scholarly journals Planar Microwave Resonant Sensors: A Review and Recent Developments

2020 ◽  
Vol 10 (7) ◽  
pp. 2615 ◽  
Author(s):  
Jonathan Muñoz-Enano ◽  
Paris Vélez ◽  
Marta Gil ◽  
Ferran Martín
Keyword(s):  
Surrounding Medium ◽  
High Sensitivity ◽  
Liquid Composition ◽  
Industrial Processes ◽  
Differential Mode ◽  
Resonant Sensors ◽  
Dielectric Characterization ◽  
Recent Developments ◽  
Microwave Sensors

Microwave sensors based on electrically small planar resonant elements are reviewed in this paper. By virtue of the high sensitivity of such resonators to the properties of their surrounding medium, particularly the dielectric constant and the loss factor, these sensors are of special interest (although not exclusive) for dielectric characterization of solids and liquids, and for the measurement of material composition. Several sensing strategies are presented, with special emphasis on differential-mode sensors. The main advantages and limitations of such techniques are discussed, and several prototype examples are reported, mainly including sensors for measuring the dielectric properties of solids, and sensors based on microfluidics (useful for liquid characterization and liquid composition). The proposed sensors have high potential for application in real scenarios (including industrial processes and characterization of biosamples).

scholarly journals A Review of Sensing Strategies for Microwave Sensors Based on Metamaterial-Inspired Resonators: Dielectric Characterization, Displacement, and Angular Velocity Measurements for Health Diagnosis, Telecommunication, and Space Applications

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Lijuan Su ◽  
Javier Mata-Contreras ◽  
Paris Vélez ◽  
Ferran Martín
Keyword(s):  
Transmission Lines ◽  
Harmonic Signal ◽  
Dielectric Materials ◽  
Frequency Variation ◽  
Space Applications ◽  
Dielectric Characterization ◽  
Communication Circuits ◽  
Symmetry Properties ◽  
Microwave Sensors

Four sensing approaches for the implementation of microwave sensors based on transmission lines loaded with metamaterial-inspired resonators are considered in this review paper, and examples of applications are pointed out. In all the cases, sensing is based on the effects that the magnitude under measurement causes in the transmission properties of the resonator-loaded line. Such four strategies are (i) resonance frequency variation, (ii) coupling modulation through symmetry disruption (causing variation of the notch depth), (iii) frequency splitting (also exploiting symmetry properties), and (iv) amplitude modulation of a harmonic signal. Such sensors are useful in various scenarios, of interest in fields as diverse as characterization of dielectric materials for communication circuits, medical diagnosis and treatment with microwave technologies, and sensors for space applications, among others.

Electrochemical Sensors Based on Architectural Diversity of the ?-Conjugated Structure: Recent Advancements from Conducting Polymers and Carbon Nanotubes

2007 ◽  
Vol 60 (7) ◽  
pp. 472 ◽  
Author(s):  
Liming Dai
Keyword(s):  
Carbon Nanotubes ◽  
Conducting Polymers ◽  
Electrochemical Sensors ◽  
Functional Materials ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Environmental Stability ◽  
Carbon Fibres ◽  
Recent Developments

Conjugated conducting polymers and carbon nanotubes, both of which possess a conjugated structure of alternating carbon–carbon single and double bonds for the delocalization of π-electrons, are two important classes of electrochemical sensing materials. The combination of carbon nanotubes with conducting polymers or other functional materials (e.g., DNA chains, proteins, metal nanoparticles, carbon fibres) was found to create synergetic effects, that provide the basis for the development of numerous novel sensors with a high sensitivity, good selectivity, excellent environmental stability, and low power consumption. This article reviews recent developments in this exciting new area of electrochemical sensing by presenting the rational strategy of the author’s group in the design and characterization of these new electrochemical sensors based on architectural diversity of the π-conjugated structure.

scholarly journals Differential microwave sensor based on microstrip lines loaded with a split-ring resonator for dielectric characterization of materials

2021 ◽  
Vol 2118 (1) ◽  
pp. 012004
Author(s):  
J Zapata-Londoño ◽  
F Umaña-Idárraga ◽  
J Morales-Guerra ◽  
S Arias-Gómez ◽  
C Valencia-Balvin ◽  
...  
Keyword(s):  
Ring Resonator ◽  
High Sensitivity ◽  
Dielectric Materials ◽  
Split Ring Resonator ◽  
Label Free ◽  
Split Ring ◽  
Total Size ◽  
Dielectric Characterization ◽  
Microwave Sensor

Abstract In this work, we propose a microwave sensor that allows the characterization of dielectric materials based on a differential configuration. A microstrip permittivity sensor of the surrounding material is proposed using a split ring-resonator to measure differentially. The geometry was optimized and was numerically analyzed using CST STUDIO. The numerical analysis of the metamaterial unit cells is carried out first, to determine the operating band. After that, the metamaterial cell was employed to design the differential microstrip permittivity sensor. The obtained results reveal that the proposed sensor has the capability to characterize different materials whose relative dielectric permittivity’s are in the range of 9.8 to 80 with great performance. The device has a total size of 86 mm × 60 mm and operates around 3 GHz. In this band, the sensor reaches a sensibility of 2.89 MHz and a Q-factor of 70.15. Thus, this work shows a compact, reusable, label-free, and non-destructive microwave sensing device and paves the way for high accuracy sensing of the dielectric properties of different materials due to its high- Q-factor as well as high sensitivity.

Ultrastructural identification of three types of sensory setae on copepod antennae

1995 ◽  
Vol 53 ◽  
pp. 956-957
Author(s):  
T. M. Weatherby ◽  
P.H. Lenz
Keyword(s):  
Phase Locking ◽  
Membrane Surface ◽  
Reaction Times ◽  
High Sensitivity ◽  
Structural Features ◽  
Calanoid Copepods ◽  
Marine Food Webs ◽  
Dendritic Membrane ◽  
Ultrastructural Characterization

Crustaceans, as well as other arthropods, are covered with sensory setae and hairs, including mechanoand chemosensory sensillae with a ciliary origin. Calanoid copepods are small planktonic crustaceans forming a major link in marine food webs. In conjunction with behavioral and physiological studies of the antennae of calanoids, we undertook the ultrastructural characterization of sensory setae on the antennae of Pleuromamma xiphias.Distal mechanoreceptive setae exhibit exceptional behavioral and physiological performance characteristics: high sensitivity (<10 nm displacements), fast reaction times (<1 msec latency) and phase locking to high frequencies (1-2 kHz). Unusual structural features of the mechanoreceptors are likely to be related to their physiological sensitivity. These features include a large number (up to 3000) of microtubules in each sensory cell dendrite, arising from or anchored to electron dense rods associated with the ciliary basal body microtubule doublets. The microtubules are arranged in a regular array, with bridges between and within rows. These bundles of microtubules extend far into each mechanoreceptive seta and terminate in a staggered fashion along the dendritic membrane, contacting a large membrane surface area and providing a large potential site of mechanotransduction.

Schottky diodes based on 2D materials for environmental gas monitoring: a review on emerging trends, recent developments and future perspectives

2021 ◽  
Author(s):  
Minu Mathew ◽  
Chandra Sekhar Rout
Keyword(s):  
Gas Sensing ◽  
2D Materials ◽  
Schottky Diodes ◽  
High Sensitivity ◽  
Future Perspectives ◽  
Working Temperature ◽  
Emerging Trends ◽  
Gas Sensing Properties ◽  
Recent Developments ◽  
Sensitivity And Selectivity

This review details the fundamentals, working principles and recent developments of Schottky junctions based on 2D materials to emphasize their improved gas sensing properties including low working temperature, high sensitivity, and selectivity.

Microwave dielectric characterization of bulk ferroelectrics

1998 ◽  
Vol 08 (PR9) ◽  
pp. Pr9-113-Pr9-116 ◽  
Author(s):  
C. M. Weil ◽  
R. G. Geyer ◽  
L. Sengupta
Keyword(s):  
Dielectric Characterization ◽  
Microwave Dielectric

Neurochemistry of L-Glutamate Transport in the CNS: A Review of Thirty Years of Progress

2001 ◽  
Vol 66 (9) ◽  
pp. 1315-1340 ◽  
Author(s):  
Vladimir J. Balcar ◽  
Akiko Takamoto ◽  
Yukio Yoneda
Keyword(s):  
Molecular Biology ◽  
Glutamate Transport ◽  
Mammalian Brain ◽  
Activity Data ◽  
System A ◽  
Recent Developments ◽  
The Central Nervous System ◽  
Health And Disease ◽  
Disease Analysis

The review highlights the landmark studies leading from the discovery and initial characterization of the Na+-dependent "high affinity" uptake in the mammalian brain to the cloning of individual transporters and the subsequent expansion of the field into the realm of molecular biology. When the data and hypotheses from 1970's are confronted with the recent developments in the field, we can conclude that the suggestions made nearly thirty years ago were essentially correct: the uptake, mediated by an active transport into neurons and glial cells, serves to control the extracellular concentrations of L-glutamate and prevents the neurotoxicity. The modern techniques of molecular biology may have provided additional data on the nature and location of the transporters but the classical neurochemical approach, using structural analogues of glutamate designed as specific inhibitors or substrates for glutamate transport, has been crucial for the investigations of particular roles that glutamate transport might play in health and disease. Analysis of recent structure/activity data presented in this review has yielded a novel insight into the pharmacological characteristics of L-glutamate transport, suggesting existence of additional heterogeneity in the system, beyond that so far discovered by molecular genetics. More compounds that specifically interact with individual glutamate transporters are urgently needed for more detailed investigations of neurochemical characteristics of glutamatergic transport and its integration into the glutamatergic synapses in the central nervous system. A review with 162 references.

scholarly journals Average fractional polarization of extragalactic sources at Planck frequencies

2018 ◽  
Vol 618 ◽  
pp. A29 ◽  
Author(s):  
T. Trombetti ◽  
C. Burigana ◽  
G. De Zotti ◽  
V. Galluzzi ◽  
M. Massardi
Keyword(s):  
High Sensitivity ◽  
Point Sources ◽  
Distribution Analysis ◽  
Microwave Background ◽  
Residual Noise ◽  
Upper Limits ◽  
Dusty Galaxies ◽  
Using Data ◽  
Polarization Fraction

Recent detailed simulations have shown that an insufficiently accurate characterization of the contamination of unresolved polarized extragalactic sources can seriously bias measurements of the primordial cosmic microwave background (CMB) power spectrum if the tensor-to-scalar ratio r ∼ 0.001, as predicted by models currently of special interest (e.g., Starobinsky’s R2 and Higgs inflation). This has motivated a reanalysis of the median polarization fraction of extragalactic sources (radio-loud AGNs and dusty galaxies) using data from the Planck polarization maps. Our approach, exploiting the intensity distribution analysis, mitigates or overcomes the most delicate aspects of earlier analyses based on stacking techniques. By means of simulations, we have shown that the residual noise bias on the median polarization fraction, Πmedian, of extragalactic sources is generally ≲0.1%. For radio sources, we have found Πmedian ≃ 2.83%, with no significant dependence on either frequency or flux density, in good agreement with the earlier estimate and with high-sensitivity measurements in the frequency range 5–40 GHz. No polarization signal is detected in the case of dusty galaxies, implying 90% confidence upper limits of Πdusty ≲ 2.2% at 353 GHz and of ≲3.9% at 217 GHz. The contamination of CMB polarization maps by unresolved point sources is discussed.

scholarly journals Persistent luminescence nanoparticles for cancer theranostics application

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Nian Liu ◽  
Xiao Chen ◽  
Xia Sun ◽  
Xiaolian Sun ◽  
Junpeng Shi
Keyword(s):  
Uv Light ◽  
Combined Therapy ◽  
Tumor Therapy ◽  
High Sensitivity ◽  
Persistent Luminescence ◽  
Therapeutic Drugs ◽  
High Penetration ◽  
Recent Developments ◽  
Cancer Theranostics

AbstractPersistent luminescence nanoparticles (PLNPs) are unique optical materials that emit afterglow luminescence after ceasing excitation. They exhibit unexpected advantages for in vivo optical imaging of tumors, such as autofluorescence-free, high sensitivity, high penetration depth, and multiple excitation sources (UV light, LED, NIR laser, X-ray, and radiopharmaceuticals). Besides, by incorporating other functional molecules, such as photosensitizers, photothermal agents, or therapeutic drugs, PLNPs are also widely used in persistent luminescence (PersL) imaging-guided tumor therapy. In this review, we first summarize the recent developments in the synthesis and surface functionalization of PLNPs, as well as their toxicity studies. We then discuss the in vivo PersL imaging and multimodal imaging from different excitation sources. Furthermore, we highlight PLNPs-based cancer theranostics applications, such as fluorescence-guided surgery, photothermal therapy, photodynamic therapy, drug/gene delivery and combined therapy. Finally, future prospects and challenges of PLNPs in the research of translational medicine are also discussed.

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