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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.

In this work, we report on ElecFET (Electrochemical Field Effect Transistor) devices potentially of interest for the detection of different molecules in solution. ElecFET are electrochemical microsensors in liquid phase, based on two elements: (i) a pH-sensitive chemical field effect transistor (pH-ChemFET) and (ii) a metallic microelectrode deposited around the sensitive gate. The coexistence of these two elements combines (i) potentiometric and (ii) amperometric detection effects at the microscale. Design, fabrication and experimental validation of ElecFETs based on silicon and polymer micro-technologies, are reported. We first demonstrate the detection of hydrogen peroxide (H(2)O(2)) in solution, showing a sensitivity of 5 mV/mM in the [10-100 mM] concentration range. The ElecFET concept is then extended to the detection of glucose and lactate in the [1-30 mM] and [1-6 mM] concentration range respectively. The sensitivities are between 2-6 mV/mM and 8-20 mV/mM respectively.

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