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Abstract Although continuous and non‐invasive measurements of sweat biomarkers may provide vital health information, sweat collection often involves intense physical activities or chemical/thermal stimuli. The natural body sweat during endogenous metabolic or stress processes, secreted at much lower rates at rest, may be continuously analyzed using microfluidic devices integrated with hydrophilic rigid fillers; however, the sweat uptake and accumulation in thermoregulatory processes take too long for near‐real‐time measurements. This work provides an innovative body fluid collection strategy using a granular hydrogel scaffold (GHS), facilitating osmotic and capillary effects to uptake and transfer an ultralow amount of sweat into a microfluidic device at rest. Taken together with a spiral microfluidic channel, the GHS‐embedded microfluidics reduce the evaporation of collected sweat and store it in a sensing well for near‐real‐time measurements. Integrating the sweat‐collecting system with an enzymatic gold‐graphene nanocomposite‐modified laser‐induced graphene (LIG) electrode and a LIG‐based pH sensor enables the accurate continuous on‐body detection of sweat lactate during normal daily activities at a low perspiration rate. The novel combination of a GHS‐integrated microfluidic system with a low‐cost, flexible, sensitive, and stable LIG‐based sensing system provides an accessible technology for sweat‐based biosensing during normal daily activities. 

Abstract Although increasing efforts have been devoted to the development of non‐invasive wearable electrochemical sweat sensors for monitoring physiological and metabolic information, most of them still suffer from poor stability and specificity over time and fluctuating temperatures. This study reports the design and fabrication of a long‐term stable and highly sensitive flexible electrochemical sensor based on nanocomposite‐modified porous graphene by facile laser treatment for detecting biomarkers such as glucose in sweat. The laser‐reduced and patterned stable conductive nanocomposite on the porous graphene electrode provides the resulting glucose sensor with an excellent sensitivity of 1317.69 µA mm⁻¹cm⁻²and an ultra‐low limit of detection of 0.079 µm. The sensor can also detect pH and exhibit extraordinary stability to maintain more than 91% sensitivity over 21 days in ambient conditions. Taken together with a temperature sensor based on the same material system, the dual glucose and pH sensor integrated with a flexible microfluidic sweat sampling network further results in accurate continuous on‐body glucose detection calibrated by the simultaneously measured pH and temperature. The low‐cost, highly sensitive, and long‐term stable platform could facilitate the early identification and continuous monitoring of different biomarkers for non‐invasive disease diagnosis and treatment evaluation.