Physiological stress monitoring using sodium ion potentiometric microsensors for sweat analysis

Abstract

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.

Human Sweat Analysis Using a Portable Device Based on a Screen‐printed Electrolyte Sensor

“…and Dam, et al. the discrepancy in their work is minor or not at all visible . However, they only used commercial ISEs for comparison measurements, but these ISEs probably responded similar to the interference of the sweat components as the printed ISEs.…”

“…Unfortunately, this was not reported in previous publications . Only a few reports carried out comparison measurements either by using commercial ISEs or other methods like ion chromatography (IC) and atomic absorption spectroscopy (AAS) .…”

“…For example, an indirect measurement of heat stress analyzing the sodium concentration in sweat was reported by Cazalé, et al. . Main effort of sweat analysis is done targeting diagnosis of cystic fibrosis (CF).…”

Wearable Potentiometric Sensors Based on Commercial Carbon Fibres for Monitoring Sodium in Sweat

“…Furthermore, sodium loss is reported to be highly variable due to individual factors such as age, gender, environment, diet or genetics 35. Even though monitoring of sodium levels in sweat using potentiometric techniques has already been proposed 36, 37, there is still a vast space of opportunities to develop devices that can allow the seamless integration within sport garments.…”

Advanced Wearable Microfluidic Sensors for Healthcare Monitoring

“…Hyein et al invented a wearable microfluidic patch for dynamic electrolyte monitoring, including Na + , K + , H + , and Cl − (Figure b) . Several groups demonstrated ion‐sensitive field‐effect transistors (ISFETs) based on the combination of FETs and ion‐sensitive membranes for electrolyte analysis of a liquid . ISFETs substitute the gate electrode for a reference electrode influenced by charged molecules or ions of liquids.…”