Flexible Panel Research Articles

P‐191: Late‐News‐Poster: Effects of Channel Doping on Flexible LTPS TFTs: Density of State, Generation Lifetime, and Image Sticking

In this paper, effects of boron channel doping on the low temperature poly‐silicon (LTPS) TFT were comprehensively investigated with respect to the density of state (DOS), generation lifetime and image sticking. The LTPS TFT and metal‐oxide‐semiconductor (MOS) capacitors fabricated in a way of varying boron doping, and flexible panels were characterized by I‐V and C‐V measurement. With increasing boron doping, the interface trap density (Nit) tends to increase. In fact, the DOS of p‐Si TFT reveals that the shallow level defects increase, whereas the deep level defects decrease with increasing dose. It is found that C‐t measurement is a useful tool for the generation lifetime (τg) associated with impurities of p‐Si. In turn, τg is inversely proportional to image sticking index that reflects one of critical attributes for display image performance and quality.

63‐1: Numerical Study on Module Stacking Design of Flexible Panel with Water‐Drop Folding Shape

Numerical simulation was performed to investigate module stacking design and optimization in inner‐folding water‐drop flexible panel. Some influencing factors on module stacking design, such as the thickness and the modulus of cover, optical clear adhesive (OCA), bottom film (BF) and bending device were analyzed and designed. The result shows that, in the inner‐folding water‐drop module, the strain of optical clear adhesive (OCA) increases significantly which occurs in the cohesive failure area during the bending test, and the touch sensor plane (TSP) top surface and the display function layers (AMOLED) bottom surface are the locations where cracks occurred easily. Cover with the characteristics of thicker and higher modulus will increase the OCA deformation and function film strain. Adopting a type of thicker OCA will be help for solving the cohesive failure occurred in OCA1 but will not increase the failure risks occurred in OCA2 and function films. Both of OCA2 and display function film strains decrease fast with the increasing of BF modulus, meanwhile, thicker BF will increase the peeling risk. Optimized bending device not only could improve the bending ability but also could provide larger space for the design of terminal products.

P‐125: Influence of Line Shape on the Durability of Bending Lines on Flexible OLED Panels

Experiments were conducted to test the durability of bending line with different shapes on the bending area of 5.85 inch flexible OLED panel. Results showed that Z shape lines owned the best performance. Additionally, other shapes were further discussed.

Wooden Boats and our “Smart Sea Energy Gene”: an Evolutionary Approach to Naval Architecture and Marine Engineering through History, Optimization, Renewable Energy, and Sustainability

In this paper, we present a brief evolutionary approach to wooden boat architecture, arguing against current misconceptions that such vessels are environmentally unsustainable and just objects of beauty. The proposition is that wooden boats evolve through time and that the combination of the fundamental elements of wooden sailing boats with new technologies for energy efficiency can ensure their sustainable future. Our claim is that wooden boats in Greece provide a low-carbon energy efficient solution to the European and International sustainability agenda. With small modifications, without changing drastically the boat shapes or typologies, wooden sailing boats can be optimized to navigate using renewable energy (e.g., by using wind energy and flexible solar panels on sails as well as electric propulsion). Mathematics, hydrodynamics, naval architecture, and marine engineering are only a few fields that come together to support this powerful synergy aiming for a smart sustainable future of seafaring.

Investigation on global analytic modes for a three-axis attitude stabilized spacecraft with jointed panels

The natural property of a three-axis attitude stabilized spacecraft is investigated by simplifying it as a rigid central body jointed with 4 solar panels in this paper. For the spacecraft composed of a rigid central body and flexible panels, the Rayleigh-Ritz method is employed to obtain global modes which are explicitly functions of space coordinates and are useful for the modeling of lower-order discrete dynamic equations and design of active vibration controllers for the system. The Gram-Schmidt process is used to construct a set of characteristic orthogonal polynomials as the displacement field of the solar panel. Lagrange multipliers are introduced to describe the constraint at joints. The characteristic equation of the whole system is derived through the Rayleigh-Ritz procedure. Then, natural frequencies and corresponding global modes of the spacecraft with jointed panels are obtained. Taking the natural frequency obtained from the finite element method as a reference value, the process of getting natural frequencies is validated by comparing results obtained with those from the finite element method. Moreover, an excellent convergence and high accuracy of the present method is demonstrated by a very good agreement between results from ANSYS and theoretical method proposed here. Finally, parametric studies on characteristics of the spacecraft are conducted. The interesting mode shift phenomenon is observed when parameters of the spacecraft are changed.

Hypersonic Fluid–Structure Interactions in Compression Corner Shock-Wave/Boundary-Layer Interaction

The fluid–structure interaction of a flexible panel exposed to a ramp-induced shock-wave/boundary-layer interaction (SWBLI) at Mach 6 is investigated experimentally for transitional and turbulent incoming boundary layers. Panel deformations are measured using photogrammetry enabled by a new marker-tracking routine, whereas pressure fluctuations are obtained with fast-response piezoresistive pressure transducers. The significance of aerothermal heating is evident in the nonlinear panel response: enhanced static deformations and frequency shifting are consistent with a temperature differential between the panel and its support structure, which induces compressive thermal strain and flexural softening. Time-domain and modal vibratory behavior are correlated to the SWBLI environment, and shear-layer reattachment near antinodes of certain mode shapes is identified as a source of enhanced panel excitation. Comparison with companion rigid-ramp experiments shows evidence of feedback into the downstream flowfield regime.

Optimization of CNT and TFT Parameters for Maximum Transconductance and Safe Temperature Operation of Carbon Nanotube Thin-Film Transistors (CNT-TFTs) Employed in Flat Panel Displays

Thin Film Transistors (TFTs) have lived to see its significant technological improvement for various display applications in recent years. Carbon nanotube (CNT) based TFT technologies have been found to be a promising component for next generation flexible electronics and flat panel displays in view of CNTs high carrier mobility, device stability and mechanical flexibility. However, the design of CNT-TFT is still not well established, especially with a view to achieve the best performance still protecting thermal stability. In this study, the authors had analysed the device structure and operation of transistor in which carbon nanotubes act as active channel region. CNT-TFT with different device geometrics and CNT physical parameters such as channel length, channel width, CNT tube length, network density and its orientation have been extensively studied using NanoNet simulation tool. This study has thrown new insight into the device performance characteristics of CNT-TFTs. The results show that it is essential to fix the length of the channel more than 5 µm for restricting the device temperature at 300 K and it can be brought down as low as 3 µm if the maximum operating temperature can be 400 K. Comparison with already reported experimental results show that the TFT parameters returned by the simulation experiments and presented in this paper match closely.

A fast-sensing readout circuit in 240 Hz enabled by code division multiple access (CDMA) implemented for an ultra-thin on-cell flexible capacitive touch panel

A new fast readout circuit employing the known coding scheme of code division multiple access (CDMA) is successfully designed and applied to a 7-inch ultra-thin, flexible on-cell touch screen panel (TSP). The adopted CDMA is known originally as a coding scheme for data communication, which is applied in this study to address the sensing electrodes of the ultra-thin flexible touch panel. Due to the orthogonality between the driving signals to the touch panel coded by Walsh transform, one type of CDMA, the interference noises between sensing electrodes can be reduced effectively to render accurate touch sensing results. The electromagnetic interference from the flexible display can also be filtered out as baseline component in the output signal. And the frame time of touch reporting can be substantially shortened. Following the sensing electrode is a new readout designed of the switched-capacitor (SC) circuit, to avoid distributing sample signals from parasitic capacitance and also to enlarge the voltage changes due to the capacitance changes caused by touches. A 12-bit analog-to-digital converter (ADC) is orchestrated after the SC circuit to transform the front-end analog signal to digital codes. The digital part of the designed readout adopts a correction algorithm to eliminate the background signals from the display, and also a moving average algorithm to minimize the higher-frequency noises from the display and other electrodes. Experiments are conducted to validate the expected performance. It is evidenced that the Walsh code driving algorithm improves the quality of the readout output signal to be in 42 dB SNR, the report rate to a fast 240 Hz, and a power consumption of 0.39 mW by each sensing channel.

Acoustic inerter: Ultra-low frequency sound attenuation in a duct.

This letter investigates an acoustic metamaterial exhibiting a unique sound pressure amplification mechanism for ultra-low frequency sound attenuation. The system is constructed by integrating a flexible panel into the side-branch duct of a Herschel-Quincke (HQ) tube. A new peak emerges in the Sound Transmission Loss (STL) at a frequency far lower than the frequencies of the HQ tube-induced STL peaks. It cannot, after careful comparisons, be attributed to any local resonances, including structural resonances of the flexible panel or air resonances inside the side-branch cavities. To explain the underlying physics, several numerical simulations are performed. The results reveal that analog to a mechanical inerter, a "push-pull" force is created by the sound pressure difference between the sub-cavities in which a pressure amplification mechanism is generated at the interface of the embedded panel. This force is large enough to activate an out-of-plane motion of the flexible panel, trapping the incident sound power in a circular flow around the duct-branch loop. The unique phenomenon is successfully reproduced in experiment, where the flexible panel is made of carbon fiber. The proposed acoustic metamaterial can be used as silencing components for ultra-low frequency noise control in duct.

Further investigation on solant–rectenna‐based flexible Hilbert‐shaped metamaterials

This study discusses the design of a low-profile metamaterial-based antenna consisting of a 3 × 5 array of Hilbert shaped unit cells organised as a rectangular patch. The antenna is backed by with a partial ground plane loaded with square electromagnetic band gap defects for energy harvesting applications in the context of ultra-wideband self-powered wearable wireless devices. The antenna is mounted on a 28 × 32 mm FR4 substrate, with a thickness of 0.394 mm, a relative permittivity of 4.2 and a loss tangent of 0.02. The antenna is also printed on a flexible solar panel for self-powered devices through solant–rectenna output terminals. The proposed solant–rectenna is found to cover the frequency range from 0.8 up to 10 GHz. The I–V characteristics of the solar panel are measured with and without the antenna structure to realize low shadowing effects. After that, the solant radiofrequency (RF) port is connected to a rectifier circuit to create a rectenna port that collects the RF energy and converts it to an output DC voltage at 0.915 GHz. It is found that the proposed rectenna provides an output DC voltage of 1.42 V with a conversion efficiency of 90%.

Design of Stable Controller for Flexible Solar Panel by H∞ Loop-Shaping Method

Flexible solar panels play an essential role in the field of aerospace. However, many difficulties appear in the control design due to the existence of a weakly damped resonance module. The design for flexible systems often causes an unstable controller so that the systems after design still have trouble in putting into practice. We adopt H∞ loop-shaping design and put forward a directive method for selecting the weighting function. The simulation results indicate that system bandwidth is optimized based on the stable controller. In this way, the control precision and response speed of the system are improved. In the meantime, the system is easy to put into use.

The effect of colonic tissue electrical stimulation and celiac branch of the abdominal vagus nerve neuromodulation on colonic motility in anesthetized pigs.

Knowledge on optimal electrical stimulation (ES) modalities and region-specific functional effects of colonic neuromodulation is lacking. We aimed to map the regional colonic motility in response to ES of (a) the colonic tissue and (b) celiac branch of the abdominal vagus nerve (CBVN) in an anesthetized porcine model. In male Yucatan pigs, direct ES (10Hz, 2ms, 15mA) of proximal (pC), transverse (tC), or distal (dC) colon was done using planar flexible multi-electrode array panels and CBVN ES (2Hz, 0.3-4ms, 5mA) using pulse train (PT), continuous (10min), or square-wave (SW) modalities, with or without afferent nerve block (200Hz, 0.1ms, 2mA). The regional luminal manometric changes were quantified as area under the curve of contractions (AUC) and luminal pressure maps generated. Contractions frequency power spectral analysis was performed. Contraction propagation was assessed using video animation of motility changes. Direct colon ES caused visible local circular (pC, tC) or longitudinal (dC) muscle contractions and increased luminal pressure AUC in pC, tC, and dC (143.0±40.7%, 135.8±59.7%, and 142.0±62%, respectively). The colon displayed prominent phasic pressure frequencies ranging from 1 to 12cpm. Direct pC and tC ES increased the dominant contraction frequency band (1-6cpm) power locally. Pulse train CBVN ES (2Hz, 4ms, 5mA) triggered pancolonic contractions, reduced by concurrent afferent block. Colon contractions propagated both orally and aborally in short distances. In anesthetized pigs, the dominant contraction frequency band is 1-6cpm. Direct colonic ES causes primarily local contractions. The CBVN ES-induced pancolonic contractions involve central neural network.

An eco-friendly hot-water therapy towards ternary layered double hydroxides laminated flexible fabrics for wearable supercapatteries

Abstract In recent years, a substantial advancement in flexible and wearable consumer electronics has expedited the research community to develop flexible, lightweight, and sophisticated energy storage systems via cost-effective and safe preparation methods. In this context, we propose a state-of-the-art hot-water therapy (HWT) method to trigger nickel-copper-cobalt layered double hydroxide nanosheets on flexible conductive fabric (Ni–Cu–Co LDH NSs/CF). In the proposed HWT method, de-ionized water plays a significant role in generating NSs from CF in a manner similar to germination of plants in a farmland. Exploiting the morphological and inherent traits of the active material, the Ni–Cu–Co LDH NSs/CF electrode delivered maximum areal capacity of 104.2 μAh cm−2 with an outstanding cycling stability of 124.5%. Furthermore, a supercapattery that fabricated with Ni–Cu–Co LDH NSs/CF and activated carbon delivered high areal capacitance of 232 mF cm−2 at 2 mA cm−2. Additionally, the device exhibited maximum areal energy and power densities of 0.0734 mWh cm−2 and 15 mW cm−2, respectively. A prototype flexible charge-storage station has been also designed using the fabricated supercapatteries in conjunction with a flexible solar cell panel to demonstrate the real-time feasibility of our flexible device. The prolific and state-of-the-art HWT approach can initiate substantial advancements in the rational design of eco-friendly electrode materials for wearable applications.

Development of a Transient Model of a Lightweight, Portable and Flexible Air-Based PV-T Module for UAV Shelter Hangars

This research paper introduces a mathematical model to predict the performance of photovoltaic–thermal systems (PV-T), based on a thin layer flexible panel and an air pipe, by using the Trnsys® software tool to simulate energetic systems. The main advantage of these types of panels is their easy portability, making them ideal to address thermal needs in several scenarios. In the military field, there is an important concern about the use of sustainable energy; for instance, cooling facilities for infantry tents used in their deployments. In this research, a PV-T panel to cover electrical power needs for an infantry’s hangar unmanned air vehicle (UAV) is introduced. The proposed thermal model, based on the novelty of inertial mass (lump) as an approach to real panel behavior, has been validated through the comparison between Trnsys’ model simulation data, a real weather station, and data obtained in a test bed. Genopt’s simulation software is used to fit the model, allowing for the prediction of heat transmission coefficient values. The good match between simulated and experimental data makes the proposed model suitable for the photovoltaic–thermal prediction of panel behavior.

Analysis of the changing geometry of flexible structure: 1. approach and formulation

An alternative approach for the analysis of flexible structure is presented. Instead of following theories of finite deformation, classical structural models with infinitesimal strain and engineering stress are assumed as the basis of formulation. A compatible concept of description is developed to handle the large geometrical change due to load. The article first discusses: (i) the condition that a classical model can be adopted to formulate a flexible theory of structure and (ii) the procedure to formulate a description of geometry that embraces assumptions of the classical model. Based on the discussion, a general procedure to develop the flexible structural model is proposed. Equations for the cylindrical deformation of a flexible panel are derived as an example. In an accompanying article: ‘Analysis of the changing geometry of flexible structure: 2. Analysis of flexible solid’, an algorithm is developed to study three-dimensional flexible solids. Numerical results are obtained to verify the concept and procedure.

Controlled Hierarchical Self-Assembly of Catenated Cages.

Constructing hierarchical superstructures to achieve comparable complexity and functions to proteins with four-level hierarchy is challenging, which relies on the elaboration of novel building blocks with complex structures. We present a series of catenated cages with unique structural complexity and tailorability. The rational design was realized as such: A catenane of two symmetric cages (CSC), CSC-1, with all rigid imine panels was converted to a catenane of two dissymmetric cages (CDC), CDC-1, with two exterior flexible amine panels, and CDC-5 was tailored from CDC-1 by introducing an additional methyl group on each blade to increase lateral hindrance. CDC-1s with the most irregular and flexible configuration formed supramolecular dimers, which self-organized into 3D continuous wavelike plank with a three-level hierarchy, previously undiscovered by conventional building blocks. A drastically different 3D triclinic crystalline phase with a four-level hierarchy and trigonal phase with a three-level hierarchy were constructed of distorted CSC-1s and the most symmetric CDC-5s, respectively. The wavelike plank exhibited the lowest order, and the triclinic phase had a lower order than the trigonal phase which had the highest order. It correlates with the configuration of the primary structures, namely, the most disordered shape of CDC-1, the low-order configuration of CSC-1, and the most ordered geometry of CDC-5. The catenated cages with subtle structural differences therefore provide a promising platform for the search of emerging hierarchical superstructures that might be applied to proton conductivity, ferroelectricity, and catalysis.

Solution‐Processable Transparent Organic Molecular Nanoadhesives for Exceptionally Durable Nanowire Electrodes

AbstractSilver (Ag) nanowires (NWs) are promising building blocks for fabrication of flexible transparent electrodes, but their poor adhesion to polymeric substrates causes delamination of NWs from a substrate during repeated deformation, which leads to degradation in electrical performance. A new and simple approach is developed to dramatically improve mechanical, chemical, and thermal stability of a Ag NW electrode by hybridizing a NW network film with an organic molecular nanoadhesive layer without sacrificing its inherent excellent optoelectrical properties. It is discovered that some of pyridine derivatives such as 4‐dimethylaminopyridine can be solution‐processed and annealed to form a transparent layer with high adhesion to polymeric substrates such as poly(ethylene terephthalate). In addition to high optical transparency and electrical conductivity, the NW‐nanoadhesive hybrid film exhibits low surface roughness, reduced optical haze, and excellent adhesion to the substrate without delamination against 100 cycles of tape detachment and 10 000 cycles of bending tests at 1 mm of bending radius. Furthermore, the hybrid film exhibits good air‐oxidation and thermal stability over 24 h at 100 °C. The hybrid electrodes show good performance in applications for flexible touch panel and thin film heater.

A Multi-Source Harvesting System Applied to Sensor-Based Smart Garments for Monitoring Workers’ Bio-Physical Parameters in Harsh Environments

This paper describes the development and characterization of a smart garment for monitoring the environmental and biophysical parameters of the user wearing it; the wearable application is focused on the control to workers’ conditions in dangerous workplaces in order to prevent or reduce the consequences of accidents. The smart jacket includes flexible solar panels, thermoelectric generators and flexible piezoelectric harvesters to scavenge energy from the human body, thus ensuring the energy autonomy of the employed sensors and electronic boards. The hardware and firmware optimization allowed the correct interfacing of the heart rate and SpO2 sensor, accelerometers, temperature and electrochemical gas sensors with a modified Arduino Pro mini board. The latter stores and processes the sensor data and, in the event of abnormal parameters, sends an alarm to a cloud database, allowing company managers to check them via a web app. The characterization of the harvesting subsection has shown that ≈ 265 mW maximum power can be obtained in a real scenario, whereas the power consumption due to the acquisition, processing and BLE data transmission functions determined that a 10 mAh/day charge is required to ensure the device’s proper operation. By charging a 380 mAh Lipo battery in a few hours by means of the harvesting system, an energy autonomy of 23 days was obtained, in the absence of any further energy contribution.

Two Novel π -Conjugated Fluorophores for Dye-Doped LC On-Off Photoluminescence Switching

Among various classes of Photoluminescent (PL) compounds, soft-matter based materials in which chromophores are embedded in a Liquid-Crystal (LC) host polymer prove to be very attractive in the production of flexible panels and on-off temperature switches. Actually, the obtainment of low cost, easily synthesizable, and stable organic molecules soluble in the LC matrix is a challenge for both scholars and technologists. Here we describe the synthesis of two new emissive dyes based on a dicyanophenylenevinylene and on a bis-azobenzene core whose PL properties were investigated as neat solids, in solution, and in particular in a dye-doped LC nematic polymer often employed in PDLC applications. 1H NMR and 13C NMR spectroscopy allow the characterization of all compounds Their thermotropic liquid- crystalline (LC) properties were examined by differential scanning calorimetry and polarizing optical microscopy. Photoluminescence properties were characterized by fluorescence spectra.

Suppression and utilisation of aeroelastic behaviour in turbine-based combined cycle inlet

This study develops a two-way loosely coupled aeroelastic analysis framework based on a finite-volume fluid solver, a nonlinear finite-element solid solver and the Mesh-based parallel Code Coupling Interface. Research focuses on aeroelastic behaviour in a turbine-based combined cycle inlet after verifying the fluid solver and the coupling strategy through three benchmarks consisting of the inlet experimental model, the classical panel flutter problem and the deformation of a cantilever plate subjected to a shock tube flow. Coupling calculation shows that structural damping is limited only to the vibration suppression of deformable components under constant backpressure but exerts no evident influence on flow field oscillation induced by splitter plate vibration or perturbation from downstream dynamic backpressure. Interestingly, panel deformation (or forced vibration) has a positive impact on the stabilisation of the flow field. The use of a flexible panel with low thickness (e05) successfully prevents the shock train from transitioning, stabilising the performance profiles at the outlet even under dynamic backpressure. Pressure adjustment in the potentially unstable region through panel deformation is assumed to be the solution to weakening the disturbance from splitter plate vibration, which differs from the energy transfer theory under dynamic backpressure that is often found in the literature.