Impedanciamérések

Impedanciamérések refer to techniques for measuring impedance, the opposition that an electrical system presents to alternating current. Impedance is a complex quantity Z = R + jX, where R is resistance and X is reactance. It depends on frequency and combines conductive, capacitive, and inductive properties of the object under test, ranging from electronic components to materials, electrochemical interfaces and biological tissues.

Instruments and methods used for impedanciamérések include impedance meters, LCR meters and impedance analyzers. A common approach is electrochemical impedance spectroscopy (EIS), which applies small sinusoidal signals over a broad frequency range and records the response. To minimize errors from lead resistance, four-terminal or Kelvin connections are often employed. Calibration typically uses known standards for open, short and load conditions, and measurements may be conducted as frequency sweeps or at selected fixed frequencies.

Results are typically presented as Nyquist plots, showing the real versus imaginary parts of impedance, or as Bode plots, showing magnitude and phase versus frequency. Impedance data are analyzed with equivalent circuit models comprising resistors, capacitors and inductors to interpret underlying physical processes, such as charge transfer, double-layer effects or dielectric relaxation.

Applications of impedanciamérések span electronics, materials science and electrochemistry, including component characterization, dielectric spectroscopy, corrosion and battery research, and biomedical impedance measurements such as bioimpedance analysis for tissue characterization or body composition.

Key considerations include electrode polarization at low frequencies, parasitic inductance or capacitance, temperature and geometry effects, and the need for appropriate modeling and calibration to ensure accurate interpretation of the measured impedance.