Volume 34, Issue 3-4

Carbon dots (CDs) are a recently discovered class of fluorescent nanomaterials with great potential to be applied in the analytical field. CDs have demonstrated to be a promising alternative to conventional organic fluorophores or quantum dots as optical nanoprobes for sensing different chemical species. In this overview, we review the progress in the design of novel nanoprobes based on fluorescent CDs for inorganic trace analysis. Representative examples of CD-based assays are described and the different sensing strategies are discussed.

Gas sensing technologies are of importance for a variety of industrial, environmental, medical, and even military applications. Many gases, such as man-made or naturally occurring volatile organic compounds (VOCs), can adversely affect human health or cause harm to the environment. Recent advances in “designer solvents” and sensor technologies have facilitated the development of ultrasensitive gas sensing ionic liquids (SILs) based on quartz crystal microbalance (QCM) that can real-time detect and discriminate VOCs. Based on specific chemical reactions at room temperature, thin-coated functionalized ionic liquids on quartz chips are able to capture VOCs chemoselectively with a single-digit parts-per-billion detection limit. The amalgamation of tailor-made functional SILs and QCM results in a new class of qualitative and semiquantitative gas sensing device, which represents a prototype of electronic nose. This review vignettes some conventional gas sensing approaches and collates latest research results in the exploration of SIL-on-QCM chips and gives an account of the state-of-the-art gas sensing technology.

Microelectrode arrays-based double electrode systems possess the property of diffusion layer overlapping between the two sets of electrodes. They have received increased attention in recent years in the field of electrochemistry and electroanalytical chemistry. This review introduces the fabrication, characterization, and applications of microelectrode arrays-based double electrode systems. The progress of photolithography enables and benefits microfabrication of the electrode systems with various geometries. As an essential step before electrochemical applications, various characterization methods are addressed to monitor the quality of the fabricated electrodes. Following that, applications as electrochemical sensors in generator-collector mode are discussed. Then, electrochemical sensors in bipolar mode, an interesting phenomenon existing in double electrode systems, are also introduced. Finally, applications of double electrode systems to the measurement of fundamentally electrochemical parameters are demonstrated.