Glucose Concentration In Solution Research Articles

Analysis of broadband linear polarization-converting meta-materials and their sensing and detection functions

In this paper, we present a broadband perfect-reflective linear polarization-converting metamaterial, which achieves perfect-reflective linear polarization conversion over a broadband frequency range of 28.15 GHz–60.80 GHz, and the narrow-band perfect-polarization-converting peaks appearing at the high frequency of 67.121 GHz can be used for microwave solution concentration detection. The design consists of a surface metal resonator structure, a Roggers 5880 dielectric layer and a copper metal backing. The surface metal resonator is a combination of a circular open ring, a square open ring, and a centrally located cross-metal cross ring nested in a modified, highly anisotropic structure. The perfect polarization transition peak at the high frequency band can be used for the solution detection function, which can detect the concentration of salt solution, glucose solution, and alcohol solution. When the refractive index of the solution sample to be tested changes gradually from 1.0 to 1.4, the polarization conversion peak shows obvious frequency shift, and the peak polarization conversion rate is always kept above 99%. The polarization principle was analyzed using surface electromagnetic field distribution and related theories, and the sample structure was processed and tested. The designed super-surface polarization conversion structure has potential applications in the field of microwave detection and microwave communication.

Cavity-Length Spectrum Sensing (CLSS) based on multi fiber Fabry-Pérot(F-P) cavities for refractive index monitoring

A Cavity-Length Spectrum Sensing (CLSS) based on multi fiber Fabry-Pérot(F-P) cavities is proposed for detecting refractive index. Traditional wavelength spectrum sensing (WSS) achieves refractive index monitoring by demodulating the wavelength shifting with changing of refractive index under fixed F-P cavity with a certain length. Fixing the wavelength as a reference, changing the refractive index and observing the intensity of wavelength, the curve shifting with length of the cavity, Length as the independent variable is called CLSS. Eight F-P cavities were fabricated and used to reconstruct the cavity-length spectrum. CLSS only need a single-frequency laser and photodetector, and avoid some expensive equipments, such as spectrometers and broadband lasers. On the other hand, compared to optical intensity sensing, CLSS remains immune to laser power fluctuations and allows for software-adjustable sensitivity, utilizing the sampling vernier effect. By demodulating the shifting of the interference dips, the refractive index of glucose solutions of different concentrations can be monitored. Experimental results show that when λ= 1550.00 nm, the sensitivity can reach −75.9778μm/RIU near a glucose solution with a refractive index of 1.341. In addition, the sampling vernier effect was utilized, and the sensitivity can be increased −2089.9705μm/RIU by changing the sampling interval. CLSS has low system cost, excellent stability and adjustable sensitivity, which has great potential applications in biomedical analysis, drug discovery, chemical production, etc.

Detection and intelligent optimization of blood glucose signals based on MXene-assisted sensors

Two-dimensional materials exhibit unique properties that make them ideal for electronic sensing applications, particularly in the field of biosensors. In this study, a Ti3C2Tx MXene/graphene composite was investigated for its potential use in non-invasive blood glucose detection. The strong electrostatic interaction between MXene and graphene nanosheets effectively reduces the self-stacking of both components, resulting in the formation of a porous interlayer structure with enlarged interlayer spacing. This unique structure creates an efficient nanoscale transport channel, which increases the number of active sites and shortens ion diffusion paths. Consequently, the electrochemical properties of the composite membrane are enhanced, making it a promising candidate for sensing element applications. As the human blood glucose level is primarily determined by the glucose concentration in the blood, the concentration of glucose solution serves as the foundation for noninvasive blood glucose concentration detection. In this work, a prediction model was established using the partial least squares fitting method to correlate the electrochemical fingerprinting data with the glucose aqueous solution concentration, and the reliability of the model was verified. To address the limitations of the partial least squares method, which lacks nonlinear fitting capabilities, an RBF (radial basis function) network model was employed. Finally, a genetic algorithm was utilized to perform global optimization of the training parameters of the RBF network, and the quantitative relationship between the NIR spectral data and glucose concentration was validated. The findings of this study provide a theoretical basis for the development of equipment and the improvement of measurement accuracy in the field of human noninvasive glucose detection.

Glucose derived carbon encapsulated boron nitride core-shell composites for efficient electromagnetic microwave absorption

Hexagonal boron nitride (h-BN) has the advantages of outstanding insulation, high thermal conductivity and excellent chemical stability, which promote the wide application of h-BN in thermal interface electronic packaging and other related fields. However, due to the poor dielectric loss ability of h-BN, which leads to its weak absorption capacity of electromagnetic waves (EMW), so it limits its practical application in related advantageous fields. In this paper, glucose-derived carbon-encapsulated BN core-shell composites (C@BN) were prepared by a simple hydrothermal reaction followed by high-temperature pyrolysis. The dielectric loss capacity of the C@BN was investigated by manipulating the concentration of glucose solution and pyrolysis temperature. Specifically, by adjusting the glucose derived carbon defect to induce polarization loss and impedance matching performance, so that more EMW entering the interior of the composite is absorbed and dissipated. The results show that C@BN obtained at 800 °C shows the best EMW absorption performance when the concentration of glucose solution is 3.6 wt%. The minimum reflection loss value (RLmin) is −43.5 dB and the maximum width effective absorption bandwidth (EABmax) of 6.72 GHz. Therefore, this study provides a reliable reference for the preparation of h-BN based EMW absorbing materials.

Facile preparation of superhydrophobic PVDF/MWCNTs distillation membranes: Synthesis, characteristics and separation performance

In recent years, membrane distillation (MD) has emerged as an effective solution to mitigate the high energy consumption associated with conventional fermentable sugar concentration processes. However, the inherent low mechanical strength of traditional organic membrane surfaces can result in issues related to membrane wetting during long-term MD experiments. In this work, superhydrophobic PVDF/MWCNTs (multi-walled carbon nanotubes) distillation membranes with high mechanical strength were prepared by a combination of templating and co-blending techniques. The process involved peeling the semi-gelation membrane from a sandpaper template, subsequently forming a high aspect ratio microstructure on the membrane surface via tearing and pulling. Additionally, the incorporation of MWCNTs further bolstered the mechanical strength of the membrane. At a peeling time of 90 s and a MWCNTs content of 0.08 wt%, the distillation membrane exhibited an impressive water contact angle of 153.2°, indicating it possess exceptional hydrophobicity while maintaining high mechanical strength. The separation performance of the prepared distillation membranes has been inspected by conducting both experimental analyses and computational fluid dynamics (CFD) modeling of the entire MD process. An appropriate elevation in both feed flow rate and temperature could effectively mitigate the problem of temperature and concentration polarization on the membrane surface. PVDF/MWCNTs distillation membrane demonstrated a modest reduction in permeate flux of about 11.69 % and a stable rejection rate exceeding 99.95 % throughout a 100-hour operational period, and it required only 15 h to concentration of aqueous glucose solution to 100 g/L, significantly enhancing the efficiency of the process. This study also employed a combination of experiments and simulations to optimizes the process conditions guiding the vacuum membrane distillation (VMD) process and could provide guidance for the future application of membrane distillation in the concentration of sugar solutions.

A Multilayered GaAs IPD Resonator with Five Airbridges for Sensor System Application.

This work proposes a microwave resonator built from gallium arsenide using integrated passive device (IPD) technology. It consists of a three-layered interlaced spiral structure with airbridges and inner interdigital structures. For integrated systems, IPD technology demonstrated outstanding performance, robustness, and a tiny size at a low cost. The airbridges were made more compact, with overall dimensions of 1590 × 800 µm2 (0.038 × 0.019 λg2). The designed microwave resonator operated at 1.99 GHz with a return loss of 39 dB, an insertion loss of 0.07 dB, and a quality factor of 1.15. Additionally, an experiment was conducted on the properties of the airbridge and how they affected resistance, inductance, and S-parameters in the construction of the resonator. To investigate the impact of airbridges on the structure, E- and H-field distributions of the resonator were simulated. Furthermore, its use in sensing applications was explored. Various concentrations of glucose solutions were used in the experiment. The proposed device featured a minimum detectable concentration of 0.2 mg/mL; high sensitivity, namely, 14.58 MHz/mg·mL-1, with a linear response; and a short response time. Thus, this work proposes a structure that exhibits potential in integrated systems and real-time sensing systems with high sensitivity.

Coupling-Based Multiple Bound States in the Continuum and Grating-Assisted Permittivity Retrieval in the Terahertz Metasurface.

The terahertz (THz) metasurfaces that support bound states in the continuum (BICs) provide a promising platform for various applications due to their high Q-factor resonance. In this study, we experimentally demonstrate multiple BICs with different resonance symmetries in the THz metasurface based on mode coupling. The proposed metasurface is composed of 2 × 2 split ring resonators (SRRs) metamolecules. The SRRs of two different gap angles in the metamolecule lattice provide intrinsic resonance with different frequencies, and the coupling between them exhibits high transmission quasi-BIC resonance, which can be tuned by varying the gap angle. The arrangement of SRRs in the 2 × 2 metamolecule lattice determines the types of coupling that govern the resonance symmetry of quasi-BIC. More interestingly, the multiple quasi-BICs enabled by different couplings can be simultaneously achieved in a metasurface. Apart from tuning the gap angles, the permittivity in the vicinity of SRRs also changes the resonance frequency. Consequently, quasi-BIC can be artificially formed by deliberately constructing the permittivity difference of the dielectric environment on the SRRs. In view of this, we introduce the scheme of permittivity retrieval for the dispersive analyte, assisted by the fixed-permittivity gratings. In addition, we experimentally demonstrate the metasurface in combination with the microfluidic chip for the sensing of the glucose solution concentration. Our findings offer a possible strategy for the existing manufactured metasurface to achieve quasi-BIC resonance and provide a promising candidate for approaching the spectral analysis of the biochemical.

Microstructure, mechanical and tribological properties of APC/Al laminated composites prepared by hydrothermal carbon adsorption on plates

Amorphous carbon (APC)/Al laminated composites were prepared by hydrothermal carbon adsorption on plates (HTCAP) and vacuum hot-press sintering process. The effect of the glucose solution concentration on the microstructure, mechanical properties and tribological properties was investigated. The results indicate that APC is uniformly distributed between layers and has good interfacial bonding with the matrix through the diffusion of Al. As the glucose solution concentration increases, the interlayer hardness, ultimate tensile strength and elongation first increase and then decrease, while the wear rate shows the opposite trend and the coefficient of friction (COF) gradually decreases. A maximum elongation of 16.4% and a minimum wear rate of 0.344×10−5 mm3/(N·m) are achieved at a glucose solution concentration of 0.3 mol/L. Adhesive wear is the dominant wear mechanism of APC/Al laminated composites. The improvement in wear resistance is attributed to the formation of uniform APC lubrication film on the wear surface.

Portable glucose sensing analysis based on laser-induced graphene composite electrode.

In this work, a portable electrochemical glucose sensor was studied based on a laser-induced graphene (LIG) composite electrode. A flexible graphene electrode was prepared using LIG technology. Poly(3,4-ethylene dioxythiophene) (PEDOT) and gold nanoparticles (Au NPs) were deposited on the electrode surface by potentiostatic deposition to obtain a composite electrode with good conductivity and stability. Glucose oxidase (GOx) was then immobilized using glutaraldehyde (GA) to create an LIG/PEDOT/Au/GOx micro-sensing interface. The concentration of glucose solution is directly related to the current value by chronoamperometry. Results show that the sensor based on the LIG/PEDOT/Au/GOx flexible electrode can detect glucose solutions within a concentration range of 0.5 × 10-5 to 2.5 × 10-3 mol L-1. The modified LIG electrode provides the resulting glucose sensor with an excellent sensitivity of 341.67 μA mM-1 cm-2 and an ultra-low limit of detection (S/N = 3) of 0.2 × 10-5 mol L-1. The prepared sensor exhibits high sensitivity, stability, and selectivity, making it suitable for analyzing biological fluid samples. The composite electrode is user-friendly, and can be built into a portable biosensor device through smartphone detection. Thus, the developed sensor has the potential to be applied in point-of-care platforms such as environmental monitoring, public health, and food safety.

Analysis of the Heat Treatment Effect of CsPbBr<sub>3</sub> Photoanode on the Photoelectrochemical Performance: Preliminary Results

The perovskite CsPbBr3 possesses good photoelectrochemical properties, making it a potential candidate for use as a photoanode. The commonly used photoanode is the FTO/TiO2/CsPbBr3 photoanode in water splitting applications. However, there has been no research conducted on the FTO/TiO2/CsPbBr3 photoanode for the oxidation of glucose derived from abundant biomass sources. This study aims to analyze the influence of heat treatment and glucose concentration on the performance of glucose oxidation, as well as the efficiency of glucose conversion and electricity production. First, CsPbBr3 solution is prepared under vacuum conditions using the Ligand Assisted Reprecipitation (LARP) method. Subsequently, the fabrication process of the FTO/TiO2/CsPbBr3 photoanode is carried out with variations including no heat treatment, heat treatment at a temperature of 110°C, and variations in glucose solution concentrations of 0.2 M and 0.5 M. XRD and SEM tests are conducted to determine the formed phases and morphology of CsPbBr3. The XRD and SEM results confirm the presence of CsPbBr3 phase and the formation of CsPb2Br5 phase due to the heat treatment process. The EIS testing reveals that the heat treatment process induces an oxidation process in the CsPbBr3 perovskite, which can decrease the glucose oxidation performance of the FTO/TiO2/CsPbBr3 photoanode. Based on HPLC analysis, the highest conversion efficiency of glucose is 97.37%, respectively under 110 oC heat treatment and with 0.5 M glucose.

An enzymatic glucose biosensor using the BESOI MOSFET

A reconfigurable transistor glucose biosensor was fabricated using the BESOI MOSFET structure. Glucose oxidase enzyme was immobilized on the sensitive regions of the device to specifically detect glucose. The experimental measurements showed a positive linear relationship between the sensitivity and the glucose solution concentration, in the measured range (0–200 mM). The maximum value of 0.52 was obtained for programming gate voltage VGB = 15 V. Next, numerical simulations based on the previous experimental results enabled the study of the channel thickness influence on the sensitivity. An optimal channel thickness value of 10 nm was obtained, in which the generated charges due to the glucose oxidation reaction most impact the drain current level of this device.

Temperature compensation measurements in the detection of glucose and sodium chloride solution concentration based on SPR in the optical fiber

The temperature variation is one of the main error factors in the process of glucose and sodium chloride solution concentrations detection based on optical fiber sensor. In this paper, we proposed a sensor with temperature compensation, which can detect the temperature while measuring the concentrations of glucose or sodium chloride solution. The dual-channel design enables the sensor to obtain accurate measurement results of glucose and sodium chloride concentrations, and also to monitor the environmental temperature simultaneously. The deposition of zinc oxide film not only enhances the sensitivity of the sensor but also prevents oxidation of the silver film. The high stability of polydimethylsiloxane (PDMS) ensures that the two sensing channels of the sensor do not interfere with each other. The proposed dual-channel sensor offers advantages of low cost, a simple structure, and high sensitivity, with potential applications in the fields of food science and biochemistry.

Minimal microfluidic metamaterial sensor for concentration detection

The design of high sensitivity and minimal size sensors for liquid concentration detection has significant importance in biomedical and chemical engineering. In this paper, we present a microfluidic liquid sensor for concentration detection based on metamaterial, with a minimal size of 20 × 16 mm2. The sensor consists of a modified square split-ring resonator (SRR) and a microstrip transmission line (MTL), integrated with a microfluidic device. The operating frequency of the sensor is 4.38 GHz. Experimental results demonstrate that the resonant frequency of the water–ethanol mixture with concentrations ranging from 0 to 100 % has a linear shift of 290 MHz. A mathematical model is established by examining the relationship between the transmission parameters and the complex dielectric constant, the maximum deviation between the ethanol solution concentration predicted by this model and the actual concentration is 0.5 %. The sensor exhibits a sensitivity of 2.14 × 10^-3 dB/(mg/dL) to aqueous glucose solutions with 0–––400 mg/dL. A fitting formula is derived from the transmission parameters to predict unknown concentrations of aqueous glucose solutions, could detect the change of 1 mg/dL glucose solution accurately with a maximum error of 0.7 %.

High birefringence photonic crystal fiber for glucose sensing

This paper focuses on designing a simple photonic crystal fiber (PCF) biosensor. The proposed glucose sensor is modelled by Lumerical software using the finite element method. To evaluate the efficiency of this model, different sensing properties such as birefringence, coupling length, and relative sensitivity are calculated at different air-filling fractions. The principle of this PCF is to detect the variations in the refractive index of the different concentration glucose solutions. The analyte will be injected into an elliptical channel surrounded by two rings of air holes in a hexagonal shape. Numerical simulations show that increasing the air-filling fraction yields high performance and more light confinement. At the air-filling fraction of 0.45, the maximum birefringence and relative sensitivity were 4.01 × 10−3 and 91%, respectively. Also, the coupling length reaches a minimum of 162.09 μm.

The effect of temperature on permittivity measurements of aqueous solutions of glucose for the development of non-invasive glucose sensors based on electromagnetic waves

This article presents for the first time an empirical study that shows the importance of considering temperature when analyzing the permittivity (dielectric constant) of aqueous glucose solutions of various concentrations. The permittivity is a parameter that is investigated by researchers as a biomarker for non-invasive measurement of glucose without drawing blood. The development of this technology will allow personalized healthcare diagnostics to monitor and prevent diabetes. Since human glucose levels in the blood vary in the range of a few milligrams per decilitre, estimating such small variations of glucose will require a highly accurate and repeatable sensing technology. Electromagnetic (EM) waves, specifically in the microwave and terahertz frequency ranges, have shown promise in detecting changes in the electrical properties of blood plasma as they relate to glucose concentration. However, it's important to note that while this technology shows promise, it is still in the research and development phase. It is shown here that the body temperature can affect the accuracy of the blood glucose measurements. Experiments were conducted with different glucose concentration solutions under various temperatures and the complex permittivity of the glucose was studied across a wide frequency range from 400 MHz to 11 GHz. The rise in thermal energy normally causes dipolar liquids like water to vibrate and rotate disrupting the alignment of the dipoles in response to an electric field thereby reducing its permittivity. Empirical results however show that for aqueous solution of glucose the permittivity increases with rise in temperature from 16 °C to 37 °C. This is attributed to the polar nature of the water and glucose molecules that becomes more pronounced with increased thermal energy. Based on the experimental results an accurate analytical expression is derived that considers the temperature of the aqueous glucose solution. The accuracy of the analytical expression is shown experimentally to be above 99%. The findings from the study should enable the design of accurate non-invasive glucose monitoring devices based on electromagnetic sensing techniques.

Monolithic integrated MQW-based optoelectronic glucose sensor.

This study presents the development process of a multi-quantum well (MQW)-based optoelectronic integrated device designed for precise glucose concentration measurements. The proposed monolithic device consists of two identical diodes containing InGaN/GaN MQWs, serving as a light emitter (LED) and a photodetector (PD), respectively. The chip is meticulously packaged with polydimethylsiloxane (PDMS) to facilitate exposure to the glucose solution. By monitoring changes in the photocurrent of the PD that detects scattered light of the LED propagating through the sapphire substrate, the chip can accurately reflect alterations in the glucose solution's concentration. The device's uniqueness lies in its ability to achieve this precision without the need for external optical components. The device exhibits a fast response, operating at a sub-second level, and can gauge glucose solutions with concentrations ranging from 5% to 40%. The fabricated optical sensing device showcases appealing characteristics, including compactness, stability, repeatability, and rapid response, making it highly suitable for glucose concentration measurement applications.

High linearity temperature-compensated SPR fiber sensor for the detection of glucose solution concentrations

In the realm of optical fiber sensing, conventional surface plasmon resonance (SPR) sensors often face challenges due to their low linearity, broad resonance, and susceptibility to external temperature changes. To that end, we evaluate a groundbreaking approach with a temperature-compensating SPR biosensor based on the Mach-Zehnder interferometer (MZI), featuring a novel tapered multimode fiber-single mode fiber-multimode fiber (MMF-SMF-MMF) architecture. Specifically, the SPR is excited on a silver film modified by reduced graphene oxide (rGO) and π-π stacked pyrene-1-boric acid providing specific glucose binding ability. The MZI effect compensating for ambient temperature influence on the SPR is realized with the MMF-SMF-MMF structure. The study also explores the use of Fast Fourier Transform (FFT) for separate, granular analysis of the MZI and SPR signals and improves the linearity of the sensor using a novel centroid-fitting technique. This method utilizes the shift of calculated centroid coordinates rather than the single dip resonance wavelength from SPR, enhancing the overall performance of the sensor. The experimental results demonstrate excellent glucose sensitivity of 2.819 nm/mM, a linear range of 0–10 mmol/L, a LOD of 0.12 mM/L and concurrent temperature compensation. Compact and easy to fabricate, the proposed SPR sensor provides a novel solution for accurate glucose concentration detection in human blood.

Theoretical study of a Janus layered photonic structures based on improved particle swarm algorithm for detection of serum creatinine and glucose concentration

An improved particle swarm optimization (IPSO) algorithm is proposed to perform parameter optimization of the sensor which is realized by Janus layered photonic structures (LPS) based on the optical Tamm state (OTS) and defect layer, which can be used to detect serum creatinine (SCR) solution concentration (CSCR ) and glucose solution concentration (CG ) by adjusting the thickness and refractive index (RI) of the medium in the structure to control the peak and frequency changes of the transmission and absorption peaks. Due to the characteristic of Janus, the light incident from different directions can produce different effects. The OTS based on metal properties has sensitive and narrow absorption peaks when the light comes in forward propagation, its absorption characteristics allowing accurate measurement of CSCR with a high sensitivity (S) of 172 THz/RIU and a relevant quality factor (Q) of 651 and a lower detection limit (DL) of 2.3163 × 10−4. It has a significant Q of 4.5 × 104, DL of 4.825 × 10−5, and S of 11.7857 THz/RIU with its transmission characteristics which can be used to detect CG when the light comes in backward propagation. It can be said that the IPSO has a certain application prospect for the design of optical sensing.

High-throughput synthesis of size-controlled Pt-based catalysts

Pt catalysts are commonly used for chemical reaction processes due to its high catalytic activity and selectivity. Notably, the size of metal particles often has a significant impact on the performance of the metal-loaded catalysts. Therefore, developing highly efficiently synthesis method for the size control of Pt catalysts has great development prospects and research value. In this study, high-throughput size tuning of Pt-based catalysts was achieved by carbonizing the carriers. The experimental and characterization results showed that the size of the loaded Pt nanoparticles varied with different concentrations of glucose solution during carriers carbonization process. The reduction of 4-nitrophenol as a template reaction indicated that the reaction rate constant of the catalyst is approximately linear with the size of Pt particles. Importantly, a laboratory-built high-throughput synthesis system was applied for the catalyst synthesis, which enhances the automation of the laboratory exploratory experiments and makes it possible to synthesize catalysts with controllable size in batches.

Homemade low-cost fabrication technique andstability analysis of a U-shaped fiber sensorstructure.

In this work, the fabrication method of a U-shaped optical fiber (UOF) structure using single-mode fiber is proposed. Few UOF sensors have been developed to date, but the fabrication process has not been described in detail. Here, its subsequent homemade fabrication, optimization strategies, and analysis are thoroughly explored. Further, the influence of transmission on U-shaped diameter is explored. The transmitted intensity is mainly used to assess the strength of the evanescent field. For this purpose, three different diameters of 2mm, 4mm, and 6mm UOFs are fabricated. The results show that the transmission of the U-shaped structure is dependent on the diameter of the UOF. Thereafter, different concentrations of glucose solutions are detected using the optimized stable UOF structure to showcase the sensing properties. Overall, this work is essential for beginners who want to conduct research on optical fiber sensors with a curved shape.