1. Background Value of Sweat: Sweat has gained significant attention as a key biomarker for diagnosing dehydration and renal dysfunction (e.g., uremia), as it contains essential indicators that reflect blood concentrations, such as electrolytes and metabolites (creatinine, urea).

Technical Transition: To overcome the limitations of conventional absorbent pads, such as contamination and evaporation, it is essential to develop flexible, wearable microfluidic devices that enable immediate collection and high-precision analysis.

Domestic and International Trends: While countries like the U.S. are already utilizing real-time IoT monitoring technologies in military and sports sectors, there is an urgent need in Korea to secure physiological data optimized for the Korean population and to establish a robust medical analysis system.

2. Objectives To develop a skin-interfaced microfluidic platform integrated with a SERS biosensor for high-sensitivity, real-time detection of Sodium and Creatinine to monitor dehydration and renal health.

3. Research Plan

1. Subject Selection: Recruit and obtain informed consent from patients visiting the hospital with renal disease (creatinine levels 1.5 mg/dL or higher).
2. Clinical Schedule: Conduct the clinical study on the subjects' scheduled routine blood test dates.
3. Patch Attachment: Apply the sweat collection patch and a control absorption pad to 1-2 body areas (e.g., center of the chest, forehead).
4. Sweat Induction: Induce sweating by having subjects wait in an electric thermal chamber for 30 minutes.
5. Absorption Pad Collection: For the control pads (which cannot collect time-series data), attach two initially and retrieve them during the early stages of sweat secretion.
6. Microfluidic Patch Collection: Measure the volume of sweat collected (~100 uL per subject) to calculate sweat loss, then seal and transport to the laboratory.
7. Comparative Sample Processing: Measure the weight of absorption pads before/after use to determine fluid loss. Extract sweat samples (~500 uL per subject) into micro-tubes for transport.
8. Contamination Control: Utilize dry ice and insulated coolers during transport to prevent sample degradation or contamination.
9. Quantitative Analysis & Evaluation: Perform quantitative analysis of sodium and creatinine levels from both samples using the proposed SERS-based method and standard analytical tools (HPLC or LC-MS). Compare the changes in biomarkers and sweat loss over time to evaluate and summarize the hydration status and renal function patterns of each subject.

Inclusion Criteria:

• Aged 19 years or older
• Patients with renal disease and a blood (serum) creatinine level of 1.5 mg/dL or higher

Exclusion Criteria:

• Subjects who do not provide consent to participate in this study
• Subjects with a medical history of skin allergies related to patches/adhesives