Abstract
<jats:p>However, sweat antibody detection remains particularly challenging because antibody concentrations are substantially lower than those of common sweat markers such as cortisol and glucose. By integrating ultra-sensitive interfacial capacitive sensing with ultra-fast AC electrothermal target enrichment, we develop detachable monolithic biosensors for sweat antibodies, which are based on antigen probe functionalized flexible electrode arrays. A wearable biosensing system, incorporating a pressure-regulated PDMS sweat-collection patch and a wristwatch-style microcapacitance detector, is further constructed to enable real-time quantitation of ultra-trace antibodies in sweat. SARS-CoV-2 N protein antibody and Hepatitis B surface antibody in sweat are tested with a limit of 10-6 ng/mL, a linear range of 10-5~10-1 ng/mL, and a responding time of 30 s. In response to the fluctuations of sweat biomarker levels, adaptive stratification algorithms are implemented by leveraging the sensor’s high dynamic range through machine learning. Validated on 25 volunteers with a stratification balanced accuracy exceeding 0.74, this system provides a versatile wearable platform capable of quantifying and stratifying a broader range of highly fluctuating, low-abundance sweat biomarkers.</jats:p>