RF Sensing System for Continuous Blood Glucose Monitoring (original) (raw)
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Microwave sensor for non‐invasive glucose measurements design and implementation of a novel linear
IET Wireless Sensor Systems, 2015
In this paper, a novel non-invasive sensor for the measurement of the glucose concentrations in blood is presented. By using a microstrip band pass filter, a wireless sensor is achieved. In the introduced design, the thumb is placed on the structure of the filter as a superstrate. The response of the filter is dependent on the permittivity of the superstrate. A compact size, linearity and cost effectiveness are the most important advantages of the proposed sensor. The linear behaviour of the filter in terms of the frequency is investigated and for a linear behaviour, a certain frequency for operation is selected. The introduced sensor can be used by diabetics for continuous self-monitoring of the glucose level. The structure of the proposed sensor is designed on the low-cost substrate, FR4, by compact dimensions of 50 mm × 40 mm × 1.6 mm. A prototype of the proposed filter was fabricated and the performance of the filter was investigated, experimentally.
Experimental Based Blood Glucose Monitoring with a Noninvasive Cylindrical Biosensor Antenna
Progress In Electromagnetics Research M
In this work, we have designed and fabricated a noninvasive flexible biosensor with a simple and printable structure for blood glucose monitoring. The proposed sensor has been experimentally proven to monitor blood sugar levels through frequency shifts. A cylindrical design with a coplanar waveguide (CPW) feeding technique has been proposed. A targeted frequency of 2.4 GHz with the best S 11 at −22.623 dB and a bandwidth of 323 MHz was obtained. However, after propagating through the finger phantom, the signal is sensitive to the blood glucose levels with a significant frequency shift. The biosensor worked well at 1.55-1.88 GHz, representing a finger, without a phantom in the ISM band of 2.4 GHz. There is a bit of shifted frequency during the biosensor measurement with less than a 1.41% error. The overall size of the biosensor is 50.66 mm × 60.31 mm. The biosensor uses a flexible Dupont Pyralux substrate; thus, the index finger is easy to insert. 25 volunteers were involved in this experimental blood glucose. For this, we use an invasive device to measure the volunteers' blood glucose levels. The invasive measurement results obtained are used as a reference for the blood sugar levels of each sample. The test results using a cylindrical biosensor show a frequency shift at 7.5 MHz for every mg/dl of blood sugar levels, with a sensitivity of 0.43 1/(mg/dL). This frequency shift can be used to observe changes in the concentration of sugar levels in the blood. This flexible sensor is a good alternative biosensor for measuring blood glucose levels due to its low cost and printable structure.
A novel compact highly sensitive non-invasive microwave antenna sensor for blood glucose monitoring
Open Physics
In the present work, a novel compact and highly sensitive microwave antenna sensor at 2.45 GHz is proposed for evaluating glucose concentration in blood. The antenna is printed on an FR-4 substrate of compact dimensions 35 mm × 13.5 mm × 1.6 mm. A human finger phantom model is constructed in the EM simulation high frequency structure simulator environment consisting of skin, blood, fat, and bone layers. In the study, finger models with various shapes like rectangular, cylindrical, and ellipsoid are considered, and the results are compared. The glucose concentration is changed from 0 to 500 mg/dL, and the corresponding shift is evaluated by keeping the finger phantom at different locations near the antenna. The frequency shifts obtained in the designed experiment are used to evaluate glucose concentration in blood samples. In this work, a minimum and a maximum frequency shift of around 1.25 and 5 MHz, respectively, are observed when the finger phantom is placed at the top of the radi...
IEEE Access
Microwave sensors are gaining increasing interest in blood glucose detection, for their potential ability to perform a continuous non-invasive monitoring of the glucose concentration, by relating the change in the blood dielectric properties to a variation in the glucose level. Usually, the involved body part (phantom) is placed on the sensor to perform the reading. However, the placement modality, as well as other external factors not related to the blood glucose concentrations (BGC) (i.e. system noise, environmental temperature, human tissues variations other than blood tissue) may also have an effect on the sensor response, due to the change in the propagation path of the electromagnetic field inside the body part under test. In this work, the variation effects induced on the microwave sensor response by the changes in the thickness and the dielectric properties of skin and fat tissues are analyzed and faced. In particular, to mitigate the above drawback in terms of sensor instability, a solid ''matching layer'' is interposed between the resonant sensor and the phantom under test. A specific optimization procedure is performed to design microwave sensors with a stable response not influenced by variations in tissues different from the blood. Various sensors configurations with related resolution metrics are considered to assess the proposed idea and design methodology. Numerical results confirm the possibility to achieve a good trade-off between the measurement stability against undesired phantom variations and the sensitivity toward blood glucose levels, allowing to discriminate concentrations in the range of [100-300] mg/dL.
Design and In Vitro Interference Test of Microwave Noninvasive Blood Glucose Monitoring Sensor
A design of a microwave noninvasive continuous blood glucose monitoring sensor and its interference test results are presented. The novelty of the proposed sensor is that it comprises two spatially separated split-ring resonators, where one interacts with the change in glucose level of a sample under test while the other ring is used as a reference. The reference ring has a slightly different resonant frequency and is desensitized to the sample owing to its location, thus allowing changes in temperature to be calibrated out. From an oral glucose tolerance test with two additional commercially available sensors (blood strip and continuous glucose monitor) in parallel, we obtained encouraging performance for our sensor comparable with those of the commercial sensors. The effects of endogenous interferents common to all subjects, i.e., common sugars, vitamins (ascorbic acid), and metabolites (uric acid) have also been investigated by using a large Franz cell assembly. From the interference test, it is shown that the change in sensor response is dominated by changes in glucose level for concentrations relevant to blood, and the effects of interferents are negligible in comparison.
Noninvasive Method for Measuring the Blood Glucose Level Using a Narrow Band Microstrip Antenna
The Applied Computational Electromagnetics Society Journal (ACES)
In this paper, a narrowband and compact antenna resonating at 6.1 GHz with a peak realized gain of 3.3 dBi is proposed to monitor the glucose concentration in the blood without taking invasive blood samples. The proposed antenna is fabricated using a low-cost FR-4 substrate with compact dimensions of 30 mm × 30 mm × 1.6 mm. The impedance bandwidth of this antenna ranges from 5.2 to 7.1 GHz. For measuring blood glucose levels, a human finger phantom model with dimensions of 15 mm × 12 mm × 10 mm is constructed using the EM simulation (HFSS) environment. The finger phantom consists of different layers such as skin, fat, muscle, blood, and bone modeled at 6.1 GHz using various dielectric materials for various glucose concentrations. The finger phantom model is placed at different locations around the antenna to measure the frequency shift for monitoring glucose concentration in blood samples. The proposed finger phantom model is validated by conducting an experimental study by placing ...
Scientific Reports
This article presents a novel design of portable planar microwave sensor for fast, accurate, and non-invasive monitoring of the blood glucose level as an effective technique for diabetes control and prevention. The proposed sensor design incorporates four cells of hexagonal-shaped complementary split ring resonators (CSRRs), arranged in a honey-cell configuration, and fabricated on a thin sheet of an FR4 dielectric substrate.The CSRR sensing elements are coupled via a planar microstrip-line to a radar board operating in the ISM band 2.4–2.5 GHz. The integrated sensor shows an impressive detection capability and a remarkable sensitivity of blood glucose levels (BGLs). The superior detection capability is attributed to the enhanced design of the CSRR sensing elements that expose the glucose samples to an intense interaction with the electromagnetic fields highly concentrated around the sensing region at the induced resonances. This feature enables the developed sensor to detect extrem...
IEEE Sensors Journal, 2017
The non-invasive measurement of blood glucose is a popular research topic where RF/microwave sensing of glucose is one of the promising methods in this area. From the many available measurement sites in the human body, fingertips appear to be a good choice due to a good amount of fresh blood supply and homogeneity in terms of biological layers present. The non-invasive RF measurement of blood glucose relies on the detection of the change in the permittivity of the blood using a resonator as a sensor. However, the change in the permittivity of blood due to the variation in glucose content has a limited range resulting in a very small shift in the sensor's frequency response. Any inconsistency between measurements may hinder the measurement results. These inconsistencies mostly arise from the varied thickness of the biological layers and variation of fingerprints that are unique to every human. Therefore, the effects of biological layers and fingerprints in fingertips were studied in detail and are reported in this paper.
Design and study of a small implantable antenna design for blood glucose monitoring
2018
In this paper, a miniaturized implantable antenna with the dimensions of 8×8×1 mm3 has been studied for continuous monitoring of Blood Glucose Levels (BGL). The antenna performance is analyzed numerically for both the free space and implanted operation. The results show that the works excellently in both the scenarios. The antenna has the lowest resonant frequency of 3.58 GHz in free space with a gain 1.18 GHz while it operates at 2.58 GHz with a gain of 4.18 dBi. Good performance, small size and resilience to the human body effects make the antenna to have a good potential use in future implantable glucose monitoring devices.