Touch-based uric acid sweat biosensor towards personal health and nutrition

Monitoring uric acid (UA) levels is critical since elevated UA levels are associated with diverse conditions, such as gout, kidney disorders, kidney stones, hypertension, cardiovascular diseases, and metabolic syndrome. Maintaining balanced UA levels demands reliable and regular monitoring. Traditionally, such frequent UA measurements rely on blood-based UA self-testing strips. Developing sensitive and reliable noninvasive sweat-based UA sensors presents challenges, including the low UA sweat concentrations and interpersonal variations. We present here an attractive on-site UA self-testing approach utilizing a touch-enabled fingertip sweat UA electrochemical biosensor based on a uricase-enzyme electrode and sweat wicking hydrogel. This noninvasive method is rapid, simple, convenient, and painless, leveraging the high sweat rate on the fingertip at rest without any sweat stimulation. The touch-based protocol exhibits a wide linear range of UA concentrations from 10 to 1000 μM, covering normal and elevated UA sweat levels with high selectivity, reproducibility (RSD = 4.94%), good storage stability (1 week), and significant tolerance to temperature and humidity variations. The performance of the UA-touch sweat biosensor was evaluated and validated by parallel blood meter measurements by monitoring dynamically-changing sweat UA levels in healthy subjects after consuming purine-rich meals. The distinct sweat UA temporal profiles among individuals highlight the potential of the touch-based UA biosensor for personal health and nutrition. The speed and simplicity of this sweat UA assay thus encourage frequent self-testing and enhance user's compliance towards dietary interventions and lifestyle changes in connection to diverse healthcare and nutrition applications.