Wireless, battery-free wearable optoelectronic-colorimetric microfluidic sensor for multiplex sweat analysis.

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Wearable Technology

Background:

• Wearable colorimetric biosensors offer noninvasive, real-time monitoring but are often limited by photography-based measurements susceptible to environmental and user factors.
• Existing platforms require external devices like smartphones for image capture, introducing variability and potential inaccuracies.

Purpose of the Study:

• To develop a fully integrated, wireless, and battery-free multi-modal optoelectronic-colorimetric microfluidic system for in situ signal quantification.
• To eliminate the need for external photography in wearable biosensing, thereby enhancing measurement robustness and reliability.

Main Methods:

• A microfluidic patch with colorimetric sensors for uric acid, alcohol, and pH was combined with a detachable near-field communication (NFC) optoelectronic module.
• Custom light-emitting diode (LED)-photodiode pairs provided localized illumination and reflectance detection for NFC-enabled reading via smartphone.

Main Results:

• The system demonstrated robust interference-resistance across varying ambient light conditions and diverse human skin tones.
• Multiplex sweat analysis accurately tracked metabolic fluctuations after specific diets and evaluated therapeutic responses in on-body studies.

Conclusions:

• The developed system offers a reliable and accurate solution for noninvasive, in situ sweat analysis, overcoming limitations of previous photographic methods.
• This technology holds promise for continuous health monitoring, particularly for metabolic conditions and personalized medicine.