Probing for stomach using the Focused Impedance Method (FIM)

Rashida Haque; Muhammad Abdul Kadir; K Siddique-e Rabbani

doi:10.2478/joeb-2019-0011

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Probing for stomach using the Focused Impedance Method (FIM)

Journal of Electrical Bioimpedance

Volume 10 (2019): Issue 1 (January 2019)

By: Rashida Haque, Muhammad Abdul Kadir and K Siddique-e Rabbani

Open Access

|Dec 2019

Figures & Tables

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.

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

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 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.

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.

Orthogonal concentric TPIMs in the vertical plane.

Geometrical reference points of electrodes, shown by arrows.

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

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

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-B for TPIM1, TPIM2 and FIM using the best combination of electrode configurations.

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 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 parameters	4	8	12
Max Sensitivity*	9.65E+05	5.10E+05	4.01E+05
Min Sensitivity*	-1.35E+07	-2.99E+06	-1.14E+06
Total Impedance (ohm)	3.08	1.63	1.06
Stomach Impedance (ohm)	0.60	0.38	0.21

% Contribution of stomach	19.53	23.07	20.22

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 parameters	TPIM1	TPIM2	FIM
Max Sensitivity*	8.41E+05	4.86E+05	4.23E+05
Min Sensitivity*	-2.41E+05	-2.09E+06	-1.05E+06
Total Impedance (ohm)	1.01	1.096	1.055
Stomach Impedance (ohm)	0.389	0.333	0.3611

% Contribution of stomach	38.51	30.38	34.23

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 parameters	TPIM1	TPIM2	FIM
Max Sensitivity*	1.27E+06	5.10E+05	6.40E+05
Min Sensitivity*	-3.66E+05	-2.99E+06	-1.48E+06
Total Impedance (ohm)	1.57	1.63	1.60
Stomach Impedance (ohm)	0.35	0.38	0.36

% Contribution of stomach	22.36	23.07	22.73

Assumed electrical values for simulation_ Frequency = 200 kHz_ Current = 1 A_

Electrical Properties	Background trunk volume*	Stomach volume**	Electrode (copper)
Conductivity (σ) [S/m]	1.2	5	6 × 10⁷
Relative Permittivity (ϵ)	80	80	1

Geometrical parameters appropriate for the chosen model

Volume of whole Trunk (including stomach)	28430 cm³
Volume of Stomach	1293 cm³
Stomach volume with respect to whole volume	4.54 %
Horizontal Cross Sectional Area of Trunk	711.4 cm²
Horizontal Cross Sectional Area of Stomach	161.4cm²
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 cm			Length = 6 cm			Length = 8 cm
Simulated Parameters	TPIM1	TPIM2	FIM	TPIM1	TPIM2	FIM	TPIM1	TPIM2	FIM
Max Sensitivity*	3.90E+04	4.47E+04	2.43E+04	2.64E+04	2.37E+04	1.67E+04	5.42E+04	3.05E+04	3.27E+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, Ω	1.49	1.57	1.53	1.40	1.48	1.44	1.47	1.55	1.51
Stomach Impedance, Ω	0.33	0.36	0.34	0.29	0.32	0.30	0.32	0.35	0.33

% Contribution of stomach	21.82	22.55	22.23	20.82	21.49	21.16	21.57	22.33	21.93

Simulation-A for Orthogonal Electrode I1-V1 = 8 cm, I1'-V1' = 15_4 cm, I2-V2 = 8 cm, I2'-V2' = 15_4 cm

Simulated parameter	TPIM1	TPIM1-O	FIM
Total Impedance (ohm)	1.58	1.40	1.49
Stomach Impedance (ohm)	0.35	0.29	0.32

% Contribution of stomach	22.34	20.90	21.67

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 parameters	4	8	12
Maximum Sensitivity*	7.71E+06	1.27E+06	8.99E+05
Minimum Sensitivity*	-2.22E+06	-3.66E+05	-2.36E+05
Total Impedance (ohm)	3.23	1.57	1.07
Stomach Impedance (ohm)	0.61	0.35	0.23

% Contribution of stomach	18.94	22.36	21.04

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DOI: https://doi.org/10.2478/joeb-2019-0011 | Journal eISSN: 1891-5469

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Language: English

Page range: 73 - 82

Submitted on: Dec 6, 2019

Published on: Dec 26, 2019

Published by: University of Oslo

In partnership with: Paradigm Publishing Services

Publication frequency: 1 issue per year

Keywords:

Electrical bio-impedance,

deep organ bio-impedance,

EIT,

TPIM,

FIM

Related subjects:

Engineering,

Bioengineering and biomedical engineering,

Biomedical electronics,

Life sciences,

Biophysics,

Medicine,

Biomedical engineering,

Physics,

Spectroscopy and metrology

© 2019 Rashida Haque, Muhammad Abdul Kadir, K Siddique-e Rabbani, published by University of Oslo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 10 (2019): Issue 1 (January 2019)

Probing for stomach using the Focused Impedance Method (FIM)

Figures & Tables

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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

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

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

Assumed electrical values for simulation_ Frequency = 200 kHz_ Current = 1 A_

Geometrical parameters appropriate for the chosen model

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

Simulation-A for Orthogonal Electrode I1-V1 = 8 cm, I1'-V1' = 15_4 cm, I2-V2 = 8 cm, I2'-V2' = 15_4 cm

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

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