This paper reviews microwave sensors and their applications in permittivity measurement. The detection, diagnosis, classification, and monitoring without contact and invasion have been the subject of numerous studies based on permittivity characteristics tracking. This review illustrates many new types of research in recent years. Firstly, the application background is briefly introduced, and several main measurement methods are presented. An overview of measurement technology in various applications is compiled and summarized based on numerous typical examples. Exciting applications are compared and presented separately, combining resonator sensors with strong electric fields. Furthermore, differential signals represent trends for future applications with strong environmental immunity, an alternative option to expensive measuring equipment. With the alternation of metamaterials, microfluidics technologies, cross-technology, algorithms, and so on, sensors play an exceptionally prominent role in practical and low-cost applications.
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http://dx.doi.org/10.3390/s24237696 | DOI Listing |
Sci Rep
January 2025
Cellulose and Paper Department, National Research Centre, 33 El Bohouth Str, P.O. 12622, Dokki Giza, Egypt.
A new method was developed to quickly produce carboxymethyl hemicellulose (CM-Hemi) and fluorescent nitrogen-doped carbon dots (N-CDs) from sugarcane bagasse (SB). These materials were then combined with calcium chloride (CaCl₂) to create hydrogel sensors with antibacterial and antifungal properties. The CM-Hemi@Ca-N-CDs hydrogel was effective against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria compared to CM-Hemi@Ca which give no antibacterial activity.
View Article and Find Full Text PDFBiosens Bioelectron
March 2025
Programa de Pós-Graduação em Engenharia Elétrica, Universidade Federal de Minas Gerais, Belo Horizonte, MG, 31270-901, Brazil; Departamento de Engenharia Eletrônica, Universidade Federal de Minas Gerais, Belo Horizonte, MG, 31270-901, Brazil. Electronic address:
Frequent glucose monitoring is essential for effective diabetes management. Currently, glucose monitoring is done using invasive methods such as finger-pricking and subcutaneous sensing. However, these methods can cause discomfort, heighten the risk of infection, and some sensing devices need frequent calibration.
View Article and Find Full Text PDFUltrasonics
December 2024
Department of Civil and Architectural Engineering and Mechanics, University of Arizona, Tucson, AZ 85721, USA; Aerospace and Mechanical Engineering Department, Materials Science and Engineering Department, University of Arizona, Tucson, AZ 85721, USA.
In the field of engineering structural health monitoring, acoustic source localization (ASL) is a common method to monitor early damage. Most of the existing ASL techniques have high requirements for accurate acquisition of time of arrival, and require complex iterative algorithms or signal processing techniques, which are not conducive to real-time monitoring. In this paper, a signal energy approach of acoustic source localization in plate structures using a discrete sensor array is proposed.
View Article and Find Full Text PDFMikrochim Acta
December 2024
Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, People's Republic of China.
A novel copper and iron doped containing chitosan and heparin sodium carbon dots (CS-Cu,Fe/HS) nanozyme was formulated through a single-step microwave digestion method. CS-Cu,Fe/HS exhibits excellent peroxidase (POD)-like activity and positive charge characteristics, and it can oxidize the negatively charged 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) in the presence of HO to produce a green compound (ox-ABTS). Furthermore, CS-Cu,Fe/HS enhances electron transfer and provides additional active sites through the valence state transformations of Fe/Fe and Cu/Cu.
View Article and Find Full Text PDFACS Meas Sci Au
December 2024
School of Pharmacy, Faculty of Science, University of Waterloo, 10 Victoria St S A, Kitchener, ON N2G 1C5, Canada.
The COVID-19 outbreak has led to notable developments in point-of-care (POC) diagnostic devices, as they can be valuable resources in identifying and managing the spread of the pandemic. Currently, the majority of techniques demand advanced laboratory equipment and professionals to execute precise, efficient, accurate, and sensitive testing. In this work, we report a new method to significantly enhance the sensitivity of microwave sensing of the SARS-CoV-2 virus by functionalizing the sensor surface using anti-SARS-CoV-2 spike antibody-gold nanoparticle (AuNPs) conjugates.
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