A wearable device for continuous immunoassay-based monitoring of C-peptide in interstitial fluid.

C-peptide is a critical biomarker for evaluating pancreatic β cell function and managing diabetes. However, conventional methods such as enzyme-linked immunosorbent assay are limited by lengthy processing times and the necessity for invasive sample collection. This study introduces a regenerable, portable, and wearable device for minimally invasive, real-time monitoring of C-peptide in dermal interstitial fluid (ISF). The device uses a microneedle array and negative pressure extraction for ISF collection. A double-antibody sandwich approach was used to detect C-peptide, and an antibody regeneration strategy was applied to remove bound antigen-antibody complexes, thereby achieving repeatable detection, enabling at least 10 detection assays on the same chip with negligible signal attenuation. The compact design features a skin contact area of only 3 cm by 5.4 cm and excellent biocompatibility. Integrated with a mobile app, the device provides real-time concentration reading. Mouse and rabbit tests confirm effective ISF sampling and monitoring accuracy, demonstrating its potential for at-home diabetes management and broader wearable biosensing applications.