SENSORS, 2002 IEEE

The development work of a novel planar mesh type micro-magnetic sensor for the quality inspection of electroplated materials has been reported in this paper. The sensor is suitable for inspecting the quality of electroplated materials. The results obtained from the analytical model for the calculation of transfer impedance of the sensor have been discussed. The transfer impedance is used for the q... View full abstract»

The impedance of a coil in proximity of any metal surface is a complex function of many parameters including near-surface properties (such as conductivity, permeability, liftoff etc.) of the material. The transfer impedance (i.e., the ratio between the sensing voltage and the exciting current) of the planar type micromagnetic sensors consisting of exciting and sensing coil is used for the estimati... View full abstract»

We have patterned multilayers of amorphous magnetic foils of Metglas/sup /spl reg// 2714a (cobalt-based) and Cu foil into microstructures of different sizes. We have studied the GM effect in these structures, and we have characterized the behavior of the relative permeability as a function of frequency and magnetic field. We obtain GMI ratios [Z/sub max/-Z(B/sub sat/)]/Z(B/sub sat/) up to 800% and... View full abstract»

This paper proposes an energy storage and attitude control system for micro-electromechanical systems (MEMS) in spacecraft using a high-temperature superconductor (HTS) magnet bearing system. This system consists of an HTS-magnet flywheel energy storage system and a brushless motor/generator. The HTS flywheel, which permits high angular momentum storage since its drag torque is nearly velocity-ind... View full abstract»

Integrated Hall plates show self-induced offset due to the current flow in its current leads. The magnetic field surrounding the current leads causes a magnetic offset signal, while their resistive heating causes thermoelectric offset voltages. This paper reports experimental results on these two effects. They are obtained using a novel test structure enabling one to separate the two contributions... View full abstract»

Quality and resolution of integrated microsystems using Hall sensors dedicated to an angular encoder are strongly dependent on the accuracy of relative position of Hall sensors and on the offset of electronic frontend circuitry. In this paper, we describe a CMOS microsystem built on two integrated circuits. This contactless encoder microsystem gives three sine and square signals with a phase shift... View full abstract»

Measuring distances, position and travel using the inductive proximity sensors (IPS) based on contactless target-approach detection is a widely used technique. In comparison to optical and capacitive technologies the biggest advantage of inductive sensors in industrial applications is the immunity against oil, water and dirt. In addition, current developments and trends in the industrial fields, e... View full abstract»

A novel DC/AC current sensor works on the fluxgate principle. The core in the form of a 7/10 mm ring made of electrodeposited Permalloy is sandwiched into the middle of the printed circuit board (PCB), while the sensor excitation winding is also integrated in the copper layers of the PCB. In order to lower the sensor power consumption, the excitation winding was tuned by a parallel capacitor. The ... View full abstract»

Sensitivity of conventional Hall sensors is strongly limited by the well known short-circuit effect. Many researches were devoted to reduce offset and noise but few works were carried out to improve sensitivity. Here, a new shape of integrated horizontal Hall device is presented. This particular shape has been developed to minimize the short-circuit effect of the sensor, allowing one to shrink the... View full abstract»

Parameters in time-varying linear or non-linear circuits could be varied in such a way as to induce an oscillation. Because this oscillation is due entirely to the variation of the circuit parameters it is usually referred to as "parametric oscillation". We explain the phenomenon of parametric oscillation and establish the common basis for the configuration of several classes of sensors. In partic... View full abstract»

Resulting from the magnetoelastic phenomena, measurement of magnetic properties of ferromagnetic materials has found many applications in evaluation of stress and force. Therefore a reliable way of measuring magnetic field is imperative. Measurements of initial magnetization curve and hysteretic curve using three Hall sensors placed at different distances from the surface of the material are compa... View full abstract»

A new system configuration of magnetic leakage flux testing using a GMR line sensor and a rotating magnetic field is proposed. The GMR line sensor, which we developed, can visualize a magnetic field distribution by a single axis scan. Directional sensitivity and frequency characteristics of the multilayer GMR element are shown. Leakage flux is generated near a defect. Using a rotating magnetic fie... View full abstract»

This paper deals with magnetic position sensors compatible with large area electronics using polycrystalline silicon deposited by a low-pressure chemical vapour deposition (LPCVD) technique. The principle of this large area position sensor is a matrix of thin film field effect transistors (TFT) with two additional Hall probes. The performances of the TFT based cells are linked to the crystalline q... View full abstract»

In this paper we discuss laboratory results from solenoidal magnetoelastic measurements performed on a sample of bridge suspension cable. The experiments were designed to answer basic questions regarding the potential effects of inhomogeneous temperature fields and differential thermal errors between sensor and sample on the accuracy of coercive force measurements. The experiments were conducted w... View full abstract»

Melexis is a developer and manufacturer of microelectronic integrated systems. It has developed patented and highly integrated magnetic sensor actuators for the control of 2 phase brushless DC motors. This paper reviews the application parameters, historical implementations of control circuits and recent advances in applying CMOS SoC solutions. Application to rotary cooling fans is emphasized. View full abstract»

To investigate and optimize the operational behavior of automobile belt drives, it is important to detect unfavorable operating conditions, such as excessive slippage. To measure slippage, the speed of the belt is compared to the peripheral velocities of pulleys in the belt drive. The velocity of the belt is obtained by a contactless optical sensor, whose signals are processed employing correlatio... View full abstract»

Novel semitransparent optoelectronic position sensors, the 'ALMY sensors,' have been developed for high-precision multi-point position and angle measurements of collimated laser beams over a large measurement range. The sensors consist of a thin film of amorphous silicon deposited on a glass substrate between two transparent layers of crossed strip electrodes. They provide a position resolution on... View full abstract»

Position sensitive detectors, or PSDs, utilise the lateral photovoltaic effect to produce an electrical output that varies linearly with the position of a light spot incident on a semiconductor junction. In fabricating PSDs, two key elements are optimised, the sensitivity and the linearity of the electrical output. Sensitivity can be optimised by varying properties of the junction layers, particul... View full abstract»

This paper presents a new approach for the design of incremental angular position and angular speed sensors, using a capacitive technology. Transmitter and receiver segments are integrated with the sensor electronics on a single PCB. As the sensor measures the change of capacitance in dependence of the rotor position, any conductive or dielectric material can be used for the gear-tooth rotor. The ... View full abstract»

This paper considers the problem of locating a stationary radar emitter from a single airborne platform making frequency measurements in the presence of aperture state uncertainty. It is shown that the location accuracy is most sensitive to aperture velocity uncertainty and that location accuracy can be improved by using a MEMS accelerometer at the aperture. A decentralized method is developed for... View full abstract»

An original experimental method is presented for measuring the stiffness and displacement characteristics of small size freestanding mechanical elements on actual MEMS devices. This setup allows, using analytic and finite-element method mechanical calculations, the extraction of the elastic modulus of the materials used in such mechanical elements, thus eliminating the need of special integrated t... View full abstract»

This paper reports a design concept for MEMS gyroscopes based on increasing the degrees-of-freedom of the oscillatory system by the use of two independently oscillating interconnected proof masses. The 4-DOF dynamical system eliminates the necessity for mode-matching due to its wide operation frequency range, and reduces the damping sensitivity problem by operating away from resonance. Thus, inher... View full abstract»

This paper presents a high-dynamic range (10/sup 6/ g) tunneling accelerometer fabricated using precision wafer bonding (< 1 um misalignment) and a wet-release process. This single-crystalline silicon cantilever device with no metal electrical interconnects on the cantilever shows superior long-term bias stability compared with previously reported surface-micromachined tunneling accelerometers.... View full abstract»