Encapsulation Concepts Research Articles

Moisture Absorption and Desorption in an Ionomer-Based Encapsulant: A Type of Self-Breathing Encapsulant for CIGS Thin-Film PV Modules

As an alternative to conventional encapsulation concepts for a double glass photovoltaic (PV) module, we introduce an innovative ionomer-based multi-layer encapsulant, by which the application of additional edge sealing to prevent moisture penetration is not required. The spontaneous moisture absorption and desorption of this encapsulant and its raw materials, poly (ethylene- co -acrylic acid) and an ionomer, are analyzed under different climatic conditions in this work. The relative air humidity is thermodynamically the driving force for these inverse processes and determines the corresponding equilibrium moisture content (EMC). Higher air humidity results in a larger EMC. The homogenization of the absorbed water molecules is a diffusion-controlled process, in which temperature plays a dominant role. Nevertheless, the diffusion coefficient at a higher temperature is still relatively low. Hence, under normal climatic conditions for the application of PV modules, we believe that the investigated ionomer-based encapsulant can “breathe” the humidity: During the day, when there is higher relative humidity, it “inhales” (absorbs) moisture and restrains it within the outer edge of the module; then at night, when there is a lower relative humidity, it “exhales” (desorbs) the moisture. In this way, the encapsulant protects the cell from moisture ingress.

Design and development of a digital stethoscope encapsulation for simultaneous acquisition of phonocardiography and electrocardiography signals: the SmartHeart case study

The stethoscope is a major symbol of modern medicine. It is used for diagnosis of different conditions and enables physicians to listen to internal body sounds. Electrocardiography was only introduced in medicine in the beginning of the twentieth century. Today measuring heart’s electrical activity is also fundamental cardiac diseases diagnosis. Although performed with independent devices, requiring physician and patient presence in the same physical space, in combination they enhance cardiovascular assessment. In this paper, a digital stethoscope encapsulation was designed, adding new functionality to this advanced medical device. Today wired and wireless communications enable different medical devices to share data and information, over long distances. Using low-cost hardware technologies, the encapsulation will add the ability to acquire and transmit via Bluetooth the Electrocardiographic activity, determined in the same cardiac focus and synchronised with the Phonocardiographic sound recordings. Several encapsulation concepts were developed and prototyped using 3D printing. They were easily fitted to the digital stethoscope and tested in a hospital environment for ergonomics, acoustic and electric signals acquisition. The best concept was chosen with the help of a physician’s opinion and the final prototype performance was very satisfactory.

Neuro-Technical Interfaces Based on Biocompatible Polymeric Substrates

AbstractMultielectrode arrays create the interfaces between nerves and technical systems in neuroprosthetic devices. MEMS (microelectromechanical systems) technologies offer opportunities to develop high density arrays with large numbers of electrodes and smallest dimensions of electrode site area and pitch. Polymers are promising candidates for flexible substrates of these electrode arrays to meet the requirements of structural biocompatibility. In addition, these substrates must be biostable and should be non-toxic. From an engineering point of view, material processing should be feasible with standard MEMS process technology. Fail-safe integration of electronic circuitry, encapsulation of the systems with substrate-integrated electrodes and connection to cables and connectors is of great importance for reliable (micro-) implants.A comprehensive overview of the application of polymers like silicone rubber, polyimide, and parylene C as substrate, insulation and encapsulation material for multielectrode arrays will be given. Assembling techniques for system integration and encapsulation concepts will be discussed with a special attention on the adhesion properties between substrate, interconnects and insulation and possible failure mechanisms. Application scenarios include peripheral nerve interfaces like cuff and sieve electrodes as well as multielectrode arrays for retinal vision prostheses and shaft and grid arrays for the central nervous system interfaces.

Key Technologies for High Density FeRAM Applications

Ferroelectric random access memories (FeRAMs) are new types of memory devices especially suitable for mobile applications due to their unique properties such as non-volatility, small cell size especially with chain cell design, fast read and write as well as low voltage / low power behavior. Although standard CMOS processes can be used for frontend processes, FeRAM technology development has to overcome major challenges due to new materials used for capacitor formation. In this paper the advantages and disadvantages of different ferroelectric materials, especially in terms of low thermal budget for crystallization and capacitor formation, are discussed. In addition, major development issues for high-density applications like different capacitor encapsulation concepts to protect the capacitor form backend process damage and degradation by hydrogen are presented. Results from a recently developed 1T / 1C 8Mb FeRAM are discussed. The FeRAM is based on a 0.25 w m CMOS process. Due to the chain cell architecture a chip size of 76mm 2 was achieved using 2 metal layers.

Specifying concurrent objects

The object-oriented style of programming (OOP) is gaining increasing importance as a practical technique for organizing large designs and programs. Another striking aspect of OOP is its potential f...

SEA LANCE WEAPON DEVELOPMENT — SYSTEM AND NAVAL ENGINEERING ASPECTS OF THE CAPSULE

ABSTRACTThe developmental Sea Lance Weapon System is an encapsulated supersonic standoff antisubmarine warfare missile, launched from an attack submarine torpedo tube. The buoyant capsule rises to the surface, broaches, the forward closure separates, and the rocket motor ignites, powering the missile and payload from the capsule to the target coordinates.This paper emphasizes the system engineering and naval engineering aspects of the Sea Lance capsule, a lightweight high strength composite material pressure hull. Performance, environmental and interface requirements were identified to which analyses and comparisons were made. Concept development tradeoff studies comparing different methods of launch, materials, and structural geometry led to reasons that drove selection of a composite material for the capsule. Encapsulation, buoyancy, and underwater propulsion concepts with advantages and disadvantages of each concept are compared. Determination of expected shock loads and the derivation of requirements this placed on the capsule to protect the missile are covered. Capsule requirements imposed by transportation and handling, submarine weapon shipping, and torpedo tube launch are explained.The capsule cylinder material is a layered composite material with a pressure vessel sandwich layer consisting of filament wound graphite‐epoxy skins with phenolic honeycomb in between, overlaid with a damage resistant layer of filament wound Kevlar over a crushable honeycomb. Future marine possibilities of composite capsule applications are presented. The paper concludes with the naval engineering advantages of composites capsules.