WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Citation - WoS: 16Citation - Scopus: 18Piezoresistivity and Piezopermittivity of Cement-Based Sensors Under Quasi-Static Stress and Changing Moisture(Elsevier Sci Ltd, 2024-04) Zhang, Jiacheng; Heath, Andrew; Ball, Richard J.; Chen, Binling; Tan, Linzhen; Li, Guisheng; Paine, KevinIntegrated cement-based sensors offer an economic alternative to extrinsic sensors for health monitoring applications in concrete structures due to their high strength to cost ratio, geometrical versatility, low shrinkage, and natural compatibility. Nonetheless, their performance under in-service conditions were in lack of investigations. While the piezoresistivity (change in resistance with stress) has been commonly used for mechanical sensing, the piezopermittivity (change in capacitive reactance with stress) is rarely characterized. Exploiting the high relative permittivity and electrical conductivity of carbon fibre reinforced cement-based sensors, this study investigates the piezoresistivity and piezopermittivity under changing stress and moisture using electrochemical impedance spectroscopy (EIS). Two types of sensors were evaluated: one containing 0.5 vol% of carbon fibres whose electrical conductivity was ionically dominant, and another with electronically dominant (1.2 vol% of carbon fibres) conductivity. Results highlighted that the piezopermittivity is "moisture content-dominant" whilst the piezoresistivity is "fibre content-dominant". As the moisture content decreased, the sensitivity of piezopermittivity for both sensor types decreased, while the sensitivity of piezoresistivity decreased for the ionically dominant sensor but increased for the electronically dominant sensor. The piezoresistivity of the electronically dominant sensor was less sensitive than piezopermittivity at a water saturation of 80%. Conversely, the piezoresistivity of the ionically dominant sensor was more sensitive than piezopermittivity at the tested water saturations <= 80%. For the first time, this study presents the combined effects of moisture and fibre content on the pressure sensitive response of cement-based sensors through a dual-phase (i.e., piezoresistivity and piezopermittivity) EIS interpretation technique, providing valuable information to benefit further behaviour prediction and single-effect recognition in the field scenario where the sensors are subject to simultaneousArticle Citation - WoS: 6Citation - Scopus: 9Impact of Red Emissive Zncdtes Quantum Dots on the Electro-Optic Switching, Dielectric and Electrochemical Features of Nematic Liquid Crystal: Towards Tunable Optoelectronic Systems(Elsevier, 2023-06) Seidalilir, Zahra; Shishehbor, Sepideh; Soheyli, Ehsan; Sabaeian, MohammadIn the present study, the concentration-dependent dielectric, electro-optical, and electrochemical properties of ZnCdTeS quantum dots (QDs) doped E7 nematic liquid crystal (NLC) mixtures were investigated. The dielectric permittivity components (epsilon(parallel to) and epsilon(perpendicular to)) and dielectric anisotropy (Delta epsilon -epsilon(parallel to) - epsilon perpendicular to.) of NLC samples containing varied concentrations of ZnCdTeS QDs (i. e. 0.10, 0.25, 0.50, 0.75, and 1 wt%) were measured at various temperatures. In the nematic phase, the results demonstrated that e. increases much more than epsilon(perpendicular to) upon an increase in the concentration of ZnCdTeS QDs. Delta epsilon enhanced as the concentration of QDs increased, reaching a maximum at 0.50 wt%, then decreased with further addition. Dielectric measurements revealed the formation of self-aligned QD arrays along the nematic director, which act similarly to multiple parallel capacitors in the NLC system. Moreover, electro-optical studies illustrated the significant effect of QDs doping on lowering the threshold voltage and response time. Interestingly, the optical switching-off time of NLC containing 0.50 wt% of the QDs decreased by similar to 50% compared to that of the pure E7 sample. The reduced screening effect resulting from the QDs ioncapturing mechanism, enhanced effective intermolecular interactions, and increased dielectric anisotropy in the NLC system are the major factors responsible for the improved electro-optical characteristics. The impedance behavior of NLC cells was studied in the frequency range of 0.1 Hz-100 kHz. It indicated that the addition of ZnCdTeS QDs results in a remarkable increase of 96% in the electrical conductivity of the NLC system. Furthermore, the QDs doping significantly improved the NLC device's charge capacitance. Such studies would undoubtedly be beneficial for designing next-generation tunable optoelectronic systems since QDs can be utilized for tuning the dielectric anisotropy, electro-optical characteristics, charge capacitance, and conductivity of NLCs.Article Citation - WoS: 6Citation - Scopus: 6Electrochemical and Optical Multi-Detection of Escherichia Coli Through Magneto-Optic Nanoparticles: A Pencil-on Biosensor(MDPI, 2024-12-10) Soysaldi, Furkan; Ekici, Derya Dincyurek; Soylu, Mehmet cagri; Mutlugun, Evren; Dincyurek Ekici, DeryaEscherichia coli (E. coli) detection suffers from slow analysis time and high costs, along with the need for specificity. While state-of-the-art electrochemical biosensors are cost-efficient and easy to implement, their sensitivity and analysis time still require improvement. In this work, we present a paper-based electrochemical biosensor utilizing magnetic core-shell Fe2O3@CdSe/ZnS quantum dots (MQDs) to achieve fast detection, low cost, and high sensitivity. Using electrochemical impedance spectroscopy (EIS) as the detection technique, the biosensor achieved a limit of detection of 2.7 x 10(2) CFU/mL for E. coli bacteria across a concentration range of 10(2)-10(8) CFU/mL, with a relative standard deviation (RSD) of 3.5781%. From an optical perspective, as E. coli concentration increased steadily from 10(4) to 10(7) CFU/mL, quantum dot fluorescence showed over 60% lifetime quenching. This hybrid biosensor thus provides rapid, highly sensitive E. coli detection with a fast analysis time of 30 min. This study, which combines the detection advantages of electrochemical and optical biosensor systems in a graphite-based paper sensor for the first time, has the potential to meet the needs of point-of-care applications. It is thought that future studies that will aim to examine the performance of the production-optimized, portable, graphite-based sensor system on real food samples, environmental samples, and especially medical clinical samples will be promising.