The instrument has been designed for Time Resolved Impedance Spectroscopy. It measures and records time evolution of impedance spectra.
In many applications, the impedance of a sample changes with time. Ordinarily, an impedance spectrometer would be used to measure the impedance for a range of frequencies. However, sometimes a sample changes fast enough that sequential over frequencies is too slow to be useful. For example, an impedance spectrum might be hard to interpret if the sample properties have changed significantly during frequency sweep.
The impedance camera takes an entire spectrum in a single shot, so that all the frequencies are handled in the same time. Such a single time spectrum is called a frame, pretty much like a movie frame.
Then one may acquire many such frames to record time development of sample’s impedance spectra.
Quantities measured by the instrument:
- Current through the sample and voltage on the sample which are used to calculate impedance and are later presented on:
- Nyquist (or Argand) plots in time,
- Bode plots in time,
- A time evolution of a impedance at a given frequency,
- Difference plots to observe changes in the impedance in time
The camera is ideal to observe the real time impedance development of electrochemical sensors. It can be setup as part of, for example, photo-electrochemical measurements, etc.
The Impedance Camera is complementary to devices performing static photocurrent/photovoltage measurements like photoelectric spectrometers or a mini photoelectric spectrometer.
The instrument consists of:
- measurement electronics module
- measurement head (sample is attached here)
- connection cables
- 12 V power supply
- PC software for signal generation and acquisition
Impedance Camera for electrochemical measurements
Optionally, the instrument is available in option with Sample Chamber and Electrochemical Head to investigate the electrochemical samples.
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- Number of frequencies in a frame: unlimited
- Measurement Head types: Basic, Electrochemical
- Basic Head current ranges: 10 mA, 1 mA
- Basic Head frequency range: 1 mHz ÷ 1 MHz
- Electrochemical Head current ranges: 1 mA, 100 μA, 10 μA, 1 μA, 100 nA, 10 nA.
- Electrochemical Head frequency ranges: 2.5 MHz, 1.3 MHz, 300 kHz, 35 kHz, 3kHz, 300 Hz
- Potential ranges: from -1 V to 1 V
- Measurement head: basic or electrochemical
The Impedance Camera software is very intuitive and does not require any additional training.
The measurement results shown below are obtained for a parallel RC circuit where the resistance was dependent on oscillating illumination intensity.
Nyquist (or Argand) plot showing real and imaginary part of impedance measured for range of frequencies at various times. One can see the resistance increases in the middle of the measuring sequence and the impedance semicircles grow in diameter.
The green color selects the same frequency measurement points in time. If only capacitance was changed, in the RC circuit, all semicircles would be the same size but position of given frequency points would move along a circle.
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A single frame 3D Nyquist (Argand) plot.
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Bode plots amplitudes in time.
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Bode plots phases in time.
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