Minimal Impedance Research Articles

Flexible yet Durable Microneedle Electrodes Based on Nanowire-Embedded Polyimide for Precise Wearable Electrophysiological Monitoring.

A precise recording of electrophysiological signals requires high-performance flexible bioelectrodes to build a robust skin interface. The past decade has witnessed encouraging progress in the development of elastomeric electrodes for wearable electrophysiological monitoring; however, it remains challenging to achieve excellent flexibility, conformal contact, and high durability simultaneously. Herein, we report on an effective method to fabricate flexible yet durable microneedle electrodes (MEs) based on vertically aligned gold nanowires (Au NWs) embedded polyimide (PI), which meet the above three design requirements. The Au NWs embedded PI MEs could build conformal contact with human skin and maintain electrical stability with minimal contact impedance by effectively penetrating the stratum corneum of the skin. In comparison studies, we found our MEs outperformed conventional gel or elastomeric soft electrodes. We further integrated the vertical Au-NW MEs into a wearable healthcare system and achieved wireless real-time recordings of electromyography (EMG) and electrocardiography (ECG) with high signal-to-noise ratios (SNRs) and low motion artifacts. Our fabrication strategy opens a new route to improve the durability and reliability of emerging nanomaterial-based soft bioelectrodes for long-term wearable healthcare applications.

BaZr0.1Ce0.7Y0.1Yb0.1O3-δ particles embedded PrBa0.5Sr0.5Co1.5Fe0.5O5+δ hollow nanofibers with 3D fast transmission path as oxygen electrode for proton-conducting solid oxide electrolysis cell

To address the challenge of low-temperature catalytic activity of oxygen electrodes, a high-activity triplex ionic conductor material, PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF), is prepared using electrospinning. The preparation PBSCF and BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) nanofibers composite electrodes are used with different composite methods to improve the catalytic activity and the proton transport pathway within the electrode. The results show that PBSCF@BZCYYb prepared by PBSCF and BZCYYb pre-mixed one-step electrospinning has high porosity and 3D interwoven continuous transmission path, exhibiting minimal polarization impedance on symmetric cells. The electrolysis cell with PBSCF@BZCYYb|BZCYYb|NiO-BZCYYb (active layer) |NiO-BZCYYb (support layer) structure shows electrolysis current densities of 775.4 mA cm−2 under 1.3 V at 650 °C with 20%H2O+80%Air atmosphere. Additionally, during the constant voltage electrolysis, the cell shows acceptable stability in 60 h at 650 °C, considered to be a promising oxygen electrode material in this work.

Boron-Silicon Alloy Nanoparticles as a Promising New Material in Lithium-Ion Battery Anodes.

Silicon's potential as a lithium-ion battery (LIB) anode is hindered by the reactivity of the lithium silicide (Li x Si) interface. This study introduces an innovative approach by alloying silicon with boron, creating boron/silicon (BSi) nanoparticles synthesized via plasma-enhanced chemical vapor deposition. These nanoparticles exhibit altered electronic structures as evidenced by optical, structural, and chemical analysis. Integrated into LIB anodes, BSi demonstrates outstanding cycle stability, surpassing 1000 lithiation and delithiation cycles with minimal capacity fade or impedance growth. Detailed electrochemical and microscopic characterization reveal very little SEI growth through 1000 cycles, which suggests that electrolyte degradation is virtually nonexistent. This unconventional strategy offers a promising avenue for high-performance LIB anodes with the potential for rapid scale-up, marking a significant advancement in silicon anode technology.

Oxygen vacancy engineering and rare earth ion modification in Er-doped Bi0.5Na0.5TiO3–BaTiO3 for piezo-photocatalysis

The pursuit of high-performance piezo-photocatalysts through structural modifications has been a focal point of investigation within the realm of related scientific disciplines. In this study, we successfully designed Er-doped Bi0.5Na0.5TiO3–BaTiO3 combined with rare earth ion doping and solid solution modification, and the prepared particles exhibited homogeneous grain sizes and optimized concentrations of oxygen vacancies (OV). The synergistic incorporation of OV (accelerator for catalytic reaction) and Er3+ results in an impressive 12-fold enhancement of the piezo-photocatalytic rate when degrading the Rhodamine B dye. The optimal composition 0.96BNT-0.04BT-Er demonstrates outstanding electrochemical properties, including a superior photocurrent response and minimal impedance, highlighting its exceptional performance in piezo-photocatalysis. The fundamental enhancement in catalytic performance can be attributed to the reconfiguration of the band structure of 0.96BNT-0.04BT-Er, which has been meticulously calculated utilizing DRS and VB-XPS and the internal mechanism was explained in detail. This research serves as a source of inspiration for the investigation of solid solutions among piezo-photocatalysts and sheds light on the vital role of band structure in governing catalytic performance.

Modulating surface microenvironment based on Ag-adorned CuO flower-liked nanospheres for strengthening C-‍C coupling during CO2RR

Modulating the surface microenvironment is crucial in strengthening CC coupling, leading to increasing selectivity in the production of multi-carbon (C2+) products during CO2 electroreduction. Herein, we have concentrated on investigating how to control the effect of surface distribution of active components of a series of Ag-decorated CuO, denoted as xAg/yCuO. These catalysts with similar chemical elements and morphology are designed, but they exhibit different selectivity in the CO2 electroreduction process. As a result, the Ag particles in 3Ag/CuO aggregates, while the Ag in 2Ag/2CuO and Ag/3CuO is uniformly distributed on the flower-like CuO nanosphere. Besides, 3Ag/CuO has the highest Faraday efficiency (FE) of CO with a value of 30.9 % at 0.8 V vs. RHE, demonstrating rich-Ag catalysts are beneficial to produce CO. 2Ag/2CuO shows excellent FEC2H4 of 51.4 % at -1.2 V vs. RHE due to the highly dispersed distribution of Ag on the flower-like CuO and higher vacancy O. Ag/3CuO exhibits higher FEH2 compared to other catalysts across a wide potential range, and its minimal impedance is attributed to its exceptional performance in the hydrogen evolution reaction. The proposed reaction pathway for the most effective catalysts 2Ag/2CuO, as determined by in-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), involves the following steps: CO2 →*CO2−→ *COOH → *CO→ *CHO→ *OCHCHO→ *OCHCH2→ C2H4. These findings demonstrate that controlling the surface structure can influence the local environment to enhance the efficiency of CO2 electroreduction.

Effect of automated head-thorax elevation during chest compressions on lung ventilation: a model study

Our goal was to investigate the effects of head-thorax elevation (HUP) during chest compressions (CC) on lung ventilation. A prospective study was performed on seven human cadavers. Chest was automatically compressed-decompressed in flat position and during progressive HUP from 18 to 35°. Lung ventilation was measured with electrical impedance tomography. In each cadaver, 5 sequences were randomly performed: one without CC at positive end-expiratory pressure (PEEP) 0cmH2O, 3 s with CC at PEEP0, 5 or 10cmH2O and 1 with CC and an impedance threshold device at PEEP0cmH2O. The minimal-to-maximal change in impedance (VTEIT in arbitrary unit a.u.) and the minimal impedance in every breathing cycle (EELI) the) were compared between flat, 18°, and 35° in each sequence by a mixed-effects model. Values are expressed as median (1st–3rd quartiles). With CC, between flat, 18° and 35° VTEIT decreased at each level of PEEP. It was 12416a.u. (10,689; 14,442), 11,239 (7667; 13,292), and 6457 (4631; 9516), respectively, at PEEP0. The same was true with the impedance threshold device. EELI/VTEIT significantly decreased from − 0.30 (− 0.40; − 0.15) before to − 1.13 (− 1.70; − 0.61) after the CC (P = 0.009). With HUP lung ventilation decreased with CC as compared to flat position. CC are associated with decreased in EELI.

Assisting walking balance using a bio-inspired exoskeleton controller

BackgroundBalance control is important for mobility, yet exoskeleton research has mainly focused on improving metabolic energy efficiency. Here we present a biomimetic exoskeleton controller that supports walking balance and reduces muscle activity.MethodsHumans restore balance after a perturbation by adjusting activity of the muscles actuating the ankle in proportion to deviations from steady-state center of mass kinematics. We designed a controller that mimics the neural control of steady-state walking and the balance recovery responses to perturbations. This controller uses both feedback from ankle kinematics in accordance with an existing model and feedback from the center of mass velocity. Control parameters were estimated by fitting the experimental relation between kinematics and ankle moments observed in humans that were walking while being perturbed by push and pull perturbations. This identified model was implemented on a bilateral ankle exoskeleton.ResultsAcross twelve subjects, exoskeleton support reduced calf muscle activity in steady-state walking by 19% with respect to a minimal impedance controller (p < 0.001). Proportional feedback of the center of mass velocity improved balance support after perturbation. Muscle activity is reduced in response to push and pull perturbations by 10% (p = 0.006) and 16% (p < 0.001) and center of mass deviations by 9% (p = 0.026) and 18% (p = 0.002) with respect to the same controller without center of mass feedback.ConclusionOur control approach implemented on bilateral ankle exoskeletons can thus effectively support steady-state walking and balance control and therefore has the potential to improve mobility in balance-impaired individuals.

Ultra-porous titanium nitride as a dual-action supercapacitor for implantable neural interfacing electrodes

Frontier applications in implantable neural interfacing have raised the demand for low-impedance, high-charge-capacity electrodes capable of retaining these properties with chronic use. Herein, we evaluate an ultra-porous electrode based on over-stoichiometric titanium nitride for its application as a dual-action supercapacitor. Electrochemical measurements demonstrate both faradaic and non-faradaic capacitive mechanisms operating simultaneously, resulting in very high charge capacity with minimal impedance limitations. These characteristics were maintained over 10,000 charge-discharge cycles without significant loss in performance. Moreover, N-vacancies hypothesized to permit the reversible faradaic reactions on the electrode surface appear to remain stable, indicating that the film is able to renew its supply with each cycle, possibly by outward diffusion of excess N from the bulk and into the surface.

Regeneration of Lithium-ion battery impedance using a novel machine learning framework and minimal empirical data

The use of Electrochemical Impedance Spectroscopy on rechargeable Lithium-ion battery characterization is an extensively recognized non-destructive procedure for both in-situ and ex-situ analyses. In an impedance measurement for a rechargeable battery, the oscillating current with an accompanying phase angle is the response for a potential perturbation. The proper evaluation of phase angle as a crucial impedance parameter, provides critical understanding of the status of the battery. Although fast and simple, impedance data is difficult to interpret. Using a novel data-centric Machine Learning framework (co-modeling) we demonstrate how to impute experimental data quickly, precisely, and inexpensively that agrees with wholly experimentally generated data. In particular, we predict the phase angle with 99.9% accuracy by training the minimal empirical impedance data. This approach demonstrates a potentially burgeoning field of Machine Learning experimental data imputation and the consequence of faster diagnostic and study of batteries.

Areas of minimal generator impedance drop during the index atrial fibrillation ablation correlate with pulmonary vein reconnection sites despite adopting the CLOSE protocol

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein (PV) isolation is the cornerstone of atrial fibrillation (AF) management. However, AF recurrence is extremely common after a single procedure. The CLOSE protocol, which is the standardisation of radiofrequency catheter ablation by delivering a point-by-point lesion set defined by ablation index (AI), has demonstrated 80% freedom of AF. Yet PV reconnection is still up to 38% in these patients (1). A small decrease in generator impedance (GI), which is not part of the AI algorithm, has been associated with recovery of PV conduction. Purpose The study aimed to identify whether lesions having a poor impedance drop (PID) after wide area circumferential ablation (WACA) are associated with PV reconnection, despite adopting to the CLOSE protocol. Methods 120 consecutive patients who had both the index (i-AFA) and redo AF ablations (r-AFA) due to AF recurrence at our centre from Jan 2018 to Jun 2021 were screened. 18 patients who had WACA around PVs using high power (40 to 50W) with a minimum AI of 400, whilst adhering the CLOSE protocol during the i-AFA, and who had evidence of PV reconnection during r-AFA, were included in the study. Ones who had left atrial (LA) substrate or cryoablation were excluded. GI was measured between the skin patch and ablation catheter. CARTO® system was used to create LA electroanatomical maps (EAMs) and register ablation lesions. Each WACA around PVs was divided into eight anatomical segments (Figure). PID was defined as an impedance change of &amp;lt;8Ω, based on previous studies (2). These lesions were identified and categorised to the relevant anatomical segment in the i-AFA. Locations of the discrete ablation lesions that re-isolated PVs during the r-AFA, were used as a surrogate to denote areas of PV reconnection. These were also spatially matched to the relevant anatomical segment. Each EAM was reviewed by two electrophysiologists. Results 30 out of the 36 WACAs (83%) and on average, at least 2 segments per WACA (2.6; 95% confidence interval (CI): 2.2-3.1) had reconnected. 54% of the reconnected segments had at least one lesion with PID. Having a lesion with PID in a PV segment in the i-AFA was significantly associated with evidence of PV reconnection in the same segment in the r-AFA (odds ratio: 2.1 [95% CI: 1.3-3.6; p&amp;lt;0.01]). Right posterior/inferior (56%) and left anterior/superior (50%) PV segments were the most common areas to reconnect and these areas were also associated with a higher incidence of PID lesions in the i-AFA (94% and 67%, respectively). Conversely, 80% of segments with all lesions having an impedance drop of ≥8Ω had no PV reconnection. Conclusion Lesions with PID in the i-AFA could impact PV reconnection, despite lesion contiguity and an adequate AI. Identifying and targeting these areas of PID, in addition to the CLOSE protocol, could potentially reduce AF recurrence. Prospective studies are needed to validate this hypothesis and its safety.

Upper extremity exoskeleton system to generate customized therapy motions for stroke survivors

This paper proposes the development of a seven degree-of-freedom (DOF) upper extremity exoskeleton to provide robotic therapy solutions for stroke survivors whose number is increasing along with the trend of ‘Aging Society’. Various robotic solutions have been illuminated and advanced along with their interfacing system in order to promote motor recovery after stroke. From this point of view, the proposed exoskeleton, RearMEX, is developed to (1) achieve active-actuation for the full range of human arm motions through the compact mechanical structure, (2) perform high force transparency through the reduction of the mechanical impedance, and (3) provide a user-interface for customized arm movements in active daily life. Especially, the exoskeleton system has a minimal impedance mode where a user can choose sequential desired postures for constituting a therapy motion by the simple button on the handgrip. Then, given a desired period for the movement, a novel interpolation method named norm-based time-allocating monotone Bézier interpolation is proposed to generate the corresponding trajectory with no jerk at each instant in the operational or configurational space. Furthermore, the disturbance observer (DOB) scheme is applied to achieve a robust tracking control performance on the interpolated trajectory even with model uncertainties and unexpected physical interactions with a wearer. The experimental results verify that the consistent performance can be achieved under various load conditions using the suggested controller.

Study on power generation and Congo red decolorization of 3D conductive PPy-CNT hydrogel in bioelectrochemical system

In this paper, a polypyrrole-carbon nanotube hydrogel (PPy-CNT) with 3D macroporous structure was prepared by secondary growth method. This self-supporting material with good conductivity and biocompatibility can be directly used as anode in a microbial fuel cell (MFC). The prepared material had a uniform structure with rich 3D porosity and showed good water retention performance. The effect of the mass ratio of PPy and CNT in the hydrogel were also investigated to evaluate the electrical performance of MFC. The MFC with 10:1 PPy-CNT hydrogel anode could reached the maximum power density of 3660.25 mW/m3 and the minimal electrochemical reaction impedance of anode was 5.06 Ω. The effects of Congo red concentration, external resistance and suspended activated sludge on decolorazation and electricity generation were also investigated in the MFC with the best performance hydrogel. When the Congo red concentration was 50 mg/L and the external resistance was 200 Ω, the dye decolorization rate and chemical oxygen demand (COD) removal rate could reach 94.35% and 42.31% at 48h while the output voltage of MFC was 480 mV. When activated sludge was present, the decolorization rate and COD removal rate could be increased to 99.55% and 48.08% at 48 h. The above results showed that the porous hydrogel anode had broad application prospects in synchronous wastewater treatment and electricity production of MFC.

Long-Term Impedance Trend in Cochlear Implant Users with Genetically Determined Congenital Profound Hearing Loss.

Impedance is a basic parameter registered at any cochlear implant (CI) fitting section. It is useful in monitoring electrode functioning and the status of the surrounding anatomical structures. The main aim of this study is to evaluate the 5-year impedance-value trend in patients affected by congenital genetically determined profound hearing loss implanted with Cochlear Nucleus devices. Observational, retrospective, monocentric study. Twenty-seven consecutive patients (9 females: 12.0 ± 7.6 years old; range: 4.2-40.4) with genetic diagnosis of GJB2 mutation causing congenital profound hearing loss who underwent cochlear implantation from 2010 to 2020 with good auditory benefit. Impedance values of the CIs were obtained from the CIs' programming software that registers those parameters for each follow-up section of each patient. Impedance values were measured over time (activation, 6, 12, 24, and 60 months after cochlear implantation), for each of the 22 electrodes, in common ground, monopolar 1, monopolar 2, and monopolar 1 + 2 stimulation modes. A significant variation was found between CI activation and 6-month follow-up. This difference was found for each of the 22 electrodes. Electrodes 1 to 4 showed higher impedance values compared with all other electrodes in each time interval. Repeated-measures analysis of variance ruled out significant variations in impedance values from 6-month to 5-year follow-up. Impedance values were extremely stable after activation, at least for the first 5 years. In these cases, even minimal impedance variations should be carefully evaluated for their possible implications on hearing performance.

Identification of Hip and Knee Joint Impedance During the Swing Phase of Walking.

Knowledge on joint impedance during walking in various conditions is relevant for clinical decision-making and the development of robotic gait trainers, leg prostheses, leg orthotics and wearable exoskeletons. Whereas ankle impedance during walking has been experimentally assessed, knee and hip joint impedance during walking have not been identified yet. Here we developed and evaluated a lower limb perturbator to identify hip, knee and ankle joint impedance during treadmill walking. The lower limb perturbator (LOPER) consists of an actuator connected to the thigh via rods. The LOPER allows to apply force perturbations to a free-hanging leg, while standing on the contralateral leg, with a bandwidth of up to 39 Hz. While walking in minimal impedance mode, the interaction forces between LOPER and the thigh were low (<5N) and the effect on the walking pattern was smaller than the within-subject variability during normal walking. Using a non-linear multibody dynamical model of swing leg dynamics, the hip, knee and ankle joint impedance were estimated at three time points during the swing phase for nine subjects walking at a speed of 0.5 m/s. The identified model was well able to predict the experimental responses for the hip and knee, since the mean variance accounted (VAF) for was 99% and 96%, respectively. The ankle lacked a consistent response and the mean VAF of the model fit was only 77%, and therefore the estimated ankle impedance was not reliable. The averaged across-subjects stiffness varied between the three time points within 34-66 and 0-3.5 Nm/rad Nm/rad for the hip and knee joint respectively. The damping varied between 1.9-4.6 and 0.02-0.14 Nms/rad Nms/rad for hip and knee respectively. The developed LOPER has a negligible effect on the unperturbed walking pattern and allows to identify hip and knee impedance during the swing phase.

Minimal Output Impedance Required for Stability of Grid-Supporting Inverters

In the field of power system dynamics, a main challenge is to properly tune the inverter control parameters, where one important parameter is the inverter's output impedance, physical or virtual. In this work, we provide a proof showing that a minimal output impedance must be used in order to keep the system stable. Although this result is well-known among practicing engineers, our proof reveals a fundamental property which causes instabililty, namely the pole excess of the inverter dynamic model. To prove this claim we model the system as a signal flow diagram, where the output impedances of the inverters are described using static gain feedback. Based on this model, we show that the typical dynamic model of grid supporting inverters has a pole excess larger than 2, which causes instability when high feedback gain is used. This result may be used to design a numerical method for estimating the minimal impedance. The theorem is validated based on an array of photovoltaic plants in the Ramat Negev region, which is part of the Israeli power grid.

A virucidal face mask based on the reverse-flow reactor concept for thermal inactivation of SARS-CoV-2.

While facial coverings reduce the spread of SARS‐CoV‐2 by viral filtration, masks capable of viral inactivation by heating can provide a complementary method to limit transmission. Inspired by reverse‐flow chemical reactors, we introduce a new virucidal face mask concept driven by the oscillatory flow of human breath. The governing heat and mass transport equations are solved to evaluate virus and CO2 transport. Given limits imposed by the kinetics of SARS‐CoV‐2 thermal inactivation, human breath, safety, and comfort, heated masks may inactivate SARS‐CoV‐2 to medical‐grade sterility. We detail one design, with a volume of 300 ml at 90°C that achieves a 3‐log reduction in viral load with minimal impedance within the mask mesh, with partition coefficient around 2. This is the first quantitative analysis of virucidal thermal inactivation within a protective face mask, and addresses a pressing need for new approaches for personal protective equipment during a global pandemic.

Carbon-coated lithium titanate: effect of carbon precursor addition processes on the electrochemical performance

In this paper, two carbon-coated lithium titanate (LTO-C1 and LTO-C2) composites were synthesized using the ball-milling-assisted calcination method with different carbon precursor addition processes. The physical and electrochemical properties of the as-synthesized negative electrode materials were characterized to investigate the effects of two carbon-coated LTO synthesis processes on the electrochemical performance of LTO. The results show that the LTO-C2 synthesized by using Li2CO3 and TiO2 as the raw materials and sucrose as the carbon source in a one-pot method has less polarization during lithium insertion and extraction, minimal charge transfer impedance value and the best electrochemical performance among all samples. At the current density of 300 mA·h·g−1, the LTO-C2 composite delivers a charge capacity of 126.9 mA·h·g−1, and the reversible capacity after 300 cycles exceeds 121.3 mA·h·g−1 in the voltage range of 1.0–3.0 V. Furthermore, the electrochemical impedance spectra show that LTO-C2 has higher electronic conductivity and lithium diffusion coefficient, which indicates the advantages in electrode kinetics over LTO and LTO-C1. The results clarify the best electrochemical properties of the carbon-coated LTO-C2 composite prepared by the one-pot method.

Achieving a Peak Capacity of 1800 Using an 8 m Long Pillar Array Column.

In the present study, the peak capacity potential of ultralong porous cylindrical pillar array columns is investigated. Coupling 4 columns of 2 m long allows for working near the minimal separation impedance of small molecules under retained conditions at a maximal pressure load of 250 bar. Minimal plate heights of H = 5.0 μm, H = 6.3 μm, and H = 7.7 μm were obtained for uracil (unretained), butyrophenone (k = 0.85), and valerophenone (k = 1.94), respectively, corresponding to a number of theoretical plates of N = 1.6 × 106, N = 1.2 × 106, and N = 1.0 × 106. The optimal linear velocities were 0.60 mm/s for a retained compound and 0.74 mm/s for an unretained compound. Based on a mixture of 9 compounds, the peak capacity nc was determined as a function of gradient time (tG). Peak capacities (tG-based) of 1103 and 1815 were obtained when applying 650 min and 2050 min gradients (tG/t0 = 4.5 and 14, respectively, with tG as the gradient time and t0 as the void time). These values are much higher than earlier reported peak capacity values for small molecules.

Techniques of impedance matching for minimal PCB channel loss at 40 GBPS signal transmission

PurposeThis paper aims to analyze the negative impact of surface mount (SMT) pad and imperfect via structure such as stub, pad, non-functional pad (NFP) and anti-pad on the signal integrity at 40 Gbps transmission on printed circuit board (PCB) due to impedance mismatch or discontinuity. The optimized modeling of via and SMT structures is performed to achieve minimal impedance mismatch and insertion loss less than 10 dB for six-inch full path transmission line between transmitter and receiver on PCB at Nyquist frequency 20 GHz.Design/methodology/approachThis work is split into two phases. The first phase involves optimization of via and SMT structures in three-dimensional electromagnetic (3DEM) simulation using Hyperlynx Via Wizard and Keysight EMPro software, respectively, followed by analysis of time domain reflectometry (TDR) and insertion loss (Sdd21). Whereas, in the second phase, full path hybrid mode simulation involving vias for signal layer transition, a 6-inch PCB channel and SMT pads is performed using Keysight ADS software to observe the TDR, Sdd21 and eye diagram at 40 Gbps transmission.FindingsImperfect via and SMT structures have a negative effect on signal reflection and attenuation. The optimized via and SMT minimizes the impedance mismatch by 81 per cent and insertion loss by 4.5 dB, ultimately enlarging the eye diagram opening to achieve minimal data loss at receiver with 40 Gbps transmission.Originality/valueThe results of original empirical research work on signal integrity analysis that optimizes the PCB channel design to achieve 40 Gbps signal transmission are presented in this study. It serves as a reference guide for high-speed PCB layout design.

Characterization of Low-Inductance Microcoaxial Cables for Power Distribution

Abstract Low-impedance microcoaxial cables have been developed to supply power to microchips. These uniquely low-inductance cables are enabled by a very thin dielectric compared with a conventional 50-Ω cable. These cables will be used in a novel packaging platform in which traditional interconnects are replaced by microscale coaxial cables. This method saves time and cost for small production volumes and custom electronics, compared with high density interconnects and silicon interposer technologies. These microcoaxial cables are designed to have minimal impedance to meet the stringent power supply requirements of today's electronics. As a concrete example, we consider a Kintex 7 Field-Programmable Gate Array (FPGA). To power this chip with interconnect lengths of 25 mm and a voltage ripple less than 30 mV, a resistance of 3.20–6.40 mΩ/mm and an inductance of 12–15 pH/mm is needed. The tight voltage ripple constraint is what makes this device challenging to design power distribution for. One cable fabricated by Draper, to achieve these power requirements, is the focus of this article. The Draper cable consists of a 127-μm Copper core, 12-μm polyesterimide dielectric layer, and 55-μm gold shield. The measured resistance per unit length at DC, inductance per unit length, capacitance per unit length, and characteristic impedance of the Draper cable are 2.0 mΩ/mm, 40 pH/mm, 118 pF/mm, and 6.56 Ω, respectively.