A liquid metal-enhanced method for low-resistance measurements: Application to a vortex magnetohydrodynamic generator

Characterization of low-electrical resistances is essential to guarantee the efficiency, security, operation, and development of electric and electronic devices across many sectors. Low-resistance measurements present several challenges, including the quality of electrical contact between the measuring probes and the sample and the sample’s geometry. Although the standard procedure (four-point technique) is commonly used to perform such measurements, one typically encounters the issues mentioned above in real systems. This paper proposes a method to address both problems by incorporating a gallium-based liquid metal in the standard procedure to ensure electrical contact. These measurements are corrected using numerical simulations with controlled measuring setups. Initially, we assessed the measurement errors related to electrical resistance within the system and compared the conventional standard procedure with the methodology introduced in this study. Next, we employed the proposed technique to examine the influence of electrical resistance measurement on the operational efficiency of a cylindrical vortex-type magnetohydrodynamic generator. A characterization system was developed and implemented to analyze this generator. The results demonstrated that the methodology enabled the measurement of resistance in the order of tenths of µΩ, thereby enhancing the characterization of previously reported results. This implied a nearly two-fold increase in generator power density, reaching approximately 72 mW/cm 3 . • Gallium-based liquid metal is integrated in the four-probe technique. • Electrical resistance measured within the order of some µΩ. • An in-house characterization system (2 mA and 5 μ V resolution) was developed. • This method leads to an enhancement in the performance of an MHD generator. • The estimated uncertainty is below 5.23%.