Novel Resistance Measurement Method: Analysis of Accuracy and Thermal Dependence with Applications in Fiber Materials

Material resistance is important since different physicochemical properties can be extracted from it. This work describes a novel resistance measurement method valid for a wide range of resistance values up to 100 GΩ at a low powered, small sized, digitally controlled and wireless communicated device. The analog and digital circuits of the design are described, analysing the main error sources affecting the accuracy. Accuracy and extended uncertainty are obtained for a pattern decade box, showing a maximum of [Formula: see text] accuracy for temperatures below 30 [Formula: see text] C in the range from 1 MΩ to 100 GΩ. Thermal analysis showed stability up to 50 [Formula: see text] C for values below 10 GΩ and systematic deviations for higher values. Power supply [Formula: see text] applied to the measurement probes is also analysed, showing no differences in case of the pattern decade box, except for resistance values above 10 GΩ and temperatures above 35 [Formula: see text] C. To evaluate the circuit behaviour under fiber materials, an 11-day drying process in timber from four species (Oregon pine-Pseudotsuga menziesii, cedar-Cedrus atlantica, ash-Fraxinus excelsior, chestnut-Castanea sativa) was monitored. Results show that the circuit, as expected, provides different resistance values (they need individual conversion curves) for different species and the same ambient conditions. Additionally, it was found that, contrary to the decade box analysis, [Formula: see text] affects the resistance value due to material properties. In summary, the proposed circuit is able to accurately measure material resistance that can be further related to material properties.