ConductivityTemperatureDepth

Conductivity testing is a measurement that characterizes a material’s or solution’s ability to conduct electric current. Conductivity is influenced by charge carriers such as ions in a solution or free electrons in a solid, and is commonly reported in siemens per meter (S/m) for solids or in millisiemens per centimeter (mS/cm) and microsiemens per centimeter (µS/cm) for liquids. In liquids, conductivity serves as a proxy for ionic content and water quality, reflecting the presence of dissolved salts and other ions. In solids, conductivity relates to an material’s electronic structure and can indicate doping levels, defects, or phase composition.

Measurement in liquids typically uses a conductivity meter with electrodes immersed in the sample. Two-electrode configurations are simple but susceptible to electrode polarization, while four-electrode setups reduce this effect and improve accuracy. Temperature compensation is standard because conductivity changes with temperature. Calibration uses reference solutions with known conductivity values.

In solid materials, conductivity is measured using techniques such as the four-point probe method to determine bulk conductivity or impedance spectroscopy across a range of frequencies to separate contributions from grains and boundaries. The conductivity σ is the reciprocal of resistivity ρ (σ = 1/ρ).

Applications of conductivity testing span water treatment and environmental monitoring, agriculture and soil science, chemical process control, battery and electrolyte research, and semiconductor fabrication. The method is valued for its speed, simplicity, and non-destructive nature, but readings are sensitive to temperature, sample homogeneity, electrode geometry, and surface conditions. Standards and procedures vary by application, and accurate interpretation requires attention to sample preparation and calibration.