Design and implementation of a wireless passive microsensor for methanol detection (original) (raw)
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Sensors (Basel, Switzerland), 2018
We present a microfabricated spiral-coupled passive resonator sensor realized through integrated passive device (IPD) technology for the sensitive detection and characterization of water-ethanol solutions. In order to validate the performance of the proposed device, we explicitly measured and analyzed the radio frequency (RF) characteristics of various water-ethanol solution compositions. The measured results showed a drift in the resonance frequency from 1.16 GHz for deionized (DI) water to 1.68 GHz for the solution containing 50% ethanol, whereas the rejection level given by the reflection coefficient decreased from -29.74 dB to -14.81 dB. The obtained limit of detection was 3.82% volume composition of ethanol in solution. The derived loaded capacitance was 21.76 pF for DI water, which gradually decreased to 8.70 pF for the 50% ethanol solution, and the corresponding relative permittivity of the solution decreased from 80.14 to 47.79. The dissipation factor increased with the conc...
Multipurpose chemical liquid sensing applications by microwave approach
PLOS ONE, 2020
In this work, a novel sensor based on printed circuit board (PCB) microstrip rectangular patch antenna is proposed to detect different ratios of ethanol alcohol in wines and isopropyl alcohol in disinfectants. The proposed sensor was designed by finite integration technique (FIT) based high-frequency electromagnetic solver (CST) and was fabricated by Proto Mat E33 machine. To implement the numerical investigations, dielectric properties of the samples were first measured by a dielectric probe kit then uploaded into the simulation program. Results showed a linear shifting in the resonant frequency of the sensor when the dielectric constant of the samples were changed due to different concentrations of ethanol alcohol and isopropyl alcohol. A good agreement was observed between the calculated and measured results, emphasizing the usability of dielectric behavior as an input sensing agent. It was concluded that the proposed sensor is viable for multipurpose chemical sensing applications.
In the present work, we studied the design and fabrication of low cost passive microsensors for measuring hazardous compounds. The sensors were fabricated with low cost and biocompatible materials, making them suitable for several industries and applications. These wireless sensors are small enough to be placed inside pipes and recipients of more than 1 cm in diameter. Sensors were tested with air, distilled water, acetic acid, pyridine, N,N-dimethylformamide and butanol, presenting high accuracy, repeatability and reproducibility among substances and sensors. The sensors showed a high resistance to corrosion and oxidation after cycling operation. The whole measuring system, that included the sensor and the coupling antenna, proved to be suitable for measuring low dielectric constant and low volatility compounds presenting an average standard deviations in the detection of any compound of 4.23%.
Complementary Split-Ring Resonator-Loaded Microfluidic Ethanol Chemical Sensor
Sensors, 2016
In this paper, a complementary split-ring resonator (CSRR)-loaded patch is proposed as a microfluidic ethanol chemical sensor. The primary objective of this chemical sensor is to detect ethanol's concentration. First, two tightly coupled concentric CSRRs loaded on a patch are realized on a Rogers RT/Duroid 5870 substrate, and then a microfluidic channel engraved on polydimethylsiloxane (PDMS) is integrated for ethanol chemical sensor applications. The resonant frequency of the structure before loading the microfluidic channel is 4.72 GHz. After loading the microfluidic channel, the 550 MHz shift in the resonant frequency is ascribed to the dielectric perturbation phenomenon when the ethanol concentration is varied from 0% to 100%. In order to assess the sensitivity range of our proposed sensor, various concentrations of ethanol are tested and analyzed. Our proposed sensor exhibits repeatability and successfully detects 10% ethanol as verified by the measurement setup. It has created headway to a miniaturized, non-contact, low-cost, reliable, reusable, and easily fabricated design using extremely small liquid volumes.
Capillary Condensation Based Wireless Volatile Molecular Sensor
In this paper, a LC (inductor capacitor) wireless gas sensor is demonstrated for the identification of volatile organic compounds (VOC's) in the air environment. A near-field LC resonant tank consisting of an interdigitated capacitor fabricated on a porous flexible substrate coupled with an inductor coil is used as a sensor and its resonance is interrogated using an external pick up coil. The porous substrate enables capillary condensation of volatiles leading to a change in effective dielectric constant of the substrate which in turn shifts the resonance frequency. The designed sensor has multiple reuse capability and is applicable for continuous monitoring of volatiles such as methanol, iso-propyl alcohol, acetone and noctane. The proposed sensor can wirelessly detect a 0.15 cc volume of volatiles in air making it highly sensitive. These sensors can be integrated with passive RFIDs in an array format for simultaneous detection of multiple volatile gases similar to an electronic nose. It can also be integrated with food packages to detect volatiles from food along the supply chain for quality control applications.
Development of a Microwave Sensor for Solid and Liquid Substances Based on Closed Loop Resonator
Sensors, 2021
In this work, a compact dielectric sensor for the detection of adulteration in solid and liquid samples using planar resonators is presented. Six types of filter prototypes operating at 2.4 GHz are presented, optimized, numerically assessed, fabricated and experimentally validated. The obtained experimental results provided an error less than 6% with respect to the simulated results. Moreover, a size reduction of about 69% was achieved for the band stop filter and a 75% reduction for band pass filter compared to standard sensors realized using open/short circuited stub microstrip lines. From the designed filters, the miniaturised filter with Q of 95 at 2.4 GHz and size of 35 mm × 35 mm is formulated as a sensor and is validated theoretically and experimentally. The designed sensor shows better sensitivity, and it depends upon the dielectric property of the sample to be tested. Simulation and experimental validation of the designed sensor is carried out by loading different samples o...
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.
Progress In Electromagnetics Research M
An optimized microfluidic sensor for extracting volume ratio of binary mixture comprising of ethanol and methanol using electrical resonance technique has been presented in this work. In order to detect small changes in composition of binary mixture, a split-ring resonator structure with enhanced sensitivity was designed to operate around 2.5 GHz. A resonator was designed using HFSS, which possessed enhanced sensitivity. A novel algorithm for optimization was devised for binary mixture of the two liquids. The resonator was fabricated and tested for validation of results. Samples of ethanol and methanol mixture in different volume ratios were prepared and filled in micro-capillary tubes. These tubes were placed inside the resonant structure to perturb electric field. Variations in resonant properties due to change in volume ratio of liquid mixtures were analyzed. Resonant frequency, s-parameters, and quality factor of structure were measured. It was observed that change in volume fraction as small as 1/100 resulted a shift of 0.25 MHz in resonant frequency (relatively high level of sensitivity). Measured results were utilized by mathematical model to compute volume fraction of liquid in these mixtures.
A Hybrid Magnetoelastic Wireless Sensor for Detection of Food Adulteration
—This paper investigates a step by step design procedure of a hybrid passive wireless sensor. The hybrid sensor measures both electrical (dielectric constant) and mechanical (viscosity) properties of liquid, providing a two-factor quality control. The hybrid sensor is based on an inductor-capacitor (LC) resonant tank coupled with a magnetoelastic strip. The mechanical and electrical resonances change as a function of viscosity and dielectric constant, respectively. Two different hybrid sensor designs are investigated, i) a parallel plate capacitor coupled with a separate amorphous ferromagnetic magnetoelastic strip (Metglas), and ii) a capacitor made using two parallel mounted magnetoelastic strips. The sensors are integrated as part of the " smart vial " making it field operable for food quality monitoring and control. Here, detection of adulteration in extra virgin olive oil is achieved by measuring the change in viscosity and dielectric constant for different adulteration levels. The real part of the dielectric constant for different liquid samples is measured in the frequency range of 3-24 MHz. The hybrid sensor is able to detect adulteration levels below 10% in volume. Theses sensors can be integrated with passive RFIDs for simultaneous measurement of multiple samples in an array format.
Microchimica Acta, 2017
The authors describe a sensor capable of detecting methanol adulteration of ethanol. The sensor is based on the use of quartz tuning forks (QTFs) that were functionalized with polymer wires made from a combination of polystyrene (PS) and aniline. Exposure to organic vapors causes the resonance frequency of the functionalized QTF to change, and this can be used to identify the type and concentration of the analyte. A mixture of methanol and ethanol vapors in varying concentrations was exposed to the QTF polymer system. The resulting shift in the resonance frequency of the QTF was firstly used to determine the concentration of alcohol vapor, which is reflected in the amount of shift. Secondly, the nature of change in resonance frequency was used to determine the type of alcohol exposed to the sensor. The sensitivity and selectivity of the sensors to ethanol and methanol vapors has been investigated. A portable hand-held prototype sensor has been developed which displays the percentage of two alcohols it is exposed to. It can detect ethanol adulteration where the methanol concentration is as low as 5%.