AC powder electroluminescent displays

Abstract— The current status of AC powder electroluminescent (ACPEL) displays is reviewed with particular emphasis given to color and lifetime. The printing of the displays in forward and reverse architectures is also discussed, in addition to the fabrication of ACPEL displays with interdigitated electrodes, and different types of ACPEL phosphors and materials for back electrodes, transparent conducting electrodes, binders, and dielectrics are considered. Furthermore, shape conformable and highly flexible ACPEL displays are surveyed.     

The electrooxidation of sulfur-containing compounds at boron-doped diamond electrode

The electrooxidation of homocysteine, glutathione (GSH), 2-mercapto ethanesulfonic acid and cephalexin at boron-doped diamond (BDD) electrodes and glassy carbon (GC) electrodes was investigated by cyclic voltammetry. The oxidation of these sulfur-containing compounds exhibited well-defined irreversible responses. This preliminary study has shown that BDD has better sensitivity than GC. Concentration dependence has been studied and indicated the promise of using BDD electrodes for quantitative determination. All of the compounds displayed recognizable oxidation peaks at BDD electrodes at millimolar concentration levels. Scan rate dependence of GSH has been examined. It was shown that there was no adsorption on the surface of the BDD electrode for the low concentration.     

Enhancing displacement of lead-zirconate-titanate (PZT) thin-film membrane microactuators via a dual electrode design

A common design of piezoelectric microactuators adopts a membrane structure that consists of a base silicon diaphragm, a layer of bottom electrode, a layer of piezoelectric thin film, and a layer of top electrode. In particular, the piezoelectric thin film is often made of lead-zirconate-titanate (PZT) for its high piezoelectric constants. When driven electrically, the PZT thin film extends or contracts flexing the membrane and generating an out-of-plane displacement. Many manufacturing defects, however, could significantly reduce the designed actuator displacement. Examples include residual stresses, warping, non-uniform etching of the silicon diaphragm, and misalignment between the top electrode and the silicon diaphragm. The purpose of this paper is to develop a dual top-electrode design to enhance the actuator displacement. In this design, the top electrode consists of two disconnected (thus independent) electrode areas, while a continuous bottom electrode serves as the ground. The two top electrodes are located in two regions with opposite curvature when the diaphragm deflects. When the two top electrodes are driven in an out-of-phase manner, the actuator displacement is enhanced. Finite element analyses and experimental measurements both confirm the feasibility of this design. When manufacturing defects are present, experimental results indicate that the actuator displacement can be optimized by adjusting the phase difference between the dual top electrodes.     

Placement of forearm surface EMG electrodes in the assessment of hand loading in manual tasks

Surface electromyography (EMG) is commonly used to study the loading of the forearm. Pro-supination movements cause surface electrodes to move in relation to the underlying muscles. We studied the effects of different electrode locations and forearm postures on the association between the EMG signals and external hand load in a laboratory experiment. Eleven subjects performed simulated work tasks with the forearm in neutral, pronated or supinated postures and with systematic variation of external load. The tasks included isometric gripping, pushing and pulling, and lifting and lowering weights. Surface EMG was recorded by six pairs of electrodes located on the forearm. The associations were studied using multiple regression models. EMG activity varied according to the forearm posture, location of electrodes and type of simulated task. Variation was lowest with a through-forearm setting of electrodes. This setting also showed the highest correlation between external loads and the EMG activity [coefficient of determination (R ²) = 0.25–0.66].

Practitioner Summary: Moving of surface electrodes in relation to the underlying muscles interferes with the assessment of loading in ergonomic settings. This laboratory experiment showed that a through-forearm location of electrodes seems to be an optimal option in the assessment of forearm loading.     

电活性聚合物薄膜万能肌肉作动器的力电非线性变形分析

该文针对美国人工肌肉公司（Artificial Muscle Inc．）开发的一款电活性聚合物薄膜作动器,建立了该产品核心部件即上下表面附着有柔顺电极的圆环形电活性聚合物薄膜在力电作用下产生面外轴对称大变形的力学模型,利用热力学的基本理论,推导得到了圆环形薄膜在受力电载荷作用时产生面外大变形的控制方程,采用打靶法对控制...     

Monolithic and Flexible ZnS/SnO2 Ultraviolet Photodetectors with Lateral Graphene Electrodes

A continuing trend of miniaturized and flexible electronics/optoelectronic calls for novel device architectures made by compatible fabrication techniques. However, traditional layer‐to‐layer structures cannot satisfy such a need. Herein, a novel monolithic optoelectronic device fabricated by a mask‐free laser direct writing method is demonstrated in which in situ laser induced graphene‐like materials are employed as lateral electrodes for flexible ZnS/SnO₂ ultraviolet photodetectors. Specifically, a ZnS/SnO₂ thin film comprised of heterogeneous ZnS/SnO₂ nanoparticles is first coated on polyimide (PI) sheets by a solution process. Then, CO₂ laser irradiation ablates designed areas of the ZnS/SnO₂ thin film and converts the underneath PI into highly conductive graphene as the lateral electrodes for the monolithic photodetectors. This in situ growth method provides good interfaces between the graphene electrodes and the semiconducting ZnS/SnO₂ resulting in high optoelectronic performance. The lateral electrode structure reduces total thickness of the devices, thus minimizing the strain and improving flexibility of the photodetectors. The demonstrated lithography‐free monolithic fabrication is a simple and cost‐effective method, showing a great potential for developement into roll‐to‐roll manufacturing of flexible electronics.