Comparative study of five instruments measuring stratum corneum hydration (Corneometer CM 820 and CM 825, Skicon 200, Nova DPM 9003, DermaLab). Part I. In vitro

Abstract

Background/aims: The hydration state of stratum corneum can be measured with different instruments. In the present study, five instruments were compared under different experimental in vitro conditions: Corneometer CM 820 and CM 825, Skicon 200, Nova DPM and DermaLab. Methods: A sorption‐desorption test, measurements on different filters and with liquids with different dielectric constants, measurement‐depth analysis and measurements on different agar plates were performed. Results: Good correlation between the values of the five instruments and μl (sorption test: varying from r= 0.8249 to r= 0.9635) and time (desorption test: correlation varying from r= 0.7615 to r=0.9909) could be demonstrated. A high Spearman correlation coefficient (r) could be proven for dielectric constant (dc)/CM 820 (r=0.9333), dc/CM 825 (r=0.9833) and dc/Nova DPM (r=0.9048). A lower correlation or no correlation was found for dc/DermaLab (r=0.8469; P=0.023) and dc/Skicon 200 (r=0.9000; P=0.083). Conclusions: For each of the five instruments, the electrical field of measurement can be assumed to cover the following depths: CM 820, between 30 and 45 μm; CM 825, around or less than 15 μm; Skicon 200, less than 15 μm; Nova DPM, between 45 and 60 μm; DermaLab, around or less than 15 nm.

Epidermal Differential Impedance Sensor for Conformal Skin Hydration Monitoring

“…As the hydration changes from 40 to 110, the impedances (at 15 kHz) of the meander electrode in channel 1 and the interdigitated electrode in channel 2 change from 255 to 24 X and from 2.54 to 2.52 MX, respectively. The interdigitated electrodes in channel 2 provides a useful design for electrodes [23,24,37], but the complexity in the associated distribution of electrical field lines leads to complications in theoretical analysis [38]. The symmetric sensor geometry of channel 3 and 4 enables direct comparison to outputs from the CMM, which has similar electrode construction, and the symmetry facilitates analytical modeling.…”

“…The other electrodes measure both resistance and capacitance changes. The circular electrodes offer symmetries that facilitate theoretical analysis; these geometries are also found in macroscale electrodes used in CMM [22,23], to enable direct comparison. Soft, stretchable and releasable connectors provide electrical interfaces between the hydration sensor systems and external impedance data acquisition (DAQ) hardware (Fig.…”

“…Among these methods, electrical impedance provides the most reliable and established assessment, due to its instrumental simplicity and minimized cost. Several commercial systems that perform this measurement are available [22][23][24][25]. Such technologies generally rely on physical contact between the soft, curved surface of the skin, and rigid, planar electrodes [22].…”

Moisturizing effect of a cosmetic formulation containing pequi oil (Caryocar brasiliense) from the Brazilian cerrado biome

“…Stratum corneum moisture content was determined by noninvasive biometrical measurements using a skin capacitance meter (Courage & Khazaka, Electronic GmbH, Khöln, Germany) (Fluhr et al, 1999a(Fluhr et al, , 1999b whereas transepidermal water loss was determined by an evaporimeter (Courage & Khazaka, Electronic GmbH, Khöln, Germany) (Gioia et al, 2002). TEWL values were registered for 2 min following a 30 s period of equilibration of the probe on the skin.…”

Use of Opuntia ficus-indica (L.) Mill extracts from Brazilian Caatinga as an alternative of natural moisturizer in cosmetic formulations

“…However, capacitance measurement is also indicative of an increase or decrease in water within the stratum corneum. This electrical property of the skin provides information that allows hydration levels to be calculated (Fluhr et al, 1999;Dykes, 2002;Heinrich et al, 2003;Darlenski et al, 2009;Gonçalves, Maia Campos, 2009a;Byrne, 2010;Sotoodian, Maibach, 2012).…”