Conductive Patterns Research Articles

Temperature and frequency dependent response of electrical conduction and dielectric relaxation mechanism in CuCr2O4 tetragonally distorted spinel chromite

Herein, the polycrystalline CuCr2O4 (CCO) electro-ceramic was prepared via the sol-gel self-combustion route. The X-ray powder diffraction analysis at room temperature revealed that the CCO chromite was synthesized in a single phase tetragonally distorted normal spinel structure with I41/amd space group. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) investigated the polycrystalline nature of the compound. The microstructural analysis by field emission scanning electron microscopy (FESEM) explored the surface morphology of micron-sized grains (Gs) distinguished by well-pronounced grain boundaries (GBs) available for electrical response of the material. The color mapping images of elements by energy-dispersive X-ray spectroscopy (EDS) divulged the homogeneous distribution of elements in the compound. The surface chemistry of the compound was studied by X-ray photoelectron spectroscopy (XPS). This information helped in understanding the electronic states of the ions contributing to the electrical networks and mechanisms responsible for the charge transport within the CCO system. The dielectric relaxation and electrical transport properties were analyzed using complex impedance spectroscopy (CIS) over the experimental range of frequency and temperature from 40 Hz to 1 MHz and 243–493 K, respectively. The experimental complex impedance data were analyzed by RGQGRGBQGB equivalent circuit model which resolved the electro-active contributions of bulk and interface of the CCO spinel to its electrical dynamics. The dispersion in AC conductivity was explained by Jonscher's double power law which provided evidence of small polaron hopping (SPH) as a dominant transport mechanism governing electrical conduction in the compound. The temperature-dependent DC conductivity pattern exhibited an Arrhenius-like behavior that followed Mott and Davis's model of SPH. The analysis of complex electrical modulus M*(ω,T) professed the localized and de-localized movements of the charge carriers. The dielectric permittivity response of CCO followed Havriliak-Negami (HN) phenomenology that divulged the existence of non-Debye type dielectric relaxation processes. The interfacial polarization was observed to be accountable for the dispersion in dielectric loss spectra.

Detunable wireless Litzcage coil for human head MRI at 1.5 T.

Inductively coupled radiofrequency (RF) coils are an inexpensive and simple method to realize wireless RF coils in magnetic resonance imaging (MRI), which can significantly ease the MRI scan setup and improve patient comfort because they do not require bulky components such as cables, baluns, preamplifiers, and connectors. However, volume-type wireless coils are typically operated in transmit/receive mode because detuning such coils is much more challenging due to their complex structure and multiple resonant modes. Meanwhile, adding too many detuning circuits to a wireless coil would decrease the coil's quality factor, impair the signal-to-noise ratio, and increase the cost. In this work, we proposed, constructed, and tested a novel wireless volume coil based on the Litzcage design for 1.5-T head imaging. Being an inductively coupled coil, it has a much simpler structure, resulting in a lighter weight and less bulky design. Despite its simpler structure, it exhibits comparable imaging performance with a commercial receive array, providing an alternative to conventional wired coils with a high cost and complex structure. The unique figure-of-8 conductor pattern within the rungs ensures that the proposed wireless Litzcage can be efficiently detuned with minimal detuning circuits.

Quantification of local heterogeneity from activation maps of omnipolar multielectrode recordings

Abstract Background and Purpose The study of cardiac arrhythmias requires understanding the heart's electrical conduction patterns. Using multielectrode catheters and other mapping systems have allowed a futher understanding of the wavefront. In particular, novel high-density (HD) grid catheters, enable the recording of omnipolar electrograms, which are purportedly not influenced by catheter orientation, allowing real-time determination of signal propagation direction. We propose a novel heterogeneity metric to quantify the degree of disorganisation in the vector maps from reconstructed omnipolar electrograms, which could potentially be utilised to detect and assess the degree of fibrosis in cardiac tissue. Methods We utilised basal and stimulated recordings from 5 Langendorff-perfused rabbit hearts, where signals were obtained using a multielectrode mapping catheter with 128 electrodes spaced at 1mm. Three recordings were taken for each series, basal at 37°C, plus stimulation performed using a bipolar electrode at 4 Hz and 6 Hz . An angle propagation matrix is computed for the local area of recording, by means of the orthogonal bipolar loops of each clique. A local heterogeneity metric is derived from the summation of angular variations of neighbouring elements. An illustration of the heterogeneity map, and heterogeneity metric for the recording area (H) is illustrated in figure 1. A statistical analysis is performed then to assess the distribution of heterogeneity values. Results Heterogeneity values for each experimental heart, and the distributions of H values obtained according to the stimulation type are shown in figure 2A. The ROC curve obtained from the values of H has an AUC of 0.996, with an optimal threshold value of 0.113, resulting in a confusion matrix presented in 12 TP, 30 TN, 3 FP and 0 FN. The study shows that the proposed heterogeneity metric can quantify the degree of disorganization in the vector maps and can be used to differentiate between basal and stimulated groups with p<0.001. Conclusion This study proposes a novel heterogeneity metric to quantify the degree of disorganization in the vector maps from reconstructed omnipolar electrograms. The methodology was assessed on basal and stimulated epicardial rabbit recordings and found to be effective in differentiating between the two groups with high accuracy. Future studies should focus on the efficiency of assessing fibrotic tissue using the proposed metric.Figure 1Figure 2

Prediction of Electrical Resistance with Conductive Sewing Patterns by Combining Artificial Neural Networks and Multiple Linear Regressions.

This study aims to estimate the impact of sewing thread patterns on changes in the resistance of conductive yarns coated with silver paste. Firstly, the structure of the conductive yarns was examined, and various variations in the length and angle of individual sewing stitches were observed and analyzed through experiments. The results revealed that as the length of an individual stitch decreased, the width of the conductive yarn increased. Additionally, variations in the stitch angle resulted in different resistance values in the conductive yarn. These findings provide essential information for optimizing sewing patterns and designing components. Secondly, the comparison between models using multiple linear regression analysis and sewing neural networks was included to show optimized resistance prediction. The multiple linear regression analysis indicated that the stitch length and angle were significant variables affecting the resistance of the conductive thread. The artificial neural network model results can be valuable for optimizing sewing patterns and controlling resistance in various applications that utilize conductive thread. In addition, understanding the resistance variation in conductive thread according to sewing patterns and using optimized models to enhance component performance provides opportunities for innovation and progress. This research is necessary for the textile industry and materials engineering fields and holds high potential for practical applications in industrial settings.

Shape-Morphing Antenna Array by 4D-Printed Multimaterial Miura Origami.

The rapid development of four-dimensional (4D) printing technology has resulted in its application in various fields, including radiofrequency (RF) electronics. Moreover, because origami-inspired RF electronics provide a physically deformable geometry, they are good candidates for reconfigurable RF applications. However, previous origami-inspired RF electronics have generally been fabricated on paper for easy folding and unfolding. Although this facilitates easy fabrication, the resultant structures suffer from a lack of rigidity and stability. In this paper, we propose a 4D-printed multimaterial Miura origami structure for RF spectrum applications. For thermal actuation and robustness, the proposed structure consists of high-temperature durable cores with shape memory polymer (SMP) hinges. The high-temperature durable cores provide rigidity to the desired part and reduce the level of distortion of the conductive pattern, while the SMP hinges enable shape morphing. To demonstrate the feasibility of the technique for RF electronics, a shape-morphing pattern reconfigurable antenna array is designed at 2.4 GHz using the proposed 4D-printed multimaterial structure. Through numerical and experimental demonstrations, the proposed antenna's maximum beam direction is changed from 0° to 50° by thermally morphing the Miura origami. In addition, the antenna successfully recovers to its memorized original state.

Scalable Electrodeposition of Liquid Metal from an Acetonitrile-Based Electrolyte for Highly Integrated Stretchable Electronics.

The advancement of highly integrated stretchable electronics requires the development of scalable sub-micrometer conductor patterning. Eutectic gallium indium (EGaIn) is an attractive conductor for stretchable electronics, as its liquid metallic character grants it high electrical conductivity upon deformation. However, its high surface tension makes its patterning with sub-micrometer resolution challenging. In this work, this limitation is overcome by way ofthe electrodeposition of EGaIn. A non-aqueous acetonitrile-based electrolyte that exhibits high electrochemical stability and chemical orthogonality is used. The electrodeposited material leads to low-resistance lines that remain stable upon (repeated) stretching to a 100% strain. Because electrodeposition benefits from the resolution of mature nanofabrication methods used to pattern the base metal, the proposed "bottom-up" approach achieves a record-high density integration of EGaIn regular lines of 300nm half-pitch on an elastomer substrate by plating on a gold seed layer prepatterned by nanoimprinting. Moreover, vertical integration is enabled by filling high-aspect-ratio vias. This capability is conceptualized by the fabrication of an omnidirectionally stretchable 3D electronic circuit, and demonstrates a soft-electronic analog of the stablished damascene process used to fabricate microchip interconnects. Overall, this work proposes a simple route to address the challenge of metallization in highly integrated (3D) stretchable electronics.

PVA-Starch-Based Biodegradable Polymer Electrolytes for Electrochemical Devices

Photovoltaic and electrochemical devices have been vital for the past two decades. These devices are capable of solving the coming energy crisis. One of the essential components of these devices is electrolytes. These electrolytes have been replaced in the past few decades by solid polymer electrolytes. The specialty of these solid polymer electrolytes is that they can be grown in a thin film and are also leak-proof. We have used biodegradable polymers like PVA, starch, and some novel salts. These polymer-based thin films were fabricated using standard solution-cast techniques with different wt% of slats in a PVA-Starch-based polymer system. The impedance spectroscopy was performed to analyze the electrical properties of thin films. The highest conductivity of the system was obtained at 20wy% of salt. The conductivity values increase from 1.46 × 10−6 S/cm to 2.69 × 10−6 S/cm. Furthermore, the concentration and mobility of charge carriers were calculated to explain the change in the conductivity pattern. This calculation was done with the Trukhan model. It is observed that the conductivity pattern follows the mobility of charge carriers.

Multilayered mullite ceramics with anisotropic properties

Anisotropic layered porous ceramics are crucial to satisfy the demand for devices with directional functions. However, challenges, such as complicated preparation processes and difficulties in regulating the oriented structure, severely limit their application. Here, multilayered mullite ceramics (MLMCs) with specific porosities and strongly anisotropy properties, were prepared by designing porous thin-layered units and an interlayer layout, in combination with a simple gel-casting. Benefiting from the suitable slurry properties, the samples did not show obvious defects, and a perfect bonding was observed between the layers. The optimized MLMCs exhibited a porosity of 65.12%, the differences in compressive and flexural strengths of 14 (±0.7) and 5 (±0.2) MPa in different pressure directions respectively, and the anisotropy factor of thermal conductivity up to 0.98, as well as exhibited good high temperature thermal insulation properties. Ultimately, the MLMCs formed transverse heat conductor and longitudinal heat insulation heat-transfer patterns, with promising applications in thermal insulation.

Evaluation of Dimensional Characteristics of Conductive Pattern Elements of 3D-Printed Circuit Boards

Introduction. A review of foreign publications on 3D printing methods shows the possibility of their application for the manufacture of printed circuit boards (PCBs), while demonstrating the growth of interest in this field. One of the available methods is fused deposition modeling, which can be used to form substrates with channels for traces. At present, the minimum channel width comprises 100 µm, which corresponds to the 5th class of PCB accuracy. However, there is no data on how to obtain such dimensions or on the magnitude of their deviation from the given nominal values.Aim. To determine the influence of such factors as nozzle diameter and the number of contours on the dimensional characteristics of PCBs (linear dimensions; trace channel width; trace spacing; via diameters).Materials and methods. To obtain linear models, a full factorial experiment was carried out. The influence of the following materials was evaluated – polylactide (PLA), acrylonitrile butadiene styrene (ABS) and glass-filled ABS; slicers – Ultimaker Cura and PrusaSlicer; 3D printers – Picaso 3D Designer Classic 2016 and Hercules Strong 2017; brass nozzle with diameters ∅0.2 and ∅0.4 mm. The possibility of using brass nozzles coated with chemical nickel for printing with glass-filled filaments was considered. The study was conducted using the facilities of the "Center for Additive Technologies" of Bauman Moscow State Technical University.Results. The possibility of manufacturing PCBs up to the 2nd and 3rd accuracy classes using nozzles with a diameter of ∅0.4 and ∅0.2 mm, respectively, was shown. It was found that galvanic deposition of chemical nickel on a ∅0.2 mm brass nozzle makes it possible to increase the PCB wearability when printing with glass-filled filaments. Recommendations are proposed for selecting an optimal combination of nozzle diameter and the number of contours.Conclusion. The conducted analysis of mathematical models shows the significance of such parameters as nozzle diameter and the number of contours. The results can be used when creating new PCB layouts

Nonpharmacological Approach to Managing Atrial Fibrillation: A Review

Background: AF's global prevalence underscores its significance as a cardiac rhythm disorder that disrupts atrial activity, impairing normal cardiac function. Over five decades of study have illuminated the pathophysiological mechanisms underlying AF, including insights into re-entrant waves and macro-reentrant circuits. The emergence of non-uniform conduction patterns and bidirectional block regions has further enriched our understanding. Risk factors contributing to AF development encompass cardiovascular conditions, advanced age, and atrial structural changes. With its implications on stroke risk and cardiovascular health, AF has become a growing public health concern. The focus on AF epidemiology has expanded, with attention on the relationship between left atrial size and AF development. Individuals with larger left atria exhibit a heightened risk. Additionally, the elevated stroke risk associated with AF has been consistently documented.
 To optimize clinical management, distinctions are drawn between chronic and paroxysmal AF, as well as the presence of structural heart disease. Mapping techniques have revealed insights into "atrial remodeling" and AF pathology. In managing AF, controlling heart rate, preventing clot formation, and restoring sinus rhythm are principal objectives. This article categorizes AF into acute, chronic, stable, or unstable forms, tailoring management approaches accordingly. While pharmacological interventions have shown efficacy, their limitations drive the exploration of nonpharmacological strategies. Approaches range from medications to cardioversion, including electrical and pharmacological methods.
 Objective: This paper aimed to provide a comprehensive exploration of non-pharmacological approaches to AF management.
 Methodology: This paper employed a structured methodology. This method involved a literature review, data synthesis, and critical analysis. During the literature review phase, we systematically searched electronic databases (PubMed, MEDLINE, Embase, and Google Scholar) for studies published from 1960 to 2023. Specific keywords and phrases such as "atrial fibrillation," "non-pharmacological interventions," "electrical cardioversion," "catheter ablation," "lifestyle modifications," "autonomic modulation," "left atrial appendage closure," and "exercise" were used. Our inclusion criteria encompassed studies addressing various non-pharmacological approaches for AF management, including observational studies and randomized controlled trials.
 Result: The initial stage of our study involved the identification of a substantial number of relevant studies. We conducted a thorough literature search across multiple databases, using specific search terms and criteria relevant to our research topic. This comprehensive search yielded a total of 1,200 studies. After applying these stringent filtering criteria, we were left with 350 studies. To further refine our final sample and categorize the studies according to type, we conducted a detailed review of the remaining 350 studies. We categorized them into various types based on study design, methodology, and focus. We then also excluded studies with duplicate ideas and finally included 103 studies that addressed the objective of our research plan. (See reference list [1-103]).
 Conclusion: This reviewed a number of non-pharmacological approaches including electrical cardioversion, catheter ablation, lifestyle modifications, autonomic modulation, left atrial appendage closure, and exercise, the paper delves into each method's advantages, potential risks, techniques, and efficacy. By offering this extensive overview, the article contributes to the expanding repository of knowledge on non-pharmacological approaches for AF management. These approaches offer potential for unique management of atrial fibrillations or in addition to pharmacologic management, may improve patient survivability or reduce complication outcomes.
 In the management of Atrial fibrillation, choice between rhythm and rate control, lifestyle modifications, and patient adherence to treatment plans are critical factors influencing outcomes are factors to consider. Emerging therapies offer promise, but timely diagnosis, individualized care, and ongoing monitoring remain essential to improving AF patients' overall prognosis.

Realization of thick copper conductive patterns using highly viscous copper oxide (CuO) nanoparticle ink and green laser sintering

The demand for lower-cost and higher-thickness metallic conductive patterns is increasing in printed electronics. Copper oxide (CuO) nanoparticle (NP) ink is a promising low-cost alternative to other metal-based nanoparticle inks such as Au and Ag. In order to obtain thick printed patterns using high viscosity (207,000 cPs) CuO NP ink, a time-pressure dispenser developed in our laboratory was used. After printing the CuO patterns, we used a continuous wave (CW) green laser with a 532 nm wavelength to reduce the CuO to Cu and sinter the reduced Cu nanoparticles. However, the laser absorption depth is known to be only a few dozens of nanometers. Therefore, when the thickness of CuO patterns exceeds 10 μm, it is unclear whether the reduction and sintering can be uniformly achieved through the thickness direction. We investigated the effects of different sintering parameters on the conversion of a thick CuO nanoparticle layer with a thickness of about 34 μm to form Cu conductive patterns. Under optimal sintering conditions, we obtained a resistivity of 8.75 μΩ·cm for a Cu conductive pattern with a width of 1 mm and a thickness of 18.4 μm, which is five times higher than the bulk resistivity. After creating Cu conductive patterns, we assessed their reliability by exposing them to elevated temperatures in an air atmosphere. The findings demonstrate notable resistance to oxidation at a temperature of 250 °C for a duration of 4 h.

How to ablate the septo-pulmonary bundle: a case-based review of percutaneous ablation strategies to achieve roof line block.

Electrical conduction through cardiac muscle fibres separated from the main myocardial wall by layers of interposed adipose tissue are notoriously difficult to target by endocardial ablation alone. They are a recognised important cause for procedural failure due to the difficulties of delivering sufficient energy via the endocardial radiofrequency catheter to reach the outer epicardial layer without risking adverse events of the otherwise thin walled atria. Left atrial ablations for atrial fibrillation (AF) and tachycardia are commonly affected by the presence of several epicardial structures, with the septo-pulmonary bundle (SPB), Bachmann's bundle, and the ligament of Marshall all posing substantial challenges for endocardial procedures. Delivery of a transmural lesion set is essential for sustained pulmonary vein isolation and for conduction block across linear atrial lines which in turn has been described to translate into a reduced AF/atrial tachycardia recurrence rate. To overcome the limitations of endocardial-only approaches, surgical ablation techniques for epicardial or combined hybrid endo-epicardial ablations have been described to successfully target these connections. Yet, these techniques confer an increase in procedure complexity, duration, cost, and morbidity. Alternatively, coronary venous system ethanol ablation has been successfully employed by sub-selecting the vein of Marshall to facilitate mitral isthmus line block, although this approach is naturally limited to this area by the coronary venous anatomy. Increased awareness of the pathophysiological relevance of these epicardial structures and their intracardiac conduction patterns in the era of high-resolution 3D electro-anatomical mapping technology has allowed greater understanding of their contribution to the persistence of AF as well as failure to achieve transmural block by traditional ablation approaches. This might translate into novel catheter ablation strategies with procedural success rates comparable to surgical 'cut-and-sew' techniques. This review aims to give an overview of percutaneous catheter ablation strategies to target the SPB, an important cause of failed block across the roof line and isolation of the left atrial posterior wall and/or the pulmonary veins. Existing and investigational technologies will be discussed and an outlook of future approaches provided.

Effective superior vena cava isolation using a novel C-shaped approach.

Superior vena cava (SVC) isolation has been proposed as part of the ablation strategy for atrial fibrillation. However, circumferential isolation of the SVC can lead to late-onset complications, such as SVC stenosis. We describe a detailed observation of the SVC conduction pattern and present a newly developed approach for SVC isolation that involves creating a C-shaped non-circumferential ablation line while sparing the lateral segment. Twelve consecutive patients were included in the study, all of whom achieved bidirectional block during the ablation procedure. This approach to SVC isolation is effective and has the potential to reduce ablation related complications; however, larger studies and long-term follow-up is warranted to confirm these findings.

Morphological performance and seasonal pattern of water relations and gas exchange in Pistacia lentiscus plants subjected to salinity and water deficit.

Soil water deficit and salinity represent a major factor impacting plant survival and agricultural production. The frequency and severity of both abiotic stresses are expected to increase in a context of climate change, especially in arid and semi-arid regions. This work studied the growth pattern, biomass and mineral distribution and the seasonal pattern of water status, photosynthetic rate and stomatal conductance in plant of Pistacia lentiscus grown under different levels of water deficit and salinity. P. lentiscus plants growing under greenhouse conditions were subjected to four irrigation treatments during 11 months: control (C, 1 dS m-1), moderate water deficit (MW, 1dS m-1, 60% of the control), severe water deficit (SW, 1 dS m-1, 40% of the control) and saline (S, 4dS m-1). The results show that Pistacia lentiscus plants were more affected by deficit irrigation than salinity. Deficit irrigation and salinity inhibited plant height, with reductions of 20%, 22% and 35% for S, MW and SW, respectively. Total leaf area was not modified by effect of the treatments, with the result that plant compactness increased in MW. The salt stressed plants only showed lower relative growth rate at the end of the experiment. Plants responded to saline or drought stress by increasing their osmotic adjustment, which was more pronounced under salinity. Saline plants had the highest values in Na+ and Cl- ions and the lowest values for K+/Na+ and Ca2+/Na+ ratios in leaves and stems, which is correlated with a decrease in growth, stomatal conductance, photosynthesis and stem water potential, and can be used as a diagnostic tool to assess plant tolerance to salinity stress. As a measure of plant hydration, relative water content was more sensitive to deficit irrigation than salinity, being a good indicator of water stress. P. lentiscus plants subjected to both deficit irrigation treatments exhibited an increase in their intrinsic water use efficiency, which is an important adaptation for plants growing in environments with water scarcity.

Additive manufacturing of low-temperature co-fired ceramic substrates and surface conductors based on material jetting

Integrated manufacturing of ceramic substrates and surface conductors using 3D material jetting (MJ) technology is a novel additive manufacturing route for low-temperature co-fired ceramics (LTCC). This study evaluates the rheological and jetting properties of LTCC nanoceramic inks with varying solids contents. Ceramic inks with 35 % solid content were found to be the optimal choice with high particle concentration and Ohnesorge numbers (Oh) below 1. The fabrication process used two piezoelectric printheads to inject nanoceramic ink and nanosilver ink to create a ceramic substrate and a surface interdigital electrode (IDE). The substrate sintering shrinkage was 21.5 % and the surface IDE co-fired at the same shrinkage rate as the substrate thus ensuring all electrode pattern details. The electrode conductors demonstrated effective line widths of up to 0.21 mm. Microscopic characterisation of the interface between silver and substrate using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) confirmed the absence of significant elemental diffusion, and X-ray diffraction spectroscopy (XRD) results demonstrate that there is no second-phase generation, thus ensuring the effectiveness of the silver electrode. The ceramic substrates exhibit good thermal stability below 400 ℃ and have a coefficient of thermal expansion (∼ 4.1 ppm/℃) similar to that of silicon, indicating reliability in packaging. A microstrip patch antenna with the design frequency at 9–11 GHz was made through the same MJ procedure, which was experimentally measured to have a resonant frequency of 10.1 GHz, an S11 measurement of −24.6 dB, a simulated radiation efficiency of 88.01 %, and a high gain of up to 7.52 dB. Finally, a curved LTCC substrate with a radius of curvature of 50 mm and curved circuits was successfully fabricated using MJ technology. Interestingly, the curvature of the substrate maintained its original shape both before and after the sintering process, and the serpentine conductor pattern exhibited synchronous contraction, which implies the potential for developing a conformal LTCC utilizing MJ technology.

Highly Stretchable and Patternable Conductive Elastomer Composites Based on Direct Cut‐Patterning Technique for Stretchable Circuit Board Applications

Stretchable interconnects, essential to the versatility of stretchable circuit boards (SCBs) in the emerging field of wearable electronic systems, are commonly made from conductive elastomer composites. However, the simultaneous realization of exceptional performance and a simple and reproducible fabrication has proven to be a challenge. In this study, high‐performance stretchable interconnects are introduced. These interconnects, constructed from highly patternable conductive composites, are produced using a straightforward, reproducible, and potentially scalable method termed as direct cut‐patterning (DCP). The DCP process enables the creation of distinctive conductive composite patterns and SCBs in a customizable manner, achieving a minimum feature size of 200 µm. The unique architecture of the proposed stretchable interconnects, featuring a fully embedded meander‐patterned composite conductor with periodic secondary cuts, enables the device to endure stretches exceeding 300%, while displaying a minimal gauge factor of ≈0.19 at 100% strain. Importantly, it fully reverts to its original form upon release. The proposed DCP‐based SCB approach is successfully applied in designing a highly stretchable and stable single‐layer light‐emitting diode array circuit, showcasing its potential for use in stretchable display panels.

PDE4D mediates impaired β-adrenergic receptor signalling in the sinoatrial node in mice with hypertensive heart disease.

The sympathetic nervous system increases HR by activating β-adrenergic receptors (β-ARs) and increasing cAMP in sinoatrial node (SAN) myocytes while phosphodiesterases (PDEs) degrade cAMP. Chronotropic incompetence, the inability to regulate heart rate (HR) in response to sympathetic nervous system activation, is common in hypertensive heart disease; however, the basis for this is poorly understood. The objective of this study was to determine the mechanisms leading to chronotropic incompetence in mice with angiotensin II (AngII)-induced hypertensive heart disease. C57BL/6 mice were infused with saline or AngII (2.5 mg/kg/day for 3 weeks) to induce hypertensive heart disease. HR and SAN function in response to the β-AR agonist isoproterenol (ISO) were studied in vivo using telemetry and electrocardiography, in isolated atrial preparations using optical mapping, in isolated SAN myocytes using patch-clamping, and using molecular biology. AngII-infused mice had smaller increases in HR in response to physical activity and during acute ISO injection. Optical mapping of the SAN in AngII-infused mice demonstrated impaired increases in conduction velocity and altered conduction patterns in response to ISO. Spontaneous AP firing responses to ISO in isolated SAN myocytes from AngII-infused mice were impaired due to smaller increases in diastolic depolarization (DD) slope, hyperpolarization-activated current (If), and L-type Ca2+ current (ICa,L). These changes were due to increased localization of PDE4D surrounding β1- and β2-ARs in the SAN, increased SAN PDE4 activity, and reduced cAMP generation in response to ISO. Knockdown of PDE4D using a virus-delivered shRNA or inhibition of PDE4 with rolipram normalized SAN sensitivity to β-AR stimulation in AngII-infused mice. AngII-induced hypertensive heart disease results in impaired HR responses to β-AR stimulation due to up-regulation of PDE4D and reduced effects of cAMP on spontaneous AP firing in SAN myocytes.

(Invited) Aerosol Jet and Laser Assisted Electrochemical Deposition for Advanced Metallization

The inkjet printing technology for conductive patterns is commonly conducted with inks that are made of metal nanoparticles or based on metal-organic decomposition. An additional step of sintering, which is usually done in oven or on a hot plate, is required after inkjet printing to obtain metallic patterns with desired electrical conductivity [1]. Laser-induced selective metal deposition on metallic and non-metallic substrates has been the subject of much attention recently. An induced deposition rate several orders of magnitude greater than conventional rates is claimed to occur at points where a laser beam impinges the electrode surface [2].In this work, electrolytic and electroless deposition processes are combined with aerosol jet technology and laser assisted setups to induce local metallization on metallic and non-metallic substrates. Single metals and alloys deposition will be discussed according to compatibility with the substrates, selectivity and achievable feature size. Examples of microfabrication and selective decorative applications will be provided, together with an evaluation of the properties of the produced deposits. J-J. Chen, Fabrication of conductive copper patterns using reactive inkjet printing followed by two-step electroless plating, Applied Surface Science 396 (2017) 202–207.R. Khan, Laser-Induced Selective Deposition on Metal Using Electroless Gold, NASF SURFACE TECHNOLOGY WHITE PAPERS 84 (2019) 6-13.

Resynchronization for shifting conduction patterns - When a coronary sinus lead is not enough

Resynchronization for shifting conduction patterns - When a coronary sinus lead is not enough

Effect of dual sintering with laser irradiation and thermal treatment on printed copper nanoparticle patterns

The dual sintering of copper (Cu) nanoparticles (NPs) was introduced to produce conductive patterns suitable for flexible electronics applications. In this method, laser irradiation using a Nd:YAG laser with a wavelength of 1064 nm was performed at laser powers of 400, 600 and 800 mJ. The laser irradiation time was 15 and 30 s for each laser power. After laser irradiation, all of the Cu NP patterns were thermally sintered under formic acid vapors. The temperature and time for thermal treatment were selected as 260 °C and 15 min, respectively. The resultant physical, chemical, electrical and mechanical properties were evaluated and compared considering the six different dual sintering conditions. The Cu NP patterns sintered using 800 mJ for 30 s showed increased necking and coalescence compared to the other patterns and featured a microstructure with increased density. Despite being oxidized, the Cu NP patterns sintered with 800 mJ for 30 s showed the lowest electrical resistivity of 11.25 μΩ cm. The surface of every sintered Cu pattern was oxidized, and mechanical hardness increased with increasing laser power. The Cu NP pattern sintered with 800 mJ for 30 s demonstrated the highest hardness of 48.64 N mm−2. After sintering using the six different conditions, the Cu NP patterns exhibited a weight loss of 0.02–3.87 wt%, and their roughness varied in the range of 26.15–74.08 nm. This can be attributed to the effective removal of organic residues and the degree of particle agglomeration. After performing folding tests up to 50 cycles, Cu NP patterns showed an upward trend in resistance with increasing laser power and time. The highest and lowest resistance ratios were observed as 3.97 and 17.24 for the patterns sintered at 400 mJ for 15 s and 800 mJ for 30 s, respectively.