Electrical impedance applied to non‐invasive detection of irritation in skin

Healthy volunteers were subjected to irritation by sodium lauryl sulphate at concentrations in the range 0.002% to 5.0% applied in Finn Chambers for 24 h. Test sites were visually assessed 1 h and 24 h niter cessation of exposure. At the same limes electrical impedance was measured with a new impedance device which allows non‐invasive local measurements to a controlled depth. Close agreement between concentration and an irritation index calculated from electrical impedance parameters was found over the whole concentration range for most test persons‐ At concentrations below 0.2%, visual scores were zero. These results suggest that electrical impedance can ht; used as an objective tool to record irritation, and furl her that electrical impedance might be a more sensitive method than the commonly used visual readings.