Development of interdigital electrodes for detecting skin impedance

Skin electrical impedance represents a critical parameter for non-invasive health monitoring, though conventional fixed spacing electrodes exhibit limited sensitivity in detecting localized impedance variations. To address this constraint, this study introduces interdigital electrodes (IDEs) for high-sensitivity localized detection. A systematic evaluation combining finite element simulations and in vivo murine experiments was conducted to assess their performance. Simulation results demonstrated that when local dielectric properties of the skin were altered, the IDE model achieved a relative impedance change of 11.73%, significantly surpassing the 2.45% observed with fixed spacing electrodes. Experimental data further validated this superior sensitivity: within the 20 Hz-5 kHz frequency range, IDEs captured an impedance variation ratio of approximately 96%, markedly higher than the 40% recorded using fixed spacing electrodes. These consistent findings confirm the distinct advantage of IDEs in detecting localized skin impedance changes, offering valuable theoretical and practical foundations for developing high-precision impedance detection systems applicable to wound monitoring, early lesion diagnosis, and related fields.