Blood lactate level is closely associated with the prognosis of patients with sepsis and septic shock. Clinical guidelines explicitly recommend blood lactate monitoring in septic patients and lactate-guided fluid resuscitation when lactate levels are elevated. Dynamic monitoring of serum lactate changes and calculation of lactate clearance can more accurately reflect the dynamic changes in tissue oxygen supply and consumption, and can be used to evaluate tissue perfusion and oxygen metabolism. However, most existing wearable sweat sensors have a detection range of only 0-20 mmol/L, which is suitable only for monitoring during exercise under normal physiological conditions and cannot meet the clinical monitoring needs of patients with hyperlactatemia. In addition, current wearable sweat lactate sensors suffer from poor reproducibility and are easily affected by environmental factors and complex sweat composition, which represent major obstacles to clinical translation. Therefore, this project aims to develop a wearable sweat sensor for high-concentration lactate monitoring and to conduct preliminary clinical validation in critically ill patients, by simultaneously measuring blood and sweat lactate concentrations and establishing their correlation, with the goal of achieving non-invasive and convenient disease monitoring through sweat biomarker detection.