Estimation of Muscles fatigue by ions and EMG sensors

There is growing interest in health monitoring using minimally invasive wearabledevices. Clinics often use blood analysis for the monitoring condition of thehuman body but it often requires invasive and annoying collection and is notsuitable for continuous monitoring. In order to solve these issues, sweat hasrecently been deeply studied by researchers and identified as a potential bloodsubstitute in diagnosis. Metabolic markers that are present in sweat, indeed,could provide a more direct indicator of human health for accurate assessment ofathletic performance, clinical diagnosis, and for managing chronic health conditionsincluding generating alerts in cases of emergencies. Sweat is promising since itis easily accessible and can be collected non invasively using the iontophoresis orchemical stimulation methods. Sweat is very rich in physiological and metabolicbiomarkers, for example, sodium from sweat can indicate the hydration statusand electrolyte imbalance in a body, lactate concentration can be an indicatorof the muscle fatigue, ammonium for metabolic conditions, potassium level formuscle cramps dehydration and cardiovascular problem and calcium for the bonemineral loss. Among all biomarkers Potassium, Sodium, Calcium and Ammoniumhave been investigated in this work with the purpose of establishing a quantitativemeasure of muscle fatigue. All solid-state potentiometric ion-selective electrodeshave been explored and applied, since they provide the necessary characteristicssuitable for miniaturization and for wearable applications. In order to have a termof comparison for the muscle fatigue the surface EMG signals of the lower limbhave been analyse. For these reasons a cycling experimental protocol based on agraded load exercise have been implemented to induce progressively muscle fatigueduring which both ions concentration in sweat and EMG are misured.