Hydrogel-based sweat chloride sensor with high sensitivity and low hysteresis

Area of Science:

• Biomedical Engineering
• Materials Science
• Analytical Chemistry

Background:

• Monitoring sweat chloride ions (Cl^-) is vital for health assessment, including hydration status and cystic fibrosis (CF) diagnosis.
• Current wearable sensors face limitations in sensitivity (potentiometric) or irreversibility (colorimetric).

Purpose of the Study:

• To develop a novel hydrogel-based wearable sensor for sensitive and reversible sweat chloride ion (Cl^-) monitoring.
• To address the limitations of existing sweat chloride sensing technologies.

Main Methods:

• Designed a sensor with a cation-selective hydrogel (CH) and high-salinity hydrogel (HH) to create an electrolyte concentration gradient.
• Integrated a superhydrophilic PVDF-HFP film to ensure device stability by preventing ion exchange and swelling.
• Incorporated a microfluidic module and temperature calibration for continuous, accurate measurements.

Main Results:

• Achieved ultrahigh sensitivity (1.7 mV/mM) and a fast response time (7.1 s) for Cl^- detection.
• Demonstrated excellent linearity and reversibility in the 10–100 mM concentration range.
• Validated continuous and calibrated sweat Cl^- measurements during physical activity.

Conclusions:

• The hydrogel-based sensor offers a promising platform for real-time sweat chloride monitoring.
• The design principles can be extended to detect other biomarkers for personalized health monitoring.
• This technology advances wearable diagnostics for various health conditions.