Wearable plasmonic paper–based microfluidics for continuous sweat analysis

Abstract

Wearable sweat sensors have the potential to provide clinically meaningful information associated with the health and disease states of individuals. Current sensors mainly rely on enzymes and antibodies as biorecognition elements to achieve specific quantification of metabolite and stress biomarkers in sweat. However, enzymes and antibodies are prone to degrade over time, compromising the sensor performance. Here, we introduce a wearable plasmonic paper–based microfluidic system for continuous and simultaneous quantitative analysis of sweat loss, sweat rate, and metabolites in sweat. Plasmonic sensors based on label-free surface-enhanced Raman spectroscopy (SERS) can provide chemical “fingerprint” information for analyte identification. We demonstrate the sensitive detection and quantification of uric acid in sweat at physiological and pathological concentrations. The well-defined flow characteristics of paper microfluidic devices enable accurate quantification of sweat loss and sweat rate. The wearable plasmonic device is soft, flexible, and stretchable, which can robustly interface with the skin without inducing chemical or physical irritation.

Flexible microfluidic nanoplasmonic sensors for refreshable and portable recognition of sweat biochemical fingerprint

“…In this way, even if there are major cracks in Ag nanomushroom arrays, the laser can be completely blocked against skin by the Si wafer (Fig. 4b), without the need of using a laser block component 41 .…”

“…Thus, an intrinsically connected SERS substrate with fine structural entirety is chosen and independently embedded in the well-defined vessel of microfluidics for in situ and continuous SERS sensing. And compared to the recently proposed paper-based microfluidic SERS device 41 , this PDMSbased microfluidic can provide a volumetric microchamber for better fixing the SERS substrate. The portable SERS analyzer (commercial device, not customized one) can decode the sweat fingerprint information of targeted biomarkers of urea, lactate, and pH at the molecular level, significantly expanding the accessible scenarios of wearable SERS sensors for point-of-care test (POCT) applications.…”

Rapid Assembly of Cellulose Microfibers into Translucent and Flexible Microfluidic Paper-Based Analytical Devices via Wettability Patterning

“…The self-assembled paper-based patterns on PET film exhibit the potential for integration with flexible electrode or other detection modules, serving as a wearable device for human health monitoring. Also, it is possible to pattern cellulose microfibers into PDMS channels to make a wearable (soft, flexible, and stretchable) paper-based microfluidic device, which might be used for sweat analysis . The μPADs assembled by cellulose microfibers are used to quantify the glucose content in serum sample, demonstrating the potential in analytical applications.…”

“…Also, it is possible to pattern cellulose microfibers into PDMS channels to make a wearable (soft, flexible, and stretchable) paper-based microfluidic device, which might be used for sweat analysis. 70 The μPADs assembled by cellulose microfibers are used to quantify the glucose content in serum sample, demonstrating the potential in analytical applications. Despite the multiple advantages of the proposed bottom-up method, automatic machines should be used instead of manual operations to further improve reproducibility and realize industrialization.…”

Fast Synthesis of Au Nanoparticles on Metal–Phenolic Network for Sweat SERS Analysis

“…SERS monitoring of the biochemical components in sweat samples is appealing, which can supply indicators of human health [ 32 , 33 , 34 ]. SERS-active nanostructures are also combined with flexible materials to fabricate wearable SERS sensors for real-time sweat monitoring [ 35 , 36 , 37 ]. Noble metal NPs such as Au, Ag, and Cu are commonly used as the active substrates for SERS analysis due to the Raman electromagnetic enhancement caused by the localized surface plasmon resonance (LSPR) effect.…”