Four electrode measurement (4EM) systems have been used to measure conductivity in tissue where electrode polarization would cause unacceptable inaccuracy in measurement results and where directional measurement of conductivity is required Less polarization than a two-electrode measurement system where the current is applied by the same electrodes that measures the potential and directional measurement as opposed to a coaxial measurement system that measures bulk conductivity but gives no information about direction. ( 1 , 2 , 3) . The system
the tissue engineered constructs. However, these methods such as histology staining, are destructive and time-consuming and require fixing and cutting the tissue cultures ( 6 ).
Therefore, there is a need for real-time and noninvasive monitoring techniques to evaluate the quality of the tissue engineered constructs before implanting them in the body, without the need to use fluorescents or radioactive labels or destructive methods. This in addition, would reduce the number of animals required for this purpose ( 5 , 6 ).
Martina Sammer, Bob Laarhoven, Ernest Mejias, Doekle Yntema, Elmar C. Fuchs, Gert Holler, Georg Brasseur and Ernst Lankmayr
as a static capacitor. The dielectric properties of biological cells and their different components (cell wall, membranes and cytoplasm) were summarized by Markx and Davey [ 4 ]. Over the last couple of decades a lot of research was done on the impedance of cell suspensions, in which a relationship between capacitance and viable cell number was reported [ 5 , 6 , 7 , 8 ]. Fehrenbach et al. [ 5 ] used online capacitive measurements for biomass estimation of Saccaromyces cerevisiae , Pitchia pastoris and Streptomyces virginiae in suspension culture. In their
Reda Abdelbaset, Mohamed El Dosoky and Mohamed T. El-Wakad
Bioimpedance is a widely used technique to measure the body composition due to its various advantages such as noninvasiveness, accuracy, applicability and low cost [ 1 ]. The measurement of artery bioimpedance is proposed in this study because it is used to diagnose numerous of blood diseases such as the cholesterol level, the foundation of stenosis, and diabetes [ 1 ]. Furthermore, the studying of the heart pulsatile effect may be used to measure the heart rate as a novel method for heart rate detection based on bioimpedance phenomena. The heart
which is an invasive method and cannot readily measure beat-to-beat changes. Electrical impedance measurements at the forearm provide a possible way to characterize hemodynamics, and in particular changes in the amount of blood in the arm as a result of vasodilatation and/or the cardiac cycle.
Although the simulation perspective to bioimpedance plethysmography is a rarity there have been several investigations pertaining to the impedance response at forearm section. Some works [ 13 , 14 , 15 , 16 ] related to multi-frequency electrical bioimpedance (MF-EBI) for
Abdul Hamid Ismail, Georg Schlieper, Marian Walter, Jürgen Floege and Steffen Leonhardt
changed if required for clinical reasons. The inclusion criteria were: in- and outpatients ≥ 18 years of age on chronic HD three times a week, who had been on dialysis for a minimum of six months. The exclusion criteria were HIV or hepatitis virus C infection, pregnancy, pacemakers, amputation of a limb, artificial joints, or receiving a blood transfusion within a week before the measurement.
Obtained measurements included the patient’s pre- and post-dialysis weight, height, thigh length and circumferences, systolic and diastolic blood pressure
Ørjan G.Martinsen, Oliver Pabst, Christian Tronstad and Sverre Grimnes
Skin conductance measurements have been used in psychophysiology for more than a century. Measurements of galvanic skin response (GSR) (also referred to by the more general term electrodermal activity (EDA)) have been reported as early as the last part of the nineteenth century (see [ 1 ] for an overview). Through many decades, the method of using direct current (DC) measurements of skin conductance with a constant applied voltage has dominated the EDA literature [ 2 ].
However, there are potential complications with the DC method, such as
Ole Martin Steihaug, Bård Bogen, Målfrid Holen Kristoffersen and Anette Hylen Ranhoff
such as ceramics, hydroxyapatites and polyethylenes. These changes can potentially increase or decrease the electrical conductance, and it is difficult to predict how they will affect BIA measurements. If BIA is to be useful in the large group of acute hip fracture patients, or other patient groups undergoing surgery, it is important to determine the influence of fracture, surgery and surgical implants on BIA readings. The aim of this study is to answer the following research questions: 1) Are BIA measurements affected by recent fracture and surgical repair? 2) Are
Analysis of the passive electrical properties of tissue (bioimpedance) can be challenging as the data is complex, the data amount can be large, methods of interpretation are vast, and the electrical properties often have a non-linear relation to the biological property of interest. Raw immittance data from bioimpedance measurements are typically presented as admittance, impedance or dielectric parameters, represented by real and imaginary components.
As the electrical properties of tissue always are frequency dependent (1), bioimpedance will
The stray capacitance between the human body and earth ground can play a significant role in bioimpedance measurement systems where it may yield, for example, apparent inductive components not associated to any magnetic phenomena [ 1 , 2 ]. It is also an intervening factor in the assessment of human body impedance for risk analysis in case of electric contacts [ 3 ] or electromagnetic radiation [ 4 ] and in electrostatic discharge studies [ 5 ], and has strong influence in power-line interference in biopotential measurements [ 6 , 7 , 8