Ultrahigh-Sensitivity Microwave Sensor for Microfluidic Complex Permittivity Measurement (original) (raw)
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Sensors, 2021
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.
Al-Furat Journal of Innovations in Electronics and Computer Engineering, 2020
a microwave microfluidic microstrip spilt ring resonator is presented in this paper for liquid sensing and characterization. The sensor is designed to operate at frequency of 1.4 GHz and quality factor of 360. The sensor has been tested with several solvents to verify its sensitivity where the resonant frequency and losses vary with each solvent. The shift in the resonant frequency and the change in the insertion loss have been used to extract the values of the complex permittivity of the solvent. The measured complex permittivities of the solvents have been compared with the theoretical values with very good agreement. This sensor can be utilized in many industrial and medical application where the characterization of liquids are needed.
High Sensitive Microwave Micro-Fluidic Sensor Using Split Ring Resonator
2020
Microwave resonators are commonly used as precise instruments for the measurements of dielectric and electromagnetic properties of materials such as the complex permeability and complex permittivity and surface resistance at microwave frequencies. Many medical and pharmaceutical applications, food industries, and chemical applications require accuracy in calculating complex permittivity of sample under test. In this work, the design and fabrication of high sensitive microwave microfluidic sensors are based on a split ring resonator for liquid permittivity characterization. A microwave microfluidic microstrip SRR is presented in this thesis for liquid sensing and characterization. The 3-D simulations of the sensor are implemented using COMSOL Multiphysics 5.4 to reach a good agreement between simulated and experimental results. The sensor is designed to operate at a frequency of 1.4 GHz and a quality factor of 360. The sensor has been tested with several solvents (water, ethanol, and chloroform) to verify its sensitivity where the resonant frequency and quality factor vary with each solvent. The shift in the resonant frequency and the change in the losses have been used to get the values of the complex permittivity of the solvents. The measured complex permittivity of the solvents has been compared with the theoretical values as there was a very good compatibility between them. Furthermore, we present a new approach for microfluidic sensing using an active split ring resonator (ASRR). ASRR with high sensitivity is presented for measure characterization of liquid with a very small liquid volume approximately 0.4 nL operations at L band. The 3-D simulations of the ASRR are implemented using Advanced Design System 2016.01 (ADS). RF amplifier LNA assists a passive planer microwave sensor inside an aluminum cylindrical cavity to be active SRR. This study consists of two parts; the first part is a calculation of the quality factor and losses of some common fluids (water,ethanol, chloroform, and petroleum ether) using both passive and active SRR to increase Q- factor from 250 to 814 with reducing the loss from 19.6 dB to 6.6 dB when passive SRR is loaded with an empty tube due to RF amplifier generate negative resistance and compensating energy and loss in the passive sensor. As the resolution of the sensor increases with the increase in the quality factor. The second part, via using an active SRR, sensing the high concentrations of sodium sulfite (1 - 3.17) M at 25°C and thus sensor can be used to measure salt concentrations in water. Microstrip stopband split ring resonator (SSRR) for microwave microfluidic is presented for measuring complex permittivity of liquid with different positions of microfluidic channel that operates at resonant frequency of 1 GHz. The sensor was fabricated and microfluidic channel is located in the gap groove with two different positions of the carrier where the electric field is as large as possible. The sensor has been tested with several solvents to verify its sensitivity where the electric field interacts with the liquid filled in a quartz tube and hence alter the SRR behavior. The electromagnetic properties (complex permittivity) of the solutions can be extracted from the change in the resonant frequency of the resonator due to the perturbation phenomenon.
Integrated microwave resonant device for dielectric analysis of microfluidic systems
Journal of Physics: Conference Series, 2011
Herein we present a device for performing non-contact dielectric spectroscopy upon liquids in a microfluidic environment. The device is comprised of a compression-sealed polytetrafluoroethylene (PTFE) chip with an embedded coaxial resonator, which is overmoded for dielectric measurements at six discrete frequencies between 1 and 8 GHz. A novel capacitive coupling structure allows transmission measurements to be taken from one end of the resonator, and an optimised microchannel design maximises sensitivity and repeatability. The use of a PTFE substrate and a non-contact measurement gives excellent chemical and biological compatibility. A simple 'fingerprint' method for identifying solvents is demonstrated, whereby a sample is characterised by air-referenced changes in complex frequency. Complex permittivity values are also obtained via a perturbation theory-based inversion. A combination of experimental and simulated results is used to characterise the device behaviour, limits of operation and measurement uncertainty. The high stability of temporal measurements, coupled with the robustness of the design, make this device ideal for analytical chemistry and industrial process control.
High-Sensitivity Metamaterial-Inspired Sensor for Microfluidic Dielectric Characterization
IEEE Sensors Journal, 2000
A new metamaterial-inspired microwave microfluidic sensor is proposed in this paper. The main part of the device is a microstrip coupled complementary split-ring resonator (CSRR). At resonance, a strong electric field will be established along the sides of CSRR producing a very sensitive area to a change in the nearby dielectric material. A micro-channel is positioned over this area for microfluidic sensing. The liquid sample flowing inside the channel modifies the resonance frequency and peak attenuation of the CSRR resonance. The dielectric properties of the liquid sample can be estimated by establishing an empirical relation between the resonance characteristics and the sample complex permittivity. The designed microfluidic sensor requires a very small amount of sample for testing since the cross-sectional area of the sensing channel is over five orders of magnitude smaller than the square of the wavelength. The proposed microfluidic sensing concept is compatible with lab-on-a-chip platforms owing to its compactness.
Design of miniaturized highly sensitive liquid sensor at microwave frequency
International Journal of RF and Microwave Computer-Aided Engineering, 2020
In this paper, we have presented a simple, miniaturized, and highly sensitive liquid sensor, which determines the dielectric properties of liquids at microwave frequency. In the proposed design, the concept of interdigital capacitor (IDC) is employed to construct the sensor. The proposed IDC based sensor responds differently depending on the liquids' dielectric property. The proposed structure utilizes the shift in resonance frequency and peak attenuation as the sensing parameter to determine the complex dielectric permittivity of the unknown liquids. The advantage of the proposed sensor structure lies in its compactness (0.08λ 0 × 0.08λ 0 × 0.003λ 0) and high sensitivity, 0.42%. The designed sensor can also be used in the biomedical field for noninvasive bioliquid characterization.
A Metamaterial-Based Microwave Sensor for Liquid Dielectrics Characterization
Proceedings of the Proceedings of the 1st International Multi-Disciplinary Conference Theme: Sustainable Development and Smart Planning, IMDC-SDSP 2020, Cyperspace, 28-30 June 2020, 2020
In this work, we propose a metamaterial-based microwave sensor. The main body of the proposed sensor is a microstrip coupled complementary spiral rectangular resonator (CSRR). At resonance, a strong electric field is established along the sides of the CSRR creating a very sensitive area to change in the nearby of the dielectric environment. The enhanced proposed contactless sensor uses liquid samples placed normal to the sensor surface retained within capillary glass tubes. Quick analysis of the liquid dielectric properties is carried out by simply replacing the capillary tube with a new sample.The introduced liquid sample shifts the resonance frequency and alters the peak attenuation of the CSRR resonance. The liquid sample dielectric properties may be estimated by establishing an empirical relationship between the resonance characteristics and the liquid complex relative permittivity. In this work, we could improve our device by simple changing of the CSRR shape of a recently published work, this makes improvement on the characteristics of the sensor and lower its working frequency to 1.8GHz.
Microwave Sensor within a Microfluidic Chip for Biological Applications
Proceedings, 2017
A miniaturized sensor operating in Radio Frequency region (RF) is proposed to address the need in picoliter liquid characterization. The sensor is based on a coplanar waveguide (CPW) combined with a microfluidic channel dedicated to microliter liquid characterization with perspectives for biology and single cell characterization. Using microtechnology process, the sensor has been designed on a 0.5 mm thick quartz wafer with Cr/Au electrodes. A prototype of the sensor has been fabricated and evaluated with ethanol/water mixtures at different molar fractions of ethanol. A good agreement between theoretical and measured electrical response of the sensor is observed.
2021
Microwave microfluidic sensors are typically designed with a channel in vicinity of a resonator's fringing electric (E)-fields, to characterize the material properties of a single fluid. This paper leverages hybrid 3D and dispenser printing to realize a scalable microfluidic sensor utilizing the parallel-plate capacitance of an open-ended microstrip stub, enabling, for the first time, a tunable sensitivity. A stub-loaded microstrip line is then proposed for characterizing multiple microfluidic samples simultaneously using a simple two-port multi-band resonator. The physical constrains which limit the scalability of the proposed sensors have been analyzed analytically and numerically, prior to implementing a three-channel triple-band sensor. The microfluidic channels have been fabricated using stereolithography 3D printing with the microstrip line directly dispenser printed on a conformable polyimide substrate. To accommodate varying channel thicknesses, a tapered microstrip line...