Development of a hydration sensor integrated on fabric

The main purpose of the European project ProeTEX is to develop equipment to improve safety, coordination and efficiency of emergency disaster intervention personnel like fire-fighters or civil protection rescuers. The equipment consists of a new generation of "smart" garments, integrating wearable sensors which will allow monitoring position and activity of the user, as well as environmental variables of the operating field in which rescuers are working and physiological parameters among whom there is the dehydration. The dehydration of emergency disaster personnel can lead to severe physiological consequences being able to go until the death. The follow-up of the sodium ions concentration in the sweat allows to evaluate this dehydration state in real time by a non invasive method and to react quickly in the event of problem. This paper deals with the development of an Ionic Selective Electrode sensor and its transfer on fabrics. The performances were evaluated in terms of sensitivity, selectivity and reproducibility initially in model solution and then in natural sweat. A portable electronic board connected to the sensing part is described too. This board drives the electrochemical and temperature sensors for analog acquisition and converts measurement data to digital value. Signal processing is implemented on the electronic board in order to correct raw data (gain, offset) and to convert them to ion concentrations.