Chavdar Roumenin

Vertical Hall Effect Devices in the Basis of Smart Silicon Sensors

Future integrated systems will benefit significantly from the progress in batch manufactured silicon sensors and signal processing techniques. Silicon technologies make possible to produce sensing microdevices combining extreme sensitivity, accuracy and compact devices. Smart sensors on the base of vertical vector Hall effect devices offer a number of benefits including reducing mass, volume and power consumption; greater redundancy of system functions and simpler architecture. In view of these remarkable characteristics, it can be expected that such smart sensors will be used extensively wide if an adequate solution is found to reduce the design cost and simplify the electrical interface. Consequently, cost effective microsystems including vector magnetic sensors, circuits and eventually actuators can be fabricated, opening new perspective markets. This paper presents a new approach in the field of signal processing for magnetic field sensors based on vertical Hall micro structures. A design example is illustrated specific problems and solutions associated with data converters and signal-processing functions for smart sensors.

Microsensors for Magnetic Fields

The devices and microsystems for measuring magnetic fields have the unique ability to reveal realities that cannot be perceived by the human senses. These transducers, which measure magnetic fields in a range not less than 15 to 16 orders of magnitude and are universal in their applications, are in continuous development.This chapter discusses recent progress in the most frequently used magnetic-field microsensors and MEMS, which are perfectly compatible with microelectronic technologies, most of which are silicon technologies. Up-to-date results are analyzed and abundant information is presented about the following topics: physical mechanisms of the origin of magnetosensitivity,device designs, sensor characteristics and the methods for their determination, biasing and inter-face circuits, the means for performance improvement and overcoming the basic transducer limitations, the most current and prospective applications, anddevelopment trends. Ample references torelevantliterature are included for all modifications of Hall effect devices (orthogonal and parallel field); micromagnetodiodes; magnetoresistors (including feromagnetic versions such as giant magnetoresistance elements); microsensors based on AniBv semiconductors; MOSFET, bipolar, CMOS, unijunction,and split-drain magnetotransistors and related devices; carrier-domain magnetometers; functional multisensorsfor the magnetic field, temperature, and light; 2-D and 3-D vector microsystems for the magnetic field; and magnetogradiometers and digital stochastic magnetotransducers.

Parallel-Field Silicon Hall Effect Microsensors With Minimal Design Complexity

A new class of Hall microsensors with minimal design complexity was suggested and experimentally tested. The devices consisting in n-Si substrate and three n+-strip contacts only are sensitive to a magnetic field parallel to the chip surface. Using a reference voltage generating with a specific bridge circuitry, the linear Hall voltage is extracted and the quadratic geometrical magnetoresistance is fully compensated. The internal noise of the design with a Hall contact located outside the sensor active region is at least ten times smaller than those of the three-contact element with an inside placed output electrode. This leads to enhanced resolution reaching Bmin ap 35 muT. A three-terminal multisensors generating simultaneously and independently strongly asymmetric voltage to the magnetic field direction and a Hall signal were devised too. The devices performance proved undoubtedly that new three-contact sensors could compete with the other well-known vertical Hall elements.

A framework for design of cloud compatible medical interfaces

A framework for design of novel interfaces for Cloud compatible medical services called User Interface as a Service (UIaaS) is presented in the paper. The aim is to support seamless and ubiquitous health monitoring based on flexible and useful Cloud services for healthcare. The paper describes the methods and new interfaces for health monitoring that have recently been developed for the proposed framework. The influence of the new methods and technologies for future Cloud computing systems for healthcare is discussed.

Integration of multiple sensor modalities in active vessel cardiology workstation

Active vessel is a new multimedia workstation which enables the visualization, acquisition and handling of different medical image modalities on- and offline for cardiology purposes. It implements DICOM v3.0 decompression and browsing, video acquisition, reproduction and storage for intravascular ultrasound (IVUS) and angiogram analysis. A distinctive implementation feature is the automatic catheter segmentation in angiography images. Another distinctive feature is the interactive mode of model correction via mouse dragging. A third and novel technical solution of the catheter path reconstruction is the integration with a magneto-sensitive micro-device inside the catheter for faster and safer minimal invasive surgical intervention. The paper gives the overview of the entire system, its basic new functionalities and the proposed technical solution of integration of four (instead of three) sensor modalities in cardiovascular practice.

Cloud Computing Approach to Novel Medical Interface Design

Interface technologies and devices need to be developed with novel functionalities for pattern analysis and data transfer in order to receive helpful and reliable healthcare service “from the Cloud”. The complexity of implementing Cloud computing for healthcare relates to a number of issues such as privacy, data protection, medical record access and update, high performance computation (HPC), etc. [1, 2, 3, 4]. At the same time interoperability needs to be achieved at all levels of provision of Cloud services—from the novel interface, via Hardware as a Service (HaaS), Software as a Service (SaaS) and Infrastructure as a Service (IaaS).

Multimodal Data Fusion for Intelligent Cardiovascular Diagnosis and Treatment in the Active Vessel Medical Workstation

ActiveVessel is a new multimedia workstation that enables the visualization, acquisition, and handling of different medical image modalities onand off-line for cardiology purposes. The workstation implements image decompression and browsing, video acquisition, reproduction, and storage for intravascular ultrasound (IVUS) and angiogram (X-ray) analysis. A distinctive implementation feature is the automatic image reconstruction with intensive use of 2D and 3D deformable models (snakes). The interactive interface allows the user to ‘correct’ deviations of catheter path reconstruction. An important characteristic feature of ActiveVessel is the interactive mode of model correction via mouse dragging. A novel technical solution for catheter path reconstruction is the integration with a magneto-sensitive micro-device (MSMD) inside the catheter/ vessel for faster and safer minimal invasive surgical intervention. This paper gives the overview of the entire system, its basic new functionalities, and the proposed technical solution of integration of four sensor modalities in cardiovascular practice.

In-plane magnetosensitive double Hall device

A novel in-plane magnetosensitive double Hall sensor, consisting of power supply and two identical three-contact и-Si cross-coupled architectures, realized in common technology process, is presented. High magnetosensitivity as well as increased metrological accuracy is achieved. The residual offset is about 160 times smaller than the internal ones. The obtained output voltage-to-residual offset ratio at magnetosensitivity of 98 V/AT (T = 300 K) is very promising, reaching 7.5×103 at magnetic induction IT.

On the Magnetically Controlled Surface Current at the Hall Structure Sides

The experimentally observed new phenomenon in conducting materials – the magnetically controlled surface current was examined again with an original measuring method and new silicon samples. The obtained results corroborate very well with the previously acquired data. The proposed registration approach utilizes the nulling compensation technique guaranteeing full offset compensation in all operating modes. The connection of the Ettingshausen effect with the new effect is clear demonstrated. A novel pressure sensor using the surface current dependence on external mechanical strain is developed and tested. The output characteristics of this transducer are very well reproducible and are suitable for measurement technologies.

An interface system based on multimodal principle for cardiological diagnosis assistance

A pilot interface system is developed for computer-aided diagnostic and interventional assistance of cardiologists based on clinical trials. The system includes optimized methods for processing and presentation of cardiological knowledge and data. The multimodal principle of the interface is based on know-how tests of a new magnetic microsensor for detection of catheter navigation in images from angiograms and intra-vascular ultrasound and on new investigations of the principle of operation of the electrocardiograph. The user interface includes interactive access to the clinical database and a cognitive approach to disease visualization.