Optical Fibre Humidity Sensor for Accessing the Wetting Condition of Oak Barrels

The use of oak barrels for wine aging is a widespread technique due to the ideal physical and structural properties of oak wood [1] . Moisture impregnation of wood induces the release of aromatic compounds and tannin in wine however oak has a limited potential for wine enrichment and after prolonged usage the barrel must be replaced. Currently, the common practice of wine makers in assessing to the condition of oak barrels is empirical and thus subjective. A sensor able to accurately detect the wetting condition of oak barrels in situ , would be instrumental in reducing unnecessary costs and assist in quantifying the wine aging process. The sensor must have miniature size and weight, for insertion into the walls of the barrel with minimal disturbance, and remote interrogation as to be operational in the restricting environment of winery cellars. Optical fibre sensors [2] constitute an ideal solution for the specific application meeting the above requirements inherently. Herein we report on the development of an optical fibre Fabry Perot (FP) humidity sensor, specifically designed as to monitor the evolution of Moisture Content (MC) of oak wine barrels during wine aging. Further correlation of the monitored MC with barrel age and oak release of characteristic compounds will offer winemakers an additional tool in monitoring the wine aging process.