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
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
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
, Schnelle T, Fuhr G. Dielectrophoretic sorting of particles and cells in a microsystem. Anal. Chem. 1998, 70: 1909-1915. http://dx.doi.org/10.1021/ac971063b 10.1021/ac971063b
Fiedler S Shirley SG Schnelle T Fuhr G Dielectrophoretic sorting of particles and cells in a microsystem Anal. Chem 1998 70 1909 – 1915 http://dx.doi.org/10.1021/ac971063b
Foster KR, Schwan HP. 1996, Dielectric properties of tissues. Handbook of biological effects of electromagnetic fields. Polk C, Postow E (Eds.) CRC Press Inc., Boca Raton, FL. 25-102.
Yun Wang, Laura Freedman, Martin Buck, Jose Bohorquez, Seward B. Rutkove and John Keel
attributable to a spinal etiology as determined by board-certified physiatrist (J.K.). Exclusion criteria included, history of a generalized neuromuscular condition, except for mild polyneuropathy or common mononeuropathies (e.g., carpal tunnel syndrome, ulnar neuropathy at the elbow), history of moderate-to-severe ongoing medical conditions producing generalized disability, such as advanced cardiac or renal disease, metal spine implants of any type. For healthy subjects, the exclusion criteria included the above items as well as a history of present or past disabling back
Parvind K Grewal, Majid Shokoufi, Jeff Liu, Krishnan Kalpagam and Kirpal S Kohli
in radiation therapy were considered in the present study. The first sample, Sample 1, was the commercially available material Superflab made of 100% Akton® viscoelastic polymer; it is a low cost, well conforming material with a tissue equivalent dose absorption properties and density of 1.03g/cc. The second sample, Sample 2, was an in-house developed material Gelatin Bolus made of gelatin (Benson Foods Ltd., Gelatine 175 Bloom). The gelatin is manufactured using pig skin and has 2% sodium by weight. Ten sub-samples of each sample were used for cross validation of