A simple novel device for air sampling by electrokinetic capture.

BackgroundA variety of different sampling devices are currently available to acquire air samples for the study of the microbiome of the air. All have a degree of technical complexity that limits deployment. Here, we evaluate the use of a novel device, which has no technical complexity and is easily deployable.ResultsAn air-cleaning device powered by electrokinetic propulsion has been adapted to provide a universal method for collecting samples of the aerobiome. Plasma-induced charge in aerosol particles causes propulsion to and capture on a counter-electrode. The flow of ions creates net bulk airflow, with no moving parts. A device and electrode assembly have been re-designed from air-cleaning technology to provide an average air flow of 120 lpm. This compares favorably with current air sampling devices based on physical air pumping. Capture efficiency was determined by comparison with a 0.4 μm polycarbonate reference filter, using fluorescent latex particles in a controlled environment chamber. Performance was compared with the same reference filter method in field studies in three different environments. For 23 common fungal species by quantitative polymerase chain reaction (qPCR), there was 100 % sensitivity and apparent specificity of 87 %, with the reference filter taken as "gold standard." Further, bacterial analysis of 16S RNA by amplicon sequencing showed equivalent community structure captured by the electrokinetic device and the reference filter. Unlike other current air sampling methods, capture of particles is determined by charge and so is not controlled by particle mass. We analyzed particle sizes captured from air, without regard to specific analyte by atomic force microscopy: particles at least as low as 100 nM could be captured from ambient air.ConclusionsThis work introduces a very simple plug-and-play device that can sample air at a high-volume flow rate with no moving parts and collect particles down to the sub-micron range. The performance of the device is substantially equivalent to capture by pumping through a filter for microbiome analysis by quantitative PCR and amplicon sequencing

A simple novel device for air sampling by electrokinetic capture

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Microbiome 3 (2015): 79, doi:10.1186/s40168-015-0141-2.A variety of different sampling devices are currently available to acquire air samples for the study of the microbiome of the air. All have a degree of technical complexity that limits deployment. Here, we evaluate the use of a novel device, which has no technical complexity and is easily deployable. An air-cleaning device powered by electrokinetic propulsion has been adapted to provide a universal method for collecting samples of the aerobiome. Plasma-induced charge in aerosol particles causes propulsion to and capture on a counter-electrode. The flow of ions creates net bulk airflow, with no moving parts. A device and electrode assembly have been re-designed from air-cleaning technology to provide an average air flow of 120 lpm. This compares favorably with current air sampling devices based on physical air pumping. Capture efficiency was determined by comparison with a 0.4 μm polycarbonate reference filter, using fluorescent latex particles in a controlled environment chamber. Performance was compared with the same reference filter method in field studies in three different environments. For 23 common fungal species by quantitative polymerase chain reaction (qPCR), there was 100 % sensitivity and apparent specificity of 87 %, with the reference filter taken as “gold standard.” Further, bacterial analysis of 16S RNA by amplicon sequencing showed equivalent community structure captured by the electrokinetic device and the reference filter. Unlike other current air sampling methods, capture of particles is determined by charge and so is not controlled by particle mass. We analyzed particle sizes captured from air, without regard to specific analyte by atomic force microscopy: particles at least as low as 100 nM could be captured from ambient air. This work introduces a very simple plug-and-play device that can sample air at a high-volume flow rate with no moving parts and collect particles down to the sub-micron range. The performance of the device is substantially equivalent to capture by pumping through a filter for microbiome analysis by quantitative PCR and amplicon sequencing.This work was partly supported by Breakout Labs, a program of the Thiel Foundation, and partly from personal funds from Julian Gordon and Prasanthi Gandhi. This work was supported in part by the US Dept. of Energy under Contract DE-AC02-06CH11357

Empirical Study of Ground Proximity Effects for Small-scale Electroaerodynamic Thrusters

Electroaerodynamic (EAD) propulsion, where thrust is produced by collisions between electrostatically-accelerated ions and neutral air, is a potentially transformative method for indoor flight owing to its silent and solid-state nature. Like rotors, EAD thrusters exhibit changes in performance based on proximity to surfaces. Unlike rotors, they have no fragile and quickly spinning parts that have to avoid those surfaces; taking advantage of the efficiency benefits from proximity effects may be a route towards longer-duration indoor operation of ion-propelled fliers. This work presents the first empirical study of ground proximity effects for EAD propulsors, both individually and as quad-thruster arrays. It focuses on multi-stage ducted centimeter-scale actuators suitable for use on small robots envisioned for deployment in human-proximal and indoor environments. Three specific effects (ground, suckdown, and fountain lift), each occurring with a different magnitude at a different spacing from the ground plane, are investigated and shown to have strong dependencies on geometric parameters including thruster-to-thruster spacing, thruster protrusion from the fuselage, and inclusion of flanges or strakes. Peak thrust enhancement ranging from 300 to 600% is found for certain configurations operated in close proximity (0.2 mm) to the ground plane and as much as a 20% increase is measured even when operated centimeters away

Marshall Space Flight Center Research and Technology Report 2018

Many of NASAs missions would not be possible if it were not for the investments made in research advancements and technology development efforts. The technologies developed at Marshall Space Flight Center contribute to NASAs strategic array of missions through technology development and accomplishments. The scientists, researchers, and technologists of Marshall Space Flight Center who are working these enabling technology efforts are facilitating NASAs ability to fulfill the ambitious goals of innovation, exploration, and discovery

MODELLING AND FAULT DIAGNOSIS APPROACH FOR PROTON EXCHANGE MEMBRANE FUEL CELL SYSTEMS INCORPORATING AMBIENT CONDITIONS

Proton exchange membrane fuel cell (PEMFC), as a source of electrical power, provides numerous benefits such as zero carbon emission and high reliability as compared to wind and solar energy. PEMFC operates at very low temperature, high power density, and has very high durability as compared to other fuel cells. Being a non-linear power source with high sensitivity to ambient conditions variation, the prediction of PEMFC voltage and temperature is a complicated issue. The most common PEMFC models are classified as mechanistic models, semi-empirical models, and purely empirical methods. The mechanistic models are complex and require differential equations to predict the voltage and temperature of PEMFC. However, the semi-empirical models are less complicated and can be used easily for the online prediction of PEMFC outputs. Therefore, the first part of this thesis attempt to model the voltage of PEMFC using simple and effective semi-empirical equations. The initial feature of the proposed technique is to incorporate the features of a mechanistic model with less complex equations. The model considers the internal currents and the internal voltage drop associated with the PEMFC. Besides, activation and concentration voltage drops are addressed based on theoretical functions. Thus, the proposed model provides an additional benefit that not only does the output voltage model satisfy the voltage for both loaded and unloaded conditions but also the component voltage drops waveforms match with the theoretical waveforms given in the mechanistic models. The second part of the thesis focuses on modelling the PEMFC temperature. Previously most temperature models use complex equations incorporating PEMFC output voltage which is not a good option as the temperature must be predicted using only load current and ambient temperature. The model proposed in this thesis is developed through an algorithm that tracks the online changes in the load current and ambient temperature. It provides the accurate temperature of PEMFC by using a simple first-order equation with the help of a tracking algorithm. Quantum lig tening search algorithm (QLSA) is used for the optimization of constant parameters for both voltage and temperature models. The PEMFC performance is affected by factors such as variations in ambient temperature, pressure, and air relative humidity and thus they are vital for predicting PEMFC performance. The thesis also attempts to directly predict the variations in PEMFC voltage under varying ambient conditions at different load resistance. For this purpose, statistical analysis is used to propose empirical equations that can predict the variations in PEMFC voltage for varying ambient conditions. In this context of the model development, the parameters which are significantly varying with ambient changes are identified with the help of statistical regression analysis and represented as ambient temperature and air relative humidity dependent parameters. The enhanced semi-empirical voltage model is verified by performing experiments on both the Horizon and NEXA PEMFC systems under different conditions of ambient temperature and relative humidity with root mean square error (RMSE) less than 0.5. Results obtained using the enhanced model are found to closely approximate those obtained using PEMFCs under various operating conditions, and in both cases, the PEMFC voltage is observed to vary with changes in the ambient and load conditions. Inherent advantages of the proposed PEMFC model include its ability to determine membrane-water content and water pressure inside PEMFCs. The membrane-water content provides clear indications regarding the occurrence of drying and flooding faults. For normal conditions, this membrane water content ranges between 12.5 to 6.5 for the Horizon PEMFC system. Based on simulation results, a threshold membrane water- content level is suggested as a possible indicator of fault occurrence under extreme ambient conditions. Limits of the said threshold are observed to be useful for fault diagnosis within the PEMFC systems

Experimental studies on electrical and lift-force models of the ionic flyer with wire-plate electrode configuration.

Chung, Chor Fung.Thesis (M.Phil.)--Chinese University of Hong Kong, 2007.Includes bibliographical references (leaves 95-97).Abstracts in English and Chinese.Acknowledgements --- p.ivTable of Contents --- p.vList of Figures --- p.viiiList of Tables --- p.xiiiNomenclature --- p.xivChapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Development of Micro Indoor Surveillance Flyers --- p.1Chapter 1.1.1 --- Overview --- p.1Chapter 1.1.2 --- Intrinsic Problem of Surveillance Helicopters --- p.2Chapter 1.2 --- Proposed Non-moving Parts and Noiseless Flyers --- p.2Chapter 1.3 --- Organization of the remaining dissertation --- p.5Chapter Chapter 2 --- The Basic Structure of the Ionic Flyers --- p.7Chapter 2.1 --- The Components and the Structural Parameters of the Ionic Flyers --- p.7Chapter 2.2 --- Proposed Operational Principles --- p.8Chapter 2.2.1 --- The Electrohydrodynamic Effect --- p.9Chapter 2.2.2 --- The Biefeld-Brown Effect --- p.10Chapter Chapter 3 --- Overview of Corona Discharge --- p.11Chapter 3.1 --- The Gaseous Discharge --- p.11Chapter 3.2 --- "Uniform Fields, Electrical Breakdown" --- p.12Chapter 3.3 --- "Non-uniform Fields, Corona Discharge" --- p.12Chapter 3.3.1 --- Positive Corona Discharge --- p.13Chapter 3.3.2 --- Negative Corona Discharge --- p.14Chapter 3.4 --- Conclusion --- p.15Chapter Chapter 4 --- Electrical Current-Voltage Model --- p.16Chapter 4.1 --- Experimental Setup and Measurement --- p.17Chapter 4.2 --- Basic Current to Voltage Relationship --- p.18Chapter 4.2.1 --- The Three Electrical Stages of the Ionic Flyers --- p.20Chapter 4.2.2 --- Proposed Quadratic Equation for the Current to Voltage Relationship --- p.22Chapter 4.3 --- Determination of the Current Gain C and the Onset Voltage V0 by the Structural Parameters of the Ionic Flyers --- p.22Chapter 4.3.1 --- The Electrode Length (L) --- p.24Chapter 4.3.2 --- The Gap Distance between the Wire-emitter and the Plate-collector (d) --- p.27Chapter 4.3.3 --- The Wire-emitter Radius (rw) --- p.31Chapter 4.3.4 --- The Plate-collector Height (h) --- p.36Chapter 4.3.5 --- The Electrode Enclosed Area (A) --- p.38Chapter 4.3.6 --- The Electrical Environmental Constant (Ke) --- p.43Chapter 4.4 --- Summary of the Experimental Derived Current-Voltage Model --- p.45Chapter Chapter 5 --- Mechanical Lift-force Models --- p.46Chapter 5.1 --- Experimental Setup and Measurement --- p.47Chapter 5.2 --- Basic Lift-force to Voltage Relationship --- p.49Chapter 5.2.1 --- The Initial Power Dissipation (IPD) --- p.50Chapter 5.2.2 --- The Maximum Lift-force --- p.51Chapter 5.2.3 --- Proposed Third-order Equation for the Lift-force to Power Relationship --- p.52Chapter 5.3 --- Determination of the Voltage Gain J and the Barrier Voltage Vfby the Structural Parameters of the Ionic Flyers --- p.54Chapter 5.3.1 --- The Electrical Length (L) --- p.55Chapter 5.3.2 --- The Gap Distance between the Wire-emitter and the Plate-collector (d) --- p.59Chapter 5.3.3 --- The Wire-emitter Radius (rw) --- p.63Chapter 5.3.4 --- The Plate-collector Height (h) --- p.66Chapter 5.3.5 --- The Electrode Enclosed Area (A) --- p.67Chapter 5.3.6 --- The Lift-force Environmental Constant (Kf) --- p.71Chapter 5.4 --- Summary of the Experimental Derived Lift-force Model --- p.73Chapter 5.5 --- Analysis on the Force/Power Ratio of the Ionic Flyers --- p.74Chapter Chapter 6 --- Further development of the Ionic Flyers --- p.76Chapter 6.1 --- Multi-directional Force Generation --- p.76Chapter 6.1.1 --- Linear Motion --- p.77Chapter 6.1.2 --- Rotation Motion --- p.78Chapter 6.2 --- Application of MEMS Motion Sensors and Wireless Signal Transmission --- p.80Chapter Chapter 7 --- Future Work --- p.84Chapter 7.1 --- Single-Emitter-Multiple-Collector Ionic Flyers --- p.84Chapter 7.2 --- Development of Miniaturized High-voltage Power Supply --- p.88Chapter Chapter 8 --- Conclusion --- p.90Chapter 8.1 --- The Electrical Current to Voltage Model --- p.90Chapter 8.2 --- The Mechanical Lift-force to Power Model --- p.91Chapter 8.3 --- The Force/Power Ratio Model --- p.91Appendix A --- p.9

Characterisation of electrohydrodynamic fluid accelerators comprising highly asymmetric high voltage electrode geometries

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University London.Electrohydrodynamics (EHD) is a promising research field with several trending applications. Even though the phenomenon was first observed centuries ago, there is very little research until the middle 20th century, as the mechanisms behind it were very poorly understood. To this date, the majority of research is based on the development of empirical models and the presentation of laboratory experiments. This work begins with an extensive literature review on the phenomenon, clarifying conflicts between researchers throughout the history and listing the findings of the latest research. The literature review reveals that there are very few mathematical models describing even the most important parameters of the EHD fluid flow and most are either empirical or greatly simplified. As such, practical mathematical models for the assessment of all primary performance characteristics describing EHD fluid accelerators (Voltage Potential, Electric Field Intensity, Corona Discharge Current and Fluid Velocity) were developed and are begin presented in this work. These cover all configurations where the emitter faces a plane or another identical electrode and has a cylindrical surface. For configurations where the emitter faces a plane or another identical electrode and has a spherical surface, Corona Discharge Current and Fluid Velocity models have been presented as well. Laboratory experiments and computer simulations were performed and are being thoroughly presented in Chapter 4, verifying the accuracy and usability of the developed mathematical models. The laboratory experiments were performed using two of the most popular EHD electrode configurations - wire-plane and needle-grid. Finally, the findings of this research are being summarized in the conclusion, alongside with suggestions for future research. The step-by-step development of the equipotential lines mathematical model is presented in Appendix A. Appendix B covers the mathematical proof that the proposed field lines model is accurate and that the arcs are perpendicular to the surface of the electrodes and to all of the equipotential lines