Fast Psychrometers as New SU-8 Based Microsystems

Nicolas Giordani (1) , Lionel Camberlein (1) , Etienne Gaviot (1) , Frédéric Polet (1) , Nicolas Pelletier (1) , Bruno Bêche (2)

1 LAUM - Laboratoire d'Acoustique de l'Université du Mans
2 PALMS - Physique des atomes, lasers, molécules et surfaces

In this paper, a new approach to designing fast micro-psychrometers devoted to measuring relative humidity is presented. Such devices are based on a planar thermopile fitted with an appropriate set of microchannels arranged for monitoring the evaporation process as a Seebeck voltage. They are fabricated out of a glass substrate, sputtered metals, and near vertical side walls made of SU-8, according to standard microtechnology processes for MEMs. Considering classical psychrometers, the new design is aimed at reducing both size and response time. Thus, besides being far less invasive than a standard unit, fast measurements (tau=5 s) are enabled. A straightforward modeling, aimed at deriving the relative humidity, is given with a view to integrating the signal conditioner. As regards validation, a prototype is calibrated and compared to a reference probe, and a discussion on its enhancement is also presented.

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]

Nicolas Giordani, Lionel Camberlein, Etienne Gaviot, Frédéric Polet, Nicolas Pelletier, et al.. Fast Psychrometers as New SU-8 Based Microsystems. IEEE Transactions on Instrumentation and Measurement, 2007, 56 (1), pp.102 - 106. ⟨10.1109/TIM.2006.887332⟩. ⟨hal-00134000⟩