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Abstract The efficacy of flow diverters is influenced by the strut configuration changes resulting from size discrepancies between the stent and the parent artery. This study aimed to quantitatively analyze the impact of size discrepancies between flow diverters and parent arteries on the flow diversion effects, using computational fluid dynamics. Four silicone models with varying parent artery sizes were developed. Real flow diverters were deployed in these models to assess stent configurations at the aneurysm neck. Virtual stents were generated based on these configurations for computational fluid dynamics analysis. The changes in the reduction rate of the hemodynamic parameters were quantified to evaluate the flow diversion effect. Implanting 4.0 mm flow diverters in aneurysm models with parent artery diameters of 3.0–4.5 mm, in 0.5 mm increments, revealed that a shift from oversized to undersized flow diverters led to an increase in the reduction rates of hemodynamic parameter, accompanied by enhanced metal coverage rate and pore density. However, the flow diversion effect observed transitioning from oversizing to matching was less pronounced when moving from matching to undersizing. This emphasizes the importance of proper sizing of flow diverters, considering the benefits of undersizing and not to exceed the threshold of advantages.

Abstract Computational fluid dynamics (CFD) has been utilized to calculate hemodynamic parameters in anterior communicating artery aneurysm (AComA), which is located at a junction between left and right A1 and A2 segments. However, complete or half circle of Willis (CoW) models are used indiscriminately. This study aims to suggest recommendations for determining suitable CoW model. Five patient-specific CoW models with AComA were used, and each model was divided into complete, left-half, and right-half models. After validating the CFD using a flow experiment, the hemodynamic parameters and flow patterns in five AComAs were compared. In four out of five cases, inflow from one A1 side had a dominant influence on the AComA, while both left and right A1 sides affected the AComA in the remaining case. Also, the average difference in time-averaged wall shear stress between the complete and half models for four cases was 4.6%, but it was 62% in the other case. The differences in the vascular resistances of left and right A1 and A2 segments greatly influenced the flow patterns in the AComA. These results may help to enhance clinicians’ understanding of blood flow in the brain, leading to improvements in diagnosis and treatment of cerebral aneurysms.

Although wire arc additive manufacturing (WAAM) of Ti alloys using gas metal arc yields a high deposition rate, cathode spots exhibit unstable behavior. In this study, the cold-metal-transfer process and an electrode-negative (EN) polarity were used in the WAAM process of the Ti–6Al–4V alloy. High-speed imaging was performed to investigate the mechanisms to stabilize cathode plasma jets, arc plasma, and molten metal transfer in the EN polarity. Arc plasma and cathode jets had the same direction, and sound cathode jets were shrouded by arc plasma in the EN mode. The metal transfer was also stabilized by balanced plasma formation under the EN mode, and inconsistent wire melting under the electrode-positive (EP) mode was mitigated. In the deposition test using the EN mode, distributed heating of the substrate and depressed molten pool were observed, which resulted in a 21.0% increase in the bead width and 27% decrease in the wetting angle compared with the EP mode. This study demonstrated that the instability of the gas metal arc WAAM process of Ti alloys can be overcome with the EN-mode cold metal arc process.

Abstract In the hemodynamic study, computational fluid dynamics (CFD) analysis has shown that high wall shear stress (WSS) is an important parameter in cerebral aneurysm formation. However, CFD analysis is not more realistic than fluid–structure interaction (FSI) analysis given its lack of considering the involvement of vascular structures. To investigate the relationship between the hemodynamic parameters and the aneurysm formation, the locations of high WSS and high strain were extracted from the CFD and FSI analyses, respectively. Then the distances between the aneurysm formation site and the locations of high WSS or high strain were calculated. A total of 37 intracranial paraclinoid aneurysms were enrolled for quantitative comparison. Additionally, the dura mater was modeled to facilitate realistic results in FSI analysis. The average distance from the location of the aneurysm formation site to the high strain (1.74 mm $$\pm $$ ± 1.04 mm) was smaller than the average distance to the high WSS (3.33 mm $$\pm $$ ± 1.18 mm). The presence of dura mater also influenced the findings in the aneurysm formation site. High strain extracted by FSI analysis is an important hemodynamic factor related to the formation of cerebral aneurysms. Strain parameter could help to predict the formation of aneurysms and elucidate the appropriate treatment.

Purpose: The flow diversion effect of an intracranial stent is closely related to its metal coverage rate (MCR). In this study, the flow diversion effects of Enterprise and low-profile visualized intraluminal support (LVIS) stents are compared with those of a Pipeline flow diverter, focusing on the MCR change. Moreover, the changes in the flow diversion effect caused by the additional manipulations of overlapping and compaction are verified using computational fluid dynamics (CFD) analysis.Methods: CFD analysis was performed using virtually generated stents mounted in an idealized aneurysm model. First, the flow diversion effects of single Enterprise, LVIS, and Pipeline devices were analyzed. The Enterprise and LVIS were sequentially overlapped and compared with a Pipeline, to evaluate the effect of stent overlapping. The effect of compacting a stent was evaluated by comparing the flow diversion effects of a single and two compacted LVIS with those of two overlapped, uncompacted LVIS and uncompacted and compacted Pipeline. Quantitative analysis was performed to evaluate the hemodynamic parameters of energy loss, average velocity, and inflow rate.Results: Statistically significant correlations were observed between the reduction rates of the hemodynamic parameters and MCR. The single LVIS without compaction induced a reduction in all the hemodynamic parameters comparable to those of the three overlapped Enterprise. Moreover, the two overlapped, uncompacted LVIS showed a flow diversion effect as large as that induced by the single uncompacted Pipeline. Compacted stents induced a better flow diversion effect than uncompacted stents. The single compacted LVIS induced a flow diversion effect similar to that induced by the two uncompacted LVIS or single uncompacted Pipeline.Conclusions: The MCR of a stent correlates with its flow diversion effect. Overlapping and compaction can increase the MCR of an intracranial stent and achieve a flow diversion effect as large as that observed with a flow diverter.

This study aims to improve the sensitivity of sensors using porous structures and cone-shaped patterns in the composition of a capacitive pressure sensor. A simple and rapid fabrication method for the production of porous structures and cone-shaped patterns using microwave irradiation of emulsions containing polydimethylsiloxane (PDMS) and a sacrificial solvent is introduced in this study. Through this method, a porous PDMS dielectric layer could be simply fabricated within a few minutes. The sensitivity was greatly improved by both enhancing deformability and increasing the dielectric constant under the external pressure. The effect of pattern distance was investigated, and the sensor with the pattern distance of 600 μm showed a remarkably high sensitivity of approximately 5 kPa−1. Moreover, the effect of aspect ratio and sharpness of the patterns were also studied through a finite element analysis. Finally, we demonstrated the performance of the sensor using a sensor array and finger attached sensors, and they showed sufficient performance for use in wearable devices applicable to artificial skin, surgical robots, and pressure monitoring systems, among others.

In recent years, innovative research has been widely conducted on flexible devices for wearable electronics applications. Many examples of wearable electronics, such as smartwatches and glasses, are already available to consumers. However, strictly speaking, the sensors used in these devices are not flexible. Many studies are underway to address a wider range of wearable electronics and the development of related fields is progressing very rapidly. In particular, there is intense interest in the research field of flexible pressure sensors because they can collect and use information regarding a wide variety of sources. Through the combination of novel materials and fabrication methods, human-machine interfaces, biomedical sensors, and motion detection techniques, it is now possible to produce sensors with a superior level of performance to meet the demands of wearable electronics. In addition, more compact and human-friendly sensors have been invented in recent years, as biodegradable and self-powered sensor systems have been studied. In this review, a comprehensive description of flexible pressure sensors will be covered, and design strategies that meet the needs for applications in wearable electronics will be presented. Moreover, we will cover several fabrication methods to implement these technologies and the corresponding real-world applications.

The fatigue life of the resistance spot weld of 980 MPa grade transformation induced plasticity (TRIP) steel was investigated and failure modes and fracture surfaces according to the fatigue load were analyzed. The fatigue life according to the nugget size was observed by using two electrodes with face diameters of 8 mm and 10 mm. When an electrode face diameter with 10 mm was used, the nugget size was large, and the fatigue life was further increased. After the fatigue test, three types of failure modes were observed, namely pull-out, plug, and heat affected zone (HAZ) failure, depending on the fatigue load. The fracture surfaces in each failure mode were analyzed. In all failure modes, a crack was initiated in the HAZ region, which is the interface between the two materials in all failure modes. In the case of pull-out failure, the crack propagates as if it surrounds the nugget at the outer edge of the nugget. In the case of HAZ failure, the crack propagates in the thickness direction of the material and outward in the nugget shell. Plug failure occurs with pull-out failure and HAZ failure mixed. The propagation patterns of cracks were different for each failure mode. The reason why the failure mode and the fracture surface are different according to the fatigue load is that the propagation speed of the fatigue crack is fast when the fatigue load is relatively large and is slow when the fatigue load is low.

The aim of this study is to design and test a new, simple, and reusable linear variable differential transformer (LVDT)-based in situ bolt preload monitoring system (L-PMS) during fastening of a truck wheel assembly. Instead of measuring the elongation of a bolt, the distance between the end surfaces of both the bolt and nut was monitored via the L-PMS. The distance obtained from the L-PMS was experimentally correlated with the actual preload measured by a washer-type load cell. Since the variation of the distance is related to the stiffness of the bolt and clamped parts, a finite element analysis was also conducted to predict the sensitivity of L-PMS. There was a strong linear relationship between the distance and bolt preload after the bolt and nut were fully snugged. However, a logarithm-shaped nonlinear relationship was irregularly observed before getting snugged, making it difficult to define a clear relationship. In order to tackle this issue, an arc-shaped conductive line was screen-printed onto the surface of the clamped parts using a conductive carbon paste. The results show that a resistance variation of the conductive line during fastening enables to determine the snug point, so the L-PMS combined with resistance measurement results in an approximately ±6% error in the measurement of bolt preload. The proposed L-PMS offers a simple but highly reliable way for measuring bolt preload during fastening, which could be utilized in a heavy-truck production line.

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Microfluidic techniques for cell manipulation have been constantly developed and integrated into small chips for high-performance bioassays. However, the drawbacks of each of the techniques often hindered their further advancement and their wide use in biotechnology. To overcome this difficulty, an examination and understanding of various aspects of the developed manipulation techniques are required. In this review, we provide the details of primary microfluidic techniques that have received much attention for bioassays. First, we introduce the manipulation techniques using a sole driving source, i.e., dielectrophoresis, electrophoresis, optical tweezers, magnetophoresis, and acoustophoresis. Next, we present rapid electrokinetic patterning, a hybrid opto-electric manipulation technique developed recently. It is introduced in detail along with the underlying physical principle, operating environment, and current challenges. This paper will offer readers the opportunity to improve existing manipulation techniques, suggest new manipulation techniques, and find new applications in biotechnology.

In this study, we investigated geometrical characteristics of the inkjet-printed lines with non-zero receding contact angle (CA) on plasma-treated substrates in terms of various printing variables and analyzed the fluidic behavior and hydrodynamic instability involved in the line formation process. The printing variables included surface energy, droplet overlap ratio, printing frequency, a number of ink droplets, substrate temperature and printing procedures. For the study, a colloidal suspension containing 56 wt % silver nanoparticles in tetradecane solvent was used as a printing ink. It has electrical resistivity of 4.7 μΩ·cm. The substrates were obtained by performing a plasma enhanced chemical vapor deposition (PECVD) process with C4F8 and O2 under various treatment conditions. As results of the experiments, the surface shape and pattern of the inkjet-printed Ag lines were dominantly influenced by the surface energy of the substrates, among the printing variables. Accordingly even when the receding CA was non-zero, bulging instability of the lines occurred forming separate circular patterns or regular bulges connected by ridges. It is a new finding of this study, which is completely different with the bulging instability of inkjet lines with zero receding CA specified by previous researches. The bulging instability decreased by increasing surface temperature of the substrates or employing interlacing procedure instead of continuous procedure for printing. The interlacing procedure also was advantageous to fabricate thick and narrow Ag lines with well-defined shape through overprinting on a hydrophobic substrate. These results will contribute greatly to not only the production of various printed electronics containing high-aspect-ratio structures but also the improvement of working performance of the devices.

Multiple aneurysms occur rarely and have not been well investigated. The purpose of this study is to verify whether high rupture risk of multiple aneurysms is due to the interaction between multiple aneurysms’ geometrical characteristics. The following geometrical characteristics were varied in an idealized sidewall-type model: aneurysm a 1 ’s dome-neck length ( S ), size ratio, inflow angle ( α ), distance between two aneurysms ( D ), and the parent vessel’s angle ( θ ). We varied the parent blood vessel and aneurysm sac a 1 ’s geometrical characteristics to analyze their hemodynamic influence on aneurysm a 2 . By comparing the influence on aneurysm a 2 , we found that parent blood vessel geometrical characteristics such as the distance between aneurysms ( D ) and the parent vessel’s angle ( θ ) were the most hemodynamically influential characteristics examined. The impact of varying the aneurysm’s geometrical characteristics such as dome-neck length ( S ), size ratio , and inflow angle ( α ) was not obvious. The reason for the higher rupture rate of multiple aneurysms is not due to interactions between the aneurysm sacs but due to factors of each individual aneurysm.

Background Numerous studies have evaluated the rupture risk of intracranial aneurysms using morphological parameters because of their good predictive capacity. However, the limitation of current morphological parameters is that they do not always allow evaluation of irregularities of intracranial aneurysms. The purpose of this study is to propose a new morphological parameter that can quantitatively describe irregularities of intracranial aneurysms and to evaluate its performance regarding rupture risk prediction. Methods In a retrospective study, conventional morphological parameters (aspect ratio, bottleneck ratio, height-to-width ratio, volume to ostium ratio, and size ratio) and a newly proposed morphological parameter (mass moment of inertia) were calculated for 125 intracranial aneurysms (80 unruptured and 45 ruptured aneurysms). Additionally, hemodynamic parameters (wall shear stress and strain) were calculated using computational fluid dynamics and fluid--structure interaction. Artificial neural networks trained with each parameter were used for rupture risk prediction. Results All components of the mass moment of inertia (Ixx, Iyy, and Izz) were significantly higher in ruptured cases than in unruptured cases (p values for Ixx, Iyy, and Izz were 0.032, 0.047, and 0.039, respectively). When the conventional morphological and hemodynamic parameters as well as the mass moment of inertia were considered together, the highest performance for rupture risk prediction was obtained (sensitivity 96.3%; specificity 85.7%; area under the receiver operating characteristic curve 0.921). Conclusions The mass moment of inertia would be a useful parameter for evaluating aneurysm irregularity and hence its risk of rupture. The new approach described here may help clinicians to predict the risk of aneurysm rupture more effectively. [ABSTRACT FROM AUTHOR]

Background Cerebral aneurysms should be treated before rupture because ruptured aneurysms result in serious disability. Therefore, accurate prediction of rupture risk is important and has been estimated using various hemodynamic factors. Objective To suggest a new way to predict rupture risk in cerebral aneurysms using a novel deep learning model based on hemodynamic parameters for better decision-making about treatment. Methods A novel convolutional neural network (CNN) model was used for rupture risk prediction retrospectively of 123 aneurysm cases. To include the effect of hemodynamic parameters into the CNN, the hemodynamic parameters were first calculated using computational fluid dynamics and fluid--structure interaction. Then, they were converted into images for training the CNN using a novel approach. In addition, new data augmentation methods were devised to obtain sufficient training data. A total of 53,136 images generated by data augmentation were used to train and test the CNN. Results The CNNs trained with wall shear stress (WSS), strain, and combination images had area under the receiver operating characteristics curve values of 0.716, 0.741, and 0.883, respectively. Based on the cut-off values, the CNN trained with WSS (sensitivity: 0.5, specificity: 0.79) or strain (sensitivity: 0.74, specificity: 0.71) images alone was not highly predictive. However, the CNN trained with combination images of WSS and strain showed a sensitivity and specificity of 0.81 and 0.82, respectively. Conclusion CNN-based deep learning algorithm using hemodynamic factors, including WSS and strain, could be an effective tool for predicting rupture risk in cerebral aneurysms with good predictive accuracy. [ABSTRACT FROM AUTHOR]

Highly sensitive capacitive pressure sensors with poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) dielectric layers were prepared. The dielectric layers were directly produced by electrospinning P(VDF-TrFE) nanofibers for various spinning times. A longer spinning time enhanced the deformability of the electrospun P(VDF-TrFE) layers, resulting in higher sensitivity owing to larger changes in the deformation of the dielectric layer. One of the capacitive pressure sensors showed a high sensitivity of 2.81 kPa-1 at a pressure ≤0.12 kPa, a good response time of 42 ms, and small hysteresis. The sensitivity of the sensor was five times higher than that of a typical capacitive pressure sensor. The fabricated pressure sensor could detect a tiny water droplet as light as 7mg. It is expected that the electrospun P(VDF-TrFE) nanofibers can be used as sensing materials for highly sensitive pressure sensors in wearable electronics applications. [ABSTRACT FROM AUTHOR]

In this study, a honeycomb-like nanofiber based triboelectric nanogenerator (HN-TENG) is presented. In order to fabricate the honeycomb-like nanofiber, we utilized self-assembly of electrospun poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) nanofibers. The honeycomb-like P(VDF-TrFE) nanofiber network was directly produced via electrospinning without any additional processing. The HN-TENG showed a maximum voltage, current, and power density of 160 V, 17 µA, and 1.6W/m2, respectively. The power density was enhanced more than twofold as compared with a typical flat nanofiber network based TENG due to the large surface area and high surface roughness of the honeycomb structure. Finally, we verified that HN-TENG has the potential to be used for practical applications by driving 100 light emitting diodes and charging capacitors. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to explore the influence of segmentation of the upstream and downstream parent artery and hemodynamic boundary conditions (BCs) on the evaluated hemodynamic factors for the computational fluid dynamics (CFD) analysis of intracranial aneurysms. Materials and Methods: Three dimensional patient-specific aneurysm models were analyzed by applying various combinations of inlet and outlet BCs. Hemodynamic factors such as velocity pattern, streamline, wall shear stress, and oscillatory shear index at the systolic time were visualized and compared among the different cases. Results: Hemodynamic factors were significantly affected by the inlet BCs while there was little influence of the outlet BCs. When the inlet length was relatively short, different inlet BCs showed different hemodynamic factors and the calculated hemodynamic factors were also dependent on the inlet length. However, when the inlet length (L) was long enough (L>20D, where D is the diameter of inlet section), the hemodynamic factors became similar regardless of the inlet BCs and lengths. The error due to different inlet BCs was negligible. The effect of the outlet length on the hemodynamic factors was similar to that of the inlet length. Conclusion: Simulated hemodynamic factors are highly sensitive to inlet BCs and upstream parent artery segmentation. The results of this work can provide an insight into how to build models and to apply BCs for more accurate estimation of hemodynamic factors from CFD simulations of intracranial aneurysms. [ABSTRACT FROM AUTHOR]

The effect of the needle shape on electrohydrodynamic (EHD) printing was investigated by comparing flat outlet needles and hypodermic needles. Line fabrication was performed to confirm the tendency of jetting stability and the printed line width with various driving voltage and stage speed by using Ag nanoparticle ink as a jetting solution on a hydrophobic surface. We verified that the hypodermic needle greatly improves the resolution in EHD printing. The ink slips down the inner wall of the hypodermic needle, and a very small meniscus is generated at the tip of the needle. Due to this phenomenon, high-resolution printing can be accomplished. The narrowest line that was fabricated using a hypodermic needle has a line width of 0.7 im, and it is smaller than 1% of the needle inner diameter. [ABSTRACT FROM AUTHOR]

A three-dimensional finite element analysis is performed to investigate the effects of fiber arrangements on the residual thermal stresses in unidirectional composites of various fiber volume fractions (FVFs). The fiber arrangements include the regular fiber arrays (square and hexagonal arrays) and a random fiber array. Normal, tangential, and shear stresses at the fiber--matrix interface are first obtained using unit cells of the regular square and hexagonal fiber arrays. To simulate better real fiber arrangements, random fiber distribution is modeled and analyzed using a finite element analysis. Statistical distributions of residual thermal stresses are obtained for various FVFs and compared with the results from regular fiber arrays. The effects of constituent material properties of composites on thermal stresses are also taken into consideration. The results indicate that the random arrangement of fibers has a significant influence on residual thermal stresses especially at high FVFs. The mode stresses of the random fibers are well estimated using the square array whereas the mean stresses are better predicted from the hexagonal array. It is shown that predicted coefficients of thermal expansion are not influenced by the microstructure of composites. [ABSTRACT FROM AUTHOR]

The micromechanical approach was used to investigate the interfacial strain distributions of a unidirectional composite under transverse loading in which fibers were usually found to be randomly packed. Representative volume elements (RVEs) for the analysis were composed of both periodic fiber arrays, such as a square array and a hexagonal array, and a random fiber array. The finite element analysis was performed to analyze the normal, tangential, and shear strains at the interface. In order to verify the RVE for describing a random fiber array, the generated RVE was statistically compared with the one constructed from typical images of a transverse cross-section of a unidirectional composite. Since the strata distributions at the interface experienced periodic characteristics along with its circumference, the Fourier series approximation with proper coefficients was utilized to evaluate the strain distributions at the interface for the periodic and random fiber arrays with respect to fiber volume fractions. From the analysis, it was found that the random arrangement of fibers had a significant influence on the strain distribution tit the interface, and the strain distribution in the periodic arrays was one of special cases of that in the random array. [ABSTRACT FROM AUTHOR]

During the curing process of thick glass/epoxy composite laminates, substantial amounts of temperature lag and overshoot at the center of the laminates is usually experienced due to the large thickness and low thermal conductivity of the glass/epoxy composites, which require a long time for full and uniform consolidation. In this work, the temperature profiles of a 20 mm thick unidirectional glass/epoxy laminate during an autoclave vacuum bag process were measured and compared with the numerically calculated results. For the calculation of distributions of the temperature, degree of cure, resin pressure, exothermic heat and required time for full consideration by three-dimensional finite element analyses, the effects of convective heat transfer coefficient and geometry of mold and bagging assembly on the temperature profiles were taken into consideration. Based on the numerical results, an optimized cure cycle with the cooling and reheating steps was developed by minimizing the objective function to reduce the temperature overshoot in the composite. From the experimental and numerical results, it was found that the measured temperature profiles were in good agreement with the numerical ones, and conventional cure cycles recommended by prepreg manufacturers for thin laminates should be modified to prevent temperature overshoot and to obtain full consolidation. [ABSTRACT FROM AUTHOR]

We demonstrate the effects of overlap condition and surface wettability of dielectric layers on the drying process and crystalline structure of inkjet-printed semiconductor layers. 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was utilized to inkjet-print the semiconductor layer. Using various overlap conditions, semiconductor layers were inkjet-printed on dielectric layers with different surface wettabilities. It is observed that crystal growth and the resulting crystalline structures in inkjet-printed semiconductor layers are primarily determined by evaporation behavior, particularly the contact line movement of the drying semiconductor layers, which can be controlled via the overlap condition. With inappropriate overlap conditions, randomly oriented TIPS pentacene crystalline structures are generated in the semiconductor layer through irregular contact line recession. One-dimensionally oriented TIPS pentacene crystal structures can be obtained using the optimized overlap condition of 50% as a result of the uniform contact line movement. Relatively hydrophobic dielectric layers help to generate good crystallinity in the semiconductor layer. All-inkjet-printed organic thin film transistors (OTFTs) with well-oriented TIPS pentacene crystalline structures in the semiconductor layer show a high field effect mobility of ~0.1 cm2 V−1s−1, suggesting that, when printing inkjet semiconductor layers, the overlap condition and surface wettability of the dielectric layer are important factors for generating a well-oriented crystalline structure and thereby fabricating high-performance all-inkjet-printed OTFTs. [ABSTRACT FROM AUTHOR]

The paper aims to investigate the influence of bottom electrode configurations in all-inkjet-printed organic thin film transistors (OTFTs) on crystalline structures of semiconductor layers as well as the electrical performance of OTFTs. Two different types of all-inkjet-printed OTFTs were fabricated: one type with a new bottom-top contact configuration and the other type with a conventional bottom-bottom contact configuration. The crystal growth of semiconductor layer and the electrical characteristics of OTFTs were evaluated and compared between two different bottom electrode configurations. The resulting crystalline structures of semiconductor layers are mostly affected by the evaporation process of semiconductor layer. Randomly-oriented crystalline structures are generated in the semiconductor layer with a conventional bottom-bottom contact configuration due to irregular evaporation. However, a new bottom-top contact configuration leads to well-oriented crystalline structures because of controlled contact line movement. The average mobility of OTFTs with well-oriented crystalline structures is about 11 times as high as that with randomly-oriented crystalline structures. [ABSTRACT FROM AUTHOR]