Waterproof sensor system for simultaneous pressure and hot-film flow measurements

For simultaneous measurement of pressure and near surface flow conditions allowing indirect determination of wall shear stress in experimental water tunnel environment an integrated hybrid sensor system has been developed. In contrast to known approaches, which are limited to the use in gas atmosphere due to protruding electrical and fragile parts, our sensor system is waterproof shielded and embedded in epoxy resin. Furthermore an amplification circuit for the pressure signal based on a programmable gain amplifier is integrated in direct vicinity to the pressure sensor in order to minimize noise by electromagnetic disturbances. Also sensor systems with on-board digitalization of the pressure signal for direct digital read-out were realized. We present all aspects of system assembly and embedding to one waterproof module. Furthermore, read-out strategies as well as sensor test results in air and water are shown and watertightness is confirmed

Structural integrated sensor and actuator systems for active flow control

An adaptive flow separation control system is designed and implemented as an essential part of a novel high-lift device for future aircraft. The system consists of MEMS pressure sensors to determine the flow conditions and adaptive lips to regulate the mass flow and the velocity of a wall near stream over the internally blown Coanda flap. By the oscillating lip the mass flow in the blowing slot changes dynamically, consequently the momentum exchange of the boundary layer over a high lift flap required mass flow can be reduced. These new compact and highly integrated systems provide a realtime monitoring and manipulation of the flow conditions. In this context the integration of pressure sensors into flow sensing airfoils of composite material is investigated. Mechanical and electrical properties of the integrated sensors are investigated under mechanical loads during tensile tests. The sensors contain a reference pressure chamber isolated to the ambient by a deformable membrane with integrated piezoresistors connected as a Wheatstone bridge, which outputs voltage signals depending on the ambient pressure. The composite material in which the sensors are embedded consists of 22 individual layers of unidirectional glass fiber reinforced plastic (GFRP) prepreg. The results of the experiments are used for adapting the design of the sensors and the layout of the laminate to ensure an optimized flux of force in highly loaded structures primarily for future aeronautical applications. It can be shown that the pressure sensor withstands the embedding process into fiber composites with full functional capability and predictable behavior under stress

MEMS Pressure Sensors Embedded into Fiber Composite Airfoils

The paper describes the integration of pressure sensors into fiber composite in order to obtain flow sensing airfoils to be used in future aircrafts. First, the sensor design and working principle is described, followed by an embedding procedure for damage-free integration. Here the sensors are faced to stresses by vacuum and curing during the embedding process into fiber-reinforced plastic. The mechanical characteristics and the influence of external mechanical stresses on the integrated sensor are further investigated. Finally, a sensor design unsusceptible to external mechanical stresses parallel to the surface of the airfoil is proposed and verified by tensile stress tests

Sensor and Actuator Systems for Active Flow Control

An adaptive flow separation control is designed and implemented as it is an essential part of the high lift airfoil designed in B1. The state of the flow is measured nonintrusively using pressure and hot-film sensors implemented on the top side of the airfoil. To avoid flow separation on the Coanda flap a closed loop controlled system is realized using a pressurized mass flow m added to the flow on the Coanda flap. The essential designs of the sensors and actuators are described in [1]. The following article reports on the fabrication and implementation of the combined actuator and sensor system. This includes the fabrication methods, the assembling and tests prior to theirs usage on the high lift airfoil. Hereby a key aspect is the water resistance of the assemblies since they are designed to be used in a water tunnel environment. Furthermore this condition has a high impact on the physical behavior of both the sensors and actuators, which is quantified in additional tests

Intra-amoebic localization of Arcobacter butzleri as an endocytobiont of Acanthamoeba castellanii

Acanthamoeba castellanii is a free-living amoeba found mainly in humid environments and Arcobacter butzleri is an emerging zoonotic pathogen, both can establish in vitro endosymbiotic relationships in the absence of bacterial replication. We analyzed the localization of A. butzleri within A. castellanii establishing their association with endoplasmic reticulum vesicles and mitochondria. Through confocal microscopy, we observed that during the early stages of endosymbiosis, there is not colocalization between amoebic vacuoles containing A. butzleri and mitochondria or ER vesicles of A. castellanii. Considering that energy production of this bacterium occurs via metabolism of amino acids or the tricarboxylic acid cycle, these results contribute to explain the absence of bacterial replication, since A. butzleri would not have access to the nutrients found in endoplasmic reticulum vesicles and mitochondria. In addition, we observe that A. butzleri induces significantly the actin polymerization of A. castellanii during the early stages of endosymbiosis

Robust Pressure Sensor in SOI Technology with Butterfly Wiring for Airfoil Integration

Current research in the field of aviation considers actively controlled high-lift structures for future civil airplanes. Therefore, pressure data must be acquired from the airfoil surface without influencing the flow due to sensor application. For experiments in the wind and water tunnel, as well as for the actual application, the requirements for the quality of the airfoil surface are demanding. Consequently, a new class of sensors is required, which can be flush-integrated into the airfoil surface, may be used under wet conditions-even under water-and should withstand the harsh environment of a high-lift scenario. A new miniature silicon on insulator (SOI)-based MEMS pressure sensor, which allows integration into airfoils in a flip-chip configuration, is presented. An internal, highly doped silicon wiring with "butterfly" geometry combined with through glass via (TGV) technology enables a watertight and application-suitable chip-scale-package (CSP). The chips were produced by reliable batch microfabrication including femtosecond laser processes at the wafer-level. Sensor characterization demonstrates a high resolution of 38 mVV-1 bar-1. The stepless ultra-smooth and electrically passivated sensor surface can be coated with thin surface protection layers to further enhance robustness against harsh environments. Accordingly, protective coatings of amorphous hydrogenated silicon nitride (a-SiN:H) and amorphous hydrogenated silicon carbide (a-SiC:H) were investigated in experiments simulating environments with high-velocity impacting particles. Topographic damage quantification demonstrates the superior robustness of a-SiC:H coatings and validates their applicability to future sensors

Interaction between zoonotic bacteria and free living amoebas. A new angle of an epidemiological polyhedron of public health importance?

Since many years ago, several studies reported the endosymbiosis between bacteria species and free living amoebas. However, the mechanisms involved in the bacteria penetration and release from the amoeba are not clear. The free living amoebas especially Acanthamoeba castellanii are considered important bacteria predators, for that reason they have a significant role in the control of microbial populations in particular environments. However, some bacteria are capable to avoid the digestion from the amoeba and take advantage of this intimate relationship. A. castellanii is an ubiquitous organism present in aquatic and soil environments. Particularly in humid environments they are found sharing with different bacteria species, including those pathogen for humans transmitted by animals. The interaction between the bacteria and the amoebas may result in a close endosymbiotic relationship that allows the bacteria to survive inside the vacuoles of the protozoa for days or months. The purpose of this review is to describe the relevant aspects of the interaction between A. castellanii and different bacteria species, mostly those with relevance in public health and related with zoonosis

Transcriptional analysis of flagellar and putative virulence genes of Arcobacter butzleri as an endocytobiont of Acanthamoeba castellanii

Arcobacter butzleri is an emerging foodborne zoonotic pathogen that has been isolated from environmental water sources. This pathogen establishes in vitro endosymbiotic relationships with Acanthamoeba castellanii, a free-living amoeba found in environmental matrices such as soil and water. The principal aim of this study was to analyse the transcriptional pattern of flagellar (flaA-flaB-flgH-motA) and other putative virulence genes (ciaB-cadF-mviN-pldA) of A. butzleri during its interaction with A. castellanii by quantitative real-time PCR. The transcriptional analysis showed up-regulation of all genes analysed before A. butzleri became established as an endocytobiont of A. castellanii. In contrast, while A. butzleri remains an endocytobiont, a significant and sustained decrease in the transcription of all analysed genes was observed. Our findings suggest that A. butzleri requires a biphasic transcriptional pattern of flagellar and other putative virulence genes to establish an endosymbiotic relationship with A. castellanii