scholarly journals Microwave Differential Frequency Splitting Sensor Using Magnetic-LC Resonators

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1066 ◽  
Author(s):  
Amir Ebrahimi ◽  
Grzegorz Beziuk ◽  
James Scott ◽  
Kamran Ghorbani
Keyword(s):  
Dielectric Properties ◽  
Transmission Line ◽  
Reference Sample ◽  
Solid Materials ◽  
Microstrip Transmission Line ◽  
Frequency Splitting ◽  
Metallic Wall ◽  
Lc Resonator ◽  
Lc Resonators

A differential microwave permittivity sensor and comparator is designed using a microstrip transmission line loaded with a magnetic-LC resonator. The microstrip transmission line is aligned with the electric wall of the resonator. The sensor shows a single transmission zero, when it is unloaded or loaded symmetrically on both halves. A second notch appears in the transmission response by asymmetrical dielectric loading on the two halves of the device. The frequency splitting is used to characterize the dielectric properties of the samples under test. The sensitivity of the sensor is enhanced by removing the mutual coupling between the two halves of the magnetic-LC resonator using a metallic wall. The sensors’ operation principle is explained through a circuit model analysis. A prototype of the designed sensor is fabricated and measurements are used for validation of the sensing concept. The sensor can be used for determination of the dielectric properties in solid materials or detecting defects and impurities in solid materials through a comparative measurement with a reference sample.

scholarly journals Extremely Sensitive Microwave Microfluidic Dielectric Sensor Using a Transmission Line Loaded with Shunt LC Resonators

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6811
Author(s):  
Haneen Abdelwahab ◽  
Amir Ebrahimi ◽  
Francisco J. Tovar-Lopez ◽  
Grzegorz Beziuk ◽  
Kamran Ghorbani
Keyword(s):  
Electric Field ◽  
Transmission Line ◽  
Microfluidic Channel ◽  
High Sensitivity ◽  
Sensor Performance ◽  
Methanol Solutions ◽  
Dielectric Sensor ◽  
Lc Resonator ◽  
Working Principle ◽  
Lc Resonators

In this paper, a very high sensitivity microwave-based planar microfluidic sensor is presented. Sensitivity enhancement is achieved and described theoretically and experimentally by eliminating any extra parasitic capacitance not contributing to the sensing mechanism. The sensor consists of a microstrip transmission line loaded with a series connected shunt LC resonator. A microfluidic channel is attached to the area of the highest electric field concentration. The electric field distribution and, therefore, the resonance characteristics are modified by applying microfluidic dielectric samples to the sensing area. The sensor performance and working principle are described through a circuit model analysis. A device prototype is fabricated, and experimental measurements using water/ethanol and water/methanol solutions are presented for validation of the sensing mathematical model.

scholarly journals High-Precision Complementary Metamaterial Sensor Using Slotted Microstrip Transmission Line

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Abdul Samad ◽  
Wei Dong Hu ◽  
Waseem Shahzad ◽  
Leo. P. Ligthart ◽  
Hamid Raza
Keyword(s):  
Dielectric Properties ◽  
Resonant Frequency ◽  
Transmission Line ◽  
Dielectric Materials ◽  
Compact Structure ◽  
Microstrip Transmission Line ◽  
Left Handed ◽  
Microwave Sensor ◽  
Constitutive Parameters

Metamaterial-based microwave sensor having novel and compact structure of the resonators and the slotted microstrip transmission line is proposed for highly precise measurement of dielectric properties of the materials under test (MUTs). The proposed sensor is designed and simulated on Rogers’ substrate RO4003C by using the ANSYS HFSS software. A single and accumulative notch depth of -44.29 dB in the transmission coefficient ( S 21 ) is achieved at the resonant frequency of 5.15 GHz. The negative constitutive parameters (permittivity and permeability) are extracted from the S -parameters which are the basic property of metamaterials or left handed materials (LHMs). The proposed sensor is fabricated and measured through the PNA-X (N5247A). The sensitivity analysis is performed by placing various standard dielectric materials onto the sensor and measuring the shift in the resonant frequencies of the MUTs. A parabolic equation of the proposed sensor is formulated to approximate the resonant frequency and the relative permittivity of the MUTs. A very strong agreement among the simulated, measured, and calculated results is found which reveals that the proposed sensor is a highly precise sensor for the characterization of dielectric properties of the MUTs. Error analysis is performed to determine the accuracy of the proposed sensor. A very small percentage of error (0.81%) and a very low standard deviation are obtained which indicate high accuracy of the proposed sensor.

Is it necessary to calculate Young’s modulus in AFM nanoindentation experiments regarding biological samples?

2020 ◽  
Vol 12 ◽  
Author(s):  
S.V. Kontomaris ◽  
A. Malamou ◽  
A. Stylianou
Keyword(s):  
Young’S Modulus ◽  
Biological Samples ◽  
Young's Modulus ◽  
Reference Sample ◽  
Nonlinear Behavior ◽  
Accurate Method ◽  
Accurate Solution ◽  
Hertz Model ◽  
Work Done

Background: The determination of the mechanical properties of biological samples using Atomic Force Microscopy (AFM) at the nanoscale is usually performed using basic models arising from the contact mechanics theory. In particular, the Hertz model is the most frequently used theoretical tool for data processing. However, the Hertz model requires several assumptions such as homogeneous and isotropic samples and indenters with perfectly spherical or conical shapes. As it is widely known, none of these requirements are 100 % fulfilled for the case of indentation experiments at the nanoscale. As a result, significant errors arise in the Young’s modulus calculation. At the same time, an analytical model that could account complexities of soft biomaterials, such as nonlinear behavior, anisotropy, and heterogeneity, may be far-reaching. In addition, this hypothetical model would be ‘too difficult’ to be applied in real clinical activities since it would require very heavy workload and highly specialized personnel. Objective: In this paper a simple solution is provided to the aforementioned dead-end. A new approach is introduced in order to provide a simple and accurate method for the mechanical characterization at the nanoscale. Method: The ratio of the work done by the indenter on the sample of interest to the work done by the indenter on a reference sample is introduced as a new physical quantity that does not require homogeneous, isotropic samples or perfect indenters. Results: The proposed approach, not only provides an accurate solution from a physical perspective but also a simpler solution which does not require activities such as the determination of the cantilever’s spring constant and the dimensions of the AFM tip. Conclusion: The proposed, by this opinion paper, solution aims to provide a significant opportunity to overcome the existing limitations provided by Hertzian mechanics and apply AFM techniques in real clinical activities.

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