Conductive Patterns Research Articles

Nacre-Like Reduced Graphene Oxide/Silver Nanowire Paper With Reinforced Chemical and Electrical Stability for Fast Electrical Heating System

Silver nanowire (AgNW) has excellent thermal conductivity, which is an ideal material for fabricating flexible electrical heating materials. However, the poor stability of AgNWs is far from meeting the requirements for the practical application of electrical heating materials. Herein, by imitating the layered structure of nacre, the reduced graphene oxide (rGO)/AgNWs paper with a nacre-like structure was successfully prepared using a simple gravity-induced deposition approach. The obtained rGO/AgNWs paper showed excellent electrical conductivity (19.61 Ω/sq) and good pattern adjustability at the rGO to AgNWs ratio of 1:1. More importantly, the rGO/AgNWs paper exhibited high resistance to oxygen and water vapor, thus realizing long-term stability and reliability. Moreover, the design of a nacre-like structure could improve the thermal management performances of rGO/AgNWs paper, making it achieve a high Joule heating temperature (∼215.83°C) at low supplied voltages (3 V), the rapid response time (∼12 s) and long-term heating stability. These results indicate that the prepared rGO/AgNWs paper promises to be an electrical heating component with high chemical stability for thermal management electric materials.

Deciphering Stomach Myoelectrical Slow Wave Conduction Patterns via Confocal Imaging of Gastric Pacemaker Cells and Fractal Geometry.

Interstitial Cells of Cajal (ICC) are specialized gastrointestinal (GI) pacemaker cells that generate and actively propagate slow waves of depolarization (SWs) of the muscularis propria. SWs regulate the motility of the GI tract necessary for digestion, absorption of nutrients, and elimination of waste. Within the gastric wall, there are three main inter-connected layers of ICC networks: longitudinal muscle ICC (ICC-LM), myenteric plexus ICC (ICC-MP) & circumferential muscle (ICC-CM). Fractal structural parameters such as Fractal Dimension (FD), Lacunarity and Succolarity, have many advantages over physically-based parameters when it comes to characterizing the complex architectures of ICC networks. The analysis of networks of ICC throughout the proximal and distal murine gastric antrum with the FD and Lacunarity metrics was previously performed. Although the application of Succolarity is relatively nascent compared to the FD and Lacunarity; nevertheless, numerous studies have demonstrated the capability of this fractal measure to extract information from images associated with flow by which neither the FD nor Lacunarity are capable of discerning. In this study, Succolarity analysis of ICC-MP and ICC-CM networks were performed with confocal images taken across the proximal and distal murine antrum. Our findings demonstrated the Succolarity of ICC-MP and ICC-CM varied with directions and antral regions. The Succolarity of ICC-MP did not vary considerably with direction, however, Succolarity was higher in the aboral direction with 0.2113 ±0.1589, and 0.0637 ±0.0822 in the proximal and distal antrum, respectively. The overall Succolarity of ICC-MP was significantly higher than that of ICC-CM in the proximal antrum ( 0.1580±0.1325 vs [Formula: see text]) and in the distal antrum ( 0.0449 ±0.0409 vs [Formula: see text]). Clinical Relevance-Modeling SWs conduction patterns via image analysis of detailed ICC networks help to facilitate an improved understanding of the mechanisms underpinning GI myoelectric activity and the diseases associated with its dysfunction.

Magnetically Actuated Reconfigurable Metamaterials as Conformal Electromagnetic Filters

Electromagnetic (EM) metamaterials with tailored properties are developed for wave manipulation, filtering, and cloaking for aerospace and defense applications. While traditional EM metamaterials exhibit fixed behaviors due to unchangeable material properties and geometries after fabrication, reconfigurable EM metamaterials allow for tunable performance through electrical/mechanical reconfiguration strategies. Traditional biasing circuit‐based electrical reconfiguration poses challenges due to complex circuit design, while motor‐driven mechanical reconfiguration can lead to bulky and tethered structures with restricted adaptability. Herein, magnetically actuated structurally reconfigurable EM metamaterials with enhanced adaptability/conformability to different geometries, showing merits of fast, reversible, and programmable shape morphing, are developed. Magnetic actuation enables metamaterial's mechanical reconfiguration between flat deployed, flat folded, curved deployed, and curved folded states for both conformal and freestanding 3D shape morphing. Locally, the EM metamaterials fold subwavelength units for tunable properties, switching between all‐pass and band‐stop behaviors upon structural reconfiguration. Globally, the structure can conform and morph to different curved surfaces. The structurally reconfigurable metamaterial also serves as a medium for customizable subwavelength units by rationally designing attached conductive patterns for varied filtering performances such as narrow‐band, dual‐band, and wide‐band filtering behaviors, illustrating the design flexibility and application versatility of the developed structurally reconfigurable EM metamaterial.

Icariin attenuates excessive alcohol consumption-induced susceptibility to atrial fibrillation through SIRT3 signaling

Excessive alcohol consumption has long been identified as a risk factor for adverse atrial remodeling and atrial fibrillation (AF). Icariin is a principal active component from traditional Chinese medicine Herba Epimedii and has been demonstrated to exert potential antiarrhythmic effect. The present study was designed to evaluate the effect of icariin against alcohol-induced atrial remodeling and disruption of mitochondrial dynamics and furthermore, to elucidate the underlying mechanisms. Excessive alcohol-treated C57BL/6 J mice were infected with serotype 9 adeno-associated virus (AAV9) carrying mouse SIRT3 gene or negative control virus. Meanwhile, icariin (50 mg/kg/d) was administered to the animals in the presence or absence of AAV9 carrying SIRT3 shRNA. We noted that 8 weeks of icariin treatment effectively attenuated alcohol consumption-induced atrial structural and electrical remodeling as evidenced by reduced AF inducibility and reversed atrial electrical conduction pattern as well as atrial enlargement. Furthermore, icariin-treated group exhibited significantly enhanced atrial SIRT3-AMPK signaling, decreased atrial mitoSOX fluorescence and mitochondrial fission markers, elevated mitochondrial fusion markers (MFN1, MFN2) as well as NRF-1-Tfam-mediated mitochondrial biogenesis. Importantly, these beneficial effects were mimicked by SIRT3 overexpression while abolished by SIRT3 knockdown. These data revealed that targeting atrial SIRT3-AMPK signaling and preserving mitochondrial dynamics might serve as the novel therapeutic strategy against alcohol-induced AF genesis. Additionally, icariin ameliorated atrial remodeling and mitochondrial dysfunction by activating SIRT3-AMPK signaling, highlighting the use of icariin as a promising antiarrhythmic agent in this circumstance.

Room-Temperature Annealing-Free Gold Printing via Anion-Assisted Photochemical Deposition.

Metal patterning via additive manufacturing has been phasing-in to broad applications in many medical, electronics, aerospace, and automotive industries. While previous efforts have produced various promising metal-patterning strategies, their complexity and high cost have limited their practical application in rapid production and prototyping. Herein, a one-step gold printing technique based on anion-assisted photochemical deposition (APD), which can directly print highly conductive gold patterns (1.08 × 107 S m-1 ) under ambient conditions without post-annealing treatment, is introduced. Uniquely, the APD uses specific ion effects with projection lithography to pattern Au nanoparticles and simultaneously sinter them into tunable porous gold structures. The significant influence of kosmotropic or chaotropic anions in the precursor ink on tuning the morphologies and conductivities of the printed patterns by employing a series of different ions, including Cl- ions, in the printing process is presented. Additionally, the resistance stabilities and the electrochemical properties of the APD-printed gold patterns are carefully investigated. The high conductivity and excellent conformability of the printed Au electrodes are demonstrated with reliable performance in electrophysiological signal delivery and acquisition for biomedical applications. This work exploits the potential of photochemical-deposition-based metal patterning in flexible electronic manufacturing.

Occurrence, sources, and spatial distribution of fluoride in the Ganga alluvial aquifer, India.

Groundwater contamination throughout India is a global concern as it feeds more than a billion people. Of all the contaminants, fluoride (F) is one of the most widespread and well documented since its toxic nature pose serious threats to human health. In India, groundwater F concentrations have been extensively studied over the past decades. These studies have generally concluded that the groundwater F concentrations are typically higher than the drinking water standard for human health. Here, we present the occurrence, distribution, and sources of groundwater F in the Kanpur Nagar and Kanpur Dehat districts covering ~ 6000 km2 of the area in the central part of the Ganga Basin. The result revealed significant spatial variability indissolved F concentration ranging between 0.2 and 5.2mg/L (average 0.9 ± 0.7mg/L, n = 172, 1 SD), which is beyond the drinking water guideline (0.5-1.5mg/L) of the Indian Standards. We find that 31% of groundwater sampled have F content below the optimal requirement of 0.5-1.0mg/L causing dental caries problems. The F levels only exceeded the safe drinking water limit of 1.5mg/L in 8% of the groundwater sampled mostly in the urban regions. Fluoride distribution shows a closer resemblance with the spatial distribution pattern of electrical conductivity, and total dissolved solids demonstrate that F in the shallow alluvial aquifers is largely derived from geogenic sources. This is further confirmed by a strong positive correlation (r = 0.91, p < 0.05) observed between chloride-normalized concentration of F and the sum of geogenic elements (∑Li, Rb, Sr, Ba). We additionally performed health risk assessments, which revealed that children are most vulnerable to dental caries (commonly known as tooth decay) and dental fluorosis problems. As F concentrations show large spatial variability in the studied aquifer, we suggest that uniform application of a single de-fluoridation and fluoridation technology on an aquifer or sub-aquifer scale without a detailed well-designed groundwater F survey will have an adversehealth impact on local residentsas optimal level of F in drinking water may not be compromised.

A prospective observational study of ototoxicity in head and neck cancers treated with chemoradiotherapy

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Head and neck cancer is a major global health problem. Cisplatin has been widely used in the treatment of head and neck malignancies. Ototoxicity is considered as the primary outcome of interest and the type of hearing loss is the secondary variable of interest. The Chi-square test/Fisher’s exact test is used to test statistical significance. P value&amp;lt;0.05 is considered statistically significant. IBM statistical package for the social sciences (SPSS) version 22 is used for statistical analysis.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; In this prospective observational study, 62 patients with head and neck cancers were evaluated for chemoradiotherapy-induced ototoxicity. The hearing assessment included air and bone conduction thresholds, frequency, and pattern of hearing loss. The assessment was done at baseline, at the end of treatment, and after 8 weeks of completion of chemoradiotherapy. &lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; Results showed the mean age group to be, between 61 to 70 years. Gender distribution showed that 80.65% are males and 19.35% are females. The most common site of malignancy is the larynx (20.97%). Cisplatin is used in 51 patients (82.26%) and carboplatin in 7 patients (11.29%). Radiotherapy was given to 82.26% of the patients. Results showed an increased incidence of sensorineural hearing loss (SNHL) after 8 weeks of treatment. There was a statistically significant difference between pure tone average (PTA) values before treatment, at the end of treatment, and after 8 weeks of chemoradiotherapy.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; Pure-tone hearing threshold was most affected at 8 kHz and sensorineural hearing loss at higher frequencies is the most common finding.&lt;/p&gt;

Design and printing of embedded conductive patterns in liquid crystal elastomer for programmable electrothermal actuation

ABSTRACT Here we developed a novel strategy to predict and control the electrothermal property and deformation pattern of electrically stimuli-responsive structures by printing programmable conductive patterns inside liquid crystal elastomer (LCE). It was found that the printed conductive patterns had excellent electrothermal performance and can be heated up to 120°C within 12 s under the stimulus of an applied voltage. By controlling the width and spacing of the conductive lines, the electrothermal temperature of bilayer LCE structures can be regionally modulated, which subsequently determines the structural deformation for desired actuation. A finite element simulation method was established to accurately predict the effect of different conductive pattern design on the final deformation profiles, which showed a good consistence to the experimental results. The presented strategy exhibited unique capability in fabricating conductive pattern-embedded electrothermal structures for various programmable deformations like wing flapping, soft robot crawling and finger bending.

Application of Ag@Cu Water-Based Nanomaterial Conductive Ink in 3D Printing.

Copper (Cu) nanoparticles are considered a promising alternative to silver (Ag) and gold (Au) for printed electronics applications. Because Cu has higher electrical conductivity, it is significantly cheaper than Ag and Au. To study the applicability of electronic printing, we prepared Ag@Cu conductive ink by using a stepwise feeding method to disperse nano Ag and nano Cu in ethanol and water. The ink has the advantages of nontoxic, low content, and low cost. A three-dimensional (3D) model was designed, and a conductive pattern was printed on the photo paper substrate using extrusion 3D printing technology. The influence of waterborne resin on the adhesion of conductive patterns is discussed. The printed conductive pattern can maintain the stability of conductivity after 100 bending cycles. The conductive pattern has good thermal stability. It can be tested 10 times under 2 conditions of 85°C and room temperature to maintain good conductivity. This shows that Ag@Cu conductive ink printed flexible electronic products are competitive.

Dispenser Printing with Electrically Conductive Microparticles

Electrically conductive textiles for wearable smart devices are in increasing demand [1]. The advantages of flexible fabric structures are combined with electronic functions, such as sensing or actuating, energy harvesting or illuminating, for the design of a multitude of smart textiles. Those functions are often created by applying conductive layers or patterns onto the textile surface with two-phase systems based on conductive filler particles in polymeric binders. However, those systems alter the textile-typical properties regarding haptic, drape, flexibility or weight, depending on the type of conductive particle used, i.e., metal-or carbon-based ones. Generally, electrical conductivity increases with the increase of conductive filler concentration. The relation between the various factors determining the electrical behavior as well as the percolation threshold for some dispersions and in particular the size and shape of the filler particles were previously assessed for planar coatings [2]. In this research work electrically, conductive patterns were printed with dispenser printing technology using such two-phase dispersions based on polyurethane and polyacrylate binders and various metal microparticle flakes. With this application method linear resistance of approx. 25 to 100 Ohm per 100 cm depending on the textile structure could be realized, which was not even significantly reduced by household washing at 40°C or abrasion by Martindale.

Reconfigurable photoinduced terahertz wave modulation using hybrid metal-silicon metasurface.

We present a photoinduced reconfigurable metasurface to enable high spatial resolution terahertz (THz) wave modulation. Conventional photoinduced THz wave modulation uses optically induced conductive patterns on a semiconductor substrate to create programmable passive THz devices. The technique, albeit versatile and straightforward, suffers from limited performance resulting from the severe lateral diffusion of the photogenerated carriers that undermines the spatial resolution and conductivity contrast of the photoinduced conductive patterns. The proposed metasurface overcomes the limitation using a metal-jointed silicon mesa array with subwavelength-scaled dimensions on an insulator substrate. The structurephysically restrains the lateral diffusion of the photogenerated carriers while ensuring the electrical conductivity between the silicon mesas , which is essential for THz wave modulation. The metasurface creates high-definition photoconductive patterns with dimensions smaller than the diffusion length of photogenerated carriers. The metasurface provides a modulation depth of -20 to -10 dB for the THz waves between 0.2 to 1.2 THz and supports a THz bandpass filter with a tunable central frequency. The new, to the best of our knowledge, design concept will benefit the implementation of reconfigurable THz devices.

High-density sequential mapping of repetitive atrial conduction patterns during atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported by PersonalizeAF project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 860974. Background Localized AF drivers are considered candidate ablation targets for patients with persistent atrial fibrillation (AF). These drivers are expected to be associated with repetitive atrial conduction patterns during AF. Thus, tools that localize atrial sites with repetitive electrical activity might be instrumental in guiding ablation. Purpose High-density mapping catheters cover only a small portion of the atria. Combining sequential recordings from those catheters could provide a more complete picture of repetitive conduction patterns, and enable AF driver localization. We hypothesize that the repetitive activity generated by local AF drivers can be detected by means of high-coverage composite activation maps generated from spatially overlapping sequential recordings. Methods Repetitive conduction patterns were detected in a goat model of AF (249-electrode epicardial mapping array, 2.4mm inter-electrode distance, n=16) by exploiting recurrence plots (Fig 1A-C). Cross-recurrences of repetitive patterns in sequential recordings were detected in spatially overlapping recording locations. Using this information, local activation maps were aligned and combined into larger composite average activation maps (Fig. 1D-F). The proposed algorithm was tested on a dataset formed by segmenting the epicardial mapping area into four spatially overlapping regions. The proposed algorithm was then used to merge these segmented regions back together to reconstruct the original mapping area. Reconstruction accuracy was measured as the correlation between original and reconstructed average activation patterns (Fig. 2.). Statistical analyses were performed to investigate a possible relation between reconstruction accuracy and pattern properties such as duration, size, complexity, and cycle length. Patterns were classified as single peripheral, multiple waves, focal source, or re-entry based on the preferential conduction velocity directions. Results Among 1021 detected repetitive patterns, 328 spatiotemporally stable- patterns were present in all four artificially segmented recordings. In 32% of these, repetitiveness was associated with a local driver-either focal or re-entrant. Composite maps could be generated in 75% of the cases, and mainly in case of larger patterns (p&amp;lt;0.01). The average correlation between the actual activation maps and the composite maps was 0.86 ±0.16. Only pattern duration showed a statistically significant low correlation with reconstruction accuracy of composite maps (r=0.126, p&amp;lt;0.05). There was no significant difference in the reconstruction accuracy for multiple waves, focal sources and re-entries. Conclusion(s) The proposed framework could align sequentially recorded repetitive epicardial patterns over different atrial regions, to produce high-fidelity composite maps. The performance was minimally affected by pattern properties, thus suggesting potential use with a diverse range of AF patterns.

Left bundle branch pacing preserves ventricular mechanical synchrony better than right ventricular pacing-a two-center study

Abstract Funding Acknowledgements Type of funding sources: None. Background Left bundle branch pacing (LBBP) has emerged as a novel pacing method. We sought to evaluate left ventricular (LV) mechanical synchrony under permanent LBBP and compare it with conventional and leadless right ventricular pacing (CRVP, LRVP). Methods Sixty-four patients with pacing indication for bradycardia were prospectively enrolled. Twenty-two patients received LBBP in the basal ventricular septum. Twenty-three patients received CRVP and 19 LRVP. All patients underwent echocardiography before and after device implantation. Myocardial work was estimated by pressure-strain analysis. Regional work in the septum (SEP) and lateral wall (LW) was calculated as the average from the respective basal and mid-ventricular segments in the apical four-chamber and three-chamber view. The absolute difference between work in LW and SEP (LW-S-work difference) was used as a measure of asymmetry in workload. Results Baseline characteristics were similar among the three groups. The electrocardiogram during LBBP showed a right bundle branch block pattern; during CRVP and LRVP a left bundle branch block pattern. The paced QRS duration was 114.27±9.9 ms in the LBBP group, significantly shorter than that in the CRVP and LRVP groups (153.9±25.26 ms and 159.1±13.99ms, respectively, both p&amp;lt;0.001). The SEP work decreased in all groups during ventricular pacing (all P&amp;lt;0.05), while the LW work remained similar. The paced LW-S work difference and work difference change between pacing on and off were more significant in the CRVP (1012.9±566.0mmHg*%) and LRVP group (1066.1±472.6mmHg*%) than the LBBP group (260.5±239.8mmHg*%, both P&amp;lt;0.001). In addition, LW-S work difference during ventricular pacing and work difference change between pacing and baseline were comparable in CRVP and LRVP group. Conclusion LBBP causes less LV dyssynchrony than CRVP and LRVP as it preserves a more physiologic conduction pattern. CRVP and LRVP did not differ in this respect. Further studies need to prove that LBBP has advantages over RVP with regards to preservation of LV synchrony and contractility.

Electrical Conductivity of Clayey Rocks and Soils: A Non‐Linear Model

AbstractIt is well‐accepted that Archie's law is only applicable to “clean” rocks and soils but fails in “dirty” ones where clay minerals possess an additional component of surface conductivity. Although several models, for example, Waxman‐Smits model, were presented to account for this phenomenon, surface conductivity is always inappropriately treated as constant, which actually only holds at high salinities. The essential non‐linear characteristic differing over fluid salinities has not been physically or mathematically explained well in those models. We scrutinize the conduction mechanism of clayey rocks and soils and ascribe this non‐linear feature to (a) variation of the electrical double layer and (b) the intrinsic clay‐and‐water conduction pattern. With effective medium theory, we develop an easy‐to‐use non‐linear model that both reflects electrochemical theories and explains the measurement data well. Our model can be used to produce more accurate results for laboratory‐ and field‐scale petrophysical parameter evaluations than the previous models.

Novel Genetic Algorithm (GA) based hybrid machine learning-pedotransfer Function (ML-PTF) for prediction of spatial pattern of saturated hydraulic conductivity

Saturated hydraulic conductivity (Ks) is an important soil characteristic that controls water moves through the soil. On the other hand, its measurement is difficult, time-consuming, and expensive; hence Pedotransfer Functions (PTFs) are commonly used for its estimation. Despite significant development over the years, the PTFs showed poor performance in predicting Ks. Using Genetic Algorithm (GA), two hybrid Machine Learning based PTFs (ML-PTF), i.e. a combination of GA with Multilayer Perceptron (MLP-GA) and Support Vector Machine (SVM-GA), were proposed in this study. We compared the performances of four machine learning algorithms for different sets of predictors. The predictor combination containing sand, clay, Field Capacity, and Wilting Point showed the highest accuracy for all the ML-PTFs. Among the ML-PTFs, the SVM-GA algorithm outperformed the rest of the PTFs. It was noticed that the SVM-GA PTF demonstrated higher efficiency than the MLP-GA algorithm. The reference model for hydraulic conductivity prediction was selected as the SVM-GA PTF paired with the K-5 predictor variables. The proposed PTFs were compared with 160 models from past literature. It was found that the algorithms advocated were an improvement over these PTFs. The current model would help in efficient spatio-temporal measurement of hydraulic conductivity using pre-available databases.

Vacuum-Formed 3D Printed Electronics: Fabrication of Thin, Rigid and Free-Form Interactive Surfaces

Vacuum-forming is a common manufacturing technique for constructing thin plastic shell products by pressing heated plastic sheets onto a mold using atmospheric pressure. Vacuum-forming is ubiquitous in packaging and casing products in the industry, spanning fast moving consumer goods to connected devices. Integrating advanced functionality, which may include sensing, computation and communication, within thin structures is desirable for various next-generation interactive devices. Hybrid additive manufacturing techniques like thermoforming are becoming popular for prototyping freeform surfaces owing to their design flexibility, speed and cost-effectiveness. This paper presents a new hybrid method for constructing thin, rigid and free-form interconnected surfaces via fused deposition modelling (FDM) 3D printing and vacuum-forming that builds on recent advances in thermoforming circuits. 3D printing the sheet material allows for the embedding of conductive traces within thin layers of the substrate, which can be vacuum-formed but remain conductive and insulated. This is an unexplored fabrication technique within the context of designing and manufacturing connected things. In addition to explaining the method, this paper characterizes the behavior of vacuum-formed 3D printed sheets, analyses the electrical performance of printed traces after vacuum-forming, and showcases a range of sample artefacts constructed using the technique. In addition, the paper describes a new design interface for designing conformal interconnects that allows designers to draw conductive patterns in 3D and export pre-distorted sheet models ready to be printed.

Bio-Based Polymeric Substrates for Printed Hybrid Electronics

Printed flexible hybrid electronics (FHE) is finding an increasing number of applications in the fields of displays, sensors, actuators and in energy harvesting and storage. The technology involves the printing of conductive and insulating patterns as well as mounting electronic devices and circuits on flexible substrate materials. Typical plastic substrates in use are, for example, non-renewable-based poly(ethylene terephthalate) (PET) or poly(imides) (PI) with high thermal and dimensional stability, solvent resistance and mechanical strength. The aim of this study was to assess whether renewable-based plastic materials can be applied on sheet-to-sheet (S2S) screen-printing of conductive silver patterns. The selected materials were biaxially oriented (BO) bio-based PET (Bio-PET BO), poly(lactic acid) (PLA BO), cellulose acetate propionate (CAP BO) and regenerated cellulose film, NatureFlex™ (Natureflex). The biaxial orientation and annealing improved the mechanical strength of Bio-PET and PLA to the same level as the reference PET (Ref-PET). All renewable-based substrates showed a transparency comparable to the Ref-PET. The printability of silver ink was good with all renewable-based substrates and printed pattern resistance on the same level as Ref-PET. The formation of the printed pattern to the cellulose-based substrates, CAP BO and Natureflex, was very good, showing 10% to 18% lower resistance compared to Ref-PET and obtained among the bio-based substrates the smallest machine and transverse direction deviation in the S2S printing process. The results will open new application possibilities for renewable-based substrates, and also potentially biodegradable solutions enabled by the regenerated cellulose film and PLA.

PO-639-08 IDENTIFICATION OF CONDUCTION PATTERNS DURING ATRIAL FIBRILLATION USING ARTIFICIAL INTELLIGENCE: HOLISTIC FULL CHAMBER VIEW

Atrial fibrillation (AF) is thought to be maintained by reentrant and focal driver regions that may have some spatial-temporal stability. Recently, several cardiac mapping systems have implemented algorithms for automatic detection of these arrhythmogenic conduction patterns (CPs) during AF. Many of these algorithms divide the atrium into overlapping patches, sequentially analyzing each patch with the driver identification algorithms. Patch-based analyses may misrepresent local CPs as the number and trajectory of wavefronts entering and leaving the analyzed patch are uncertain. However, when a holistic view of chamber-wide activation is used, machine learning algorithms can ubiquitously identify arrhythmogenic CPs. Develop and evaluate a machine learning approach that can automatically identify and locate arrhythmogenic CPs. Propagation maps of clinical AF from nine patients were transformed into a 2D image space using conformal mapping, and these images were used to train and evaluate a UNet architecture model. Rotational and focal CPs were identified by the AcQTrack algorithm (Acutus Medical) and manually confirmed. The clinical dataset was supplemented with eikonal simulations of focally (n=400) and rotationally driven (n=200) AF, where the time and location of the rotational and focal drivers were randomized and known. The UNet architecture was trained using five of the clinical AF cases (n=7,880 frames) and simulated AF (200 focal and 100 rotational simulations, n=14,380 frames). A test set, consisting of five clinical AF cases (n=6,172 frames) and simulated AF (200 focal and 100 rotational simulations, n=14382 frames), were independently used to evaluate the model performance. The UNet model accurately detected the time and location of arrhythmogenic CPs in the atrium - Clinical AF DICE 0.91 and Simulated AF DICE 0.98. The presented machine learning approach can accurately identify and locate arrhythmogenic targets. It has potential to overcome limited view problem in detecting arrhythmogenic targets that is inherent problem of patch-based heuristic algorithms.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

PO-691-01 PHYSIOLOGIC, REALISTIC, COMPUTER MODELING OF ATRIAL FIBRILLATION TO FACILITATE THE DEVELOPMENT AND TESTING OF TREATMENT STRATEGIES

An interactive, physiologically realistic (PR), and accurate computer simulation allows multiple scenarios to be tested in a “live” environment and has become a key step in the rapid development and testing of treatment strategies for atrial fibrillation (AF). Develop an accurate model of AF that allows the user to define the regions and zones of anisotropic conduction to test the effectiveness of a variety of AF treatment strategies. A model was developed using standard electrophysiologic (EP) parameters established in the literature. An advanced implementation of the Fitzhugh-Nagumo model reproduces the action potential morphology of the human atrium enabling live simulation. To reproduce the complex conduction patterns (CCPs) of AF identified in the EP lab, a bi-layer model was implemented to represent epi- and endocardial dissociation. The model allows a user to define regions of fibrosis, zones of slow conduction, and action potential duration (APD). The user graphically draws these regions and zones with gradients that span entered max and min values of conduction velocity (CV) and APD. The EP lab experience and workflow is reproduced, with CCPs visualized on a 3D anatomy and calculated potentials displayed as 2D traces. To test the CCPs and performance of the model, isolated zones of conduction were delineated on a 3D LA model, with assigned sites of pacing and recording. Model produces accurate atrial CCPs for anatomical meshes > 20k triangles, with expected source-sink block-velocity < 5 cm/s (Figure 1). Regions of anisotropic conduction were applied to match a human AF substrate mapped by Acutus AcQMap, with PVI-block plus 2 anterior, 1 posterior, 1 roof, 1 mitral-isthmus slow conduction zones (0.1 - 50 cm/s); 1 anterior APD zone (65 - 110 ms); and anterior and posterior regions of endo-epi fibrosis (density = 25%, CV = 8 - 25 cm/s). Model produced similar CCPs to human with rotational and pivoting reentry at the same locations (Figure 2). A PR model of AF was developed that allows a user to define regions of fibrosis and zones of conduction abnormalities prominent in AF. The model can be used for developing and testing advanced treatment strategies. Clinical application is feasible, including input of procedural data to achieve optimal treatment strategies.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

PO-690-08 REPETITIVE CONDUCTION PATTERNS IN ATRIAL FIBRILLATION: SPATIAL RELATIONSHIP WITH RE-ENTRANT DRIVERS

the outcome of catheter ablation for treatment of atrial fibrillation (AF) is still suboptimal, possibly due to the difficulty in localizing arrhythmic sources outside the pulmonary veins. Such AF sources may generate repetitive conduction patterns in their vicinity, which could aid in their localization.