Novel Microwave Frequency-Locked-Loop-Based Sensor for Complex Permittivity Measurement of Liquid Solutions

Tseng, Chao‐Hsiung; Yang, Chengyou

doi:10.1109/tmtt.2022.3198691

Cited by 19 publications

(6 citation statements)

References 29 publications

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“…In recent years, non-invasive blood glucose detection technology based on electromagnetic (EM) technique has generated great interest among researchers. A lot of EM-based research works on glucose concentration detection have been reported [4][5][6][7][8][9][10][11]. The principle of EM-based sensor is that the EM parameter changes of medium under test (MUT) lead to the change of EM-based sensor response.…”

Section: Introductionmentioning

confidence: 99%

“…The principle of EM-based sensor is that the EM parameter changes of medium under test (MUT) lead to the change of EM-based sensor response. Tseng and Yang reported a new microwave frequency-locked-loop (FLL)-based sensor, in which frequency deviation was used to characterize the concentration levels of glucose solution [8]. However, the reported sensing system requires very long delay lines to achieve the accuracy and stability of the measurement results, which will present a significant challenge for system integration and miniaturization.…”

Section: Introductionmentioning

confidence: 99%

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Accurate blood glucose level monitoring using microwave imaging

Wang,

Xiao,

Pang

et al. 2024

Meas. Sci. Technol.

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Painless, and non-invasive detection techniques are needed to replace finger-pick blood for diabetic. In this paper, a first-of-its-kind, noninvasive, and continuous blood glucose level (BGL) detection method based on microwave imaging is introduced. This method avoids the complex task of frequency choice for the design of electromagnetic sensor. A radar-based microwave imaging technology combined with improved very-deep super resolution (VDSR-BL) method is introduced to obtain high-resolution (HR) microwave images. After image super-resolution reconstruction by VDSR-BL, the peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM) of HR images reach 35.4461 dB and 0.9761, respectively. Then an ensemble learning strategy based on support vector regression (SVR) and random forest algorithms is proposed to identify HR microwave images for BGL estimation. The developed detection system has been verified on the medium under tests (MUT) with different glucose solution. The final detection results obtain the root mean squared error (RMSE) of 0.1394 mg/mL and the mean absolute relative difference (MARD) of 8.02%, which show well accuracy with clinical acceptance. Meanwhile, we also conducted human trials. The high correlation coefficient (R) of 0.9254 was achieved between the results of microwave imaging and invasive BGL. Together, these results show that microwave imaging offers a promising new approach for noninvasive BGL monitoring.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Accurate blood glucose level monitoring using microwave imaging

Wang,

Xiao,

Pang

et al. 2024

Meas. Sci. Technol.

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“…The measured changes in the resonator operating frequency enabled the detection of concentration changes in the liquid. Microwave sensors are also widely exploited for the dielectric characterization of liquids, whereby an accurate measurement of the complex permittivity is very important in scientific research and industrial applications [ 10 , 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Microstrip Copper Nanowires Antenna Array for Connected Microwave Liquid Sensors

Cardillo

Tavella

Ampelli

2023

Sensors

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In this contribution, a 25 GHz planar antenna, designed and realized in microstrip technology, is exploited as a lightweight and compact liquid sensor. The high working frequency allows minimization of the sensor dimension. Moreover, particular attention was paid to keeping the design cost low. Indeed, the frequency of 25 GHz is widely exploited for many applications, e.g., up to the last decade concerning radars and, recently, 5G technology. Available commercial antennas allowed minimization of the effort that is usually required to design the microstrip sensor. The antenna was in-house realized, and the microstrip Cu conductor was modified through controlled anodic oxidation in order to enhance the sensing features. The sensor capability of detecting the presence and concentration of ethanol in water was experimentally demonstrated. In detail, a sensitivity of 0.21 kHz/(mg/L) and an average quality factor of 117 were achieved in a very compact size, i.e., 18 mm × 19 mm, and in a cost-effective way. As a matter of fact, the availability of devices able to collect data and then to send the related information wirelessly to a remote receiver represents a key feature for the next generation of connected smart sensors.

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“…Minimally invasive measurements can be made with microneedle patches − or implantable sensors , consisting of glucose-responsive materials such as glucose oxidase ,, or phenylboronic acid gel. − Although securing enough glucose selectivity is a challenging issue, noninvasive measurements using electromagnetic waves, − ultrasonic waves, and magnetic resonance have great potential to liberate patients of the above-mentioned burden. In particular, gigahertz-band electromagnetic waves (microwaves) that penetrate the skin can be used to measure glucose in aqueous solutions, − saline solutions, − and hydrogels, − as well as in animals and humans. , In addition, there are various means of radiating radio waves, for example, open-ended coaxial probes, split-ring resonators, , microstripe antennas, patch antennas, cavity sensors, coplanar sensors, and multimodality analysis . Biomimetic homogeneous hydrogel phantoms − made of, for instance, gelatin, agarose, poly(methyl methacrylate), and flour can be used in combination with computer simulations , for validation before the experiments are conducted on actual organisms.…”

Section: Introductionmentioning

confidence: 99%

“…Here, the skin is not a uniform tissue but rather is multilayered consisting of the stratum corneum, epidermis, and dermis with sweat glands or moles. Its appearance differs, depending on its location on the body. − Thus, making complex and well-reproduced skin phantoms, such as parafilm-attached gels, have a role in the analysis of skin responses to physical stimuli by perforation and neutron beams and in the analysis of chemical compositions such as glucose by microneedles. , In addition, simulations of complex structures with cancer embedded in the skin enable tumor exploration. − However, the microwave-based glucose sensing methods developed so far have been mostly for uniform materials rather than for multilayer structures, − and some phantoms suffer dielectric loss differences below 1 GHz, making perfect dielectric matching difficult; the parafilm-gel phantom also needs further adjustments for radio waves. Therefore, noninvasive glucose sensing requires a multilayer skin phantom for microwaves and an analysis method for detecting slight amounts of glucose in a complex skin environment.…”

Section: Introductionmentioning

confidence: 99%

Noninvasive Glucose Sensing in Dielectrically Equivalent Multilayer Skin Phantoms

Fukada,

Nakamura,

Tajima

et al. 2023

Langmuir

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The interstitial fluid of the skin contains glucose levels comparable to those of blood. Noninvasive glucose sensing by microwaves has great potential to relieve diabetics from the burden of daily blood sampling, but improving the selectivity of this method remains a challenge. This study reports a dielectrically equivalent multilayer skin phantom and provides insight into the criteria for noninvasive glucose sensing by conducting dielectric analysis. The skin phantom was a hydrogel composed of gelatin, glucose, sodium chloride, and water covered by paraffin-impregnated paper. Investigations conducted on a wide range of component concentrations revealed characteristic relative permittivity and dielectric loss determined by the amount of electrolyte and solution that was independent of the amount of glucose. Since the microwave response due to glucose tends to be buried in noise, we developed a flowchart that first identifies the amounts of electrolytes and proteins, which are the major components other than glucose, and then quantifies the remaining glucose content. This noninvasive glucose sensing method would not be limited to the medical healthcare field; it could potentially be used in food manufacturing processes, livestock farming, and plant cultivation management.

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Novel Microwave Frequency-Locked-Loop-Based Sensor for Complex Permittivity Measurement of Liquid Solutions

Cited by 19 publications

References 29 publications

Accurate blood glucose level monitoring using microwave imaging

Accurate blood glucose level monitoring using microwave imaging

Microstrip Copper Nanowires Antenna Array for Connected Microwave Liquid Sensors

Noninvasive Glucose Sensing in Dielectrically Equivalent Multilayer Skin Phantoms

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