Electrical impedance depends on frequency and includes both magnitude and phase. Electrode contact, hydration, temperature, electrode material, and barrier state can all influence the measured spectrum.
That makes impedance useful for observing whether the skin–electrode interface remains within defined session conditions.
Interface sensing controls the session. Tissue analysis establishes deposition.
What the signal can support
A frequency-dependent response can help characterize contact, identify unstable conditions, and provide a repeatable electrical record of the interface during operation.
What the signal cannot establish
Impedance does not identify PDRN, quantify its concentration, or determine the skin layer in which material is deposited. Those questions require recovered-dose tissue analysis.
The validation question
AXIS validation will first characterize interface sensing, then measure physical deposition, and only then test whether specific signal features correlate with measured outcomes under controlled conditions.
Sources
- Goyal et al. · 2022Dependence of Skin–Electrode Contact Impedance on Material and Skin Hydration
- Björklund et al. · 2013Skin membrane electrical impedance properties under the influence of a varying water gradient
- Yamamoto and Yamamoto · 1976Electrical impedance spectroscopy of human skin: theory and experiment