Wearable Analytical Platform with Enzyme-Modulated Dynamic Range for the Simultaneous Colorimetric Detection of Sweat Volume and Sweat Biomarkers

Abstract

In this manuscript, we introduce a wearable analytical platform that simultaneously measures the concentration of sweat lactate and sample volume. It contains two sensors entirely made of filter paper that can be easily affixed on the skin with medical-grade tape. The lactate biosensor features a unique signal modulation mechanism that enables fine-tuning the dynamic range. It consists of adding a competitive enzyme inhibitor in different reservoirs. Thanks to this, it is possible to choose between a very low limit of detection (0.06 mM) and a linear response in the physiological concentration range (10–30 mM). The sweat volume sensor was obtained by adding a reservoir containing gold nanoparticles. As the wearer sweats, the nanoparticles are carried through a paper channel. This is used to gauge the volume of sample by measuring the distance traveled by the nanoprobes. Using fine-tuned lactate biosensors and combining them with the volume sensors allowed us to quantify variations in the levels of sweat lactate independently of the wearer’s sweat rate during an exercise routine. The platform design can be customized to meet the end user’s needs, which makes it ideal for developing a wide array of disposable wearable biosensors.

Wearable Sweat Loss Measuring Devices: From the Role of Sweat Loss to Advanced Mechanisms and Designs

“…Vaquer et al developed a sweat volume colorimetric platform made of filter paper and simply attached to the skin with tape based on colorimetry. [162] As illustrated in Figure 11a,b, dyes are stored in a reservoir, which were carried through the paper strip by the absorbed sensible sweat from the user. Then, the SSV was estimated by additionally gauging the length of the stained paper.…”

“…As the sponge absorbed sensible sweat, the resonance frequency of the SLMD becomes inversely proportional to the water content in the sponge owing to the change in the dielectric property (Figure 12b,c). As a result, such device design enabled wireless quan- [162] Copyright 2020, American Chemical Society. c) Conceptual illustration and photograph of a finger-shaped wearable colorimetric patch.…”

“…b) Calibration curve of the colorimetric platform for measuring SSV. Reproduced with permission [162]. Copyright 2020, American Chemical Society.…”

Smart Materials Enabled with Artificial Intelligence for Healthcare Wearables

“…Section 2.1.2) have been used in many wearable devices. [133][134][135][136][137][138] Color changes can be detected by the Figure 6. Electrochemical sensors for wearable applications.…”

“…[139] Colorimetric sensors can be fabricated on different wearable substrates, such as paper, [140] hydrogel, [141] fiber, [142] fabric, [143] and yarn. [133,134] Wearable colorimetric devices include onskin platform, [135,144,145] smart band, [143] wristband, [146] contact lenses, [138] T-shirt, [133] etc., and are usually used to detect human sweat, [136,137,143] tears, [138] VOCs, [134] UV, [147] etc. Kim et al [134] demonstrated an eye-readable and wearable H 2 S sensing platform based on colorimetric dye-loaded nanofiber yarn, which could be incorporated into a worker's garment as a visual indicator; and was adequate for inexpensive mass-production (Figure 7A).…”