Presenter : Yu-Chun HuaPresenter : Yu-Chun Hua Adviser : Dr. Ji-Jer Huang Adviser : Dr. Ji-Jer Huang Date : 99.12.09Date : 99.12.09

Paper review(1) purposeFrom :R. A. Stiz, P. Bertemes-Filho, A. Ramos, V. C. Vincence. “Wide

Band Howland Bipolar Current Source using AGC Amplifier “IEEE LATIN AMERICA TRANSACTIONS, VOL. 7, NO. 5, SEPTEMBER 2009

Purpose• Optimizing the output impedance (Zout) and voltage controlled current source (VCCS)• In this system, it uses a current source balanced (also called "bipolar“)

Automatic gain control (AGC) : 自動控制增益放大器

Paper review(1) materials and Paper review(1) materials and methodsmethodsHowland Circuit

Paper review(1) materials and Paper review(1) materials and methods methods

4

35

1

2

R

RR

R

R

13

2

RR

RVI inout

Paper review(1) resultsPaper review(1) results

Amplitude of the current source output as a function of frequency,using a load of 500 Ω.

Amplitude of the current source output as a function of frequency, using a capacitive load.

Paper review(2) purposePaper review(2) purposeFrom: Tushar Kanti Bera and J. Nagaraju ”﹐ A Simple Instrumentation Calibration Technique for Electrical Impedance Tomography (EIT) Using A 16-Electrode Phantom ” 5th Annual IEEE Conference on Automation Science and Engineering Bangalore, India, August 22-25, 2009

PurposeIntended to investigate the phantom responses for different electrode geometry

Electrode array position in bathing solution column and the instrumentation is calibrated accordingly

Paper review(2) materials and Paper review(2) materials and methodsmethodsA. Instrumentation(VCO)

B. EIT-Phantom

C. Forward Solution with Forward Solver

D. Boundary Potentials Measurements

B. EIT-PhantomB. EIT-PhantomAll the lead wires are of equal lengthsCGE or CME is placed at the phantom centre and connected to the groundPrepared with a 0.5%(w/v) solution of KCl

Practical biological phantom with stainless steel electrodes

C. Forward Solution with C. Forward Solution with Forward SolverForward SolverForward Problem (FP) is the basis of EIT and it

is essentially to be solved to calculate the boundary potential for estimating the conductivity update (Δσ) for each iteration in Inverse Problem (IP) .

Studying the FP, for an EIT system, the instrumentation error can be detected to eliminate the noise in the voltage signal

for better image resolution .

Equation

IK

A relation between the measured potentials and the domain conductivity equation using FEM as:

[Ф] is the vector of nodal voltage [K(σ)] is the transformation matrix which is a function of elemental conductivities of the FEM mesh [I] is the vector of currents at each nodes

Equation

h

gds

gh

VF

F is the Jacobean matrix which formed from the transformation matrix K and it is defined as:

g = 1, 2 …number of elementh = 1, 2…M [M = (number of data measured per current projections) x (number of current projections)]