ImpedanceFitter

Impedance spectroscopy (IS) is a great tool to analyse the behaviour of an electrical circuit, to characterise the response of a sample (e.g. biological tissue), to determine the dielectric properties of a sample, and much more¹.

In IS, often (complex) non-linear least squares is used for parameter estimation of equivalent circuit models. ImpedanceFitter is a software that facilitates parameter estimation for arbitrary equivalent circuit models. The equivalent circuit may comprise different standard elements or other models that have been formulated in the context of impedance spectroscopy. The unknown parameters are found by fitting the model to experimental impedance data. The underlying fitting software is LMFIT², which offers an interface to different optimization and curve-fitting methods going beyond standard least-squares.

ImpedanceFitter allows one to build a custom equivalent circuit, fit an arbitrary amount of data sets and perform statistical analysis of the results using OpenTurns³.

Documentation

The documentation is available at Read the Docs.

If you want to compile it locally: The documentation is in the doc directory and requires Sphinx to be compiled. A requirements file can be found in the doc directory.

Installation

ImpedanceFitter works with Python >= 3.6.

ImpedanceFitter can be installed using pip

pip install impedancefitter

If you want to install the code from source, clone into a local directory.

cd into this directory and run

pip install -e . --user

in this directory. It will install all requirements automatically. Moreover, you can edit the source code and run the edited version without reinstalling.

Testing

The tests use pytest. Simply run pytest inside the repository main directory.

Use ImpedanceFitter

Check out the examples directory and the documentation to see how ImpedanceFitter is supposed to work.

Contribute

If you find bugs or missing functionality, feel free to raise an issue here on github or create a pull request!

References

1: Barsoukov, E., & Macdonald, J. R. (Eds.). (2018). Impedance Spectroscopy: Theory, Experiment, and Applications. (3rd ed.). Hoboken, NJ: John Wiley & Sons, Inc. https://doi.org/10.1002/9781119381860

2: Newville, M., & et al. (2020, May 7). lmfit/lmfit-py 1.0.1 (Version 1.0.1). Zenodo. http://doi.org/10.5281/zenodo.3814709

3: Baudin, M., Dutfoy, A., Looss, B., & Popelin, A. L. (2017). OpenTURNS: An industrial software for uncertainty quantification in simulation. In Handbook of Uncertainty Quantification (pp. 2001–2038). https://doi.org/10.1007/978-3-319-12385-1_64