Wearable Flexible Perspiration Biosensors Using Laser-Induced Graphene and Polymeric Tape Microfluidics

Abstract

Wearable biosensors promise real-time measurements of chemicals in human sweat, with the potential for dramatic improvements in medical diagnostics and athletic performance through continuous metabolite and electrolyte monitoring. However, sweat sensing is still in its infancy, and questions remain about whether sweat can be used for medical purposes. Wearable sensors are focused on proof-of-concept designs that are not scalable for multisubject trials, which could elucidate the utility of sweat sensing for health monitoring. Moreover, many wearable sensors do not include the microfluidics necessary to protect and channel consistent and clean sweat volumes to the sensor surface or are not designed to be disposable to prevent sensor biofouling and inaccuracies due to repeated use. Hence, there is a need to produce low-cost and single-use wearable sensors with integrated microfluidics to ensure reliable sweat sensing. Herein, we demonstrate the convergence of laser-induced graphene (LIG) based sensors with soft tape polymeric microfluidics to quantify both sweat metabolites (glucose and lactate) and electrolytes (sodium) for potential hydration and fatigue monitoring. Distinct LIG-electrodes were functionalized with glucose oxidase and lactate oxidase for selective sensing of glucose and lactate across physiological ranges found in sweat with sensitivities of 26.2 and 2.47 × 10–3 μA mM–1 cm–2, detection limits of 8 and 220 μM, and linear response ranges of 0–1 mM and 0–32 mM, respectively. LIG-electrodes functionalized with a sodium-ion-selective membrane displayed Nernstian sensitivity of 58.8 mV decade−1 and a linear response over the physiological range in sweat (10–100 mM). The sensors were tested in a simulated sweating skin microfluidic system and on-body during cycling tests in a multisubject trial. Results demonstrate the utility of LIG integrated with microfluidics for real-time, continuous measurements of biological analytes in sweat and help pave the way for the development of personalized wearable diagnostic tools.

Laser-Induced Graphene Decorated with Platinum Nanoparticles for Electrochemical Analysis of Saliva

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EBiIn-Cu-GaIn Composite Electrodes inside Microfluidic Chips

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Reagent-Free Lactate Detection Using Prussian Blue and Electropolymerized-Molecularly Imprinted Polymers-Based Electrochemical Biosensors

“…The rapid advancement of biosensing, microfluidics, flexible electronics, and wireless communications technologies has led to the development of wearable biosensors for sweat analysis, − including lactate monitoring. − However, these lactate sensors predominantly incorporate enzymes such as lactate oxidase and lactate dehydrogenase, , which often face stability issues due to temperature and pH variations . As an alternative, Molecularly Imprinted Polymers (MIPs) have emerged as tailored synthetic molecular recognition elements, offering remarkable cost-effectiveness and superior stability.…”