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It is urgent that a convenient and sensitive technique of detecting Hg2+ be developed because of its toxicity. Conventional fluorescence analysis works with a single fluorescence probe, and it often suffers from signal fluctuations which are influenced by external factors. In this research, a novel dual-emission probe assembled through utilizing CdTe quantum dots (QDs) and rhodamine B was designed to detect Hg2+ visually. Only the emission of CdTe QDs was quenched after adding Hg2+ in the dual-emission probe, which caused an intensity ratio change of the two different emission wavelengths and hence facilitated the visual detection of Hg2+. Compared to single emission QDs-based probe, a better linear relationship was shown between the variation of fluorescence intensity and the concentration of Hg2+, and the limit of detection (LOD) was found to be11.4 nM in the range of 0–2.6 μM. Interestingly, the intensity of the probe containing Hg2+ could be recovered in presence of glutathione (GSH) due to the stronger binding affinity of Hg2+ towards GSH than that towards CdTe QDs. Based on this phenomenon, an IMPLICATION logic gate using Hg2+/GSH as inputs and the fluorescence signal of QDs as an output was constructed.

Inductive wear debris sensor has been widely used in real time machine lubricant oil condition monitoring and fault forecasting. However, the small sensing zone, which is designed for high sensitivity, of the existing sensors leads to low throughput. In order to improve the throughput, a novel multichannel wear debris sensor that is based on phase division multiplexing is presented. By introducing the phase shift circuit into the system, multiple sensing coils could work at different initial phases. Multiple signals of sensing coils could be combined into one output without information loss. Synchronized sampling is used for data recording, and output signals of multiple sensing coils are extracted from the recorded data. A four-channel wear debris sensor system was designed to demonstrate our method. Subsequently, crosstalk analysis, pseudo-dynamic testing and dynamic testing were conducted to check the sensing system. Results show that signals of four sensing coils could be simultaneously detected and the detection limit for ferrous wear debris is 33 &mu, m. Using the presented method, real time wear debris detection in multiple channels could be achieved without increasing the number of excitation source and data acquisition equipment.