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Article

Passively Addressable Ultra-Low Volume Sweat Chloride Sensor

Department of Bioengineering, University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, USA
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Author to whom correspondence should be addressed.
Sensors 2019, 19(20), 4590; https://doi.org/10.3390/s19204590
Received: 16 September 2019 / Revised: 16 October 2019 / Accepted: 17 October 2019 / Published: 22 October 2019
(This article belongs to the Section Biosensors)
This work demonstrates a novel electrochemical biosensor for the detection of chloride ion levels in ultra-low volumes (1–3 microliters) of passively expressed human sweat. We present here a hydration monitor that the pediatric, geriatric, and other immune-compromised or physically inactive/sedentary population cohort can utilize, for whom the current methods of chloride quantification of active stimulation of sweat glands through iontophoresis or treadmill runs are unsuitable. In this work, non-faradaic electroanalysis using gold microelectrodes deposited on a flexible nanoporous substrate, for high nanoscale surface area to volume enhancement, was leveraged to operate in ultra-low sweat volumes of <3 µL eluted at natural rates. The specific chloride ionophore-based affinity of chloride ions resulted in the modulation of charge transfer within the electrical double layer at the electrode–sweat buffer interface, which was transduced using electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). Linear calibration dose responses with R-squared values of 0.9746 and 0.9403 for EIS and CA respectively were obtained for a dynamic range of 10–100 mM. The surface charge and the binding chemistry of the capture probe were studied using zeta potential studies and UV-Vis. The dynamic sweat chloride-tracking capability of the sensor was evaluated for a duration of 180 min. Studies were conducted to probe the efficacy of the developed sensor for passive ultra-low sweat chloride assessment on human subjects (n = 3). View Full-Text
Keywords: wearables; sweat chloride sensor; continuous monitoring; non-faradaic electrochemical impedance spectroscopy; chronoamperometry; chloride ionophore wearables; sweat chloride sensor; continuous monitoring; non-faradaic electrochemical impedance spectroscopy; chronoamperometry; chloride ionophore
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MDPI and ACS Style

Ganguly, A.; Prasad, S. Passively Addressable Ultra-Low Volume Sweat Chloride Sensor. Sensors 2019, 19, 4590. https://doi.org/10.3390/s19204590

AMA Style

Ganguly A, Prasad S. Passively Addressable Ultra-Low Volume Sweat Chloride Sensor. Sensors. 2019; 19(20):4590. https://doi.org/10.3390/s19204590

Chicago/Turabian Style

Ganguly, Antra, and Shalini Prasad. 2019. "Passively Addressable Ultra-Low Volume Sweat Chloride Sensor" Sensors 19, no. 20: 4590. https://doi.org/10.3390/s19204590

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