A Fully Integrated Wearable Microfluidic Electrochemical Sensor with Ultrasonic Connecting and Hot-Pressing Bonded Multilayer Structure for Sweat Biomarker Analysis

Abstract

Wearable microfluidic sweat sensors serve as critical devices for the continuous monitoring of human biomarkers. This research has developed a fully integrated wearable microfluidic electrochemical sensor (FIWMES) for noninvasive, continuous monitoring of glucose, Na⁺, K⁺, and Ca²⁺ in human sweat. To address challenges including sample leakage, structure damage, and difficulties of multiple-biomarker detection, a hybrid bonding process that combines ultrasonic connecting and hot-pressing procedures is presented for structural integration of the FIWMES. The bonding process ensures high interfacial bonding strength (>65 N), excellent sealing performance (no leakage after 200 bends), and precise temperature control (<51 °C) inside the microfluidic chamber. By integrating the dendritic sweat-collecting module, microfluidic chamber, and 3D-arranged sensing units, the FIWMES can achieve efficient sweat capture, sample manipulation, and simultaneous biomarker detection. The glucose sensor exhibits a sensitivity of 6.4 μA/mM with strong anti-interference capability, while the Na⁺, K⁺, and Ca²⁺ sensors display near-Nernstian responses with sensitivities of 65.3, 64.3, and 38.2 mV/decade, respectively. On-body trials confirm the practical wearability and its ability to accurately track dynamic metabolic changes, such as postprandial increases in sweat glucose and electrolyte variation under water deficiency. With its stability and monitoring capabilities, FIWMES offers a technical platform for the effective management of chronic diseases.