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Chemical and biological sensors have attracted great interest due to their importance in applications of healthcare, food quality monitoring, environmental monitoring, etc. Carbon nanotube (CNT)-based field-effect transistors (FETs) are novel sensing device configurations and are very promising for their potential to drive many technological advancements in this field due to the extraordinary electrical properties of CNTs. This review focuses on the implementation of CNT-based FETs (CNTFETs) in chemical and biological sensors. It begins with the introduction of properties, and surface functionalization of CNTs for sensing. Then, configurations and sensing mechanisms for CNT FETs are introduced. Next, recent progresses of CNTFET-based chemical sensors, and biological sensors are summarized. Finally, we end the review with an overview about the current application status and the remaining challenges for the CNTFET-based chemical and biological sensors. [ABSTRACT FROM AUTHOR]

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. • A flexible electrochemical sensor is fabricated. • Au nanostructure is utilized for signal amplification. • Both glucose and lactate in sweat are detected. • High sensitivity is achieved due to Au nanostructure. • The developed sensor shows satisfactory selectivity. [ABSTRACT FROM AUTHOR]