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Based on the experimentally discovered regularity – emission of micro-sized particles during monoaxial deformation of non-homogeneous structures, such as rocks and concretes, a sensor technology to identify their pre-destruction processes is proposed. At nearing the stressed state until the disintegration of the massifs, exponential increase of particles generation appears. The innovation is applicable to risky rock formations where vertical measurement boreholes are made, by which kernels are obtained. Using the specimens formed by the kernels, through monoaxial load by press in laboratory conditions and corresponding particle emissions, the reference pressure values for different stages of the pre-destructive state development are determined. The reference data from the pressure are compared with the results for the deformation loads in the rock structure, corresponding to the generated particles in a borehole model. The values of the stress determine the occurrence of critical states in the structure. This information is an integrated indicator for the timely identification of pre-destructive processes in rocks. The described system increases the accuracy of determining the appearance of failure conditions. One of the strategic applications of the new technology is in seismically active regions.

Regularity has been observed in the generation of microparticles during uniaxial deformation of rocks and building concretes with the following formula: a previously unknown phenomenon in solid non-regular structures has been experimentally established and investigated, which is expressed in emission of microparticles under the action of strong uniaxial pressures. The size and amount of the fine-dispersed microfractions depend on the substance’s physicalmechanical properties and pressure values. The paper presents the first results of the observed phenomenon in rock structures – granite and limestone originating from some regions of Bulgaria. The effect motivates the option for using the emission process as a new sensor method for assessment of the stress condition of solid-state systems.

A novel method and a device measuring the mobility of majority carriers in semiconductors using the Hall current is proposed and experimentally tested. The geometry of the mobility-determining structures is similar to the topology of the so-called Corbino disk. The semiconductor wafer, in our case, n-silicon, has circular form and two concentric ohmic contacts: one of them in the central zone of the disk, and the other around the circumference. In contrast to this well-known Corbino configuration, the peripheral electrode is interrupted, whereas the size of the so-formed arc is many times smaller than the remaining section of the external perimeter. The two ohmic contacts are brought together to a current source, and the external magnetic field is applied perpendicularly to the disk plane. The ends of the interrupted electrode are connected to an electronic galvanometer measuring the Hall current involved in the Corbino structure. The experiments were carried out at room temperature and in liquid nitrogen. The results obtained with the new device are comparable to the previously known mobility values.

A novel in-plane sensitive Hall arrangement consisting of two identical n-Si three-contact (3C) elements and realized in a common technological process, is presented. In the solution, the minimization of the offset and its temperature drift is achieved by cross-coupling of the outer device contacts. This terminals’ connection provides equalizing currents between the two substrates which strongly compensate the inevitable difference in the electrical conditions in the two parts of the arrangement. As a result, the residual offset of both integrated Hall elements at the output Vout(0) and its temperature drift are strongly minimized. The residual offset is about 160 times smaller than the single-configuration one. The obtained output voltage-to-residual offset ratio at sensitivity of SRI ≈ 98 V/AT is very promising, reaching 6 × 103 at temperature T = 40 °C and induction 1 T. As a result, increased metrological accuracy for numerous applications is achieved. For a first time through the novel arrangement a suppression of sensitivity in the presence of external magnetic field could be achieved in order to obtain permanent offset information. This is one of the key results in the Hall device investigation.

A novel coupling of a pair of identical two-contact (2C) magnetoresistors transformed into an in-plane sensitive Hall device is presented. The ohmic contacts are cross-linked, also adding a load resistor bridge, providing for constant current mode of operation and eliminating the inevitable parasitic offset. This silicon configuration, apart from its simplified layout, has linear and odd output voltage as a function of the magnetic field and current. The quadratic and even magnetoresistance in the two parts of this innovative device is completely compensated, which ensures high measurement accuracy alongside with identification of the magnetic field polarity. The experimental prototypes feature sensitivity of 110 V/AT. The mean lowest detected magnetic induction B at supply current of 3 mA over frequency range f ≤ 100 Hz at a signal-to-noise ratio equal to unity is Bmin ≈ 10 μT. Тhe high performance and the complete electrical, temperature and technological matching of the parts of this unusual Hall device make it very promising for many practical applications.

A new 2D (two-dimensional) in-plane sensitive Hall-effect sensor comprising two identical n-Si Greek-crosses is presented. Each of the crosses contains one central square contact and, symmetrically to each of their four sides, an outer contact is available. Outer electrode from one configuration is connected with the respective opposite contact from the other configuration, thus forming four parallel three-contact (3C) Hall elements. These original connections provide pairs of opposite supply currents in each of the cross-Hall structure. Also the obligatory load resistors in the outer contacts of 3С Hall elements are replaced by internal resistances of crosses themselves. The samples have been implemented by IC technology, using four masks. The magnetic field is parallel to the structures’ plane. The couples of opposite contacts of each Greek-cross are the outputs for the two orthogonal components of the magnetic vector at sensitivities S ≈ 115 V/AT whereas the cross-talk is very promising, reaching no more than 2.4%. The mean lowest detected magnetic induction B at a supply current Is = 3 mA over the frequency range f ≤ 500 Hz at a signal to noise ratio equal to unity, is Bmin ≈ 14 μT.

A novel Hall magnetometer using dynamic offset cancellation principle is presented. It consists from a single triangular silicon plate with three contacts and interface electronics. The proposed dynamic offset-cancelling measurement cycle includes three states. During each state, an external circuit is switched to the plate contacts in a certain way. This way, the direction of current flow through the Hall plate is changed from phase to phase. At the same time, the output voltage is measured. After averaging the obtained three voltages per a measurement cycle, the offset voltage cancelled and this way the offset-free Hall voltage is obtained. The obtained offset reduction factor is very promising, reaching 120–130. The Hall device sensitivity is about 25 V/AT.

A new three-axis magnetometer for both 3-D magnetic field sensing and contactless in-plane 360° absolute angle encoding has been developed. The magnetometer is based on the Hall effect and consists of a circular in-plane sensitive CMOS Hall-effect microsensor, biasing and signal conditioning circuits. The sensing device contains a narrow n-well ring with a chain of contacts positioned radial on the ring. The signal conditioning circuit gives two output analogue signals: a voltage Vz, proportional to the magnetic field component Bz, and a sine wave function Vxy(t). The magnitude of the in-plane magnetic field B(x,y) is directly proportional to the sine amplitude and the phase Ψ corresponds to the angle between the applied in-plane magnetic field and a reference direction.

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 maximal sensitivity, high accuracy and minimal design complexity. Smart sensors on the base of Vertical vector Hall effect devices offer a number of advantages including reducing mass, volume and power consumption; greater redundancy of system functions and simpler architecture. In view of these 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. This paper presents a new approach in the field of signal processing for magnetic field sensors based on vertical Hall elements. A design example is illustrated specific problems and solutions associated with data converters and signal-processing functions for smart sensors.

A novel Hall device with enhanced magnetosensitivity has been implemented and tested. For the first time the transducer efficiency of the Hall sensor is increased due to the growth of surface charge density on Hall boundaries by reducing the area of the edges on which the Lorentz force deflects the carriers. The original shape of the Hall sides represents an isosceles acute triangle on whose vertex the Hall contact is formed. Discrete structures with four terminals and a three-contact version are developed in n-Si wafers. The experimentally obtained sensitivity is about 18% greater than the efficiency of a standard Hall element made of the same material and with the same input conditions. The new Hall sensors allow IC realization and are very promising for magnetometry.

An innovative parallel-field double-Hall microsensor comprising a silicon substrate, four planar contacts providing simultaneously two supply inputs and two differential outputs and a voltage source is characterized. This device functionally integrates two Hall devices sharing the same transducer zone and activated by unique supply current. The magnetosensitivities are equal but opposite in sign consisting of 40 V/AT and the two offsets are low and nearly equal. A self-reduction of the residual offset and its temperature drift is achieved by appropriate conditioning circuit, subtracting the two output voltages. A drastic compensation of the offset and the drift of more than two orders within a wide temperature range ( − 40 ≤ T ≤ 80 ∘ C ) is obtained.

A new amperometric mode of operation of bipolar magnetotransistor (AMOBMT) is studied both theoretically and experimentally. This mode is achieved without reverse-biasing of the collector junctions and by using the current between the two ‘floating’ collectors as an information signal. The output current is a linear and anti-symmetrical function of the applied magnetic field. AMOBMT has some advantages with respect to the conventional mode of operation of bipolar magnetotransistor which utilizes reverse-biasing of the collector junctions.

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.

A novel three-axis sensor for simultaneous and independent magnetic-field components measurement based on the Hall effect has been implemented and tested. On the upper side of n-Si substrate, a 10 colonm deep rectangular- shaped p-ring sized 50 x 160 colonm2 has been formed. In the n-zone surrounded by p-well, through six ohmic contacts, two parallel-field Hall devices for in-plane BBx and BBy components registration and one orthogonal Hall element for Bz detection has been functional integrated. The 3D magnetometer has been fabricated using silicon planar technology. The experimentally obtained magnetosensitivities are Sx ≈ 41V/AT, Sy ≈ 43V/AT and Sz ≈ 49V/AT, the cross- sensitivity reaches no more than 3%, the non-linearity is 1–2%, the noise spectral density on all outputs at frequency f ≤ 1000Hz is of the 1/f type and the sensor detectivity is BBmin ≈ 21 colonT. The spatial resolution is 50 x 160 x 10μm3.

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.