Recent Progress of Textile‐Based Wearable Electronics: A Comprehensive Review of Materials,Devices, and Applications

Wearable electronics are emerging as a platform for next‐generation, human‐friendly, electronic devices. A new class of devices with various functionality and amenability for the human body is essential. These new conceptual devices are likely to be a set of various functional devices such as displays, sensors, batteries, etc., which have quite different working conditions, on or in the human body. In these aspects, electronic textiles seem to be a highly suitable possibility, due to the unique characteristics of textiles such as being light weight and flexible and their inherent warmth and the property to conform. Therefore, e‐textiles have evolved into fiber‐based electronic apparel or body attachable types in order to foster significant industrialization of the key components with adaptable formats. Although the advances are noteworthy, their electrical performance and device features are still unsatisfactory for consumer level e‐textile systems. To solve these issues, innovative structural and material designs, and novel processing technologies have been introduced into e‐textile systems. Recently reported and significantly developed functional materials and devices are summarized, including their enhanced optoelectrical and mechanical properties. Furthermore, the remaining challenges are discussed, and effective strategies to facilitate the full realization of e‐textile systems are suggested.     

Potential materials for food packaging from nanoclay/natural fibres filled hybrid composites

The increasing demand for new food packaging materials which satisfy people requirements provided thrust for advancement of nano-materials science. Inherent permeability of polymeric materials to gases and vapours; and poor barrier and mechanical properties of biopolymers have boosted interest in developing new strategies to improve these properties. Research and development in polymeric materials coupled with appropriate filler, matrix-filler interaction and new formulation strategies to develop composites have potential applications in food packaging. Advancement in food packaging materials expected to grow with the advent of cheap, renewable and sustainable materials with enhanced barrier and mechanical properties. Nanoparticles have proportionally larger surface area and significant aspect ratio than their micro-scale counterparts, which promotes the development of mechanical and barrier properties. Nanocomposites are attracting considerable interest in food packaging because of these fascinating features. On the other hand, natural fibres are susceptible to microorganisms and their biodegradability is one of the most promising aspects of their incorporation in polymeric materials. Present review article explain about different categories of nanoclay and natural fibre based composite with particular regard to its applications as packaging materials and also gives an overview of the most recent advances and emerging new aspects of nanotechnology for development of hybrid composites for environmentally compatible food packaging materials.     

Failure Analysis of Thermal Actuators,Comb Drives,and Other Microelectromechanical Elements

This paper reports on an investigation in which several standard Microelectromechanical Systems (MEMS) elements consisting of thermal actuators, inchworm drives, and comb drives were subjected to vibration loading representative of the environment seen in space applications. Finite-element analysis of the MEMS devices showed that sufficient margins existed under the expected environmental loading. Vibration testing, however, resulted in several failures in the devices, and analysis showed that progressive failure initiated from large local displacements. Debris transport and entrapment was another source of failure leading to shorting of thermal actuators. The results illustrate the importance of debris control and packaging design for reliable MEMS operation. Suggestions for improving the reliability of MEMS devices through practical layout and packaging guidelines are made.     

圆片级气密封装及通孔垂直互连研究

提出了一种新颖的圆片级气密封装结构.其中芯片互连采用了通孔垂直互连技术:KOH腐蚀和DRIE相结合的薄硅晶片通孔刻蚀技术、由下向上铜电镀的通孔金属化技术、纯Sn焊料气密键合和凸点制备相结合的通孔互连技术.整个工艺过程与IC工艺相匹配,并在圆片级的基础上完成,可实现互连密度200/cm2的垂直通孔密度.该结构在降低封装成本,提高封装密度的同时可有效地保护MEMS器件不受损伤.实验还对结构的键合强度和气密性进行了研究.初步实验表明,该结构能够满足MIL-STD对封装结构气密性的要求,同时其焊层键合强度可达8MPa以上.本工作初步在工艺方面实现了该封装结构,为进一步的实用化研究奠定了基础.     

Smart magnetic structures for MEMS

By exploiting the special properties of magnetic materials, magnetic microelectromechanical system (MEMS) technology offers many challenging opportunities for useful device development in the future. This article discusses some of the magnetic materials used in MEMS devices and methods of fabricating them. Some key design issues are addressed, and applications of these technologies to electromagnetic devices developed at RMIT and to thermally controlled magnetic devices are examined.     

阳极键合研究现状及影响因素

为了提高键合质量、优化键合材料,促进阳极键合技术在工业生产中的应用,本文以“硅/玻璃”的阳极键合为例,阐述了阳极键合作为新型连接工艺的键合机理及工艺过程,介绍了现阶段阳极键合在国内外工业生产中的应用实例及相关研究,尤其是在微电子封装领域所展现的杰出应用前景,同时结合阳极键合过程中对键合参数、材料处理等要求,给出了影响键合质量的各种因素,以及在键合过程中常出现的问题及其解决办法.本文立足于键合机理及键合工艺过程,结合不同材料特性,重点阐述了阳极键合这一新型连接工艺的国内外研究现状及影响键合的因素,为进一步提高键合质量、优化键合工艺、开发新的键合材料等提供理论依据.     

Advances in piezoelectric thin films for acoustic biosensors,acoustofluidics and lab-on-chip applications

Recently, piezoelectric thin films including zinc oxide (ZnO) and aluminium nitride (AlN) have found a broad range of lab-on-chip applications such as biosensing, particle/cell concentrating, sorting/patterning, pumping, mixing, nebulisation and jetting. Integrated acoustic wave sensing/microfluidic devices have been fabricated by depositing these piezoelectric films onto a number of substrates such as silicon, ceramics, diamond, quartz, glass, and more recently also polymer, metallic foils and bendable glass/silicon for making flexible devices. Such thin film acoustic wave devices have great potential for implementing integrated, disposable, or bendable/flexible lab-on-a-chip devices into various sensing and actuating applications. This paper discusses the recent development in engineering high performance piezoelectric thin films, and highlights the critical issues such as film deposition, MEMS processing techniques, control of deposition/processing parametres, film texture, doping, dispersion effects, film stress, multilayer design, electrode materials/designs and substrate selections. Finally, advances in using thin film devices for lab-on-chip applications are summarised and future development trends are identified.     

Integrated optoelectronics for optical interconnections and optical processing

Integrated optoelectronics using III–V compound semiconductor technology has so far shown exciting advances for application in optical telecommunication systems. New applications of this technology are in optical interconnections and signal processing systems. The technology is expected to be very effective in solving the wiring limit in data transmission within electronic systems, using the advantages of optical techniques such as high data transmission rate and high parallelism, and thus improve the performance of overall systems. Optical interconnection devices currently being developed aim both at multiplexing vast amounts of data and exhibiting flexible interconnection functions using the advantageous characteristics of light. Future research is expected to explore new techniques such as that for multiplexing and processing data in the wavelength division as well as for integrating functional devices in two-dimensions. Synergetic collaboration among materials and processing, design and fabrication, and packaging areas is extremely important and this will lead to practical optical interconnections and signal processing systems.     

Strain Engineering of 2D Materials: Issues and Opportunities at the Interface

Triggered by the growing needs of developing semiconductor devices at ever‐decreasing scales, strain engineering of 2D materials has recently seen a surge of interest. The goal of this principle is to exploit mechanical strain to tune the electronic and photonic performance of 2D materials and to ultimately achieve high‐performance 2D‐material‐based devices. Although strain engineering has been well studied for traditional semiconductor materials and is now routinely used in their manufacturing, recent experiments on strain engineering of 2D materials have shown new opportunities for fundamental physics and exciting applications, along with new challenges, due to the atomic nature of 2D materials. Here, recent advances in the application of mechanical strain into 2D materials are reviewed. These developments are categorized by the deformation modes of the 2D material–substrate system: in‐plane mode and out‐of‐plane mode. Recent state‐of‐the‐art characterization of the interface mechanics for these 2D material–substrate systems is also summarized. These advances highlight how the strain or strain‐coupled applications of 2D materials rely on the interfacial properties, essentially shear and adhesion, and finally offer direct guidelines for deterministic design of mechanical strains into 2D materials for ultrathin semiconductor applications.     

Polymers Move in Response to Light

Significant advances have recently been made in the development of functional polymers that are able to undergo light‐induced shape changes. The main challenge in the development of such polymer systems is the conversion of photoinduced effects at the molecular level to macroscopic movement of working pieces. This article highlights some selected polymer architectures and their tailored functionalization processes. Examples include the contraction and bending of azobenzene‐containing liquid‐crystal elastomers and volume changes in gels. We focus especially on light‐induced shape‐memory polymers. These materials can be deformed and temporarily fixed in a new shape. They only recover their original, permanent shape when irradiated with light of appropriate wavelengths. Using light as a trigger for the shape‐memory effect will extend the applications of shape‐memory polymers, especially in the field of medical devices where triggers other than heat are highly desirable.     

Miniature and MEMS-type vacuum sensors and pumps

In the paper, the observable trends of the actual research and development of selected types of miniature and MEMS-type vacuum sensors are presented. Some information about the new types of active vacuum gauges, which are offered by the leading manufacturers of the vacuum measurement instruments, is given. Next, the list of MEMS devices that need vacuum for proper operation is presented. Some aspects of vacuum-encapsulation of MEMS devices, on wafer level and package level are shown. The new conceptions of obtaining and maintenance of high and ultra-high vacuum in MEMS devices are described. They concern the conception of integration of a miniature orbitron pump on-chip with MEMS-type device or with vacuum part of the portable advanced instruments such as electron microscope, ion mass spectrometer, and free electron laser.     

Monolayer Transition Metal Dichalcogenides as Light Sources

Reducing the dimensions of materials is one of the key approaches to discovering novel optical phenomena. The recent emergence of 2D transition metal dichalcogenides (TMDCs) has provided a promising platform for exploring new optoelectronic device applications, with their tunable electronic properties, structural controllability, and unique spin valley–coupled systems. This progress report provides an overview of recent advances in TMDC‐based light‐emitting devices discussed from several aspects in terms of device concepts, material designs, device fabrication, and their diverse functionalities. First, the advantages of TMDCs used in light‐emitting devices and their possible functionalities are presented. Second, conventional approaches for fabricating TMDC light‐emitting devices are emphasized, followed by introducing a newly established, versatile method for generating light emission in TMDCs. Third, current growing technologies for heterostructure fabrication, in which distinct TMDCs are vertically stacked or laterally stitched, are explained as a possible means for designing high‐performance light‐emitting devices. Finally, utilizing the topological features of TMDCs, the challenges for controlling circularly polarized light emission and its device applications are discussed from both theoretical and experimental points of view.     

Oxygen ion conductors

Ionic conductors have always provided a fascinating interdisciplinary field of study ever since their discovery by Faraday at the Royal Institution in London over 200 years ago. More recently, and particularly in the past decade, the pace of research has been rapid, driven by the requirements for new clean energy sources, sensors, and high energy density batteries.A very interesting subgroup of this class of materials are the oxides that display oxygen ion conductivity. As well as the intrinsic interest in these materials, there has been a continued drive for their development because of the promise of important technological devices such as the solid oxide fuel cell (SOFC), oxygen separation membranes, and membranes for the conversion of methane to syngas¹. All of these devices offer the potential of enormous commercial and ecological benefits provided suitable high performance materials can be developed. In this article we will review the materials currently under development for application in such devices with particular reference to some of the newly discovered oxide ion conductors.     

25th Anniversary Article: Design of Polymethine Dyes for All‐Optical Switching Applications: Guidance from Theoretical and Computational Studies

All‐optical switching—controlling light with light—has the potential to meet the ever‐increasing demand for data transmission bandwidth. The development of organic π‐conjugated molecular materials with the requisite properties for all‐optical switching applications has long proven to be a significant challenge. However, recent advances demonstrate that polymethine dyes have the potential to meet the necessary requirements. In this review, we explore the theoretical underpinnings that guide the design of π‐conjugated materials for all‐optical switching applications. We underline, from a computational chemistry standpoint, the relationships among chemical structure, electronic structure, and optical properties that make polymethines such promising materials.     

Flourishing Bioinspired Antifogging Materials with Superwettability: Progresses and Challenges

Antifogging (AF) structure materials found in nature have great potential for enabling novel and emerging products and technologies to facilitate the daily life of human societies, attracting enormous research interests owing to their potential applications in display devices, traffics, agricultural greenhouse, food packaging, solar products, and other fields. The outstanding performance of biological AF surfaces encourages the rapid development and wide application of new AF materials. In fact, AF properties are inextricably associated with their surface superwettability. Generally, the superwettability of AF materials depends on a combination of their surface geometrical structures and surface chemical compositions. To explore their general design principles, recent progresses in the investigation of bioinspired AF materials are summarized herein. Recent developments of the mechanism, fabrication, and applications of bioinspired AF materials with superwettability are also a focus. This includes information on constructing superwetting AF materials based on designing the topographical structure and regulating the surface chemical composition. Finally, the remaining challenges and promising breakthroughs in this field are also briefly discussed.     

用于微电子机械系统封装的体硅键合技术和薄膜密封技术

对静电键合、体硅直接键合和界面层辅助键合等三种体硅键合技术，整片操作、局部操作和选择保护等三种密封技术，以及这些技术用于微电子机械系统的密封作了评述，强调在器件研究开始时应考虑封装问题，具体技术则应在保证器件功能和尽量减少芯片复杂性两者之间权衡决定。     

Compensation of Angular Errors Using Decision Feedback Equalizer Approach

Speed and position measurements of rotating shafts are very important in the field of mechanical engineering. In automotive applications, magnetic field sensors for such measurements (camshaft, crankshaft, anti-lock braking system, windshield wiper, etc.) have the largest market share of all sensor types. Camshaft applications are challenging due to their requirements on high angular accuracy under harsh environmental conditions. Due to mounting and packaging tolerances, the magnetic field at the sensors position varies, resulting in angular measurement errors for sensor concepts in use today. Mounting and packaging tolerances cannot be avoided; however, they can be compensated by a new filter structure which is described in this paper. The decision feedback equalizer (DFE)—known from digital communication—was analyzed and modified for the use in angular measurement applications. A new filter structure, using data prediction and an adaptive algorithm based on a physical model, is proposed. This filter calculates and compensates angular errors caused by mounting and packaging tolerances.      

3D Printed Stretchable Tactile Sensors

The development of methods for the 3D printing of multifunctional devices could impact areas ranging from wearable electronics and energy harvesting devices to smart prosthetics and human–machine interfaces. Recently, the development of stretchable electronic devices has accelerated, concomitant with advances in functional materials and fabrication processes. In particular, novel strategies have been developed to enable the intimate biointegration of wearable electronic devices with human skin in ways that bypass the mechanical and thermal restrictions of traditional microfabrication technologies. Here, a multimaterial, multiscale, and multifunctional 3D printing approach is employed to fabricate 3D tactile sensors under ambient conditions conformally onto freeform surfaces. The customized sensor is demonstrated with the capabilities of detecting and differentiating human movements, including pulse monitoring and finger motions. The custom 3D printing of functional materials and devices opens new routes for the biointegration of various sensors in wearable electronics systems, and toward advanced bionic skin applications.     

Molecular Glass Resists as High‐Resolution Patterning Materials

The success of the semiconductor industry is based on the ability to fabricate hundreds of millions of devices on a single chip. In order to fulfill the ever‐shrinking feature sizes, the industry requires new patternable materials in order to operate in the sub‐50 nm regime. Molecular glass (MG) resists are a new type of patterning material that has gained considerable attention over the past few years. This Research News article describes the chemical and structural aspects of MGs as well as important concepts of MG resist design. We also highlight some of the recent advances in high‐resolution patterning capabilities with next‐generation imaging tools.     

BioMEMS for drug delivery

Recent research into methods of using microelectromechanical systems (MEMS) technology for medical and biological applications has developed several interesting devices. This paper reviews various approaches to the use of MEMS for drug therapy, including devices based on microporous silicon, microneedles, micropumps, and microreservoirs. Microdevices can improve drug therapy because they allow precise and complex dosing, induce less pain, or increase compliance. Microneedles have been tested on humans, and the other drug delivery MEMS have shown promise in vitro and in vivo. Investigations into the use of microelectromechanical systems (MEMS) technology to produce microdevices for drug delivery have expanded recently. We present several different approaches to the use of microdevices for drug therapy and the current state of the field.