There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Exciting advancements have been made in the field of flexible electronic devices in the last two decades and will certainly lead to a revolution in peoples’ lives in the future. However, because of the poor sustainability of the active materials in complex stress environments, new requirements have been adopted for the construction of flexible devices. Thus, hierarchical architectures in natural materials, which have developed various environment-adapted structures and materials through natural selection, can serve as guides to solve the limitations of materials and engineering techniques. This review covers the smart designs of structural materials inspired by natural materials and their utility in the construction of flexible devices. First, we summarize structural materials that accommodate mechanical deformations, which is the fundamental requirement for flexible devices to work properly in complex environments. Second, we discuss the functionalities of flexible devices induced by nature-inspired stru...

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Nature-Inspired Structural Materials for Flexible Electronic Devices

In a world where resources are scarce and urban areas consume the vast majority of these resources, it is vital to make cities greener and more sustainable. Advanced systems to improve and automate processes within a city will play a leading role in smart cities. From smart design of buildings, which capture rain water for later use, to intelligent control systems, which can monitor infrastructures autonomously, the possible improvements enabled by sensing technologies are immense. Ubiquitous sensing poses numerous challenges, which are of a technological or social nature. This paper presents an overview of the state of the art with regards to sensing in smart cities. Topics include sensing applications in smart cities, sensing platforms and technical challenges associated with these technologies. In an effort to provide a holistic view of how sensing technologies play a role in smart cities, a range of applications and technical challenges associated with these applications are discussed. As some of these applications and technologies belong to different disciplines, the material presented in this paper attempts to bridge these to provide a broad overview, which can be of help to researchers and developers in understanding how advanced sensing can play a role in smart cities.

The Role of Advanced Sensing in Smart Cities

Optimal State Estimation

The Wireless sensor network play a vital role in collecting a Real – Time data, monitoring environmental conditions based on technology adoption. These sensor network is the combination of sensing, computation, and communication through a single tiny device. Here many tiny nodes assemble and configure themselves. It also controls actuators that extend control from cyberspace into the physical world. Here the sensor nodes communicate with the local peers rather than the high – power control tower or base station. Instead, of relying on a predeployed infrastructure, each individual sensor or actuator become part of the overall infrastructure. Here we have three hardware platforms that addresses the needs of wireless sensor netwoks. The operating system here uses an event based execution to support concurrency. The platform serves as a baseline and does not contain any hardware accelerators. . First platform serves as a baseline and it produces Operating system concepts for refining concurrency mechanisms. The second node validates the architectural designs and improve the communicational rates. The third node represents the full realization of the general architecture. Keywords— node, platform, concurrency.

A Wireless Sensor Network.

This paper emphasis on state-of-the-art of the earlier until the current trend and demand, principles, design considerations, key performance and fabrication technology of RF MEMS switch devices developed over the past few years. RF MEMS switch performance and features such as actuation voltage, insertion loss, isolation and ease with cost of fabrication and applications are compared and discussed.

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A comprehensive study on RF MEMS switch

In this study, MWCNTs were used as a filler for epoxy thin film composites, where the thin film was fabricated using the spin coating method. We investigated the dielectric properties of the MWCNT-filled epoxy composite, with filler loading in the range from 0 to 1.5 vol%. Additionally, the effect of various type of MWCNT filler treatments using polyoxyethylene octyl phenyl ether (Triton X-100), sodium dodecyl sulfate (SDS) and 3-aminopropyltriethoxy silane (AMPTES) on the dielectric properties of epoxy thin film composites were investigated. The results showed that the increment of MWCNT loading increased the dielectric properties of the composite system. Meanwhile, chemically treated MWCNTs, especially MWCNT treated with SDS, showed good dielectric properties. Furthermore, morphological study showed an improvement in the dispersion of filler throughout the epoxy matrix in the treated composite system compared to the untreated system. TEM images also showed that treated MWCNT filler increased wall thickness of nanotube.

Dielectric properties of surface treated multi-walled carbon nanotube/epoxy thin film composites

A study on a fabricated piezoresistive micro-electro-mechanical systems (MEMS) cantilever for a mass-based sensor has been carried out to enhance sensor sensitivity by introducing the stress concentration region (SCR). Three types of SCR geometry designs were first analysed using finite element analysis (FEA) software ANSYS ® to study the effect of stress and its distribution when varying mass is applied at the free end. FEA results show that the rectangular SCR design has the highest stress. Then, the length of rectangular SCR is varied from 1000 m (A1) to 3000 m (A3) to study the stress distribution along the cantilever. The piezoresistive MEMS cantilever with rectangular SCR A3 produced the highest stress and was thus selected for fabrication along with the piezoresistive MEMS cantilever without SCR. From the testing results, the piezoresistive MEMS cantilever with rectangular SCR A3 successfully enhanced sensitivity by 1.97 times as compared to the piezoresistive MEMS cantilever without SCR when varying mass is applied. Therefore this SCR approach appears to be suitable for enhancing the sensitivity of a mass-based piezoresistive MEMS cantilever sensor.

Enhancing the sensitivity of a mass-based piezoresistive micro-electro-mechanical systems cantilever sensor

The ambient vibration-based micro electromechanical systems (MEMS) piezoelectric harvester has become an important subject in most research publications. Providing a green and virtually infinite alternative power source to traditional energy sources, this harvester will significantly expand the applications of wireless sensor networks and other technologies. Using piezoelectric materials to harvest the ambient vibrations that surround a system is one method that has seen a dramatic rise in the power-harvesting applications. The simplicity associated with piezoelectric micro-generators makes them very attractive for MEMS applications in which ambient vibrations are harvested and converted into electric energy. These micro-generators can become an alternative to the battery-based solutions in the future, especially for remote systems. In this paper, we propose a model and present the simulation of a MEMS-based energy harvester under ambient vibration excitation using the COVENTORWARE2010 approaches. This E-shaped cantilever-based MEMS energy harvester that operates under ambient excitation in frequencies of 12.8, 17.1, and 21.3 Hz within a base acceleration of 1 m/s2 produces an output power of 1.0 W at 2kO load.

Shape Optimization of Cantilever-based MEMS Piezoelectric Energy Harvester for Low Frequency Applications

An artificial hair cell sensor is the current technology based on a biological inspiration and is widely used in underwater applications including the glider, robotic and autonomous surface vehicle. These papers discuss a few strategies in relation to the principles of sensing, fabrication, performance, and preliminary measurement data. The MEMS flow sensor is generally needed to replace existing commercial sensors that are inadequate for some applications. Material also provides some advantages to the hair cell sensor. Some materials such as Polydimethylsilaxone and Polyurethane have been investigated. The sensing element is reviewed including the doped piezoresistors, strain gauge and force sensitive resistors. Performance and result of each design will be presented briefly. Finally, the importance and the need for modeling, simulation and experiments will be reviewed based on the latest achievements on that particular research area.

Othman Sidek

Papers

A comprehensive study on RF MEMS switch

Dielectric properties of surface treated multi-walled carbon nanotube/epoxy thin film composites

Enhancing the sensitivity of a mass-based piezoresistive micro-electro-mechanical systems cantilever sensor

Shape Optimization of Cantilever-based MEMS Piezoelectric Energy Harvester for Low Frequency Applications

Review of MEMS flow sensors based on artificial hair cell sensor