesNRC publication: Ye

Energy Harvesting Using Piezoelectric Thick Films Fabricated by a Sol-Gel Process

Peer reviewed: YesNRC publication: Ye

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Flexible ultrasonic tranducers using ferroelectric sol-gel composite films for non-destructive testing and structual health monitoring

High temperature (HT) flexible ultrasonic transducers (FUTs) for nondestructive testing (NDT) and structural health monitoring (SHM) were developed using the sol gel spray method. Although the integrated ultrasonic transducer (IUT) is highly desirable as a NDT and SHM solution since it is a technique of directly coupling a fabricated UT to an inspected structure such an on-site fabrication solution may not be particularly attractive. FUTs acting as small and lightweight UTs may be fabricated off-site and then on-site installed. Lead-zirconate titanate composite (PZT-c) and bismuth titanate composite (BIT-c) films were sprayed onto 75 µm or 38 µm thick metallic membranes. At room temperature, these FUTs demonstrate consistently high piezoelectric performance comparable to commercially available UTs when used to perform thickness measurements over flat surfaces. Such FUTs offer the advantage that they may be conformed to curved surfaces. Additionally, these may be fabricated off-site and installed on-site. Therefore, bonding techniques such as glueing and brazing onto pipes were studied with the brazing demonstrating operability at 490ºC, thereby offering a HT, conformable, semi-permanent and on-site installed NDT and SHM solution. Techniques of room temperature selective area Corona poling and expanded area Corona poling were demonstrated, allowing for the patterning of the films and a method for integrating the Corona poling technique to either maintain or repair a network of on-site installed FUTs. The development of these techniques had started with the use of UV to replace the heating of the sol-gel composite film necessary during Corona poling. It was however found that under the same conditions, neither heat nor UV was required for the poling o f the film. Nonethless, this prompted optical studies with respect to some semiconductor and ferroelectric properties of these sol-gel films. Non-bonded FUTs are also presented as dry contact and momentary FUTs. The spray technique used with a shadow mask and other techniques was used to fabricate different devices such as ultrasonic phased-arrays and unimorph, piezoelectric vibrational energy harvesters, meant to be integrated with a battery network of NDT, SHM FUTs as an intermittent, self-sustained power source. These demonstrated an amplification in charge generation with a pre-stressed configuration, allowable by the flexible film and substrate. With such high piezoelectric performance inherent in the sol-gel film, a study into some ferroelectric properties of the film was performed, in particular by the optical approach using UV. The results demonstrated PZT-c films were absorbant between 200 and ~400 nm both before and after crystallization from HT treatment with an approximated bandgap of 2.8-3.1 eV. A photoconductivity of 0.0205 Ω-1cm-1 was measured for a 5 μm thick PZT-c film. An effect in which a lowering of the Curie temperature (Tc) was observed demonstrates that study in relation to the field of photoferroelectrics with such composite films may be of scientific interest. Lastly, the poling of the film in nanoscale using Piezo Force Microscopy (PFM) was demonstrated.Dans cette thèse, des capteurs flexibles ultrasonores (CFU) à haute température (HT) ont été développés pour des applications dans le domaine de l'évaluation non destructive (END) et celui de la surveillance de la santé structurelle (SSS). Alors que les capteurs intégrés (CIU) qui peuvent être fabriqués sur site et qui ne nécessitent pas de couplant sont des solutions attrayantes dans ces domaines, la fabrication sur site peut souvent être difficile ou infaisable selon les conditions. Par contre, les CFUs qui sont petits et légers peuvent être fabriqués à part et installés sur site. Les couches composées piézo-électriques, avec lesquelles les capteurs ultrasoniques à haute température (CUHT) sont fabriqués, sont développés à partir de la technique sol-gel. Ces couches constituées de zirconate titanate de plomb (PZT-c), ou de titanate de bismuth (BIT-c) sont déposées sur des substrats métalliques d'épaisseurs de 75 m ou de 38 m. À la température de la pièce, ces CFUs démontrent une performance piézo-électrique comparable aux capteurs commerciaux lors des mesures d'épaisseur sur des surfaces plates. L'avantage de ces CFUs est que ceux-ci peuvent se conformer à des surfaces courbes. De plus, les CFUs peuvent être fabriqués à part et installés sur-site. De plus, des moyens pour attacher ces capteurs aux structures courbes comme les tuyaux ont été essayés. Des techniques de collage et de brasage ont été démontrées, avec les CFUs opérationnels à ces hautes températures jusqu'à 490ºC, offrant une solution conformable, HT, moyennement permanente, en plus de l'avantage de l'installation sur site. Les techniques de polarisation Corona à température de la pièce qui permettent une polarisation sélective ou à grande surface ont été développées, permettant de polariser des motifs. Le développement de ces techniques avait débuté avec l'utilisation d'ondes UV pour remplacer le chauffage qui était nécessaire durant la polarisation Corona, permettant une polarisation des couches piézo-électriques sol-gel à température de la pièce. Il a cependant été découvert que sous ces conditions, ni le chauffage, ni l'UV n'étaient nécessaires, ce qui a néanmoins motivé des études optiques vis-à-vis ces couches sol-gel par rapport à leurs propriétés semi-conductrices et ferroélectriques. La méthode de sol-gel utilisée avec un masque ainsi que d'autres techniques ont aussi été utilisées pour fabriquer des capteurs de configurations différentes comme le capteur à éléments en phase ou le capteur à contact momentané. Le sol-gel a aussi été utilisé pour fabriquer un capteur d'énergie vibratoire unimorphe dans le but d'être intégré avec un système de batteries et avec le réseau de CFU pour END et SSS come source d'énergie de façon discontinue mais autonome. Ces capteurs démontrent une augmentation de charge générée lorsqu'ils sont mis sous une tension pré-courbée, une configuration possible avec la couche et le substrat flexible. Les résultats optiques ont démontré une absorbance envers les ondes UV (~200-400 nm) dans l'état sol-gel des couches ainsi qu'après cristallisation à HT, avec une structure de bande de 2.8-3.1 eV. Une photoconductivité de 0.0205 Ω-1cm-1 a été mesurée pour une couche de PZT-c d'épaisseur de 5 μm. Un effet où une baisse en température du point Curie (Tc) a été observée sous ondes UV pour les couches de PZT-c démontre que des études dans le domaine de la photoferroélectricité avec ces couches seraient d'intérêt scientifique. La polarisation d'une couche de PZT-c sur une surface 500 nm x 500 nm utilisant la microscopie à force piezo (MFP) a aussi été démontrée

Zinc oxide-silicon heterojunction solar cells by sputtering

Heterojunctions of n-ZnO/p-Si solar cells were fabricated by RF sputtering ZnO:Al onto boron-doped (100) silicon (Si) substrates. Zinc Oxide (ZnO) films were also deposited onto soda lime glass for electrical measurements. Sheet resistance measurements were performed with a four-point-probe on the glass samples. Values for samples evacuated for 14 hours prior to deposition increased from 7.9 to 10.17 and 11.5 O/□ for 40 W, 120 and 160 W in RF power respectively. In contrast, those evacuated for 2 hours started with a higher value of 22.5 O/□, and decreased down to 7.6 and 5.8 O/□. Vacuum annealing was performed for both the glass and the Si samples. Current-voltage measurements were performed on the ZnO/Si junctions in the dark and under illumination. Parameters such as open-circuit voltage, Voc; short-circuit current, Isc; fill factor, FF; and efficiency, eta were determined. A maximum efficiency of 0.25% among all samples was produced, with an I sc of 2.16 mA, Voc of 0.31V and a FF of 0.37. This was a sample fabricated at an RF power of 80 W. Efficiency was found to decline with vacuum annealing. Furthermore, interfacial state density calculated based on capacitance-voltage measurements showed an increase in the value with vacuum annealing. The results found suggest that the interface states may be due to an interdiffusion of atoms, possibly those of Zn into the Si surface. The Electron Beam Induced Current (EBIC) method was used to determine diffusion length to be at a value ∼40--80 mum and therefore a minority carrier lifetime calculated of 3 musec. It was also used to determine the surface recombination velocity (SRV) of the fractured surface of the Si bulk from the fabricated solar cells. An SRV of ∼500 cm/sec was determined from the fractured Si surface, at a point located at 30 and 20 mum away from the junction interface

Flexible metallic ultrasonic transducers for structural health monitoring of pipes at high temperatures

Piezoelectric films have been deposited by a solgel spray technique onto 75-\u3bcm-thick titanium and stainless steel (SS) membranes and have been fabricated into flexible ultrasonic transducers (FUTs). FUTs using titanium membranes were glued and those using SS membranes brazed onto steel pipes, procedures that serve as on-site installation techniques for the purpose of offering continuous thickness monitoring capabilities at up to 490\ub0C. At 150\ub0C, the thickness measurement accuracy of a pipe with an outer diameter of 26.6 mm and a wall thickness of 2.5 mm was estimated to be 26 \u3bc m and the center frequency of the FUT was 10.8 MHz. It is demonstrated that the frequency bandwidth of the FUTs and SNR of signals using glue or brazing materials as high-temperature couplant for FUTs are sufficient to inspect the steel pipes even with a 2.5 mm wall thickness.Peer reviewed: YesNRC publication: Ye

Standalone high temperature broadband ultrasonic transducers for non-destructive testing

Peer reviewed: YesNRC publication: Ye

Applications of Flexible Ultrasonic Transducer Array for Defect Detection at 150 °C

sensor

Correction to: Comparative effectiveness and safety of non-vitamin K antagonists for atrial fibrillation in clinical practice: GLORIA-AF Registry

International audienceIn this article, the name of the GLORIA-AF investigator Anastasios Kollias was given incorrectly as Athanasios Kollias in the Acknowledgements. The original article has been corrected

Patterns of oral anticoagulant use and outcomes in Asian patients with atrial fibrillation: a post-hoc analysis from the GLORIA-AF Registry

Background: Previous studies suggested potential ethnic differences in the management and outcomes of atrial fibrillation (AF). We aim to analyse oral anticoagulant (OAC) prescription, discontinuation, and risk of adverse outcomes in Asian patients with AF, using data from a global prospective cohort study. Methods: From the GLORIA-AF Registry Phase II-III (November 2011-December 2014 for Phase II, and January 2014-December 2016 for Phase III), we analysed patients according to their self-reported ethnicity (Asian vs. non-Asian), as well as according to Asian subgroups (Chinese, Japanese, Korean and other Asian). Logistic regression was used to analyse OAC prescription, while the risk of OAC discontinuation and adverse outcomes were analysed through Cox-regression model. Our primary outcome was the composite of all-cause death and major adverse cardiovascular events (MACE). The original studies were registered with ClinicalTrials.gov, NCT01468701, NCT01671007, and NCT01937377. Findings: 34,421 patients were included (70.0 ± 10.5 years, 45.1% females, 6900 (20.0%) Asian: 3829 (55.5%) Chinese, 814 (11.8%) Japanese, 1964 (28.5%) Korean and 293 (4.2%) other Asian). Most of the Asian patients were recruited in Asia (n = 6701, 97.1%), while non-Asian patients were mainly recruited in Europe (n = 15,449, 56.1%) and North America (n = 8378, 30.4%). Compared to non-Asian individuals, prescription of OAC and non-vitamin K antagonist oral anticoagulant (NOAC) was lower in Asian patients (Odds Ratio [OR] and 95% Confidence Intervals (CI): 0.23 [0.22-0.25] and 0.66 [0.61-0.71], respectively), but higher in the Japanese subgroup. Asian ethnicity was also associated with higher risk of OAC discontinuation (Hazard Ratio [HR] and [95% CI]: 1.79 [1.67-1.92]), and lower risk of the primary composite outcome (HR [95% CI]: 0.86 [0.76-0.96]). Among the exploratory secondary outcomes, Asian ethnicity was associated with higher risks of thromboembolism and intracranial haemorrhage, and lower risk of major bleeding. Interpretation: Our results showed that Asian patients with AF showed suboptimal thromboembolic risk management and a specific risk profile of adverse outcomes; these differences may also reflect differences in country-specific factors. Ensuring integrated and appropriate treatment of these patients is crucial to improve their prognosis. Funding: The GLORIA-AF Registry was funded by Boehringer Ingelheim GmbH