Real-time on-body sweat sensing: Electrochemical insights, progress, and prospects

초록

Among various biofluids, human sweat has attracted increasing interest because it can be readily accessed noninvasively at the skin surface and contains a wide range of metabolites, biomarkers, and electroactive species that convey valuable physiological information related to human health. Electrochemical-based sweat monitoring techniques are particularly well-suited due to their inherent sensitivity, low power consumption, ease of miniaturization and compatibility with wearable platforms. Accordingly, significant advances have been reported in electrochemical sweat sensors integrated with nanostructured electrodes, microfluidics, and flexible wearable platforms. However, the analytical relevance of many reported systems remains limited, as sensor performance is frequently evaluated using artificial or collected sweat, conditions that fail to capture the dynamic, nonequilibrium conditions. To emphasize the significance of on-body sweat sensing, this review critically examines electrochemical sweat sensors that operate directly on the human body and perform real-time measurements in native sweat. Representative studies targeting stress and neurochemical markers, metabolic analytes, and small molecules are analyzed, with particular emphasis on analytical performance under physiological sweating conditions rather than device architecture alone. Across different analyte classes, recurring challenges are identified, including sweat-rate-dependent dilution and accumulation effects, pH-induced signal modulation, matrix interference, calibration instability, electrode-skin interface degradation, and pronounced interindividual variability. By integrating these cross-cutting limitations, this review highlights that reliable sweat electrochemistry is fundamentally constrained by signal interpretation within a dynamic biological matrix, rather than by detection sensitivity alone. Ultimately, this review outlines key directions necessary for advancing wearable sweat electrochemistry toward robust, reliable, and physiologically meaningful applications.

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