The aim of this study was
to assess the performance of a condenser-chamber TEWL instrument for
barrier integrity testing. According to Netzlaff et
al [1] open-chamber
TEWL measurements appears to be of limited use for such tests, being
able to detect only severe damage in the samples they examined. Problems
identified included topically adhering water and the permeation of condensed
water via capillary action through deliberately made pinholes in artificial
membranes.
Topically adhering water is less of a problem with the condenser-chamber
TEWL method, because the chamber microclimate provides consistent conditions
for rapid evaporation, irrespective of ambient humidity. Topical water
shows up as a transient peak in the recorded water vapour flux time-series
curve, whereas the water diffusing through the membrane generally settles
to a lower level. Such flux curves give detailed information about the
properties of the membranes and the validity of the tests.
We report measurements using both artificial membranes (Sil-Tec
and PTFE) and bio-membranes (excised human stratum corneum and epidermis)
to illustrate the capabilities of this approach.
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