Sensors of volatile compounds based on the dielectric relaxation of organic molecules

Organic molecules can have their dielectric relaxation characteristics altered by their exposition to volatile substances and when immobilized in a porous silica substrate, they exhibit a very large number of active sites available for interaction with molecules of volatile organic compounds (VOCs). Here, we propose to exploit these properties for the development of chemical sensors by showing that the changes in the total capacitance of the system resulting from the adsorption of the VOCs can be unequivocally associated to the nature of the compound tested, so that the overall characteristics of any one of sensors constructed in this manner can be closely related to the corresponding molecules that were immobilized. Considering the stability of the electrical response of the system, its sensitivity towards different volatile compounds and the simplicity of the procedure for immobilizing molecules, this technique appears a promising manner of manufacturing devices that could be used in the development of competitive chemical sensors.