Performance degradation effect countermeasures in residence times difference (RTD) fluxgate magnetic sensors

This paper aims to explore the detection defect of residence times difference (RTD) fluxgate working in low-power mode and present the countermeasures for sensor resolution improvement and linearity enhancement. The main defects are amplitude and symmetry changes induced in the output spikes of fluxgate probe due to the magnetic field. These defects lead to thresholds deviation and asymmetry, then cause severe performance degradation especially on detection resolution and linearity according to the RTD theory. To overcome such effects, the optimized RTD method based on voltage extraction and feedback technology is proposed to implement magnetic field compensation and achieve a zero-field running regime of the RTD fluxgate. In this regard, the sensor linearity is improved by a factor of 38, and the resolution degradation effect is suppressed more than 6 times, verified by the laboratory experiments. The optimized detection method proposed in this paper demonstrated a great potential to achieve lower power consumption and will make the RTD fluxgate more promising technology among bio-magnetic applications

Fluxgate Impedanzanalysator für Empfindlichkeits- und Rauscheigenschaften

The fluxgate sensor is known as a precision, low noise, reliable magnetic field sensor, and has been developed for decades. The sensor has been used in measurement systems, which need high precision in magnetic field measurements such as in satellite systems, navigation, and geological exploration. Although there are lots of competitors to the fluxgate such as Hall, GMR, and AMR sensors, the development of fluxgate sensors is still continuing to get better performance. There are still many potential developments of fluxgate sensors, to make it better than what is nowadays commercially available. The main big potential is the development of sensitivity and noise properties. Many efforts have been done to obtain this such as treatment of the core material, tuning the coils, making a new model of output voltage involving the core permeability or coil inductance, and the electronics signal processing optimization. The new model is intended to obtain the good permeability, inductance, or any other parameters for the best sensitivity and noise performance by designing the geometry. This thesis describes the development of a novel fluxgate analyzer for fluxgate sensor characterization, which is used for modeling the fluxgate sensor output to study the parameters that affect fluxgate sensor output. The characterization is based on the impedance of fluxgate sensor coils, which contain high permeability material as fluxgate sensor core. The non-linearity of the core permeability becomes the crucial and important topic in designing the impedance analyzer. The instrument has been designed to comply with the fluxgate sensor characteristics, which has low impedance and high core permeability. For that reason, the fluxgate analyzer has been designed with low output impedance and to be able to provide a very low current for fluxgate impedance measurement. A model from the impedance measurement is used to calculate and predict the fluxgate output sensitivity. Together with other physical parameters such as winding number and length, the model is utilized to set-up an equation to calculate the fluxgate output voltage and sensitivity.Der Fluxgate-Sensor ist als präziser, rauscharmer, zuverlässiger Magnetfeldsensor bekannt, und wird seit Jahrzehnten entwickelt. Der Sensor wurde in Messsystemen verwendet, die eine hohe Präzision bei Magnetfeldmessungen erfordern, beispielsweise bei Satellitensystemen, bei der Navigation und bei der geologischen Erkundung. Obwohl für das Fluxgate viele Konkurrenten wie Hall-, GMR- und AMR-Sensoren vorhanden sind, wird die Entwicklung an Fluxgates für eine bessere Performance weiter geführt. Es gibt noch viele mögliche Entwicklungen an Fluxgate-Sensoren, um sie besser zu machen als die, die heutzutage kommerziell erhältlich sind. Das wichtigste und größte Potenzial ist die Verbesserung der Empfindlichkeits- und Rauscheigenschaften. Viele Anstrengungen wurden unternommen, um dies zu erreichen, wie eine Bearbeitung des Kernmaterials, ein Abstimmen der Spulen, ein neues Modell der Ausgangsspannung, die die Kernpermeabilität oder Spuleninduktivität beinhaltet, und die Optimierung der Elektroniksignalverarbeitung.Das neue Modell soll die gute Permeabilität, Induktivität oder andere Parameter für die beste Empfindlichkeit und Rauschleistung durch die Gestaltung der Geometrie enthalten. Diese Arbeit beschreibt die Entwicklung eines neuartigen Fluxgate-Analysators zur Fluxgate-Sensorcharakterisierung. Dieser wird zur Modellierung des Fluxgate-Sensorausgangs verwendet, um die Parameter zu untersuchen, die den Fluxgate-Sensorausgang beeinflussen. Die Charakterisierung basiert auf der Impedanz von Fluxgate-Sensorspulen, die als Fluxgate-Sensorkern hochpermeables Material enthalten. Die Nichtlinearität der Kernpermeabilität wird zum entscheidenden und wichtigen Thema beim Entwurf des Impedanzanalysators. Das Gerät wurde so entwickelt, dass es den Eigenschaften des Fluxgate-Sensors entspricht, der eine niedrige Impedanz und eine hohe Kernpermeabilität aufweist. Aus diesem Grund wurde der Fluxgate-Analysator mit einer niedrigen Ausgangsimpedanz entworfen und kann einen sehr niedrigen Strom für die Fluxgate-Impedanzmessung bereitstellen. Ein Modell aus der Impedanzmessung wird verwendet, um die Fluxgate-Ausgangsempfindlichkeit zu berechnen und vorherzusagen. Zusammen mit anderen physikalischen Parametern wie Wicklungszahlen und -länge wird das Modell verwendet, um eine Gleichung zur Berechnung der Fluxgate-Ausgangsspannung und -empfindlichkeit zu erstellen

Report on active and planned spacecraft and experiments

Information concerning active and planned spacecraft and experiments is included. The information covers a wide range of scientific disciplines: astronomy, earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. These spacecraft projects represent the efforts and fundng of individual countries as well as cooperative arrangements among different countries

The Space Investigations Documentation System (SIDS) report

Descriptions of past and future flight experiments are provided, along with information regarding the spacecraft and the principal investigator

On-Chip Magnetorelaxometry Using Planar Hall Effect Magnetic Field Sensors

I de senere år er der opstået en interesse for at udvikle lab-on-a-chip systemer, der potentielt kan benyttes som point-of-care biosensorer. Fordelen ved point-of-care biosensorer er at de straks kan analysere prøver udtaget fra patienter og der derved undgas spildtid ved at sende prøven til et laboratorium for at blive analyseret. Mange forskellige udlæsningsmetoder kan benyttes til point-of-care biosensorer, heriblandt magnetiske udlæsningsmetoder, hvilke er specielt interessante da de fleste biologiske prøver er umagnetiske. Målet med denne afhandling er at udforske mulighederne og begrænsningerne ved at brugeplanar Hall effekt magnetisk felt sensorer til at måle magnetorelaksometry af magnetiske kugler. Dette kan benyttes som udlæsningsmetode for volumen-baseret biodetektion, ved at måle ændringer af magnetiske kuglers hydrodynamiske diameter forsaget af binding til analytter. Traditionelt måles magnetorelaksometry ved at måle AC susceptibilitet med store dyre instrumenter, der ikke let kan integreres med lab-on-a-chip systemer. Fordelene ved planar Hall effekt sensorer er at de er små og derfor let integreres som udlæsningsmetode i lab-on-a-chip systemer.I denne afhandling er den teoretiske baggrund udledt for hvordan magnetorelaksometry måles med planar Hall effect sensorer. Dette inkluderer en beskrivelse af relaksationsmekanismer for magnetiske kugler i både tids og frekvens domænerne, hvordan planar Hall effekt sensorer kan måle relaksation af magnetiske kugler uden brug af eksterne magnetfelter samt estimater for dekræfter, der påvirker magnetiske kugler i nærheden af planar Hall effekt sensorer.Temperatur afhængigheden af målinger med planar Hall effekt sensorer er undersøgt. Herunder hvordan sensor signalerne afhænger af temperaturen og hvordan den Brownske relaksation af magnetiske kugler påvirkes. Det vises at magnetiske kuglers hydrodynamiske diametre kan bestemmes udfra AC susceptibilitetsmålinger med planar Hall effect sensorer, når temperaturenog væskens viskositet er kendte.AC susceptibilitetsmålinger på magnetiske kugler er påvist mulige for to forskellige sensor geometrier, planar Hall effekt kryds sensorer og planar Hall effekt bro sensorer. Med de benyttede geometrier, viste bro sensorerne at give seks gange signalet målt med kryds sensorerne uden at tilføje signifikant mere støj til målingerne. Et studie hvor koncentrationen af magnetiske kugler med diametre på 40 nm blev varieret viste, at hydrodynamiske diametre kan bestemmes for koncentrationer over 64 μg/mL, og tilstedeværelsen af magnetiske kugler kan spores ned til 16 μg/mL. Når det er sagt, så giver højere koncentrationer større signaler og hermed kan de hydrodynamiske diametre bestemmes mere nøjagtigt.Herudover er det påvist at planar Hall effekt sensorer kan benyttes i frekvens området fra DC til 1 MHz. Dette brede frekvensområde tillader at måle den Brownske relaksation of magnetiske kugler med diametre fra 10 nm til 250 nm. Det viste sig dog at 250 nm ikke er egnede til målinger med planar Hall effect sensorer, da de bliver indfanget af magnetostatiske kræfter fra sensor stacken.Eksperimenter udført med magnetiske kugler med streptavidin blandet med biotin-konjugeret bovine serum albumin viser at planar Hall effekt sensorer kan måle tilstedeværelsen af biotinkonjugeret bovine serum albumin i nanomolar området. Til slut er målinger med planar Hall effect sensorer foretaget for at detektere DNA coils fremstillet ved rolling circle amplicering. Disse resultater viser at DNA coils kan detekteres ned til koncentrationer pa 4 pM, hvilket er sammenligneligt med hvad der er opnået på lignende prøver målt med kommercielt tilgængeligt måleudstyr. Planar Hall effect sensorer har dog den fordel at de er betydelig mindre, simplere og potentielt billigere.In recent years there has been an increasing interest in developing lab-on-a-chip devices that potentially can be used as point-of-care biosensors. The advantage of point-of-care biosensors is that they can analyze samples obtained from patients immediately, cutting away the time needed for sending the sample to a laboratory for analysis. Many different read out techniques can be used for point-of-care biosensors, among these are magnetic readouts, which are especially interesting because most biological samples are non-magnetic. The goal of this thesis is to explore the possibilities and limitations of using planar Hall effect magnetic field sensors to measure magnetorelaxomety of magnetic beads. This can be used as the readout principle for volume-based biosensing, by detecting changes in the hydrodynamic diameter of magnetic beads due to binding of analytes. Traditionally magnetorelaxomety is measured by AC susceptibility measurements performed with large expensive instruments, which cannot easily be integrated with a lab-on-a-chip system. The advantages of planar Hall effect sensors are that they are small and can easily be integrated as the readout method for a lab-ona-chip device.In this thesis, the theoretical background for how magnetorelaxometry is measured using planar Hall effect sensors is derived. This includes a description of the relaxation mechanism of magnetic beads in both the time and frequency domains, how the planar Hall effect sensors are utilized for measuring the relaxation of magnetic beads without the need of any external fields and estimates of the forces that influence magnetic beads near a planar Hall effect sensor. The temperature dependence of measurements using planar Hall effect sensors is investigated.This is done both with respect to how the sensor signals depend on temperature and how temperature influences the Brownian relaxation of magnetic beads. It is shown that the hydrodynamic diameter of the magnetic beads can be extracted from AC susceptibility measurements with planar Hall effect sensors when the temperature and dynamic viscosity of the liquid in which the beads are suspended are known.AC susceptibility measurements of beads are shown to be possible using two different sensor geometries, planar Hall effect cross sensors and planar Hall effect bridge sensors. For the geometries used, the bridge sensor yields an amplification of the bead signals by a factor of six compared to the cross sensor without significant noise being added to the measurements. A study varying the concentration of magnetic beads with a nominal diameter of 40 nm shows that the hydrodynamic diameters can be extracted reliably for concentrations down to 64 _g/mL, and the presence of beads can be detected down to 16 _g/mL. However, higher bead concentration leads to higher signal and thereby hydrodynamic diameters can be extracted more reliably.Furthermore, it is shown that the planar Hall effect can be operated at frequencies ranging from DC to 1 MHz. This wide range of frequencies allows for measuring Brownian relaxation of magnetic beads with nominal diameters ranging from 10 nm to 250 nm. However, it is not appropriate to use beads as large as 250 nm with the planar Hall effect sensors as they are captured by magnetostatic forces from the sensor stack.Experiments with streptavidin coated beads and biotin-conjugated bovine serum albumin show that planar Hall effect sensors can detect the presence of biotin-conjugated bovine serum albumin in the nanomolar range. Finally, measurements are performed to detect DNA-coils formed by rolling amplification using planar Hall effect bridge sensors. These results show that DNA-coils can be detected in concentrations down to 4 pM, which is comparable to what has been obtained for similar samples using commercially available measurement equipment. However, the planar Hall effect sensor have the advantage of being considerably smaller, much more simple and potentially cheaper.<br/

OGO program summary

An overview of the OGO program is presented. Brief descriptions of the six OGO spacecraft, and the experiments on each are included

The design, construction, and commissioning of the KATRIN experiment

The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [1] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [2]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns