Low Frequency Mechanical Actuation Accelerates Reperfusion In-Vitro

Background Rapid restoration of vessel patency after acute myocardial infarction is key to reducing myocardial muscle death and increases survival rates. Standard therapies include thrombolysis and direct PTCA. Alternative or adjunctive emergency therapies that could be initiated by minimally trained personnel in the field are of potential clinical benefit. This paper evaluates a method of accelerating reperfusion through application of low frequency mechanical stimulus to the blood carrying vessels. Materials and method We consider a stenosed, heparinized flow system with aortic-like pressure variations subject to direct vessel vibration at the occlusion site or vessel deformation proximal and distal to the occlusion site, versus a reference system lacking any form of mechanical stimulus on the vessels. Results The experimental results show limited effectiveness of the direct mechanical vibration method and a drastic increase in the patency rate when vessel deformation is induced. For vessel deformation at occlusion site 95% of clots perfused within 11 minutes of application of mechanical stimulus, for vessel deformation 60 centimeters from the occlusion site 95% percent of clots perfused within 16 minutes of stimulus application, while only 2.3% of clots perfused within 20 minutes in the reference system. Conclusion The presented in-vitro results suggest that low frequency mechanical actuation applied during the pre-hospitalization phase in patients with acute myocardial infarction have potential of being a simple and efficient adjunct therapy

Conception de microgénérateurs intégrés pour systèmes sur puce autonomes

Cette thèse explore la thématique des microsystèmes autonomes, notamment la problématique de leur alimentation en énergie. Jusqu à présent, l énergie nécessaire pour faire fonctionner ces dispositifs était fournie par une source finie, par exemple une batterie électrochimique. Cela implique, qu après un certain temps, le réservoir doit être rempli, sinon le dispositif cesse de fonctionner. De plus, un compromis doit être fait entre la taille et la durée de vie du système. L objectif de ce travail est d étudier la possibilité d alimenter de tels systèmes à partir de l énergie des vibrations mécaniques ambiantes. Nous nous sommes focalisés sur la miniaturisation du dispositif de récupération d énergie, et sur la possibilité de son élaboration en employant les techniques de micro fabrication et les couches minces piézoélectriques. L utilisation d un dispositif de type MEMS permettrait de créer des systèmes autonomes sur une seule puce (SoC) où dans un boîtier (SoP). Au cours de cette thèse nous avons créé des modèles analytiques et par éléments finis des structures de générateurs piézoélectriques. Nous avons conçu et fabriqué les dispositifs en utilisant deux matériaux piézoélectriques : le nitrure d aluminium (AlN) et le zirconate titanate de plomb (PZT). Nous avons démontré que de telles structures peuvent fournir une puissance de l ordre de quelques microwatts. De plus, avec des circuits spécifiques de gestion de puissance elles permettent de charger des dispositifs de stockage à partir des vibrations d une très faible amplitude. Les dispositifs présentés sont pour le moment les seuls microgénérateurs piézoélectriques au monde adaptés aux vibrations ambiantes. Cette thèse s inscrit dans le cadre du projet VIBES (VIBration Energy Scavenging) qui est un STREP du sixième programme cadre de l Union Européenne (IST-1-STREP-507911)This PhD thesis addresses the subject of autonomous microsystems and their energy supply. Until now the energy needed for operation of these devices was provided by a finite source, like an electrochemical battery. It implies that the lifetime of the device is directly linked with the size of this reservoir and therefore a trade-off must be made between the size and the longevity of the system. The goal of this work consists in exploring the possibility of using the energy of ambient mechanical vibrations for powering autonomous devices. Furthermore we analyse the possibility of miniaturisation of such generators by using microfabrication techniques and piezoelectric thin layers. A MEMS micro energy scavenger would enable creation of autonomous systems on chip (SoC) or on a package (SoP). During this work we have developed detailed analytical and FEM models of piezoelectric micro power generators. The results obtained were used for design and fabrication of prototype structures using two types of piezoelectric thin layer materials: Aluminium Nitride (AlN) and Lead Zirconate Titanate (PZT). We have proven that these devices can generate powers up to several microwatts on a matched resistive load. We have also shown that in conjunction with special power management ASICs they can charge energy storage elements from very low amplitude vibrations. Finally we have assembled the entire energy harvesting system as a System on a Package. The presented devices are at the moment the sole examples of MEMS piezoelectric micro power generators adapted for ambient vibration energy harvesting. This PhD work is a part of the VIBES (VIBration Energy Scavenging) project founded by the European Commission (IST-1-STREP-507911)GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Complete Platform for Remote Health Management

Practical usability of the majority of the current wearable body sensor systems for multiple parameter physiological signal acquisition is limited by the multiple physical connections between the sensors and the data acquisition modules. In order to improve the user comfort and enable the use of this type of systems on active mobile subjects, we propose a wireless body sensor system that incorporates multiple sensors on a single node. This multi-sensor node includes signal acquisition, processing, and wireless data transmission fitted on multiple layers of a thin flexible substrate with very small footprint. Considerations for design include size, form factor, reliable body attachment, good signal coupling, and user convenience. The prototype device measures 55mm by 15mm and is 3mm thick. The unit is attached to the patient's chest, and is capable of performing simultaneous measurements of parameters such as body motion, activityintensity, tilt, respiration, cardiac vibration, cardiac potential (ECG), heart-rate, body surface temperature. In this paper, we discuss the architecture of this system, including the multisensor hardware, the firmware, a mobile phone receiver unit, and assembly of the first prototype

Thermo-Magnetic, Piezo-Electric and Electroactive Energy Harvesting Devices.

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