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Probing for stomach using the Focused Impedance Method (FIM)

Rashida Haque
Rashida Haque
, 
Muhammad Abdul Kadir
Muhammad Abdul Kadir
 and 
K Siddique-e Rabbani
K Siddique-e Rabbani
   | Dec 26, 2019
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Published Online: Dec 26, 2019
Page range: 73 - 82
Received: Dec 06, 2019
DOI: https://doi.org/10.2478/joeb-2019-0011
Keywords
© 2019 Haque, Kadir, Rabbani., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig 1

8-electrode FIM to localise a deep target object in a volume conductor. Two pairs of electrodes indicated by I1-I1’ and V1-V1’ form the first TPIM configuration while I2-I2’ and V2-V2’ indicate the second TPIM. The average of the two TPIM values make the FIM [14]. The dashed lines in the left hand figure show the maximum current lines between respective pairs of electrodes, which also includes the potential measuring electrodes, while the dotted lines on the right hand figure show approximate equipotential lines through the potential measuring electrodes.
8-electrode FIM to localise a deep target object in a volume conductor. Two pairs of electrodes indicated by I1-I1’ and V1-V1’ form the first TPIM configuration while I2-I2’ and V2-V2’ indicate the second TPIM. The average of the two TPIM values make the FIM [14]. The dashed lines in the left hand figure show the maximum current lines between respective pairs of electrodes, which also includes the potential measuring electrodes, while the dotted lines on the right hand figure show approximate equipotential lines through the potential measuring electrodes.

Fig 2

The simplified model for human trunk and an embedded stomach as used in the simulation. Some relevant dimensions are shown.
The simplified model for human trunk and an embedded stomach as used in the simulation. Some relevant dimensions are shown.

Fig 3

Cross sectional view of the trunk and the embedded stomach model as used in the simulation. The dimensions and position of the stomach are shown. The right and left side of the trunk are also indicated.
Cross sectional view of the trunk and the embedded stomach model as used in the simulation. The dimensions and position of the stomach are shown. The right and left side of the trunk are also indicated.

Fig 4

Cross sectional view showing the initial suggested positions of electrodes for the trunk and the embedded stomach model. The dashed straight lines represent the maximum current lines driven between the respective electrodes.
Cross sectional view showing the initial suggested positions of electrodes for the trunk and the embedded stomach model. The dashed straight lines represent the maximum current lines driven between the respective electrodes.

Fig 5

Visualization of electrode placement based on equipotential concept for both TPIM1 and TPIM2. Dashed lines show the maximum current lines through the current-drive electrodes. Dotted lines show approximate shape of equipotential lines through the potential electrodes due to the respective currents. For TPIM1, the equipotential lines bound the stomach region well. The equipotential lines for the electrode configuration for Trial-TPIM2 includes a large amount of background space on the left side of the stomach. For the new configuration of TPIM2, the lower potential electrode V2’ has been shifted to V2N’ based on equipotential visualization so that the stomach is bounded well between the two equipotential lines. This results in an improvement.
Visualization of electrode placement based on equipotential concept for both TPIM1 and TPIM2. Dashed lines show the maximum current lines through the current-drive electrodes. Dotted lines show approximate shape of equipotential lines through the potential electrodes due to the respective currents. For TPIM1, the equipotential lines bound the stomach region well. The equipotential lines for the electrode configuration for Trial-TPIM2 includes a large amount of background space on the left side of the stomach. For the new configuration of TPIM2, the lower potential electrode V2’ has been shifted to V2N’ based on equipotential visualization so that the stomach is bounded well between the two equipotential lines. This results in an improvement.

Fig 6

Orthogonal concentric TPIMs in the vertical plane.
Orthogonal concentric TPIMs in the vertical plane.

Fig 7

Geometrical reference points of electrodes, shown by arrows.
Geometrical reference points of electrodes, shown by arrows.

Fig 8

Percentage Contribution of stomach in Simulation-A for TPIM1 for varying separation of I1-V1
Percentage Contribution of stomach in Simulation-A for TPIM1 for varying separation of I1-V1

Fig 9

Percentage Contribution of stomach in Simulation-A for TPIM2 for varying separation of I2-V2
Percentage Contribution of stomach in Simulation-A for TPIM2 for varying separation of I2-V2

Fig 10

Percentage Contribution of stomach in Simulation-A for TPIM1, TPIM2 and FIM using the best combination of electrode configurations
Percentage Contribution of stomach in Simulation-A for TPIM1, TPIM2 and FIM using the best combination of electrode configurations

Fig 11

Percentage Contribution of stomach in Simulation-B for TPIM1, TPIM2 and FIM using the best combination of electrode configurations.
Percentage Contribution of stomach in Simulation-B for TPIM1, TPIM2 and FIM using the best combination of electrode configurations.

Fig 12

Percentage Contribution of stomach in Simulation-A for long strip electrodes of different lengths, for all the three configurations, TPIM1, TPIM2 and FIM using the electrode placements used for the small round electrodes.
Percentage Contribution of stomach in Simulation-A for long strip electrodes of different lengths, for all the three configurations, TPIM1, TPIM2 and FIM using the electrode placements used for the small round electrodes.

Fig 13

Percentage Contribution of stomach in Simulation-A for 2cm round electrodes and for 5cm long strip electrodes of 2cmx2cm cross section, for all the three configurations, TPIM1, TPIM2 and FIM.
Percentage Contribution of stomach in Simulation-A for 2cm round electrodes and for 5cm long strip electrodes of 2cmx2cm cross section, for all the three configurations, TPIM1, TPIM2 and FIM.

Simulation-A for TPIM2 for varying separation of I2-V2 Electrode Co-ordinates for 3 separations: [I2:( 30,14,19), V2: (30,18,19)]; [I2:( 30,12,19), V2:( 30,20,19)]; [I2:( 30,10,19), V2: ( 30,22,19)]. Fixed [I1’=(13,-3,19), V1’=(2,21,19)] Direct straight-line separation for I2'-V2' = 24.7 cm

I2-V2, cm
Simulated parameters4812
Max Sensitivity*9.65E+055.10E+054.01E+05
Min Sensitivity*-1.35E+07-2.99E+06-1.14E+06
Total Impedance (ohm)3.081.631.06
Stomach Impedance (ohm)0.600.380.21
% Contribution of stomach19.5323.0720.22

Simulation-B for FIM with best TPIM configurations Direct straight-line separations: I1-V1 = 8 cm, I1'-V1' = 15.4 cm, I2-V2 = 8 cm, I2'-V2' = 24.7 cm

Simulated parametersTPIM1TPIM2FIM
Max Sensitivity*8.41E+054.86E+054.23E+05
Min Sensitivity*-2.41E+05-2.09E+06-1.05E+06
Total Impedance (ohm)1.011.0961.055
Stomach Impedance (ohm)0.3890.3330.3611
% Contribution of stomach38.5130.3834.23

Simulation-A for FIM with best TPIM configurations Direct straight-line separations: I1-V1 = 8 cm, I1'-V1' = 15.4 cm, I2-V2 = 8 cm, I2'-V2' = 24.7 cm

Simulated parametersTPIM1TPIM2FIM
Max Sensitivity*1.27E+065.10E+056.40E+05
Min Sensitivity*-3.66E+05-2.99E+06-1.48E+06
Total Impedance (ohm)1.571.631.60
Stomach Impedance (ohm)0.350.380.36
% Contribution of stomach22.3623.0722.73

Assumed electrical values for simulation. Frequency = 200 kHz. Current = 1 A.

Electrical PropertiesBackground trunk volume*Stomach volume**Electrode (copper)
Conductivity (σ) [S/m]1.256 × 107
Relative Permittivity (ϵ)80801

Geometrical parameters appropriate for the chosen model

Volume of whole Trunk (including stomach)28430 cm3
Volume of Stomach1293 cm3
Stomach volume with respect to whole volume4.54 %
Horizontal Cross Sectional Area of Trunk711.4 cm2
Horizontal Cross Sectional Area of Stomach161.4cm2
Area of Stomach with respect to Area of Trunk
(cross-sectional)22.69 %

Simulation-A for Strip Electrodes of different lengths Strip electrode cross section: 2 cm × 2 cm Direct straight-line separations: I1-V1 = 8 cm, I1'-V1' = 15.4 cm, I2-V2 = 8 cm, I2'-V2' = 24.7 cm

Length = 5 cmLength = 6 cmLength = 8 cm
Simulated ParametersTPIM1TPIM2FIMTPIM1TPIM2FIMTPIM1TPIM2FIM
Max Sensitivity*3.90E+044.47E+042.43E+042.64E+042.37E+041.67E+045.42E+043.05E+043.27E+04
Min Sensitivity*-6.32E+04-7.53E+04-3.60E+04-5.14E+04-6.73E+04-3.26E+04-5.77E+04-1.57E+05-7.80E+04
Total Impedance, Ω1.491.571.531.401.481.441.471.551.51
Stomach Impedance, Ω0.330.360.340.290.320.300.320.350.33
% Contribution of stomach21.8222.5522.2320.8221.4921.1621.5722.3321.93

Simulation-A for Orthogonal Electrode I1-V1 = 8 cm, I1'-V1' = 15.4 cm, I2-V2 = 8 cm, I2'-V2' = 15.4 cm

Simulated parameterTPIM1TPIM1-OFIM
Total Impedance (ohm)1.581.401.49
Stomach Impedance (ohm)0.350.290.32
% Contribution of stomach22.3420.9021.67

Simulation-A for TPIM1 for varying separation of I1-V1 Electrode Co-ordinates for 3 separations: [I1:(16,25,19), V1:(20,25,19)]; [I1:(14,25,19), V1:(22,25,19)]; [I1:(12,25,19), V1:(24,25,19)]. Fixed [I1’=(16,-3,19); V1’=(29,6.5,19)] Direct straight-line separation for I1'-V1' = 15.4 cm

Separation of I1-V1, cm
Simulated parameters4812
Maximum Sensitivity*7.71E+061.27E+068.99E+05
Minimum Sensitivity*-2.22E+06-3.66E+05-2.36E+05
Total Impedance (ohm)3.231.571.07
Stomach Impedance (ohm)0.610.350.23
% Contribution of stomach18.9422.3621.04
eISSN:
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Language:
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Journal Subjects:
Engineering, Bioengineering and Biomedical Engineering, Biomedical Electronics, Life Sciences, Biophysics, Medicine, Biomedical Engineering, Physics, Spectroscopy and Metrology
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