Gold nanostructure-programmed flexible electrochemical biosensor for detection of glucose and lactate in sweat

Flexible electrochemical biosensors used for sweat analysis have aroused great interests in the field of intelligent instruments. Due to the complexity of body fluids, development of ultrasensitive and miniaturized sensors for analysis of sweat is always challengeable. In this research, we fabricate a sensitive and flexible sensor for real-time monitoring of glucose and lactate in sweat at micromolar level and millimolar level by using gold nanopine needles (AuNNs) as the signal amplification strategy. A flexible chip with gold electrode arrays was fabricated in a standard semi-conductor laboratory. AuNNs were deposited on the working electrode by electrochemical deposition method. Enzyme immobilization was carried out on the electrode surface via a cross-linker poly(ethylene glycol) diglycidylether (PEGDE), which is an important component of redox hydrogels capable of retaining the activity of the enzyme to a greater extent than other linkers like glutaraldehyde. The catalytic behavior of AuNNs under different conditions was investigated. The as-fabricated electrochemical sweat biosensor was found to achieve low detection limit down to 7 μmol L−1 for glucose, 54 μmol L−1 for lactate, respectively. The sensor also exhibited great selectivity, reproducibility and stability. In addition, human sweat samples were analyzed by the sensor, indicating its potential applications in determination of glucose and lactate as a wearable skin sensor.