Real-time smart multisensing wearable platform for monitoring sweat biomarkers during exercise

Sweat secreted by the human eccrine sweat glands can provide valuable biomarker information during exercise in hot and humid conditions. Real-time noninvasive biomarker recordings are therefore useful for evaluating the physiological conditions of an athlete such as their hydration status during endurance exercise. In this work, we describe a platform that in- cludes different sweat biomonitoring prototypes of cost-effective, smart wearable devices for continuous biomonitoring of sweat during exercise. One prototype is based on conformable and disposable soft sensing patches with an integrated multi-sensor array requiring the integration of different sensors and printed sensors with their corresponding functionalization protocols on the same substrate. The second is based on silicon based sensors and paper microfluidics. Both platforms integrate a multi-sensor array for measuring sodium, potassium, and pH in sweat. We show preliminary results obtained from the multi-sensor prototypes placed on two athletes during exercise. We also show that the machine learning algorithms can predict the percentage of body weight loss during exercise from biomarkers such as heart rate and sweat sodium concentration collected over multiple subjects

Multisensing wearables for real-time monitoring of sweat electrolyte biomarkers during exercise and analysis on their correlation with core body temperature

Sweat secreted by the human eccrine sweat glands can provide valuable biomarker information during exercise. Real-time non-invasive biomarker recordings are therefore useful for evaluating the physiological conditions of an athlete such as their hydration status during endurance exercise. This work describes a wearable sweat biomonitoring patch incorporating printed electrochemical sensors into a plastic microfluidic sweat collector and data analysis that shows the real-time recorded sweat biomarkers can be used to predict a physiological biomarker. The system was placed on subjects carrying out an hour-long exercise session and results were compared to a wearable system using potentiometric robust silicon-based sensors and to commercially available HORIBA-LAQUAtwin devices. Both prototypes were applied to the real-time monitoring of sweat during cycling sessions and showed stable readings for around an hour. Analysis of the sweat biomarkers collected from the printed patch prototype shows that their real-time measurements correlate well (correlation coefficient ≥0.65 ) with other physiological biomarkers such as heart rate and regional sweat rate collected in the same session. We show for the first time, that the real-time sweat sodium and potassium concentration biomarker measurements from the printed sensors can be used to predict the core body temperature with root mean square error (RMSE) of 0.02 °C which is 71% lower compared to the use of only the physiological biomarkers. These results show that these wearable patch technologies are promising for real-time portable sweat monitoring analytical platforms, especially for athletes performing endurance exercise

Real-Time Multi-Ion Detection in the Sweat Concentration Range Enabled by Flexible, Printed, and Microfluidics-Integrated Organic Transistor Arrays

Organic electrochemical transistors (OECTs) show remarkable promise as biosensors, thanks to their high signal amplification, simple architecture, and the intrinsic flexibility of the organic material. Despite these properties, their use for real-time sensing in complex biological fluids, such as human sweat, is strongly limited due to the lack of cross-sensitivity and selectivity studies and the use of rigid and bulky device configurations. Here, the development of a novel flexible microfluidics-integrated platform with an array of printed ion-selective OECTs enables multi-ion detection in a wearable fashion. This is achieved by coating the poly(3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS) channels of the transistors with three different ion-selective membranes (ISMs). Systematic electrical and sensing analysis of the OECTs with ISMs show a minimal impact of the membranes on the electrical and time responses of the transistors while providing high ion selectivity. This work combines for the first time real-time and selective multi-ion detection with an array of inkjet-printed and flexible organic transistors coated with different ISMs, demonstrating state-of-the-art sensing capabilities of approximate to 10 mu A dec(-1)for potassium, sodium, and pH. This flexible OECTs sensing platform paves the way to the next generation devices for continuous electrolytes monitoring in body fluids

Thin film organic electrochemical transistors based on hybrid PANI/PEDOT:PSS active layers for enhanced pH sensing

We report on organic electrochemical transistors (OECTs) with active channels made of hybrid inkjet-printed poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and electropolymerized polyaniline (PANI) layers, exhibiting simultaneously improved electrical and pH sensing characteristics. The aniline electropolymerization with an optimum 6-cycles of cyclic voltammetry forms a porous PANI microstructured layer on the PEDOT:PSS film, resulting in high signal linearity and sensitivity of about 100 mV/pH and 20 μA/pH. The electrochemical impedance spectroscopy analysis demonstrates a 9X higher-change of interfacial capacitance when decreasing the pH with the hybrid PANI-PEDOT:PSS layer, in comparison to a bare PEDOT:PSS layer. The simple fabrication process and the high signal amplification pave the way for flexible and higher-performance pH-sensitive OECTs. These scalable devices, combined with ion-selective OECTs, would lead to a novel tool for multi-parametric analysis in different biofluids