Planar Sensor Research Articles

Massive enhancement in sensitivity of mixed potential sensors towards methane and natural gas through magnesia stabilized zirconia low ionic conductivity substrate

Monitoring of methane leaks from natural gas (NG) sources during production and transport is vital to combating the threat of greenhouse gases to the global climate. An additive manufacturing route was developed for the printing of a CTE matched, low reactivity and low ionic conductivity magnesia stabilized zirconia (MSZ) substrate for production of a four-electrode (indium tin oxide, lanthanum strontium chromite, and Au sensing electrodes measured against a Pt negative electrode) same-side planar mixed potential electrochemical sensor (MPES) with porous 3 mol% YSZ as electrolyte. The MSZ substrate based MPES achieves a 40 ppm limit of detection for methane in a simulated natural gas mix. Additionally, a 20 times enhanced response in the ITO vs. Pt signal over sensors using yttria-stabilized zirconia (YSZ) substrates at 100 ppm CH4 in simulated natural gas is observed. This research illustrates the importance of a CTE matched, low reactivity, low conductivity substrate for optimal performance of same-side planar MPES devices for NG leak detection while allowing for application of high temperature co-fired ceramic technologies.

Application of variable spacing planar capacitance sensor in inhomogeneous media detection

In order to detect different non-uniform media, this thesis proposes a variable spacing type planar capacitance sensor, design the sensor hardware circuit system and PCB, experimental results show that the proposed planar capacitance sensor can realize the detection of different non-uniform media, non-uniform media detection provides a new method.

Parallel array of planar Hall effect sensors for high resolution magnetometry

We introduce a planar Hall effect magnetometer in the form of a parallel array of permalloy-based elliptical sensors. The number of ellipses in the array and other fabrication parameters are optimized with the support of numerical simulations. We obtain equivalent magnetic noise (EMN) of 16 pT/Hz at 100 Hz, 25 pT/Hz at 10 Hz, 98 pT/Hz at 1 Hz, and 470 pT/Hz at 0.1 Hz. The exceptional EMN without the use of magnetic flux concentrators highlights the advantages of the design. The presented magnetometer, characterized by its simplicity, affordability, and ability to operate at room temperature, is anticipated to be useful for applications requiring pT resolution.

Sensing High 17β-Estradiol Concentrations Using a Planar Microwave Sensor Integrated with a Microfluidic Channel.

The global issue of pollution caused by endocrine-disrupting chemicals (EDCs) has been gaining increasing attention. Among the EDCs of environmental concern, 17β-estradiol (E2) can produce the strongest estrogenic effects when it enters the organism exogenously through various routes and has the potential to cause harm, including malfunctions of the endocrine system and development of growth and reproductive disorders in humans and animals. Additionally, in humans, supraphysiological levels of E2 have been associated with a range of E2-dependent disorders and cancers. To ensure environmental safety and prevent potential risks of E2 to human and animal health, it is crucial to develop rapid, sensitive, low cost and simple approaches for detecting E2 contamination in the environment. A planar microwave sensor for E2 sensing is presented based on the integration of a microstrip transmission line (TL) loaded with a Peano fractal geometry with a narrow slot complementary split-ring resonator (PF-NSCSRR) and a microfluidic channel. The proposed technique offers a wide linear range for detecting E2, ranging from 0.001 to 10 mM, and can achieve high sensitivity with small sample volumes and simple operation methods. The proposed microwave sensor was validated through simulations and empirical measurements within a frequency range of 0.5-3.5 GHz. The E2 solution was delivered to the sensitive area of the sensor device via a microfluidic polydimethylsiloxane (PDMS) channel with an area of 2.7 mm2 and sample value of 1.37 µL and measured by a proposed sensor. The injection of E2 into the channel resulted in changes in the transmission coefficient (S21) and resonance frequency (Fr), which can be used as an indicator of E2 levels in solution. The maximum quality factor of 114.89 and the maximum sensitivity based on S21 and Fr at a concentration of 0.01 mM were 1746.98 dB/mM and 40 GHz/mM, respectively. Upon comparing the proposed sensor with the original Peano fractal geometry with complementary split-ring (PF-CSRR) sensors without a narrow slot, several parameters were evaluated, including sensitivity, quality factor, operating frequency, active area, and sample volume. The results showed that the proposed sensor exhibited an increased sensitivity of 6.08% and had a 40.72% higher quality factor, while the operating frequency, active area, and sample volume showed decreases of 1.71%, 25%, and 28.27%, respectively. The materials under tests (MUTs) were analyzed and categorized into groups using principal component analysis (PCA) with a K-mean clustering algorithm. The proposed E2 sensor has a compact size and simple structure that can be easily fabricated with low-cost materials. With the small sample volume requirement, fast measurement with a wide dynamic range, and a simple protocol, this proposed sensor can also be applied to measure high E2 levels in environmental, human, and animal samples.

Evaluation of HPK [formula omitted] planar pixel sensors for the CMS Phase-2 upgrade

To cope with the challenging environment of the planned high luminosity upgrade of the Large Hadron Collider (HL-LHC), scheduled to start operation in 2029, CMS will replace its entire tracking system. The requirements for the tracker are largely determined by the long operation time of 10 years with an instantaneous peak luminosity of up to 7.5 × 1034cm−2s−1 in the ultimate performance scenario. Depending on the radial distance from the interaction point, the silicon sensors will receive a particle fluence corresponding to a non-ionising energy loss of up to Φeq= 3.5 × 1016cm−2. This paper focuses on planar pixel sensor design and qualification up to a fluence of Φeq = 1.4 × 1016cm−2.For the development of appropriate planar pixel sensors an R&D program was initiated, which includes n+-p sensors on 150mm (6”) wafers with an active thickness of 150µm with pixel sizes of 100×25 µm2 and 50×50 µm2 manufactured by Hamamatsu Photonics K.K. (HPK). Single chip modules with ROC4Sens and RD53A readout chips were made. Irradiation with protons and neutrons, as well was an extensive test beam campaign at DESY were carried out. This paper presents the investigation of various assemblies mainly with ROC4Sens readout chips. It demonstrates that multiple designs fulfil the requirements in terms of breakdown voltage, leakage current and efficiency. The single point resolution for 50×50 µm2 pixels is measured as 4.0µm for non-irradiated samples, and 6.3µm after irradiation to Φeq = 7.2 × 1015cm−2.

A planar microwave sensor for noninvasive detection of glucose concentration using regression analysis

AbstractThis paper presents a planar microwave sensor for the noninvasive detection of glucose concentration in diabetic patients. The designed sensor operates from the 3.8 to 6.2 GHz frequency band, which covers the 5.8 GHz Industrial Scientific and Medical (ISM) band. The designed sensor shows a percentage bandwidth of 23.8% with a reflection coefficient (S11) of −50 dB at the resonance frequency of 5.7 GHz. The detection was carried out by varying the relative permittivity of the blood in accordance with the glucose concentration based on the Cole–Cole model. The measured result is calculated in terms of varying resonance frequency with variation in the reflection coefficient |S11| of the designed sensor. The observed frequency shift and corresponding sensitivity of the sensor are found at 1.7 GHz and 0.089 MHz/mg dL−1, respectively. An experimental validation has also been performed, and the frequency shift is analyzed by interacting the human thumb with the sensor. The simulated and experimental results of the designed sensor suggest that it can be useful for detecting glucose concentration noninvasively for diabetic patients.

Role of polyaniline/molybdenum trioxide nanocomposites in tuning the characteristics of humidity sensors

AbstractReal time humidity monitoring is crucial in several fields such as pharmaceuticals, electronic device manufacturing, in agricultural irrigation system due to drastic changing climates and so forth. In this work, we studied humidity sensing behavior of molybdenum trioxide (MoO3) in composition with conductive polyaniline (PAni). The conductive PAni used in the present study was in the emeraldine salt (ES) form and was doped with amino tris‐methylene phosphonic acid (PAni‐ATMPA) as a potential candidate for humidity sensors. PAni‐ATMPA is synthesized by oxidative polymerization of aniline monomers and ATMPA in the ratio of 1:1. Thus synthesized PAni and hydrothermally synthesized MoO3 were mixed together to form nanocomposites. The synthesized composites were then used to fabricate planar sensors on alumina substrate with pre‐deposited silver electrodes. XRD analysis of synthesized MoO3 shows an orthorhombic crystal structure whereas synthesized PAni shows amorphous nature. FESEM analysis of synthesized MoO3 shows sheet‐type morphology. Different compositions of MoO3:PAni were prepared by varying MoO3 and PAni wt%. The fabricated sensors were then tested over the range of 20%–90% RH and concluded that the sensitivity of the composite is seen to be higher for the composite with 20% PANi and 80% MoO3 with response time, recovery time and the linearity 7 s, 4 s, 13–62 RH% respectively. The above mentioned parameters are found to be improved in the composites as a result of PAni addition to MoO3 than the pristine MoO3. The experimental knowledge demonstrates that the films showed good repeatability (with and reproducibility (with uncertainty). Altogether, these results indicate that it is possible to tune the humidity sensing characteristics by optimizing the amount of MoO3 and PAni in MoO3:PAni composite.

Design of slot radiating RF planar sensor for homogeneity check of dielectric discontinuity

AbstractIn this paper, a 2.8‐GHz RF planar sensor with radiating slots is proposed for effective checking of discontinuity in homogeneous dielectric samples. The slots etched in the ground plane reduce the effective area for sample placement, which increases in the case of a conventional ring at the desired frequency. Several forms of discontinuity are analyzed and measured with the help of varying geometrical configurations of Teflon, wood, and polyethylene samples with varying permittivity. It is observed that due to the uniform distribution of fields among all the radiating slots any sort of configurational discontinuity is detected by the sensor in terms of the shift in resonant frequency and S21 transmission notch. The simulations are carried out using CST‐MWS and the equivalent model is developed using ADS. The numerical analysis is carried out using Origin software and the measurement is carried out using Taconic TLY‐5 substrate by photolithographic etching.

Improving self-supported nanowire arrays using response surface methodology for the synthesis of a H2O2 nanostructured sensor

In this paper, we introduce a data-driven approach for optimizing the design of highly sensitive hydrogen peroxide (H2O2) sensors based on self-supported nickel nanowire (Ni NW) arrays using response surface methodology (RSM). Our goal is to enhance the performance of the sensor by customizing the length of Ni NW while optimizing the working conditions, including the H2O2 concentration and applied potential. Focusing solely on the commercially available porous membranes, we successfully employ RSM to identify the optimal conditions for the sensor: a NW length of 2.64 μm, an optimal concentration of 3.25 mM H2O2, and a detection potential of 0.02 V. We fabricate a sensor with the optimal NW length and validate its performance through comparison to sensors with different NW lengths, such as a planar Ni sensor and a previously investigated nanostructured sensor. Our optimized sensor achieves a 50% reduction in the limit of detection (LOD) and an 18% increase in sensitivity compared with the previously investigated nanostructured sensor. Moreover, the optimized sensor is at least 35 times more sensitive for H2O2 detection than sensors with planar geometries, which are standard in commercial applications. Our results highlight the potential of RSM as a powerful, cost-effective, and theoretically agnostic tool for optimizing nanostructured sensors and accelerating the design-build-test cycle. The optimized H2O2 sensor can be applied in various fields, including the food industry, medical diagnostics, and environmental monitoring. This sensor can significantly enhance glucose detection in non-invasive samples such as tears and saliva when combined with immobilized glucose oxidase enzymes, which is crucial for continuous glucose monitoring in diabetes mellitus patients. The methodology presented in this study allows further extensions to investigate other design variables and sensing materials as well as optimize sensors for detecting different substances, fostering advancements in sensor technologies.

Development of Integrated Thermoelectric Sensors for Power Components

Power components such as High Electron Mobility Transistors (HEMTs) are used for high power and high frequency applications. These tend to overheat and destroy their packaging and connections to the wire bondings. This paper presents planar micro-thermoelectric sensors (μTESs) developed to measure partial heat flow dissipated by the HEMTs to avoid the HEMTs from reaching critical temperatures. These sensors use the same active materials as well as the same fabrication process as the HEMTs, enabling them to be fabricated simultaneously for a simple integration. The HEMTs’ active layers consist in AlGaN/GaN heterostructures resulting in the formation of a 2D Electron Gas (2DEG) at the interface. Tension factors of 47 mV/(K.mm2) were obtained with these sensors and heat flows of 0.2 W to 7 W were measured.

High performance of p-p heterojunction LaFeO3/YFeO3 planar electrode sensor for volatile organic compounds under multi-wavelength light illumination

The challenge encountered by the sensor in practical application is that the optimal working temperature is high, which will cause certain dangers in the work. Herein, we fabricated a p-p heterojunction composite LaFeO3/YFeO3 planar electrode sensor for gas detection. The planar electrode sensor adopts the method of direct heating, which reduces the optimal working temperature of the sensor compared with the traditional side-heated alumina ceramic tube sensor. The optimal operating temperature of the LaFeO3/YFeO3 (0.8:0.2) planar electrode sensor is 110 °C. In addition, we also performed multi-wavelength (470, 420, and 370 nm) light illumination experiments on the LaFeO3/YFeO3 sensor to improve gas response. Under 370 nm light illumination, the response values of the LaFeO3/YFeO3 (0.8:0.2) sensor to 30 ppm methanol, acetone, and ethanol were 166.82, 199.58, and 292.67, which were 1.19, 1.33, and 1.36 times than those in the dark. The lowest detection limits of the LaFeO3/YFeO3 (0.8:0.2) sensor under 370 nm light illumination for methanol, acetone, and ethanol were 0.3, 0.8, and 0.2 ppm, respectively. Therefore, the LaFeO3/YFeO3 (0.8:0.2) planar electrode sensor has the advantages of small size, low optimal operating temperature, low power consumption, high response value to volatile organic compounds gases, and high-cost performance for use in different gas environments.

Design and Analysis of Planar Waveguide-Based SPR Sensor for Formalin Detection Using Ag-Chloride-BP Structure.

Nowadays, Food additives and preservatives have become a hot topic especially formalin, which is a chemical substance used to preserve food. Chronic cancer is caused by swallowing the formalin-contaminated food on a regular basis. As a result, detection of the formalin in food ingredients is a critical need, and this requirement is becoming increasingly important in new terrains. Therefore, a new approach, planar waveguide-based surface plasmon resonance (SPR) sensor is presented in this paper employing silver-chloride materials-black phosphorus structure to detect the formalin. In this study, the optimization of metal thickness and optimal performance of chloride material are analyzed by observing the transmittance power and resonance shift for conventional and chloride-based sensors, respectively. Moreover, the performance parameters, such as sensitivity of 344°/RIU, quality-factor of 166.99RIU-1, detection-accuracy of 3.34 and figure-of-merit of 164.74, are observed for the proposed sensor. Furthermore, the performance comparative study is conducted and found that the proposed sensor highlighted the enhanced the SPR sensor and highlighted the performance of FOM. Finally, the electromagnetic filed distributions of the proposed WG-based SPR sensor are shown using the Opti-FDTD software.

High-Resolution Dielectric Characterization of Single Cells and Microparticles Using Integrated Microfluidic Microwave Sensors

Microwave sensors can probe intrinsic material properties of analytes in a microfluidic channel at physiologically relevant ion concentrations. While microwave sensors have been used to detect single cells and microparticles in earlier studies, the synergistic use and comparative analysis of microwave sensors with optical microscopy for material classification and size tracking applications have been scarcely investigated so far. Here we combined microwave and optical sensing to differentiate microscale objects based on their dielectric properties. We designed and fabricated two types of planar sensor: a Coplanar Waveguide Resonator (CPW) and a Split-Ring Resonator (SRR). Both sensors possessed sensing electrodes with a narrow gap to detect single cells passing through a microfluidic channel integrated on the same chip. We also show that standalone microwave sensors can track the relative changes in cellular size in real-time. In sensing single 20-micron diameter polystyrene particles, Signal-to-Noise ratio values of approximately 100 for CPW and 70 for SRR sensors were obtained. These findings demonstrate that microwave sensing technology can serve as a complementary technique for single-cell biophysical experiments and microscale pollutant screening.

Modified planar sensors for cefepime determination

Planar screen-printed potentiometric sensors sensitive to cefepime, cephalosporine antibiotic of the fourth generation, has been developed. Cefepime is an amphoteric antibiotic with carboxyl and aminothiazole groups which exists as a cation in a strongly acidic media, a zwitter-ion in a weakly acidic and neutral media, and as an anion in an alkaline media. The interval of pH = 1.5 - 2.0 is set for obtaining cationic electrode functions for the cefepime determination. Cefepime-tetraphenylborate associates are used as electrode-active components (EAC). The optimal EAC content for planar sensors is 2-3%. The electrode functions are linear in the range of 1 x 10 -5 - 1 x 10 -2 M, angular coefficients 50 ± 2 mV/pC, response time 20 sec for unmodified cefepime sensors. The role of the modifier, ZnO nanoparticles, in improving the electroanalytic properties of sensors is shown. The introduction of a binary mixture of zinc oxide and cetylpyridinium chloride into carbon-containing ink leads to a decrease in the detection limit of cefepime (1 x КГ6 M), an increase in the angular coefficient (58 ± 1 mV/pC) and the interval of linearity of electrode functions (1 x 10 -6 - 1 x 10 -2 mole/liter), sensor response time being 17 sec. The use of a surfactant as an electrode surface comodifier leads to stabilization of the nanoparticle dispersion. The use of modified screen-printed sensors for the cefepime determination in medicinal and biological media, in particular, in saliva, is shown.

Электроаналитические свойства немодифицированных и модифицированных полианилином планарных сенсоров, чувствительных к доксициклину

Doxycycline has a wide range of antimicrobial and anti-inflammatory properties and is used to treat various infectious diseases. Spectroscopic, chromatographic, electrochemical, immunoassay and other methods are used to determine tetracycline antibiotics in various objects. Planar sensors allow express detection of antibiotics in small sample volumes. Planar potentiometric sensors based on ion associations doxycycline – tetraphenylborate (Copt = 2–3%), modifier – polyaniline, for the quantitative determination of doxycycline have been developed. It has been found that for non-modificated sensors, the linearity intervals of electrode functions are 1×10 -4 – 5×10 -3 M, Cmin – 5,0×10-5 M, angular coefficients – 50±2 mV/pC, response time – 25 s. It is shown that the introduction of a modifier into the carbon-containing ink of sensors leads to the stabilization of their potential, to an increase in the angular coefficients of electrode functions (56±1), reduced response time (20 s) and reduced detection limit (4.0 ×10-5 M). It is shown that the introduction of the modifier into the carbon-containing ink of the sensors leads to stabilization of their potential, to an increase in the angular coefficients of electrode functions (56±1), a decrease in response time (20 seconds) and a decrease in the detection limit (4.0 ×10-5 M). Doxycycline sensitive sensors have selectivity to the base ion (Ki/j < < 1) and inorganic cations (Ki/j (K+) = 0.61; Ki/j (Na+) = 0,01; Ki/j (Mg 2+) = 0,01; Ki/j (Ca2+) = 0.09), and indicate the possibility of determining doxycycline in human biological fluids. Against the background of oral liquid, the angular coefficients of electrode functions (45±1 mV/pS) decrease, which is associated with the background influence of oral liquid. The developed planar sensors are used to determination doxycycline in medicinal and biological media.

A Dual Mode Nondestructive Evaluation Sensor With Simultaneous Inductive and Capacitive Outputs

Conventional electromagnetic Non-Destructive Evaluation (NDE) techniques are usually sensitive to either conductors or insulators. The emerging non-destructive assessment of "insulator-conductor" composite structures is thus faced with cost and efficiency problems due to this limitation. In this paper, a novel detection technique that combines inductive and capacitive methods is proposed for the inspection of "insulator-conductor" composite structures. A new structure of a planar inductive-capacitive dual-mode sensor in which the inductive and capacitive modes can be excited simultaneously with a single excitation signal without the need for mode switching is developed. The output signal of this sensor is analyzed in relation to the spatial electromagnetic field using equivalent circuit analysis and finite element (FE) simulation. A signal conditioning module for the proposed sensor is designed and a dual-mode test system that simultaneously detects signals from both modes is built. Experimental results from the test system show that the proposed detection method is sensitive to defects in both the insulating and conducting layers of the "insulator-conductor" composite structure and thus can detect corrosion under the insulation, surface cracks on the conductor and interface debonding with the detected signals able to reflect the size of the defects. The detection information of the two modes is complementary, proving that the method is able to comprehensively evaluate "insulator-conductor" composite structures.

Application of a Robust Thermoelectric Gas Sensor in Firewood Combustion Exhausts

The quality of wood combustion processes can be effectively improved by achieving the automated control of the combustion air feed. For this purpose, continuous flue gas analysis using in situ sensors is essential. Besides the successfully introduced monitoring of the combustion temperature and the residual oxygen concentration, in this study, in addition, a planar gas sensor is suggested that utilizes the thermoelectric principle to measure the exothermic heat generated by the oxidation of unburnt reducing exhaust gas components such as carbon monoxide (CO) and hydrocarbons (CxHy). The robust design made of high-temperature stable materials is tailored to the needs of flue gas analysis and offers numerous optimization options. Sensor signals are compared to flue gas analysis data from FTIR measurements during wood log batch firing. In general, impressive correlations between both data were found. Discrepancies occur during the cold start combustion phase. They can be attributed to changes in the ambient conditions around the sensor housing.

Development of a Low-Profile Planar Sensor for the Detection of Normal and Shear Forces

Individuals with balance and mobility problems might benefit by the use of devices that detect small changes in ground reaction forces and potentially be used to assist movement. For maximum effectiveness, such sensors must measure pressure in all three dimensions. Impact and shear plantar force are essential variables in inverse dynamics reconstructions of the human joint force. Various force sensors have been proposed to monitor plantar forces of the human foot. Most of them have a single-axis measurement, and few are intended for monitoring normal and shear stress. This article proposes a low-cost, biocompatible triaxial piezoresistive sensor developed using simple fabrication techniques and inexpensive machinery. The sensor can detect pressures from 0-800kPa with high response and recovery with minimum hysteresis and repeatable results of over than 100 cycles.

FDTD Simulations for Rhodium and Platinum Nanoparticles for UV Plasmonics.

The article describes the results of finite-difference time-domain (FDTD) mathematical modeling of electromagnetic fields distortion near the surfaces of two transition metals: rhodium (Rh) and platinum (Pt) on glass (SiO2) substrates. Results were compared with calculated optical properties of classical SERS generating metals (Au and Ag). We have performed FDTD-based theoretical calculations for UV SERS-active nanoparticles (NPs) and structures based on hemispheres of Rh and Pt and planar surfaces, consisting of single NPs with varied gaps between them. The results have been compared with gold stars, silver spheres and hexagons. The prospects of the theoretical approach for single NPs and planar surfaces modeling to evaluate optimal field amplification and light scattering parameters have been shown. The presented approach could be applied as a basis for performing the methods of controlled synthesis for LPSR tunable colloidal and planar metal-based biocompatible optical sensors for UV and deep-UV plasmonics. The difference between UV-plasmonic NPs and plasmonics in a visible range has been evaluated.

Experimental detection of chlorpyrifos by MoS2 coated planar polymer waveguide sensor utilizing common path interferometric principle

A common path Mach-Zehnder interferometer is fabricated using a planer polymer waveguide having MoS2 as an adlayer for chlorpyrifos detection. The dispersion characteristic and cutoff condition of proposed waveguide are obtained theoretically and hence the cutoff film thickness is optimized to get TE0 and TM0 propagating modes. Variations between the phase shift of propagating modes with the concentration of pure chlorpyrifos and its commercial sample are obtained. A good linear variation between phase shift and concentration of chlorpyrifos is obtained in our fabricated waveguide for all considered temperatures. The obtained maximum sensitivity, minimum limit of detection, and limit of quantification of chlorpyrifos are 5.66 degree/μM, 1.57 μM, and 5.24 μM respectively, at 45° C. The capability of the fabricated sensor to generate distinct response for a pure and commercial sample of chlorpyrifos at different concentration and temperature were confirmed by principal component analysis. Since the response of sensor is better for commercial samples at a lower temperature, therefore it is recommended that the concentration of chlorpyrifos in commercial samples should be measured at low temperatures.