Wearable electronic tattoo for real-time hydration monitoring

Background

Accurate hydration assessment is essential for maintaining health, perfor­mance, and safety; even mild dehydration can impair cognition, physical function, and cardiovascular stability. Populations such as older adults, athletes, outdoor laborers, military personnel, and individuals with limited access to clinical care are particularly at risk, creating a strong demand for reliable and continuous hydration monitoring tools.

Current methods fall short of practical use. Urine color charts are subjective, laboratory assays are invasive and incapable of continuous measurement, sweat-based sensors suffer from high variability, and conventional bio­electrical impedance systems are bulky and unsuitable for mobile environ­ments. These limitations underscore a growing need for a non-invasive, wearable solution that can continuously track hydration status in real time across a wide range of daily activities.

Technology overview

This technology is a flexible, wearable electronic tattoo that performs con­tinuous, non-invasive hydration monitoring using advanced bioimpedance analysis. Built on a polyimide flexible circuit with island–serpentine architec­ture, the device conforms comfortably to the upper arm and uses dry graphite polyurethane electrodes transferred to medical dressing for stable long-term skin contact.

A four-terminal Kelvin configuration in a cross-arm geometry injects a 40 kHz, 100 µA current and measures resulting voltage changes with high sensitivity to fluid shifts across the full arm cross-section. Integrated low-power electronics, including a MAX30002 analog front end and an nRF52832 microcontroller, transmit resistance and reactance data wirelessly to a smartphone app for real-time visualization.

Validated in both controlled dehydration protocols and 24-hour free-living conditions, the device demonstrates strong correlation with gold-standard whole-body hydration measurements. Its flexible materials, dry electrodes, and optimized electrode placement deliver reliable signal quality during movement, enabling practical ambulatory hydration monitoring not achievable with existing methods.

Benefits

• Continuous, non-invasive hydration monitoring in real-world environments
• Dry, flexible electrodes provide comfortable, long-term wear without gels
• Cross-arm Kelvin configuration improves sensitivity to whole-body fluid shifts
• Wireless, low-power system enables real-time smartphone data access
• Strong correlation with gold-standard hydration metrics supports clinical relevance

Applications

• Athletic performance monitoring
• Clinical hydration assessment
• Occupational and military safety
• Remote patient monitoring
• Consumer wellness devices

Opportunity

• Addresses unmet need for mobile, accurate hydration monitoring across clinical and commercial markets
• Validated performance supports integration into digital health, sports technology, and wearable medical device portfolios.
• Strong potential for partnerships in healthcare, fitness, and diagnostics
• Available for exclusive licensing

Intellectual property

U.S. Provisional application serial no. 63/634,140 filed on 04/15/2024

PCT application serial no. PCT/US2025/022793 filed on 04/02/2025