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

Area of Science:

• Biomedical Engineering
• Sensor Technology
• Analytical Chemistry

Background:

• Wearable biosensors offer potential for real-time chemical measurements in sweat, aiding medical diagnostics and athletic performance.
• Current sweat sensing technology faces challenges in scalability, microfluidic integration, and preventing sensor inaccuracies from biofouling and repeated use.
• There is a critical need for low-cost, disposable wearable sensors with integrated microfluidics for reliable sweat analysis.

Purpose of the Study:

• To develop and validate a novel wearable biosensor system integrating laser-induced graphene (LIG) with soft tape polymeric microfluidics.
• To enable simultaneous quantification of key sweat metabolites (glucose, lactate) and electrolytes (sodium) for hydration and fatigue monitoring.
• To assess the sensor's performance in simulated and real-world on-body conditions for personalized diagnostic applications.

Main Methods:

• Fabrication of LIG-based electrodes functionalized with glucose oxidase and lactate oxidase for metabolite detection.
• Development of LIG-electrodes with a sodium-ion-selective membrane for electrolyte measurement.
• Integration of LIG sensors with soft tape polymeric microfluidics for controlled sweat sample delivery and analysis.
• Testing in a simulated sweating skin microfluidic system and on-body during cycling trials with multiple subjects.

Main Results:

• LIG-electrodes demonstrated high sensitivity and selectivity for glucose (0-1 mM range) and lactate (0-32 mM range) within physiological sweat concentrations.
• Sodium-ion-selective LIG-electrodes exhibited Nernstian sensitivity (58.8 mV decade-1) and a linear response across the physiological sweat range (10-100 mM).
• The integrated LIG-microfluidic system successfully performed real-time, continuous measurements of analytes in sweat during simulated and on-body tests.

Conclusions:

• The convergence of LIG sensors and microfluidics provides a viable platform for reliable and continuous sweat analysis.
• This technology holds significant promise for developing personalized wearable diagnostic tools for monitoring hydration, fatigue, and overall health.
• The low-cost, single-use nature of the developed sensors addresses key limitations of current wearable sweat sensing technologies.