Multifunctional flexible and stretchable polyurethane/carbon nanotube strain sensor for human breath monitoring

Flexible and stretchable polyurethane/carbon nanotube composite with strain detection ability was used for human breath monitoring. The composite material consisted of a network of multiwalled carbon nanotubes and thermoplastic high elastic polyurethane. It was found that elongation of the composite led to a macroscopic increase in electrical resistance, which can be used as a principle for applied strain detection. This detection was reversible, durable, and sensitive with gauge factor reaching very promising value, as, for example, ~46 at applied deformation of 8.7%. Further, the composite could be elongated to very large extend of deformation without discontinuity in measured resistance change reaching gauge factor ~ 450 at composite mechanical break at ~300% of strain. Sensor durability was also confirmed by sine wave deformation cycling when any decrease in the sensor properties for more than 10³ cycles was observed. Simultaneously, the prepared composite possessed other utility properties also and was considered as multifunctional when it was tested as an organic solvent vapor sensor, an element for Joule heating and finally as a microstrip antenna.     

Reliable stretchable gold interconnects in biocompatible elastomers

One of the key issues in realization of stretchable and curvilinear electronics is the fabrication of stretchable interconnects. Stretchable interconnects are basically conductor lines embedded in elastomer substrates. Currently, metal interconnects embedded in polydimethylsiloxane are one of the major candidates. In this work, a novel straightforward method is presented that allows the fabrication of 20 μm wide stretchable gold interconnects starting from commercial double sided flexes (Cu–PI–Cu). These interconnects are still fully functional after a minimum of 100 k cycles at 40% elongation. In addition to outstanding reliability in this method of fabrication, fine pitch and biocompatibility are the added values paving the way for medical grade stretchable electronics. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Progresses in organic field-effect transistors and molecular electronics

In the past years, organic semiconductors have been extensively investigated as electronic materials for organic field-effect transistors (OFETs). In this review, we briefly summarize the current status of organic field-effect transistors including materials design, device physics, molecular electronics and the applications of carbon nanotubes in molecular electronics. Future prospects and investigations required to improve the OFET performance are also involved. __________ Translated from Huaxue Tongbao (Chemistry), 2006, 69(6) (in Chinese)     

Highly sensitive,stretchable and durable strain sensors based on conductive double-network polymer hydrogels

Hydrogel-based strain sensors have been attracting immense attention for wearable electronic devices owing to their intrinsic soft characteristics and flexibility. However, developing hydrogel sensors with hightensile strength, stretchability, and strain sensitivity remains a great challenge. Herein, we report a technique to synthesize highly sensitive hydrogel-based strain sensors by integrating carbon nanofibers (CNFs) with a double-network (DN) polymer hydrogel matrix comprising of a physically cross-linked agar network and a covalently cross-linked polyacrylamide (PAAm) network. The resultant nanocomposite sensors display superior piezoresistive sensitivity with a hightrue gauge factor (GF_T = 1.78) at an ultrahigh strain of 1,000%, a fast response time and linear correlation of ln(R/R₀) and ln(L/L₀) up to 1,000% strain. Most significantly, these sensors possess highmechanical strength (~0.6 MPa) and superb durability (>1,000 cycles at strain of 100%), stemming from the effective energy dissipation mechanism of the first agar network acting as sacrificial bonds and the CNFs serving as dynamic nanofillers. The combination of highstrain sensitivity and ultrahigh stretchability of hydrogel sensors makes it possible to sense both small mechanical deformations induced by human motions and large strain up to 1,000%.     

MXene-composited highly stretchable,sensitive and durable hydrogel for flexible strain sensors

The flourishing development in flexible electronics has provoked intensive research in flexible strain sensors to realize accurate perception acquisition under different external stimuli.However,building hydrogel-based strain sensors with high stretchability and sensitivity remains a great challenge.Herein,MXene nanosheets were composited into polyacrylamide-sodium alginate matrix to construct mechanical robust and sensitive double networked hydrogel strain sensor.The hydrophilic MXene nanosheets formed strong interactions with the polymer matrix and endowed the hydrogel with excellent tensile properties(3150%),compliant mechanical strength(2.03 kPa~(-1) in Young's Module) and long-lasting stability and fatigue resistance(1000 dynamic cycles under 1,600% strain).Due to the highly oriented MXene-based three dimensional conductive networks,the hydrogel sensor achieved extremely high tensile sensitivity(18.15 in gauge factor) and compression sensitivity(0.38 kPa~(-1) below 3 kPa).MXene hydrogel-based strain sensors also displayed negligible hysteresis in electromechanical performance,typical frequent-independent feature and rapid response time to external stimuli.Moreover,the sensor exhibited accurate response to different scales of human movements,providing potential application in speech recognition,expression recognition and handwriting verification.     

Recent progress in organic field-effect transistor-based integrated circuits

Organic integrated circuits are undergoing rapid development with the extensive research on organic semiconducting materials and the performance improvement of organic field-effect transistors. Organic integrated circuits not only cover all the major circuit types, their complexity, degree of integration, and performance have also been improved in recent years. In this review, recent advances in the design and fabrication of integrated circuits based on organic field-effect transistors are reported. The circuits are categorized into digital and analog, which are discussed in detail centering on the structure, fabrication process, and performance. In addition, progress in the modeling and simulation of organic integrated circuits are discussed as well, as they are key issues for the future development of organic electronics.     

Recent advances in electrochemical sensors for antibiotics and their applications

The abuse of antibiotics will cause an increase of drug-resistant strains and environmental pollution,which in turn will affect human health.Therefore,it is important to develop effective detection techniques to determine the level of antibiotics contamination in various fields.Compared with traditional detection methods,electrochemical sensors have received extensive attention due to their advantages such as high sensitivity,low detection limit,and good selectivity.In this mini review,we summarized the latest developments and new trends in electrochemical sensors for antibiotics.Here,modification methods and materials of electrode are discussed.We also pay more attention to the practical applications of antibiotics electrochemical sensors in different fields.In addition,the existing problems and the future challenges ahead have been proposed.We hope that this review can provide new ideas for the development of electrochemical sensors for antibiotics in the future.     

Recent advances in large-scale assembly of semiconducting inorganic nanowires and nanofibers for electronics, sensors and photovoltaics

Semiconducting inorganic nanowires (NWs), nanotubes and nanofibers have been extensively explored in recent years as potential building blocks for nanoscale electronics, optoelectronics, chemical/biological/optical sensing, and energy harvesting, storage and conversion, etc. Besides the top-down approaches such as conventional lithography technologies, nanowires are commonly grown by the bottom-up approaches such as solution growth, template-guided synthesis, and vapor-liquid-solid process at a relatively low cost. Superior performance has been demonstrated using nanowires devices. However, most of the nanowire devices are limited to the demonstration of single devices, an initial step toward nanoelectronic circuits, not adequate for production on a large scale at low cost. Controlled and uniform assembly of nanowires with high scalability is still one of the major bottleneck challenges towards the materials and device integration for electronics. In this review, we aim to present recent progress toward nanowire device assembly technologies, including flow-assisted alignment, Langmuir-Blodgett assembly, bubble-blown technique, electric/magnetic- field-directed assembly, contact/roll printing, planar growth, bridging method, and electrospinning, etc. And their applications in high-performance, flexible electronics, sensors, photovoltaics, bioelectronic interfaces and nano-resonators are also presented.     

Recent Advances in Mechanically Robust and Stretchable Bulk Heterojunction Polymer Solar Cells

Organic bulk heterojunction solar cells are promising candidates as future photovoltaic technologies for large‐scale and low‐cost energy production. It is, therefore, not surprising that research on the design and preparation of these types of organic photovoltaics has attracted a lot of attention since the last two decades, leading to constantly growing values of energy conversion and efficiency. Combined with the possibility of a large‐scale production via roll‐to‐roll printing techniques, bulk heterojunction solar cells enable the fabrication of conformable, light‐weight and flexible light‐harvesting devices for point‐of‐use applications. This perspective review will highlight the recent advances toward mechanically robust and intrinsically stretchable bulk heterojunction solar cells. Mechanically robust fullerene‐based and all‐polymer devices will be presented, as well as a comprehensive overview of the recent challenges and characterization techniques recently developed to overcome some of the challenges of this research area, which is still in its infancy.     

PEDOT导电高分子在柔性能量转化与存储器件的研究进展

近年来,柔性有机和钙钛矿光伏器件、有机薄膜晶体管和医用传感器等因其具有可穿戴性、柔性、半透明性等优点,成为科学研究的热门领域.利用具有优异力学性能的导电聚合物是实现这些高性能器件的有效途径之一.在导电聚合物中,3,4-亚乙基二氧噻吩(PEDOT)及其水性分散液3,4-亚乙基二氧噻吩:聚苯乙烯磺酸盐(PEDOT:PSS)...     

Recent advances in electrochemical sensors for the detection of 2, 4, 6-trinitrotoluene

2, 4, 6-Trinitrotoluene (TNT) is a frequently used explosive compound, and it easily gathers in soil and water during transportation, use, and storage. Except for the security issue, it also has high toxicity and mutagenic effect on the environment and all life forms. Thus, it is critical to develop high-efficiency sensing methods for the detection of TNT at trace levels with high sensitivity and selectivity. This brief review highlights the research progress of using electrochemical sensors to analyze TNT molecules in recent years. Specifically, this minireview mainly focuses on the recently developed nanostructured electrocatalysts and electrochemical methods combined with other techniques for electrochemical detection of TNT.     

A Transparent,Highly Stretchable,Autonomous Self‐Healing Poly(dimethyl siloxane) Elastomer

An innovative self‐healing polydimethylsiloxane (PDMS) elastomer, namely, PDMS‐TFB, is reported by incorporating the reversibly dynamic imine bond as the self‐healing points into the PDMS networks. The PDMS‐TFB elastomer features good optical transmittance (80%) in full visible light region, high stretchability (≈700%), and excellent autonomous self‐healing ability at room temperature. Surprisingly, the self‐healing behavior can take place in water and even at a temperature as low as −20 °C in air, showing a promising outlook for broader applications. As a proof‐of‐concept, this study demonstrates the use of the PDMS‐TFB elastomer for preparing anticorrosion coating and adhesive layer, and also the use of such an elastomer to be the platform for fabricating the flexible interconnector and chemical sensor. Remarkably, no significant difference is observed between the pristine and healed samples. Taking full advantage of these unique properties, it is anticipated that such a PDMS‐TFB elastomer shows wide applications in the fields of materials science, electronics, biology, optics, etc.

     

Preparation of stable aqueous conductive ink with silver nanoflakes and its application on paper‐based flexible electronics

A new kind of stable aqueous conductive ink with silver nanoflakes was developed, which was also used to fabricate conductive patterns on weighing paper for flexible electronics by direct writing. Silver nanoflakes of different sizes were characterized by transmission electron microscopy. The physical properties of the conductive ink were investigated by a dynamic contact angle system, Ubbelohde viscometer, and a surface tension instrument. Conductive properties of paper‐based conductive patterns were also investigated by 4‐point probe, scanning electron microscopy, X‐ray diffraction and Uscan explorer with a 3D profilometer system. It is demonstrated how the formulation of conductive ink affects the surface morphology, microstructure conductivity, and line width of conductive patterns. It can be obtained that the paper‐based conductive patterns have low resistivity. Especially, when the sintering condition is 200 °C for 20 min, the resistivity can be down to 9.4 μΩ?cm. The application of the ink on an antenna for radio frequency identification was also studied. Copyright © 2011 John Wiley & Sons, Ltd.     

印刷有机数字电路及应用

印刷有机电子技术是基于印刷原理的有机电子器件制造技术,是指将有机电子材料配制成功能性油墨,用印刷方式来制造电子器件与系统的方法,其发展涉及到材料化学、微电子学等多个学科方面的知识。其独特的制造方式和器件形态具有柔性、低成本、大面积制造等优势,并且与传统硅基电子器件在应用场合上形成了互补,在生物传感、电子皮肤、柔性显示等领域展示出优势。为了及时跟进这一快速发展的领域,对领域的发展有宏观的把握,本文从印刷技术和电路系统的角度进行了全面概述,介绍了喷墨打印、丝网印刷和转印印刷等印刷技术和基于印刷技术制备的有机数字电路(反相器、与非门、环形振荡器、D触发器),以及实现功能化的印刷电子应用(RFID、电子皮肤、OLED显示驱动背板等);最后,对本领域目前存在的问题和未来发展方向做了简要探讨。     

Repurposing aromaticity for organic electronics: Making,breaking, and stacking π‐circuits

This article summarizes a series of lectures I presented in Taiwan as a visiting lecturer sponsored by the Ministry of Science and Technology.     

Recent advances on the development of graphene-based field-effect transistors,electrochemical biosensors and electrochemiluminescence biosensors

Graphene, a honeycomb lattice of carbon material with single-atom-layer structure, demonstrates extraordinary mechanical, thermal, chemical and electronic properties. Thus, it has sparked tremendous interests in various fields, such as energy storage and conversion devices, field-effect transistors (FET), chemical sensors and biosensors. In this review, we will first focus on the synthesis method of graphene and the fabrication strategy of graphene-based materials. Subsequently, the construction of graphene-based biosensors are introduced, in which three kinds of biosensors are discussed in details, including the FET, electrochemical biosensors and electrochemiluminescence (ECL) biosensors. The performances of the state-of-the-art biosensors on the detection of biomolecules are also displayed. Finally, we also highlight some critical challenges remain to be solved and the development in this field for further research.     

Recent Advances in Flexible Perovskite Solar Cells: Fabrication and Applications

Flexible perovskite solar cells have attracted widespread research effort because of their potential in portable electronics. The efficiency has exceeded 18 % owing to the high‐quality perovskite film achieved by various low‐temperature fabrication methods and matching of the interface and electrode materials. This Review focuses on recent progress in flexible perovskite solar cells concerning low‐temperature fabrication methods to improve the properties of perovskite films, such as full coverage, uniform morphology, and good crystallinity; demonstrated interface layers used in flexible perovskite solar cells, considering key figures‐of‐merit such as high transmittance, high carrier mobility, suitable band gap, and easy fabrication via low‐temperature methods; flexible transparent electrode materials developed to enhance the mechanical stability of the devices; mechanical and long‐term environmental stability; an outlook of flexible perovskite solar cells in portable electronic devices; and perspectives of commercialization for flexible perovskite solar cells based on cost.     

Recent advances in sensing and biosensing with arrays of nanoelectrodes

This review deals with recent advances in the field of electrochemical sensing and biosensing with nanoelectrode ensembles (NEEs) and nanoelectrode arrays (NEAs), focusing mainly on articles published since 2015. At first, a brief introduction on the properties and possible advantages which characterize electroanalytical signals at the NEE/NEA is presented, followed by an overview on the most recent theoretical advances concerning the modeling of relevant electrochemical signals. Novel nanofabrication methods and nanoelectrode materials are discussed together with original (bio)funtionalization procedures, suitable to obtain more sensitive and reliable sensors. Advanced applications of NEE/NEA-based sensors in the biological and biomedical field are presented, including their integration with living cells and application for neurochemical studies. Advances, present limits, and prospects for research in the area are finally discussed. As far as future research trends are concerned, on the one hand, there is a need for development of theoretical models which take into account specific effects that can rule electrochemistry with arrays of nanosized electrodes, such as double layer and quantum mechanical effects. On the other hand, frontier studies concerning the application of the NEE/NEA to the biomedical and neurochemical fields can open new tracks both to fundamental knowledge and application.     

Recent advances in voltammetric,amperometric and ion-selective (bio)sensors fabricated by microengineering manufacturing approaches

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微结构化柔性压力传感器的性能增强机制、实现方法与应用优势

柔性压力传感器具有易共形、高灵敏、快响应等特点,是发展物联网、可穿戴电子、触觉人工智能等领域的关键核心器件。通过敏感功能材料开发、功能层微结构设计、微纳制造方法优化等策略,可提升柔性压力传感器的综合性能,扩张其应用场景。其中,功能层微结构的创新设计被普遍认为是增强柔性传感器性能最有效的手段之一。本文综述了近年来基于微结构化的柔性压力传感器的最新研究进展,围绕微结构对于柔性压力传感器性能增强的机制、微结构的设计与实现方法以及微结构化柔性压力传感器在人机交互、医疗健康等领域的应用等方面进行详细阐述,并在此基础上对其未来发展方向进行展望。