scholarly journals Very Low Resource Digital Implementation of Bioimpedance Analysis

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3381 ◽  
Author(s):  
Fabien Soulier ◽  
Achraf Lamlih ◽  
Vincent Kerzérho ◽  
Serge Bernard ◽  
Tristan Rouyer
Keyword(s):  
Integrated Circuit ◽  
Complex Analysis ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Biological Tissues ◽  
Frequency Range ◽  
Digital Implementation ◽  
Analysis Algorithm ◽  
Low Resource ◽  
Wide Range

Bioimpedance spectroscopy consists of measuring the complex impedance of biological tissues over a large frequency domain. This method is particularly convenient for physiological studies or health monitoring systems. For a wide range of applications, devices need to be portable, wearable or even implantable. Next generation of bioimpedance sensing systems thus require to be implemented with power and resource savings in mind. Impedance measurement methods are divided into two main categories. Some are based on “single-tone” signals while the others use “multi-tone” signals. The firsts benefit from a very simple analysis that may consist of synchronous demodulation. However, due to necessary frequency sweep, the total measurement may take a long time. On the other hand, generating a multi-frequency signal allows the seconds to cover the whole frequency range simultaneously. This is at the cost of a more complex analysis algorithm. This makes both approaches hardly suitable for embedded applications. In this paper, we propose an intermediate approach that combines the speed of multi-tone systems with a low-resource analysis algorithm. This results in a minimal implementation using only adders and synchronous adc. For optimal performances, this small footprint digital processing can be synthesized and embedded on a mixed-mode integrated circuit together with the analog front-end. Moreover, the proposed implementation is easily scalable to fit an arbitrary frequency range. We also show that the resulting impact on noise sensitivity can be mitigated.

Complex Impedance Measurement System for the Frequency Range from 5 kHz to 100 kHz

2015 ◽  
Vol 644 ◽  
pp. 133-136 ◽  
Author(s):  
Mitar Simić
Keyword(s):  
Measurement System ◽  
Integrated Circuit ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Wide Range ◽  
Measurement Results ◽  
Improved Design ◽  
Sd Card ◽  
Complex Impedance Measurement ◽  
Line Analysis

The improved design of previously developed complex impedance measurement system is described. Realized system for measurement of complex impedance is based on integrated circuit AD5933 which is controlled by microcontroller ATmega128. Device has full standalone capabilities with LCD for displaying of results and keyboard for configuration on the field. Created report with measured values of impedance magnitude and phase angle is stored on micro SD card in format compatible with MS Excel which ensures easy off-line analysis on PC. Realized device is equipped with self-calibration system which ensures high accuracy in wide range of impedance and frequency. In the aim of the verification of developed system, the measurement results are plotted and compared with theoretical impedance values. Realized system can be used for complex impedance measurement, impedance spectrometry, biomedical and automotive sensors, proximity sensors, FFT processing, structural health monitoring, etc.

scholarly journals Relationship between moisture content and electrical impedance of carrot slices during drying

2015 ◽  
Vol 29 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Ákos Kertész ◽  
Zuzana Hlaváčová ◽  
Eszter Vozáry ◽  
Lenka Staroňová
Keyword(s):  
Moisture Content ◽  
Electrical Impedance ◽  
Fruits And Vegetables ◽  
Physiological State ◽  
Impedance Measurement ◽  
Biological Tissues ◽  
Impedance Spectra ◽  
Frequency Range ◽  
Impedance Parameters ◽  
Precision Balance

Abstract Electrical properties of food materials can give information about the inner structure and physiological state of biological tissues. Generally, the process of drying of fruits and vegetables is followed by weight loss. The aim of this study was to measure the impedance spectra of carrot slices during drying and to correlate impedance parameters to moisture content in different drying periods. Cylindrical slices were cut out from the carrot root along the axis. The slices were dried in a Venticell 111 air oven at 50°C. The weight of the slices was measured with a Denver SI-603 electronic analytical and precision balance. The weighing of the samples was performed every 30 min at the beginning of drying and every 60 min after the process. The moisture content of the samples was calculated on wet basis. The magnitude and phase angle of electrical impedance of the slices were measured with HP 4284A and 4285A precision LCR meters in the frequency range from 30 Hz to 1 MHz and from 75 kHz to 30 MHz, respectively, at voltage 1 V. The impedance measurement was performed after weighting. The change in the magnitude of impedance during drying showed a good correlation with the change in the moisture content.

Electrical Properties in Large Frequency and Temperature Ranges of Sr0.6Ca0.4TiO3 Ceramics

2020 ◽  
Vol 13 (3) ◽  
pp. 201-210
Keyword(s):  
Dielectric Permittivity ◽  
High Temperatures ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Conductivity Measurement ◽  
Calcium Titanate ◽  
Lead Free ◽  
Dielectric Losses ◽  
Low Frequencies ◽  
Wide Range

Abstract: Lead-free Sr0.6Ca0.4TiO3 (SCT) ceramic was prepared by the solid state reaction route. X-Ray diffraction technique showed the phase purity and identified the orthorhombic perovskite structure of the material. Scanning Electronic Microscopy observation evidenced homogeneous morphology and dense microstructure for the ceramic. The dielectric and conductivity properties of the sample were studied using complex impedance measurement technique in a wide range of frequencies and temperatures: from 100 Hz to 1.8 GHz and from 25°C to 550°C. The ceramic exhibits a stable dielectric permittivity and low dielectric losses in frequency and temperature up to 200°C. This is very interesting in view of developing high-quality lead-free ceramic capacitors for applications requiring high temperatures; for example, in cars. The increase in dielectric permittivity for temperatures higher than 200°C may be related to oxygen vacancies that are heat-activated in the material. Dielectric losses show the existence of a dielectric relaxation at low temperatures and low frequencies. Conductivity measurement investigated at high temperatures show on one hand high AC conductivity values attributed to the high temperature jumping process and on the other hand two electrical conductivity mechanisms above 400° C in the material. Keywords: Strontium calcium titanate, Ceramic, Structure, Dielectric properties, Conductivity.

IMPEDANCE SPECTROSCOPIC STUDIES ON GdBi5Fe2Ti3O18 CERAMIC

2001 ◽  
Vol 15 (14) ◽  
pp. 2053-2065 ◽  
Author(s):  
N. V. PRASAD ◽  
G. PRASAD ◽  
T. BHIMASANKARAM ◽  
S. V. SURYANARAYANA ◽  
G. S. KUMAR
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Solid State Reaction Method ◽  
Spectroscopic Studies ◽  
Conductivity Measurements ◽  
Frequency Range ◽  
Reaction Method ◽  
Complex Impedance Measurement

GdBi 5 Fe 2 Ti 3 O 18 (GBFT), a compound of Aurivillius family, was prepared by solid state reaction method. Complex impedance measurement was made on these samples from room temperature to 500°C in the frequency range of 1 kHz–1 MHz. Cole–Cole plots were found to become very broad near 400°C. Dielectric and dc conductivity measurements were made on these samples. The results are analysed to understand the conductivity mechanism.

Simple circuit for pacing hearts of experimental animals

1992 ◽  
Vol 262 (6) ◽  
pp. H1939-H1940 ◽  
Author(s):  
G. L. Freeman ◽  
J. T. Colston
Keyword(s):  
Integrated Circuit ◽  
Simple Circuit ◽  
Cardiovascular Research ◽  
Experimental Animals ◽  
Wide Range ◽  
Astable Multivibrator

In this paper we describe a simple pacing circuit which can be used to drive the heart over a wide range of rates. The circuit is an astable multivibrator, based on an LM555 integrated circuit. It is powered by a 9-V battery and is small enough for use in rabbits. The circuit is easily constructed and inexpensive, making it attractive for numerous applications in cardiovascular research.

scholarly journals Modelling natural electromagnetic interference in man-made conductors for space weather applications

2016 ◽  
Vol 34 (4) ◽  
pp. 427-436 ◽  
Author(s):  
Larisa Trichtchenko
Keyword(s):  
Exact Solution ◽  
Space Weather ◽  
Electromagnetic Interference ◽  
Geomagnetic Storms ◽  
Electromagnetic Properties ◽  
Electromagnetic Response ◽  
Frequency Range ◽  
Geomagnetically Induced Currents ◽  
Geomagnetic Variations ◽  
Wide Range

Abstract. Power transmission lines above the ground, cables and pipelines in the ground and under the sea, and in general all man-made long grounded conductors are exposed to the variations of the natural electromagnetic field. The resulting currents in the networks (commonly named geomagnetically induced currents, GIC), are produced by the conductive and/or inductive coupling and can compromise or even disrupt system operations and, in extreme cases, cause power blackouts, railway signalling mis-operation, or interfere with pipeline corrosion protection systems. To properly model the GIC in order to mitigate their impacts it is necessary to know the frequency dependence of the response of these systems to the geomagnetic variations which naturally span a wide frequency range. For that, the general equations of the electromagnetic induction in a multi-layered infinitely long cylinder (representing cable, power line wire, rail or pipeline) embedded in uniform media have been solved utilising methods widely used in geophysics. The derived electromagnetic fields and currents include the effects of the electromagnetic properties of each layer and of the different types of the surrounding media. This exact solution then has been used to examine the electromagnetic response of particular samples of long conducting structures to the external electromagnetic wave for a wide range of frequencies. Because the exact solution has a rather complicated structure, simple approximate analytical formulas have been proposed, analysed and compared with the results from the exact model. These approximate formulas show good coincidence in the frequency range spanning from geomagnetic storms (less than mHz) to pulsations (mHz to Hz) to atmospherics (kHz) and above, and can be recommended for use in space weather applications.

scholarly journals High Frequency Magnetoimpedance of FeNi/Cu/FeNi Sensitive Elements with Different Geometries

2009 ◽  
Vol 152-153 ◽  
pp. 373-376 ◽  
Author(s):  
Stanislav O. Volchkov ◽  
Andrey V. Svalov ◽  
G.V. Kurlyandskaya
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
External Magnetic Field ◽  
Finite Elements ◽  
Magnetic Anisotropy ◽  
Constant Magnetic Field ◽  
High Frequency ◽  
Complex Impedance ◽  
Rf Sputtering ◽  
Frequency Range

In this work magnetoimpedance (MI) behaviour was studied experimentally for Fe19Ni81(175 nm)/Cu(350 nm)/Fe19Ni81(175 nm) sensitive elements deposited by rf-sputtering. A constant magnetic field was applied in plane of the sandwiches during deposition perpendicular to the Cu-lead in order to induce a magnetic anisotropy. Sandwiches with different width (w) of FeNi parts were obtained. The complex impedance was measured as a function of the external magnetic field for a frequency range of 1 MHz to 700 MHz for MI elements with different geometries. Some of MI experimental data are comparatively analysed with finite elements numerical calculations data. The obtained results can be useful for optimization of the design of miniaturized MI detectors.

scholarly journals An Event-Based, Digital Time Difference Encoder Model Implementation for Neuromorphic Systems

2020 ◽  
Author(s):  
Daniel Gutierrez-galan ◽  
Thorben Schoepe ◽  
Juan Pedro Dominguez-Morales ◽  
Angel Jimenez-Fernandez ◽  
Elisabetta Chicca ◽  
...  
Keyword(s):  
Power Consumption ◽  
Source Localization ◽  
Sound Source ◽  
Digital Circuit ◽  
Temporal Information ◽  
Time Difference ◽  
Digital Implementation ◽  
Wide Range ◽  
Neuromorphic Systems ◽  
Event Based

Neuromorphic systems are a viable alternative to conventional systems for real-time tasks with constrained resources. Their low power consumption, compact hardware realization, and low-latency response characteristics are the key ingredients of such systems. Furthermore, the event-based signal processing approach can be exploited for reducing the computational load and avoiding data loss, thanks to its inherently sparse representation of sensed data and adaptive sampling time. In event-based systems, the information is commonly coded by the number of spikes within a specific temporal window. However, event-based signals may contain temporal information which is complex to extract when using rate coding. In this work, we present a novel digital implementation of the model, called Time Difference Encoder, for temporal encoding on event-based signals, which translates the time difference between two consecutive input events into a burst of output events. The number of output events along with the time between them encodes the temporal information. The proposed model has been implemented as a digital circuit with a configurable time constant, allowing it to be used in a wide range of sensing tasks which require the encoding of the time difference between events, such as optical flow based obstacle avoidance, sound source localization and gas source localization. This proposed bio-inspired model offers an alternative to the Jeffress model for the Interaural Time Difference estimation, validated with a sound source lateralization proof-of-concept. The model has been simulated and implemented on an FPGA, requiring 122 slice registers of hardware resources and less than 1 mW of power consumption.

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