The Tinsley LCR Databridge Model 6401 and electrical impedance measurements to evaluate skin integrity in vitro

Electrical impedance is used to confirm skin integrity for in vitro dermal regulatory testing and as a tool to evaluate skin condition to determine the irritation and corrosion potential of various chemicals and personal care products. In this experiment, samples of dermatomed human skin were mounted onto static diffusion cells (0.64 cm2) maintained at 32 degrees C. Following equilibration with 0.9% saline in the donor and receptor chambers, an impedance measurement was taken with a Tinsley LCR Databridge Model 6401 set in the resistance mode (R) and in (a) the serial-equivalent mode (SER) with an alternating current (AC) frequency of 100 hertz (Hz), (b) SER and 1000 Hz, (c) parallel-equivalent mode (PAR) and 100 Hz, and (d) PAR and 1000 Hz. With the databridge set in the SER-equivalent mode and an AC frequency of 1000 Hz, the minimum (7.2 kOmega), maximum (10.0 kOmega), and median (8.6 kOmega) impedance values exhibited a limited response range (2.8 kOmega). However, when the Tinsley 6401 was set in the PAR-equivalent mode at the lower AC frequency of 100 Hz the minimum (16.7 kOmega), maximum (134.6 kOmega), median (83.2 kOmega), and range (117.9 kOmega) of values were the highest obtained. The results confirm that the operator-selected settings on the Tinsley LCR Databridge Model 6401 affect the impedance measurement and the dynamic range of values observed for dermatomed human skin in vitro.