How do AquaFlux™ TEWL measurements compare with Delfin VapoMeter measurements ?

The AquaFlux™ and the VapoMeter use different closed-chamber measurement methods, as follows:-

 

1. VapoMeter = Unventilated-chamber method

This method was first used in the 1960s for measuring water loss from plant leaves [1]. Its use for TEWL measurement was first described by Miller et al [2]. Water vapour is captured in a closed measurement chamber, causing the humidity of the trapped air to rise. Water vapour flux is determined from the rate of rise of humidity with time.

 

2. AquaFlux™ = Condenser-chamber method

This measurement principle is unique to the AquaFlux™ [3, 4]. The closed chamber is equipped with a condenser cooled to below the freezing point of water, which acts as a sink for the water vapour. Water vapour flux is determined using Nilsson’s diffusion gradient principle [5].

 

References

[1]	EF Wallihan. Modification and use of an electric hygrometer for estimating relative stomatal apertures. Plant Physiol. 39: 86-90, 1964.
[2]	DL Miller, AM Brown & EJ Artz. Indirect Measures of Transepidermal Water Loss. In Bioengineering and the Skin (R Marks & PA Payne Eds), 161-71, MTP Press Lancaster, 1981.
[3]	RE Imhof, EP Berg, RP Chilcott, LI Ciortea and FC Pascut. New instrument for measuring water vapour flux density from arbitrary surfaces. IFSCC Magazine. 5(4): 297-301, 2002. Click here to download in pdf format.
[4]	RE Imhof, MEP De Jesus, P Xiao, LI Ciortea & EP Berg. Closed-chamber TEWL measurement:- microclimate, calibration and performance. Int J Cosmet Sci 31: 97-118, 2009.
[5]	GE Nilsson. Measurement of Water Exchange through Skin. Med Biol Comput. 15: 209-18, 1977.