Multi-level, dynamic optical anti-counterfeiting has been achieved using multi-mode phosphors as luminescent inks. The ZGGO:Cr,Yb,Er phosphors exhibit quintuple luminescence modes, while the ZLGO:Mn phosphors possess quadruple luminescence modes.
Fluorescence
latent fingerprinting (LFP) imaging is a convenient
and frequently used in situ detection technique. In recent years,
various types of phosphors have been widely used for LFP imaging.
However, traditional phosphor powders are suffering from a formidable
challenge to design effective fluorescent LFP powders with low background
interference and high detection sensitivity. In this work, we have
synthesized Zn2GeO4:Mn,Li,K (ZGO:Mn,Li,K) nanophosphors
with the high persistent luminescence (PersL) brightness and long
duration using hydrothermal method by optimizing synthesis conditions.
The ZGO:Mn,Li,K phosphors, with a perceptible green PersL, have been
successfully used for developing LFPs on non-fluorescent substrate,
fluorescent substrate, and PersL substrate without special equipment.
Besides the level 1 and level 2 details, the other details of LFPs
even exceeding level 3 details including the ridge width and boundary
streamline of LFPs and the sweat pore feature are distinguishable.
These findings show that the ZGO:Mn,Li,K phosphors, with multimode
luminescence and high detection sensitivity, will promise a more sophisticated
luminescent label for LFP detection on various substrates.
The primary emphasis in this paper is on the major developments in the field of air-stable organic field-effect transistors (OFETs) over the past 20 years. The studies about the factors influencing the stability of OFETs, including air, humidity, oxygen and temperature, are reviewed and analyzed. The possible mechanisms that result in the degradation of OFETs, such as the penetrating of H2O molecules, the doping effect of oxygen or the crystalline structure difference caused by temperature, are summarized. At same time, the reason why the field-effect mobility and the on/off current ratio of the transistor might change greatly with different ambient is concluded. The overall lives of OFET-based sensor in the detection of hazardous gases including nitrogen dioxide and ammonia are discussed, several breakthrough findings and technologies about how to solve the problem of instability of OFETs are also presented.
SrTiO 3 (STO) thin film was coated on the cladding of a fiber Bragg grating (FBG) by pulsed laser deposition, and the associated temperature sensing properties were tested. The surface of the FBG coating was smooth, uniform, compact and without obvious defects; the structure and properties of the FBG were well protected. Temperature sensing results showed that the sensitivity of the STO coated FBG was about 9.97 pm °C−1 , which is about 28% higher than that of the bare FBG (7.8 pm °C−1 ) before coating. In order to further study the thermal sensing properties of the FBG, a concatenated optical path, two optical paths based on a Michelson interferometer and a Sagnac interferometer, were constructed by using STO coated FBG and another bare FBG as the sensitivity results 9.0 pm °C−1 , 10.5 pm °C−1 and 11.4 pm °C−1 , respectively. Among them, the fiber sensor based on the Sagnac interferometer was more sensitive, which was increased by 46.2%. Moreover, the interference optical path has the advantages of simple structure and good practicality.
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