Flexible and stretchable circuit technologies for space applications

Flexible and stretchable circuit technologies offer reduced volume and weight, increased electrical performance, larger design freedom and improved interconnect reliability. All of these advantages are appealing for space applications. In this paper, two example technologies, the ultra-thin chip package (UTCP) and stretchable moulded interconnect (SMI), are described. The UTCP technology results in a 60 µm thick chip package, including the embedding of a 20 µm thick chip, laser or protolithic via definition to the chip contacts and application of fan out metallization. Imec’s stretchable interconnect technology is inspired by conventional rigid and flexible printed circuit board (PCB) technology. Stretchable interconnects are realized by copper meanders supported by a flexible material e.g. polyimide. Elastic materials, predominantly silicone rubbers, are used to embed the conductors and the components, thus serving as circuit carrier. The possible advantages of these technologies with respect to space applications are discussed

Functionality-power-packaging considerations in context aware wearable systems

Wearable computing places tighter constraints on architecture design than traditional mobile computing. The architecture is described in terms of miniaturization, power-awareness, global low-power design and suitability for an application. In this article we present a new methodology based on three different system properties. Functionality, power and electronic Packaging metrics are proposed and evaluated to study different trade offs. We analyze the trade offs in different context recognition scenarios. The proof of concept case study is analyzed by studying (a) interaction with household appliances by a wrist worn device (acceleration, light sensors) (b) studying walking behavior with acceleration sensors, (c) computational task and (d) gesture recognition in a wood-workshop using the combination of accelerometer and microphone sensors. After analyzing the case study, we highlight the size aspect by electronic packaging for a given functionality and present the miniaturization trends for ‘autonomous sensor button

High-performance flexible energy storage and harvesting system for wearable electronics.

This paper reports on the design and operation of a flexible power source integrating a lithium ion battery and amorphous silicon solar module, optimized to supply power to a wearable health monitoring device. The battery consists of printed anode and cathode layers based on graphite and lithium cobalt oxide, respectively, on thin flexible current collectors. It displays energy density of 6.98 mWh/cm(2) and demonstrates capacity retention of 90% at 3C discharge rate and ~99% under 100 charge/discharge cycles and 600 cycles of mechanical flexing. A solar module with appropriate voltage and dimensions is used to charge the battery under both full sun and indoor illumination conditions, and the addition of the solar module is shown to extend the battery lifetime between charging cycles while powering a load. Furthermore, we show that by selecting the appropriate load duty cycle, the average load current can be matched to the solar module current and the battery can be maintained at a constant state of charge. Finally, the battery is used to power a pulse oximeter, demonstrating its effectiveness as a power source for wearable medical devices

Signal and Power Integrity Challenges for High Density System-on-Package

As the increasing desire for more compact, portable devices outpaces Moore’s law, innovation in packaging and system design has played a significant role in the continued miniaturization of electronic systems.Integrating more active and passive components into the package itself, as the case for system-on-package (SoP), has shown very promising results in overall size reduction and increased performance of electronic systems.With this ability to shrink electrical systems comes the many challenges of sustaining, let alone improving, reliability and performance. The fundamental signal, power, and thermal integrity issues are discussed in detail, along with published techniques from around the industry to mitigate these issues in SoP applications

Small-Scale Energy Harvesting from Environment by Triboelectric Nanogenerators

The increasing needs to power trillions of sensors and devices for the Internet of Things require effective technology to harvest small-scale energy from renewable natural resources. As a new energy technology, triboelectric nanogenerators (TENGs) can harvest ambient mechanical energy and convert it into electricity for powering small electronic devices continuously. In this chapter, the fundamental working mechanism and fundamental modes of a TENG will be presented. It can harvest all kinds of mechanical energy, especially at low frequencies, such as human motion, walking, vibration, mechanical triggering, rotating tire, wind, moving automobile, flowing water, rain drops, ocean waves, and so on. Such variety of energy harvesting methods promises TENG as a new approach for small-scale energy harvesting

E-Textiles. Study of the interaction between devices, connection methods and substrates

It is common knowledge that textiles and textile products are available in different forms along the textile chain. However, right now, all the attention is paid to the relationship between these materials and the most recent developments in the world of electronics. When a garment is implementing electronic components, ranging from sensors to conductor paths, that are applied or integrated into the textile surface, it’s commonly called an E-Textile. Nowadays there is a continuous demand for these products because they can satisfy a great extent of needs without interfering too much with the user’s life or without the obligation of modifying too much the original product in the beginning. This study, however, focuses on analyzing the interaction and interactivity which allows electronic communication between the components present in the textiles. It is believed that there is a knowledge gap in these most recent developments. In this paper, a literature investigation is carried out using various databases, which resulted in different contributions to the researched subjects. Also, an overview of materials, production technologies and testing methods is given. The concepts of smart and e-textile, textile structure, conductive materials, electronic communication and connection are classified. The influencing factors on the properties of the material structure are presented and a discussion is made referring to the potentials and challenges related to e-textiles. Finally, a brief consideration of sustainability and environmental aspects is done and, in the end, the main conclusions of the investigation are stated. The main focus of the research lies in defining processes and material properties for improving connection techniques between the textiles and the electronic components, and also between the components themselves. Only limited research will be conducted on simulating the behavior of these technologies. Various ideas for applications exist, starting from ones of classical nature (flexural rigid materials), to 3d printed additive manufacturing or other ones of a textile nature in the form of embroidered conductor paths. Unluckily little research has been conducted on real applications. Therefore, the challenges are only identified, and future research directions are derive

Electronics Thermal Management in Information and Communications Technologies: Challenges and Future Directions

This paper reviews thermal management challenges encountered in a wide range of electronics cooling applications from large-scale (data center and telecommunication) to smallscale systems (personal, portable/wearable, and automotive). This paper identifies drivers for progress and immediate and future challenges based on discussions at the 3rd Workshop on Thermal Management in Telecommunication Systems and Data Centers held in Redwood City, CA, USA, on November 4–5, 2015. Participants in this workshop represented industry and academia, with backgrounds ranging from data center thermal management and energy efficiency to high-performance computing and liquid cooling, thermal management in wearable and mobile devices, and acoustic noise management. By considering a wide range of electronics cooling applications with different lengths and time scales, this paper identifies both common themes and diverging views in the thermal management community

Wearable uBrain : Fabric Based-Spiking Neural Network

On garment intelligence influenced by artificial neural networks and neuromorphic computing is emerging as a research direction in the e-textile sector. In particular, bio inspired Spiking Neural Networks mimicking the workings of the brain show promise in recent ICT research applications. Taking such technological advancements and new research directions driving forward the next generation of e-textiles and smart materials, we present a wearable micro Brain capable of event driven artificial spiking neural network computation in a fabric based environment. We demonstrate a wearable Brain SNN prototype with multi-layer computation, enabling scalability and flexibility in terms of modifications for hidden layers to be augmented to the network. The wearable micro Brain provides a low size, weight and power artificial on-garment intelligent wearable solution with embedded functionality enabling offline adaptive learning through the provision of interchangeable resistor synaptic weightings. The prototype has been evaluated for fault tolerance, where we have determine the robustness of the circuit when certain parts are damaged. Validations were also conducted for movements to determine if the circuit can still perform accurate computation

異種ダイレット積層を用いたフレキシブルハイブリッドデバイスの集積技術に関する研究

Tohoku University福島誉史課