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Pot.
Tutorial EIS with RCB200
(position C) – Impedance
and R1R2C fitting
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Files:
RCB200-C .EXP
RCB200-C 000_00Z.CRV
Abstract
A Potentiostatic Electrochemical Impedance Spectrum
is obtained and an automatic R1R2C fitting establishes that the
measurements are performed according to the specifications.
Sample
RCB200 with WORK connected to position C and
functional ground connected to the potentiostat rear panel.
Dummy cell RCB200 position C
R1R2C = 1.21 kOhm ±1% +[(4.99kOhms ±1% )//(4.7nF ±10%)]
Settings - Experimental
The impedance data are collected at 0 mV
versus REF from 100 KHz down to 100 Hz with an AC sine wave amplitude
of 10 mV and 20 frequencies per decade. The impedance spectrum will
have 61 points.
Curve examination
Display: Type = Nyquist
A simple way to evaluate the quality of
the measurement is to operate a circular regression which includes
R1R2C fitting. The values can be compared to the value of the resistors
and the capacitor involved.
Circular regression--------------------- 02-09-1999, 12:10:42
Point1 : 0
Point2 : 59
Center, X : 3.693 kohm.cm²
Center, Y : -0.05558 kohm.cm²
Diameter : 5.048 kohm.cm²
Coefficient : 1
Depletion angle : -0.631 °
X min. : 1.170 kohm.cm²
X max. : 6.216 kohm.cm²
R1 : 1.1699 Kohm.cm² 1.1616 < R1 < 1.2584
R2 : 5.0464 Kohm.cm² 4.8902 < R2 < 5.0898
C : 4.4153 nF/cm² 4.23 < C < 5.17
The RCB200 contains resistor at 1% and capacity at 10%.
****R1 value
is determined at high frequency, the accuracy of the measurement
is equal to 1%+0.02%*f. with f in kHz. So R1 could be between 1.21*0.96
and 1.21*1.04 kOhm 1.1616 < R1 < 1.2584
****R2 value
is determined at low frequency, the accuracy of the measurement
is equal to 1%+0.02%*f. with f in kHz. So R2 could be between 4.99*0.98
and 4.99*1.02 kOhm 4.8902 < R2 < 5.0898
****C value
The error on the capacity value is essentially due to its specification
(±10%). So C could be between 4.7*0.9 and 4.7*1.1 µF 4.23 < C
< 5.17
Conclusion
The measurements are within specifications.
References and notes
You can also evaluate the performances
regarding the resolution and the accuracy with the pure resistances.
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