Orthogonal Sensors Research Articles

New ferromagnetic core shapes for induction sensors

Abstract. Induction sensors are used in a wide range of scientific and industrial applications. One way to improve these is rigorous modelling of the sensor combined with a low voltage and current input noise preamplifier aiming to optimize the whole induction magnetometer. In this paper, we explore another way, which consists in the use of original ferromagnetic core shapes of induction sensors, which bring substantial improvements. These new configurations are the cubic, orthogonal and coiled-core induction sensors. For each of them we give modelling elements and discuss their benefits and drawbacks with respect to a given noise-equivalent magnetic induction goal. Our discussion is supported by experimental results for the cubic and orthogonal configurations, while the coiled-core configuration remains open to experimental validation. The transposition of these induction sensor configurations to other magnetic sensors (fluxgate and giant magneto-impedance) is an exciting prospect of this work.

Crack Detection Using Fluxgate Magnetic Field Sensor

In this study, the variation of the magnetic ux distribution in a magnetised ferromagnetic material which has in homogeneity as a crack is studied. An orthogonal uxgate magnetic eld sensor was used in the inspection of cracks. In the uxgate sensor, the sensing element (Co0.94Fe0.06)72.5Si12.5B15 amorphous ferromagnetic wire was placed inside a pickup coil winding with 50 μm copper wire and connected to a signal generator and the output from pick-up coil was detected using a lock-in ampli er. The surface pro le of magnetic materials with a crack was obtained using a specially designed 3-dimensional moving system. A large decrease in the output voltage of the sensor was observed when the sensor was moved on the top of the crack, after the further movement of the sensor the output voltage came back to the previous value.

Nano-level instrumentation for analyzing the dynamic accuracy of a rolling element bearing

The rotational performance of high-precision rolling bearings is fundamental to the overall accuracy of complex mechanical systems. A nano-level instrument to analyze rotational accuracy of high-precision bearings of machine tools under working conditions was developed. In this instrument, a high-precision (error motion < 0.15 μm) and high-stiffness (2600 N axial loading capacity) aerostatic spindle was applied to spin the test bearing. Operating conditions could be simulated effectively because of the large axial loading capacity. An air-cylinder, controlled by a proportional pressure regulator, was applied to drive an air-bearing subjected to non-contact and precise loaded axial forces. The measurement results on axial loading and rotation constraint with five remaining degrees of freedom were completely unconstrained and uninfluenced by the instrument's structure. Dual capacity displacement sensors with 10 nm resolution were applied to measure the error motion of the spindle using a double-probe error separation method. This enabled the separation of the spindle's error motion from the measurement results of the test bearing which were measured using two orthogonal laser displacement sensors with 5 nm resolution. Finally, a Lissajous figure was used to evaluate the non-repetitive run-out (NRRO) of the bearing at different axial forces and speeds. The measurement results at various axial loadings and speeds showed the standard deviations of the measurements' repeatability and accuracy were less than 1% and 2%. Future studies will analyze the relationship between geometrical errors and NRRO, such as the ball diameter differences of and the geometrical errors in the grooves of rings.

Azimuth-elevation direction finding using a microphone and three orthogonal velocity sensors as a non-collocated subarray

An acoustic vector-sensor consists of three identical but orthogonally oriented acoustic particle-velocity sensors, plus a pressure sensor-all spatially collocated in a point-like geometry. At any point in space, this tri-axial acoustic vector-sensor can sample an acoustic wavefield as a 3 × 1 vector, instead of simply as a scalar of pressure. This vector, after proper self-normalization, would indicate the incident wave-field's propagation direction, and thus the incident emitter's azimuth-elevation direction-of-arrival. This "self-normalization" direction-of-arrival estimator is predicated on the spatial-collocation among the three particle-velocity sensors and the pressure-sensor. This collocation constriction is relaxed here by this presently proposed idea, to realize a spatially distributed acoustic vector-sensor, allowing its four component-sensors to be separately located. This proposed scheme not only retains the algorithmic advantages of the aforementioned "self-normalization" direction-of-arrival estimator, but also will significantly extend the spatial aperture to improve the direction-finding accuracy by orders of magnitude.

Zwitterionic polymer-modified silicon microring resonators for label-free biosensing in undiluted humanplasma

A widely acknowledged goal in personalized medicine is to radically reduce the costs of highly parallelized, small fluid volume, point-of-care and home-based diagnostics. Recently, there has been a surge of interest in using complementary metal-oxide-semiconductor (CMOS)-compatible silicon photonic circuits for biosensing, with the promise of producing chip-scale integrated devices containing thousands of orthogonal sensors, at minimal cost on a per-chip basis. A central challenge in biosensor translation is to engineer devices that are both sensitive and specific to a target analyte within unprocessed biological fluids. Despite advances in the sensitivity of silicon photonic biosensors, poor biological specificity at the sensor surface remains a significant factor limiting assay performance in complex media (i.e. whole blood, plasma, serum) due to the non-specific adsorption of proteins and other biomolecules. Here, we chemically modify the surface of silicon microring resonator biosensors for the label-free detection of an analyte in undiluted human plasma. This work highlights the first application of a non-fouling zwitterionic surface coating to enable silicon photonic-based label-free detection of a protein analyte at clinically relevant sensitivities in undiluted human plasma.

Joint Space-Time Parameter Estimation for Underwater Communication Channels with Velocity Vector Sensor Arrays

In this paper, the problem of joint space-time parameter estimation for underwater wireless communication channels in a multipath environment is addressed. We consider the receive antenna array to be configured with multiple vector sensors, each of which consists of a pair of orthogonal velocity sensors. A quadrilinear model for the channel is formulated, and a quadrilinear decomposition method developed for joint angle and delay estimation (JADE). In addition, a computationally simple subspace-based algorithm is proposed for the problem under consideration. The basic idea behind this algorithm is to use the angle information embedded in the velocity vector sensors to start two polynomial rooting procedures for the angle and delay in succession. Simulation results are finally presented to verify the efficacy of the proposed algorithms.

Towards Higher Reliability in Cantilever-Based Sensing - High Data Rate and Orthogonal Sensors

not Available.

Spatial shape reconstruction using orthogonal fiber Bragg grating sensor array

With distributed orthogonal fiber Bragg grating (FBG) sensor arrays used as modular detection units, an implementation method for deformation detection and spatial shape reconstruction of a frame model structure was proposed in this paper. After brief introduction of curvature detection principle of FBG sensor, the design, fabrication and encapsulation of the FBG modular detection unit were illustrated detailedly. Every unit was composed of four optical fibers, each containing an array of FBG strain sensors. In addition, the method and procedure of the reconstruction algorithm of three dimensional spatial curve based on orthogonal curvature were also described in detail, as well as discrete curvature continuity method. The constructed algorithm was applied to reconstruction the vibration deformation of the experimental frame model, in which four FBG modular detection units were embedded. Afterward, experimental test and verification were performed for static bending and dynamic excitation of the frame model structure, using the developed experiment system. And experimental results verified the feasibility and effectiveness of deformation detection and spatial shape reconstruction based on orthogonal FBG sensor array. Moreover, the results indicated that the proposed method can provide useful research thinking for the further study of active monitoring of flexible space structures.

Femtosecond laser machining of high permeability permalloy

For the multi-core orthogonal fluxgate magnetic field sensor, in which the sensor sensitivity increases exponentially with the number of cores in the sensing element, a micro/nano multi-core structured high permeability magnetic material, such as permalloy, is expected. A permalloy sheet can be formed into such a multi-core structure material by laser machining if the magnetic properties are not damaged. In this study, the effects of femtosecond laser machining of permalloy on the magnetic properties of the machined permalloy workpiece are investigated. The results show that changes in the coercivity of the machined permalloy workpiece are dependent on the surface morphology modification induced by the femtosecond laser. It appears that there is a laser fluence threshold for the permalloy coercivity to decrease to a minimum (as indicated by the formation of ripples on the machined surface), beyond which the coercivity will increases with the laser fluence at a gradual rate.

Demagnetization Performance According to Vertical and Horizontal Magnetic Bias Fields

Demagnetization for a tube sample which was made of a galvanized steel sheet was performed by applying a magnetic field with a decrement to remove the remanent magnetization of the material. An orthogonal fluxgate magnetic field sensor was used to measure a magnetic field created from a ferromagnetic material. To evaluate the remanent magnetization, the measured magnetic fields were separated into two magnetic field components by the remnant magnetization and the induced one. The horizontal and the vertical bias fields should be controlled separately during demagnetization to remove the horizontal and the vertical components of the remanent magnetization of the tube sample.

Optical tomography: Velocity profile measurement using orthogonal and rectilinear arrangements

In tomography applications, flow velocity is an important flow characteristic for analysis. Excessively high particle velocity will cause high energy consumption, severe pipeline wear and particle degradation. This paper demonstrates a method of measuring velocity profile using the orthogonal and rectilinear sensors. Several experiments have been conducted to measure the velocity using those sensors and the results will be described at the end of the paper.

Applications of rhythm algorithm for periodic broadband signals

Rhythm algorithm, recently published in J. Acoust. Soc. Am. 129(3), 2011 was developed for any periodic broadband signals. This algorithm was applied in human and animal footsteps studies for signals from a node of orthogonal sensors and for underwater signals of sperm mammals clicks measured with hydrophones. Some new applications of this rhythm algorithm are presented and discussed. The rhythm algorithm was applied for water breaking waves on a lake shore. The signals were from a node of two orthogonal sensors placed on the lake shore. This node had a narrow band ultrasonic microphone and a Doppler sonar unit. The narrow band ultrasonic microphone showed detectable levels of ultrasonic signals for breaking waves while Doppler sonar showed maximum wave velocities. Signals from this node were recorded and processed simultaneously with the rhythm algorithm. Another application of this rhythm algorithm for music periodic sound is presented also. In this case, it was possible to see the music rhythms and variations of these rhythms with time using short term Fourier transform.

Rhythm analysis of orthogonal signals from human walking

In physical terms, periodic movements of a human body resulting from walking produce a pulse sequence with repetition time T(1) (instant cadence frequency, 1/T(1)) and duration time T(2). Footstep forces generate periodic T(1) broadband seismic and sound signals due to the dynamic forces between the foot and the ground/floor with duration time T(2), which is equal to the time interval for a single footstep from heel strike to toe slap and weight transfer. In a human gait study (for normal speeds of walking), T(1) was detected as 0.5-0.69 s and double limb support takes up about 12% of the gait cycle (2T(1)), so T(2) is greater than 0.12-0.17 s. Short range (of about 50 m) signatures for 30 humans were recorded simultaneously by four orthogonal sensor types at two locations. The sensor types were active Doppler sonar/radar and passive seismic/acoustics. Analysis of signals from these four sensors collected for walking humans showed temporal synchronization and stability of the cadence frequencies, and the cadence frequency from each sensor was equivalent. The time delay between signals from these sensors due to the differences in speeds of propagation for seismic, sound, and electromagnetic waves allows calculation of the distance from a walker to the sensor suite.

Analysis and Design of a FBG Intelligent Flexible Structure Based on Orthogonal Curvatures

With the research model of intelligent flexible structure by Fiber Bragg Grating (FBG) sensor, the dissertation deals with a design and manufacture methodology for FBG sensor array based on orthogonal curvatures, and offers the experiential analysis and validation. On basis of brief introduction to the principle of FBG sensor to detect curvatures and methodology of structural morphological reconstruction, detailed description of design solutions and manufacture processes have yielded based on orthogonal distributed FBG sensor array which includes some technological parts as the configuration of orthogonal distributed FBG sensor array, the technology of perception range-proportion and orthogonally contrapuntal-pasting, the method of casing and encapsulation, calibration for model structure and so on. Fitting and reconstructing of the model structure and validation of visualization is split up based on intelligent flexible model structure we make and experimental platform we develop. Thus, the result of the experiment adequately shows the FBG intelligent flexible structure designed and produced in the dissertation gives a splendid on fitting and reconstruction, in which the feasibility and validity of the design methodology and key technology has been proved deeply.

A fully integrated GaAs-based three-axis Hall magnetic sensor exploiting self-positioned strain released structures

In this work, we demonstrate a fully integrated three-axis Hall magnetic sensor by exploiting microfabrication technologies applied to a GaAs-based heterostructure. This allows us to obtain, by the same process, three mutually orthogonal sensors: an in-plane Hall sensor and two out-of-plane Hall sensors. The micromachined devices consist of a two-dimensional electron gas AlGaAs/InGaAs/GaAs multilayer which represents the sensing structure, grown on the top of an InGaAs/GaAs strained bilayer. After the release from the substrate, the strained bilayer acts as a hinge for the multilayered structure allowing the out-of-plane self-positioning of devices. Both the in-plane and out-of-plane Hall sensors show a linear response versus the magnetic field with a sensitivity for current-biased devices higher than 1000 V A−1 T−1, corresponding to an absolute sensitivity more than 0.05 V T−1 at 50 µA. Moreover, Hall voltage measurements, as a function of the mechanical angle for both in-plane and out-of-plane sensors, demonstrate the potential of such a device for measurements of the three vector components of a magnetic field.

Multidimensional Dynamic Displacement and Strain Measurement Using an Intensity Demodulation-Based Fiber Bragg Grating Sensing System

We set up a multidimensional dynamic fiber Bragg grating (FBG) displacement and strain sensing system. The proposed sensing system allows the FBGs to have the ability to measure transient point-wise displacement (in-plane and out-of-plane) and strain responses simultaneously with high sensitivity. The sensing system employs a long-period fiber grating filter and two FBG filters to dynamically demodulate the responses of the FBG sensors. To demonstrate the dynamic sensing ability and the application of the proposed system, the transient elastic wave propagation in a solid subjected to vertical and lateral impact loadings are investigated. A laser Doppler vibrometer is employed in our experiments simultaneously to verify the transient responses of out-of-plane particle transient motions measured by the out-of-plane FBG displacement sensor. The in-plane displacement measurement ability is demonstrated by the responses obtained by two geometrically orthogonal in-plane FBG displacement sensors. Dynamic strain sensing ability of our all-fiber sensing system is also demonstrated. The experimental results both in time domain and frequency domain show that the proposed FBG sensing system is capable of performing real-time displacement (out-of-plane and in-plane) and strain measurements.

Spread Spectrum Orthogonal Frequency Coded SAW Tags and Sensors Using Harmonic Operation

This paper presents a preliminary investigation of orthogonal frequency coding (OFC) surface acoustic wave tags and sensors at a 500- and 900-MHz operational frequency range using conventional contact lithography techniques. The higher frequency devices are achieved using second harmonic operation; eliminating the need for advanced lithography techniques. The objective of this effort is to increase the technology readiness level of wideband OFC tags at higher frequencies. Measured device results are presented and compared with coupling of modes model predictions to demonstrate performance. The fundamental and harmonic device response is compared for devices designed for operation in the 900-MHz frequency band. The experimental correlation against an ideal matched filter is also presented.

Determination of the location of a sound source in three dimensional based on acoustic vector sensors on the ground.

An acoustic vector sensor (AVS) consists of three orthogonal particle velocity sensors in combination with a sound pressure microphone. In several publications it has been proven that multiple sources can be located in three dimensions with a single AVS. In this paper it will be shown that it is possible to measure the instantaneous location (this means bearing, elevation, and range) of a single dominant sound source in three dimensional space as well as the angle dependent local ground impedance. Theory as well as results of experiments will be presented.

Fully integrated three-axis Hall magnetic sensor based on micromachined structures

In this work we propose a new technological approach to fabricate a fully integrated three-axis Hall magnetic sensor. The three axial device fabrication process exploits microfabrication technologies applied to a GaAs-based heterostructure to obtain at the same time three mutually orthogonal sensors: an in-plane Hall sensor and two out-of-plane Hall sensors. A two dimensional electron gas (2DEG) AlGaAs/InGaAs/GaAs multilayered structure constitutes the sensing medium of the micromachined devices, whereas an underlying strained InGaAs/GaAs bilayer allows the self-positioning of the out-of-plane devices by virtue of sacrificial layer removal and strain release. The in-plane and out-of-plane Hall sensors, show an excellent linearity versus the magnetic field with an absolute sensitivity as high as 0.03 V/T at 0.6 V bias voltage.

Multisensor Hot Wire Vorticity Probe Measurements of the Formation Field of Two Corotating Vortices

Experimental evidence is reported, regarding the formation of a pair of co-rotating tip vortices by a split wing configuration, consisting of two half wings at equal and opposite angles of attack. Simultaneous measurements of the three-dimensional vector fields of velocity and vorticity were conducted on a cross plane at a downstream distance corresponding to 0.3 cord lengths (near wake), using an in-house constructed 12-sensor hot wire anemometry vorticity probe. The probe consists of three closely separated orthogonal 4-wire velocity sensor arrays, measuring simultaneously the three-dimensional velocity vector at three closely spaced locations on a cross plane of the flow filed. This configuration makes possible the estimation of spatial velocity derivatives by means of a forward difference scheme of first order accuracy. Velocity measurements obtained with an X-wire are also presented for comparison. In this near wake location, the flow field is dictated by the pressure distribution established by the flow around the wings, mobilizing large masses of air and leading to the roll up of fluid sheets. Fluid streams penetrating between the wings collide, creating on the cross plane flow a stagnation point and an “impermeable” line joining the two vortex centres. Along this line fluid is directed towards the two vortices, expanding their cores and increasing their separation distance. This feeding process generates a dipole of opposite sign streamwise mean vorticity within each vortex. The rotational flow within the vortices obligates an adverse streamwise pressure gradient leading to a significant streamwise velocity deficit characterizing the vortices. The turbulent flow field is the result of temporal changes in the intensity of the vortex formation and changes in the position of the cores (wandering).