Circuit Board Technology Research Articles

Innovative Method for Reliable Measurement of PEM Water Electrolyzer Component Resistances.

Understanding the sheet resistance of porous electrodes is essential for improving the performance of polymer electrolyte membrane (PEM) water electrolyzers and related technologies. Despite its importance, existing methods often fail to provide reliable and comprehensive data, especially for porous materials with complex morphologies and non-uniform thicknesses. This study introduces a robust and straightforward method for determining the sheet resistance of porous electrodes using a novel probe concept based on industrial printed circuit board (PCB) technology. This probe measures resistance across ten distances, ranging from 250 µm to 2500µm, enabling local mapping of resistance. The study focuses on the sheet resistance of key components in PEM water electrolyzers, including the gas diffusion layer (GDL), porous transport layer (PTL), and catalyst layers deposited on a membrane. Additionally, an image-processing-based method is presented to obtain the thickness distribution of the studied catalyst layers, facilitating a detailed analysis of the electrical in-plane resistivity with thickness variations. Overall, this methodology has the potential to expedite material integration and bridge the gap between electrode engineering and single-cell testing, thereby advancing the development of PEM water electrolyzers.

A Conformal Transmissive Metasurface with Dual‐Band Dual‐Circularly Polarized Conversion and Low Scattering

AbstractGenerally, the existing metasurfaces are periodically or non‐periodically planar micro‐structures, which hardly satisfy the practical applications such as stealth aircraft, carrier and so on. In order to meet the application, a conformal transmissive metasurface are proposed with multi‐function of converting linear polarization into dual‐circular polarization in dual‐band and low scattering for incidences. The metasurface composed of a non‐metallic dielectric material of polyvinyl chloride and the ultra‐thin conventional material to achieve a flexible configuration. The mechanism is illustrated by the characteristic parameters, electric field distributions, and equivalent circuit. The simulated results demonstrate that the metasurface can transform y‐polarized waves into right‐handed circularly polarized waves in 6.8–10.3 GHz and to left‐handed circularly polarized waves in 18.77–21.15 GHz, while vice versa for x‐polarized waves. Additionally, the conformal metasurface shows an excellent scattering section reduction in operational frequency and that above 10 dB can be realized as the frequency increases. A conformal metasurface sample is fabricated by the printed circuit board (PCB) and 3D printing technology, which is measured in a microwave anechoic chamber that conforms to the simulated results. The conformal transmission metasurface holds significant promise for applications in radomes and electromagnetic shielding.

Experimental study on crack detection performance of multilayer Koch differential pick-up planar fractal eddy current probe

The planar flexible Koch fractal eddy current probe exhibits high consistency in detecting short cracks in all orientations. However, it is limited by a weak signal caused by the small number of coil turns. This paper utilizes multilayer flexible circuit board technology to address the issue. The probe is designed with a mutual inductance coil structure and is arranged on a 10-layer flexible circuit board. This board includes one layer for the excitation coil and nine layers for the pick-up coil. The probe’s performance was studied through C-scan experiments, which examined cracks of varying depths, widths, orientations, and lengths. The experimental results show that the probe can detect minimum crack sizes of 0.5 mm × 0.15 mm × 1 mm for 5083-aluminum alloy, 3 mm × 0.15 mm × 1 mm for GH4169 superalloy, and 1 mm × 0.15 mm × 1 mm for Q235 steel. The results demonstrate that the flexible fractal eddy current probe has significant advantages in detecting small cracks.

High-order-mode cavity fed 45° linear polarized antenna for 5G applications

Abstract In this paper, a high-order-mode (HOM) (TE330) cavity-fed 45° linear polarized 6×6 slot array antenna is proposed. The 45° linear polarization is achieved by introducing asymmetric cross slots on the HOM cavity, resulting in low profile and wide bandwidth. The antenna array was verified using standard printed circuit board technology. Measured results show that the impedance bandwidth ( $|S_{11}|\le$ −10 dB) is 13.9% (36.98–42.92 GHz), and the peak gain is 19.3 dBi with a 3-dB gain bandwidth of 13.6%. Attributed to its simple structure, low profile, and wide bandwidth, the presented antenna is a good candidate for 5G applications.

Modeling of intermodulation in a loaded-line phase shifter based on a polynomial varactor model

Abstract This paper investigates if there is an optimum design of loaded-line phase shifters with respect to phase shift/loss figure of merit (FOM) and linearity. The investigation was performed by comparing six loaded-line phase shifters that were implemented in printed circuit board (PCB)technology with shunt-loaded hyperabrupt varactor-diodes. It was demonstrated that the hyperabrupt varactor’s C-V characteristics must be modeled with high accuracy to predict the nonlinear behavior. A polynomial varactor model was employed and experimentally validated. To extend the range of investigated parameter values, the extracted model was scaled and evaluated further in a circuit simulator. The investigation reveals that for a given varactor-capacitance, the phase shift/loss FOM is improved if the varactor-capacitance is evenly distributed and the unit cell length is much shorter than a quarter wavelength. The study demonstrates that the phase shift/loss depends mainly on the distribution of varactor-capacitance and Q factor. The intermodulation (IM) distortion is primarily proportional to the total varactor-capacitance per unit cell. The study also revealed that an increase in the varactor’s Q factor results in higher IM. Therefore, it is a trade-off between low loss and low IM.

Miniaturized broadband high out-of-band rejection bandpass filter based on spoof surface plasmon polaritons with defected ground structure

In this paper, a novel compact bandpass filter (BPF) with a wide out-of-band rejection is proposed. It can achieve broadband characteristics by combining hollow bowtie-type spoof surface plasmon polaritons (SSPPs) with complementary H-type defected grounded structures (DGSs) through aperture coupling. Compared with the conventional SSPP unit cells, the hollow bowtie-type structure exhibits much better slow-wave characteristics. The introduced slant antenna type port-coupling can produce a very strong high-performance rejection outside the high frequency stopband. Simulation results show that the SSPPs-DGS-based BPF has an excellent band pass characteristics in a broadband range with − 3dB fractional bandwidth of 43.5% at center frequency f0 of 2.04 GHz. The return loss in the passband is better than − 12 dB. Furthermore, because of the multiple transmission zeros generated in upper-stop-band, the designed BPF has an extremely strong out-of-band rejection of -40dB from 1.5 f0 to 4 f0 (f0 is the center frequency). The designed SSPPs-DGS-based BPF is fabricated by conventional printed circuit board (PCB) technology with a compact size of only 0.68λg*0.34λg (λg is the wavelength at the center frequency). The measured results have a good agreement with the simulation ones, which verifies the rationality and feasibility of the design. The miniaturized wideband BPF with broad out-of-band rejection may make it has good application prospect in the new generation microwave communication field.

Flexible printing paper-based reconfigurable smart metasurfaces

In the rapidly evolving wireless communication landscape, achieving full-dimensional coverage poses a gamut of challenges such as intricacy, high hardware costs and energy consumption. In addressing these issues, reconfigurable metasurfaces are being considered as a potential solution. However, traditional methods of producing reconfigurable metasurfaces via printed circuit board (PCB) technologies possess limitations such as high cost and extended production cycles. Particularly, in the context of large-scale communication scenarios, reconfigurable metasurfaces can also present high energy consumption issues. Therefore, this paper proposes a novel type of intelligent reflection surface (IRS) characterized by lower production costs, reduced energy consumption, enhanced flexibility, ease of manufacture, and superior electromagnetic wave modulation capabilities. The proposed reconfigurable smart metasurface is a paper-based metasurface printed with conductive ink, which uses conductive ink to draw base metal blocks on a flexible substrate, and uses silver-tin as a metal patch between the metal blocks, and the phase response is reconstructed with silver ink. By adjusting the distribution of these metallic patches, we tailor the phase and amplitude distributions to generate specific scattering effects. This paper presents designs of six patterns that yield single-beam and dual-beam, with experimental results aligning closely with simulated results, validating the feasibility of the proposed method. This low-power, low-cost, and efficient IRS is expected to pave a new path for advanced 5 G/6G wireless communication technologies.

Aging characterization of dielectric materials using microstrip spiral resonator sensor: application in high frequency range, up to 18 GHz

This current work aims to propose a complete microwave procedure for dielectric materials aging characterization. To achieve this aim, a microstrip spiral resonator sensor, based on printed circuit board (PCB) technology, is designed to attend polyvinyl chloride (PVC) aging behavior through microwave measurements. The resonator is composed of a spiral microstrip, excited by coupling 50-Ohm transmission line on the top layer of the substrate; meanwhile a rectangular slot is etched in the bottom layer, behind the spiral shape to achieve high inductive effect. Structure optimization was conducted using high-frequency structure simulator (HFSS). The sensor is then used as a holder of the UV-aged PVC material while reflection (S11) and transmission (S21) coefficients are measured by vector network analyzer (VNA) in high frequency range, up to 18 GHz. The aging effect is finally perceived by observing the frequency shift of the resonance frequency between the empty and the aged-PVC loaded sensor, together with a variation in the S21 parameter amplitude. It is then found that for 864 h of UV-exposure is provided more than 0.45% frequency shift and about 4.67% decrease in electromagnetic energy transmission. Moreover, comparison between S11 and S21 results reveals that using S11 parameter is more practical to investigate material aging as it allows for simple visual checking of the frequency shift.

Design and Comparative Characterization of Water Level IDE Sensors at Resonant Frequencies

Background: This paper reports the design and characterization of three Interdigital electrode (IDE) water-level sensors at resonant frequencies. The geometries of the proposed IDE sensors are comb type, circular type, and Archimedean spiral type. These IDE sensors have been fabricated by the printed circuit board technology. The sensor’s performance has been evaluated on both tap and distilled water. Methods: The multiple resonant frequencies are investigated for the frequency span of 40 Hz to 110 MHz using a 4294A impedance analyzer. The peak of the projected admittance graph appeared at the first resonant frequency. This first resonant frequency is chosen here for the characterization of the proposed sensors. Results: The study asses that the variations in resonant frequency are caused by both the sensor's geometry and the water under test. The resonant frequency subtly states that sensors can be presented as lumped element equivalent series RLC circuits. In this work, an attempt has been made to show that the change in capacitance plays a pivotal role in estimating the resonant frequency. It is found that the sensor’s sensitivity decreases with water elevation and always be negative. Conclusion: The circular and Archimedean spiral sensors have comparable sensitivity performance, while the comb IDE sensor is found to be the most sensitive. The IDE sensor features the highest sensitivity at 1 cm of water elevation. The circular and spiral IDE sensor more closely follows the reference resonant frequency fr α 1/(√C) when compared with the comb IDE sensor.

Design and research of multi-information fusion RFID sensor for fruit and vegetable quality detection.

With the increasing demand for fruits and vegetables in the market, the development of cold chain logistics has put forward higher requirements for the quality of fruits and vegetables in storage. To ensure the freshness of fruits and vegetables during storage and transportation and avoid unnecessary loss, it is necessary to conduct real-time detection of their odor to ensure their quality. Therefore, based on nano-composite materials combined with Radio Frequency Identification (RFID) technology, this paper designs an integrated RFID sensor that can simultaneously detect temperature, carbon dioxide, and ethanol concentrations. The test results show that the sensor has a high sensitivity of 0.25dB/°C, 0.011dB/ppm, and 0.65MHz/ppm for detecting temperature, carbon dioxide, and ethanol concentration, respectively. The sensor also uses Printed Circuit Board (PCB) technology to make the sensor base, which has the advantages of low cost, easy portability, and mass production capability. The results obtained evidencethat the system meets the requirements of environmental monitoring for fruit and vegetable storage, runs stably, and has a high use value.

A vertical transition for suspended line with two transition modes

In this article, we propose a substrate-integrated suspended line (SISL) vertical transition for chip packaging. The transition structure supports both counter-directional and co-directional modes for single-module packaging and vertical integration, respectively. Furthermore, the incorporation of an electromagnetic band gap (EBG) reduces the demands on substrate electrical contact and simplifies the assembly process. A transition structure was designed to convert SISL to a grounded coplanar waveguide (GCPW) to facilitate measurement. The overall structure can be implemented using cost-effective printed circuit board (PCB) technology. Two prototypes of this transition were designed and fabricated. In the frequency range of 12–18 GHz, corresponding to a fractional bandwidth of 40%, the measured return loss is better than 12 dB, while the insertion loss remains consistently below 2.2 dB.

Bidirectional beam generation by metasurface for 6G communication

This paper presents a bidirectional metasurface that is polarization dependent and consists of 2-bit coding reflect-transmit (RT) elements. The proposed metasurface can transmit the vertical polarized (VP) incident wave and reflect the horizontal polarized (HP) wave with the same focal length. The 2-bit coding passive RT elements, named UC0 to UC3, have 0°, 90°, 180°, and 270° phase responses for both vertical and horizontal incidences. The array samples were fabricated using standard print circuit board (PCB) technology. The results of both numerical and experimental investigations demonstrate that the proposed metasurface is capable of beam control with an angular range of ±30° in the xoy, xoz, and diagonal planes. The reflected and transmitted beams have been found to exhibit peak gains of 22 dBi at 94.5 GHz with 7% 3-dB gain bandwidth and 22.1 dBi at 93 GHz with 14.8% 3-dB gain bandwidth, respectively. The proposed metasurface shows great potential for use in 6G wireless communication applications.

A 10 µH Inductance Standard in PCB Technology with Enhanced Protection against Magnetic Fields

Low-frequency working standards of inductance are generally uniformly wound toroids on a ceramic core. Planar inductors made using printed circuit board (PCB) technology are simple and cheap to manufacture in comparison to inductors wound on toroid cores, but they are significantly prone to the influence of external magnetic fields. In this paper, we propose the design of a PCB inductance working standard of 10 μH, consisting of a duplex system of planar PCB coils, electrostatic shielding, and an enclosure. Alongside an electromagnetic analysis and design procedure, the measurements on the manufactured prototype included the generated magnetic field, the thermal time constant of the enclosure, temperature coefficients, and its error analysis. The measurements show negligible generated magnetic fields (<1.68 nT at 7 cm, 49 mA, 10 kHz). The minimum thermal time constant of the enclosure is 1270 s and the temperature coefficient of resistance is 0.00384 1/℃. The presented method of temperature coefficient measurement using a climate chamber allows for measurements in the temperature range of 10 °C to 40 °C. In this temperature range, the results show an inductance variation of 0.05 µH at 50 kHz, while the uncertainty of inductance measurement at this frequency was 0.03 µH (k = 2).

A high-performance sub-THz planar antenna array for THz sensing and imaging applications

Terahertz (THz) spectral region from 0.1 to 3 THz is envisaged to hold immense potential in the next generation of wireless technologies. Recently, research has focused on this terahertz gap, because of its unprecedented channel capacities. At the physical layer, the design complexities and fabrication of THz devices, especially antennas are the prime bottlenecks to realize its full potential. This article introduces a cost-effective, easy-to-fabricate, and reproducible sub-THz antenna design based on a single-layer planar printed circuit board technology. The antenna incorporates carefully designed quasi-cross slots and applied machine learning-assisted global optimization techniques to achieve the desired performance metrics. The antenna performance is elucidated through numerical simulations and verified through a rigorous in-house THz experimental framework around 100–110 GHz. The proposed antenna offers a peak gain of 13.90 dBi with less than 1 dB variation within the entire band of 100–110 GHz. The antenna holds the potential to achieve terabits per second data rates and futuristic high-resolution short-range THz imaging applications.

Design, preparation and firing characterization of PCB-EBW

Exploding Bridge Wire (EBW) is a special actuator that drives high-temperature and high-pressure plasma. To address the issues of low efficiency and high cost in the preparation process of EBW detonators, an EBW chip based on Printed Circuit Board (PCB) technology was designed and studied. By utilizing a specially designed "S"-shaped transition region and using copper (Cu) as the bridge wire material, the PCB method has enabled batch production of the PCB-EBW device. Four different types of PCB-EBW chips were constructed by designing bridge wires of varying lengths. Subsequently, electro-thermal simulations, electrical explosion performance studies, and shock wave simulations were conducted on the PCB-EBW. It is inferred from the research findings that the main factor triggering the explosive detonation of the PCB-EBW chip is the coupling effect between the high-temperature plasma generated by the electrical explosion and the electrical explosion shock wave. The speculation on the working mechanism of the PCB-EBW was validated by igniting PETN, with the minimum firing voltage determined to be 550 V (for a bridge wire length of 200 μm). This novel EBW design expands the application prospects and provides new insights into the mechanism of EBW for future research.

Low‐cost and easy‐to‐embed 7‐bit 360° phase shifter with transitions for large‐scale phased arrays

AbstractIn this letter, a low‐cost and easy‐to‐embed 7‐bit 360° phase shifter with transitions is presented for applications to beamforming in the large‐scale phased array. In the proposed 360° phase shifter, the topology of the reflection‐type phase shifter (RTPS) is employed, composed of a 3‐dB branchline coupler terminated with two tunable parallel L–C loads. First, a two‐step phase extraction process for RTPS is applied to design the RTPS rapidly with competitive performance, including 360° phase range and low insertion loss. A huge amount of parameter sweep is reduced in the design and test. Meanwhile, the parameter of inductors in the tunable loads is investigated effectively, to achieve the minimal phase step. Second, aiming at the enhanced performance of beamforming and improved flexibility of integration, the stripline is adopted in the design of the phase shifter, avoiding the interference on antenna radiation effectively. To facilitate the integration with antenna and radio frequency connectors of the input and output signals, a stripline‐to‐microstrip line transition with electromagnetic bandgap structures is adopted. By this means, the complexity and cost of fabrication are decreased. Finally, fabricated in the low‐cost printed circuit board technology, our proof‐of‐concept design operated from 2.4 to 2.5 GHz is measured and achieves a 386.8° phase shift range with an insertion loss of 2.21 ± 0.82 dB at 2.45 GHz.

Size-reduced substrate-integrated waveguide resonator designed using the quadrangular-star-slot metasurfaces

A particular kind of substrate-integrated waveguide (SIW) resonator is studied inspired by loading new quadrangular-star-slot metasurfaces (QSSMs). It is demonstrated that the QSSMs can effectively make the resonator electrically smaller. Good agreement has been observed between the numerical and experimental results for a specific QSSMs-loaded SIW resonator. It is revealed that the practical SIW resonator has a patch size of 0.585λg × 0.585λg, which is smaller than the conventional 0.707λg × 0.707λg. The QSSMs-loaded SIW resonators are simple to fabricate using the current print circuit board technology at a low cost.

A new label free spiral sensor using impedance spectroscopy to characterize hepatocellular carcinoma in tissue and serum samples

Hepatocellular carcinoma (HCC) stands as the most prevalent form of primary liver cancer, predominantly affecting patients with chronic liver diseases such as hepatitis B or C-induced cirrhosis. Diagnosis typically involves blood tests (assessing liver functions and HCC biomarkers), imaging procedures such as Computed Tomography (CT) and Magnetic Resonance Imaging (MRI), and liver biopsies requiring the removal of liver tissue for laboratory analysis. However, these diagnostic methods either entail lengthy lab processes, require expensive imaging equipment, or involve invasive techniques like liver biopsies. Hence, there exists a crucial need for rapid, cost-effective, and noninvasive techniques to characterize HCC, whether in serum or tissue samples. In this study, we developed a spiral sensor implemented on a printed circuit board (PCB) technology that utilizes impedance spectroscopy and applied it to 24 tissues and sera samples as proof of concept. This newly devised circuit has successfully characterized HCC and normal tissue and serum samples. Utilizing the distinct dielectric properties between HCC cells and serum samples versus the normal samples across a specific frequency range, the differentiation between normal and HCC samples is achieved. Moreover, the sensor effectively characterizes two HCC grades and distinguishes cirrhotic/non-cirrhotic samples from tissue specimens. In addition, the sensor distinguishes cirrhotic/non-cirrhotic samples from serum specimens. This pioneering study introduces Electrical Impedance Spectroscopy (EIS) spiral sensor for diagnosing HCC and liver cirrhosis in clinical serum—an innovative, low-cost, rapid (< 2 min), and precise PCB-based technology without elaborate sample preparation, offering a novel non-labeled screening approach for disease staging and liver conditions.

Theory vs. Reality: Using Printed Circuit Board Technology for Grounded Coplanar Waveguide at Millimeter-Wave Frequencies: Understanding PCB Technology for Millimeter-Wave Applications

Theory vs. Reality: Using Printed Circuit Board Technology for Grounded Coplanar Waveguide at Millimeter-Wave Frequencies: Understanding PCB Technology for Millimeter-Wave Applications

Modelling of Whispering Gallery Mode Resonators for Dielectric Measurement Applications

This study presents a method for measuring the permittivity of dielectric materials using a whispering gallery mode ring resonator. By detecting changes in coupling resulting from variations in resonant frequency caused by alterations in dielectric constant, the method offers a reliable means of characterizing dielectric properties. Operating within the 5-6 GHz frequency range, the presented resonator design leverages printed circuit board (PCB) technology and FR4 substrate material for cost-effective fabrication and flexibility in design. Through comprehensive electromagnetic simulations using ANSYS HFSS software, the study optimizes resonator parameters to enhance sensitivity and effectiveness for various applications. Experimental validation demonstrates exceptional coupling efficiency and sensitivity, underscoring the potential of whispering gallery mode resonators for environmental monitoring, chemical sensing, telecommunications, and biomedical diagnostics. This research contributes to advancing sensing technology, offering valuable insights into the design and optimization of whispering gallery mode resonators for practical use. Further exploration is warranted to fully realize their potential across diverse applications and operating conditions.