Sepideh M. Moqadam, Parvind Grewal, Majid Shokoufi and Farid Golnaraghi
averaged admittance Nyquist plots, resulted in the extracted Cole features ( G 0 , G ∞ , a and f yc ) within each pressure level. Cole circuit equivalent parameters ( R ext , R int and C m ) were then calculated from equations 3 to 5 . Thus for all twenty chicken samples, two rat samples and eleven human subjects, R ext , R int and C m were acquired at various pressure levels.
Table 1 represents the average of the Cole parameters of all subjects and samples at the first pressure levels (2.5 N in human subjects and 2.2 N in chicken and rat samples) and
. Meas vol. 27 no. 5 S25 S42 2006 doi.org/10.1088/0967-3334/27/5/S03
59 F. S. Lee, Optimum array processing, vol. 35, no. July. John Wiley and Sons, 2008. Lee F. S. Optimum array processing vol. 35 no. July John Wiley and Sons 2008
60 S. Manohar, A. Kharine, J. C. G. van Hespen, W. Steenbergen, and T. G. van Leeuwen, "The Twente Photoacoustic Mammoscope: system overview and performance.," Phys. Med. Biol., vol. 50, no. 11, pp. 2543–57, 2005. https://doi.org/10.1088/0031-9155/50/11/007 10.1088/0031-9155/50/11/007 Manohar S. Kharine A
Sören Weyer, Hannes Weber, Christian Kleeberg, Steffen Leonhardt and Tobias Wartzek
Since the device should measure through an isolating material, a capacitive measurement system was developed. The capacitive measuring was done by active electrodes as an impedance converter, which enables a low-impedance processing of the measured potential φ G . Figure 2 shows the measurement of a potential φ G with a capacitive electrode. The lower part of the Figure shows the corresponding equivalent circuit.
Measuring arrangement for impedance measurement with two or four electrodes and the corresponding equivalent electric circuit.
Maureen A.J.M. van Eijnatten, Michael J. van Rijssel, Rob J.A. Peters, Rudolf M. Verdaasdonk and Jan H. Meijer
, various physiological models and algorithms were used, e.g. by Sramek et al. and Bernstein [ 2 , 3 , 4 ]. Most of the estimates of SV were essentially based on the assumptions that the C-wave originates from small fluctuations in a simply distributed electrical field caused by blood volume changes or velocity changes in the aorta. Meanwhile, several studies have shown that these assumptions are too simplistic [ 5 , 6 , 7 , 8 , 9 ]. Therefore, it appears to be futile to make an interpretation of the amplitude of the ICG-signal based on simplistic models.
Tushar Kanti Bera, Nagaraju Jampana and Gilles Lubineau
, 25 , 26 ] reveal the impedance response of biological tissues at one, two or more specified frequencies (f). EIS has been proven as an effective technique for noninvasive tissue characterization in medical, biomedical and biological applications [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Because EIS is a more generalized method that provides impedance variations over a wide range of frequencies, it can be used on its own to provide information that explains other bioelectrical phenomena like dielectric polarization [ 37 , 38 , 39 , 40 , 41
Tushar Kanti Bera, Samir Kumar Biswas, K. Rajan and J. Nagaraju
system has, generally, poor signal to noise ratio [ 19 ] and poor spatial resolution [ 20 ] due to the factors associated with it. The boundary data profile [ 21 ] of the practical phantom [ 22 , 23 , 24 , 25 , 26 ] is highly sensitive to modeling parameters [ 27 ] such as the phantom structure [ 23 , 26 ], surface electrodes geometry [ 21 ], experimental errors [ 23 , 26 , 28 ] and errors of the EIT-instrumentation [ 29 , 30 , 31 , 32 ]. That is why there are a number of opportunities and challenges in EIT to make this technology as an efficient medical
readings, all did so under steady-state conditions, disregarding the dynamic relaxation behavior of the tissue under consideration. In this study, we consider the relationship between the viscoelastic behavior of a phantom material – namely tofu – to its measured bioimpedance in real-time.
Tofu has become a popular phantom material in many fields of biological interest including elastography ( 24 ) and ultrasound imaging ( 25 ). Tofu, also referred to as bean curd, is a food made by pressing curds from coagulated soymilk into blocks of relative homogeneity. Coagulation
lists the electrical resistivity of forearm biological tissues at a frequency of 100 kHz [ 6 ].
The electrical resistivity of forearm biological tissues.
Electrical resistivity ρ [Ωm]
2.76 ± 0.3
2.5 ± 0.5
1.42 ± 0.6
12.5 ± 0.5
25 ± 0.7
Blood vessel wall
3.13 ± 0.2
Materials and methods
To perform electrical impedance measurements, a special electrode system was designed to be attached to the study area. The electrode system
The brain has ongoing, substantial energy requirements but minimal stores of energy-generating substrates. As a result, it is completely dependent on a continuous, uninterrupted supply of substrate (oxygen, glucose). Although the demand by the brain for energy-generating substrates is substantial (the central nervous system consumes 20% of the oxygen (that is, 170 mmol/l00 g per min or 3-5 ml O 2 /100 g brain tissue per mm or, approximately, 40-70 ml O 2 /min) and 25% of the glucose (31 mmol/l00 g per mm) utilized by the resting individual under physiological