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EIS
EIS Extraction: CHI Instrument Data Preprocessing

EIS Extraction: CHI Instrument Data Preprocessing

EIS Extraction: CHI Instrument Data Preprocessing

If you just received raw .txt files exported from a CHI electrochemical workstation and aren’t sure where to start, this Workflow is the right first step.

This step automatically organizes raw EIS text into standardized tables (*_eis.csv) and fills in key columns needed for subsequent plotting and fitting. You don’t need to manually rename columns or worry about minor differences between export formats.

What You’ll Get

  • One *_eis.csv file per sample
  • Unified fields: freq_hz, z_real_ohm, z_imag_ohm, z_mod_ohm, phase_deg
  • Automatic removal of invalid data (e.g., non-positive frequencies, null values)
  • Automatic sorting by frequency from high to low, ready for direct Nyquist/Bode/DRT usage

Steps

  1. Select input folder: Select the directory containing the CHI .txt raw EIS files.
  2. The system automatically traverses .txt files in the directory and processes them one by one.
  3. Upon completion, an xxx-eis-extract output folder is generated in the same directory.

If a file has an abnormal format during processing, the system will skip it with a warning without affecting the processing of other files.

Data Recognition Logic (Brief)

The program first locates the Freq/Hz data header, then automatically matches from common column name aliases:

  • Frequency column: Freq/Hz / Frequency/Hz / f/Hz
  • Real part column: Z'/ohm / Zreal/ohm / Z'/Ω
  • Imaginary part column: Z"/ohm / Z''/ohm / Zimag/ohm

And calculates accordingly:

∣Z∣=Z′2+Z′′2,ϕ=arctan⁡(Z′′Z′)|Z| = \sqrt{Z'^2 + Z''^2}, \quad \phi = \arctan\left(\frac{Z''}{Z'}\right)

where the phase angle is output in degrees (phase_deg).

Output File Description

Each *_eis.csv contains at minimum:

  • freq_hz: Frequency (Hz)
  • z_real_ohm: Impedance real part (Ω)
  • z_imag_ohm: Impedance imaginary part (Ω)
  • z_mod_ohm: Impedance modulus (Ω)
  • phase_deg: Phase angle (°)

Recommended Next Steps

In-Situ EIS Extraction: Donghua Instrument