In the frame of sweat analysis, two technologies, based on either ISE or ISFET devices, were developed for the implementation of pNa potentiometric microsensors. Both of them demonstrated good sodium ion Na + detection properties with a global sensitivity of around 110 mV/pNa in NaClbased solutions due to the use of an integrated "Ag/AgCl ink" pseudo-reference electrode. Then, in order to deal with in-vivo analysis of sweat natremia, a physiological sweatband prototype was developed, consisting of pNa-ISE and pNa-ISFET electronic detection modules as well as a textilebased sweat pump. Finally, sweating process was studied during series of experiments on twentyfive healthy consenting subjects. The sodium ion concentration [Na + ] was successfully monitored in sweat during various heat exposures, demonstrating a global increase with exercise trial duration. Furthermore, a strong correlation was found between the sweat [Na + ] concentration and the subject's internal temperature θ, allowing monitoring the subject's heat stress state. All in all, the relevance of the Na + ion analysis was demonstrated for the physiological stress monitoring and pNa potentiometric microsensors were shown to be very promising for the development of smart sweatbands.

A membrane for the development of Na + sodium ion sensitive field effect transistor (pNa-ISFET) is described in this work. This membrane is based on a fluoropolysiloxane (FPSX) polymer modified by sodium ionophore. The advantages of using such polymer are several: it permits good adhesion properties on silicon-based layers, it is characterized by a lower resistivity and it is fully compatible with ink jet printing technique. Thus, FPSX membranes were developed in the frame of a pH-ChemFET / Ag/AgCl reference electrode industrial fabrication process. Studies involve the deposition of FPSX-based, sodium ion sensitive layers by ink jet printing, the integration and characterization of Ag/AgCl reference electrode, as well as the pNa measurement in solution. Thus, whatever the reference electrode used, FPSX-based pNa-ISFET microsensors show good detection properties with sensitivity around 57 mV/pNa, detection limit around 10-4 M, low pH interferences (7 mV/pH in the [9-12] basic range) and selectivity coefficient versus potassium K + ion-3. Final application is done through analysis of real sweat samples.