Tracking metabolic responses based on macronutrient consumption: A comprehensive study to continuously monitor and quantify dual markers (cortisol and glucose) in human sweat using WATCH sensor

Abstract

Wearable Awareness Through Continuous Hidrosis (WATCH) sensor is a sweat based monitoring platform that tracks cortisol and glucose for the purpose of understanding metabolic responses related to macronutrient consumption. In this research article, we have demonstrated the ability of tracking these two biomarkers in passive human sweat over a workday period (8 hours) for 10 human subjects in conjunction with their macronutrient consumption. The validation of the WATCH sensor performance was carried out via standard reference methods such as Luminex and ELISA This is a first demonstration of a passive sweat sensing technology that can detect interrelated dual metabolites, cortisol, and glucose, on a single sensing platform. The significance of detecting the two biomarkers simultaneously is that capturing the body's metabolic and endocrinal responses to dietary triggers can lead to improved lifestyle management. For sweat cortisol, we achieved a detection limit of 1ng/mL (range ˷1-12.5 ng/mL) with Pearson's 'r' of 0.897 in reference studies and 0.868 in WATCH studies. Similarly, for sweat glucose, we achieved a detection limit of 1 mg/dL (range ˷ 1-11 mg/dL) with Pearson's 'r' of 0.968 in reference studies and 0.947 in WATCH studies, respectively. The statistical robustness of the WATCH sensor was established through the Bland-Altman analysis, whereby the sweat cortisol and sweat glucose levels are comparable to the standard reference method. The probability distribution (t-test), power analysis (power 0.82 -0.87), α = 0.05. Mean absolute relative difference (MARD) outcome of ˷ 5.10-5.15% further confirmed the statistical robustness of the sweat sensing WATCH device output.

A machine learning-based on-demand sweat glucose reporting platform

“…Sweat was collected from the subject, and the blood glucose measurements and sweat glucose values were established using ELISA methods. The output of the proposed device and reporting system was validated against the blood glucose values measured using an AimStrip® glucometer (Germaine Diabetes Diagnostics, USA) 27 .…”

“…Written and informed consent was obtained from all participants before sample collection. All enrolled subjects wore the devices during the testing, and continuous measurements were recorded in compliance with the protocol approved by the IRB committee 27 . The wearable sweat sensor device was placed on the antebrachial region (lower forearm) of the subject.…”

“…Human subjects were not allowed to exert themselves physically, and their skin was excited using a sweat induction method such as iontophoresis. This ensured an entire passive generation of sweat to be sampled 27 . Continuous on-body measurements were sampled every minute for the duration of the testing and depending on the availability of the subject.…”

Flexible Sweat Sensors: From Films to Textiles

“…This approach uses a gel with pilocarpine and applies a voltage to it. , At this voltage, pilocarpine induces local sweat secretion. It allows sweat to be obtained on demand, while facilitating people who are unable to increase sweat volume by means of exercise, such as patients, infants, and the elderly …”

“…It allows sweat to be obtained on demand, while facilitating people who are unable to increase sweat volume by means of exercise, such as patients, infants, and the elderly. 61 However, on the other hand, in some situations, it is necessary to demonstrate that pilocarpine does not interfere with them when testing electrode selectivity. 62,63 Moreover, electrochemical film-based sensor on the neck, 13 back, 14 wrist, 15 finger, 16 and thigh; 17 textile-based electrochemical sensor on the forehead, 18 arm, 19 armpit, 20 and foot; 21 textile-based colorimetric sensor on the forehead 22 and arm.…”