Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore Center for Intelligent Sensors and MEMS, National University of Singapore, Singapore, 117608, Singapore Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore, 117608, Singapore NUS Suzhou Research Institute (NUSRI), Suzhou, 215123, China NUS Graduate School for Integrative Science and Engineering, National University of Singapore, Singapore, 117456, Singapore

Progress in wearable electronics/photonics—Moving toward the era of artificial intelligence and internet of things

Stretchable electronics, which can retain their functions under stretching, have attracted great interest in recent decades. Elastic substrates, which bear the applied strain and regulate the strain distribution in circuits, are indispensable components in stretchable electronics. Moreover, the self-healing property of the substrate is a premise to endow stretchable electronics with the same characteristics, so the device may recover from failure resulting from large and frequent deformations. Therefore, the properties of the elastic substrate are crucial to the overall performance of stretchable devices. Poly(dimethylsiloxane) (PDMS) is widely used as the substrate material for stretchable electronics, not only because of its advantages, which include stable chemical properties, good thermal stability, transparency, and biological compatibility, but also because of its capability of attaining designer functionalities via surface modification and bulk property tailoring. Herein, the strategies for fabricating stretchable electronics on PDMS substrates are summarized, and the influence of the physical and chemical properties of PDMS, including surface chemical status, physical modulus, geometric structures, and self-healing properties, on the performance of stretchable electronics is discussed. Finally, the challenges and future opportunities of stretchable electronics based on PDMS substrates are considered.

Stretchable Electronics Based on PDMS Substrates.

Exceptional piezoelectricity, high thermal conductivity and stiffness and promising photocatalysis in two-dimensional MoSi2N4 family confirmed by first-principles

Wearable triboelectric nanogenerators for biomechanical energy harvesting

Recently, flexible and wearable electronics have gained considerable research interest due to their potential applications in wearable devices, energy storage materials, electronic skins, sensors, etc. Compared to elastomers, hydrogels demonstrate more potential for flexible electronics because of their biomimetic structures, suitable mechanical properties and excellent biocompatibility. Among all the designs, nanocomposite hydrogel-based strain and pressure sensors which can transmit external stimulus to electrical signals have been intensely investigated due to their high mechanical strength, considerable conductivity and outstanding sensitivity. Numerous reports have been dedicated to the designs, preparations and applications of nanocomposite hydrogels. This review provides an up-to-date and comprehensive summary of research progresses of nanocomposite hydrogel-based strain and pressure sensors including designing strategies, preparing methods and applications of the five nanofiller based hydrogel sensors including carbon nanotube based, graphene oxide based, MXene based, polymer nanofiller based and other nanofiller based sensors. Representative cases are carefully selected and discussed regarding the fabrication, merits and demerits, respectively. Finally, perspectives and challenges are presented for the designs of future nanocomposite hydrogel-based strain and pressure sensors.

Nanocomposite hydrogel-based strain and pressure sensors: a review

Stretchable, self-healing, conductive hydrogel fibers for strain sensing and triboelectric energy-harvesting smart textiles

© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1909252 (1 of 9) Dr. P. Zhang, Y. Chen, Z. H. Guo, W. Guo, Prof. X. Pu, Prof. Z. L. Wang CAS Center for Excellence in Nanoscience Beijing Key Laboratory of Micro-Nano Energy and Sensor Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of Sciences Beijing 100083, China E-mail: puxiong@binn.cas.cn Y. Chen, Z. H. Guo, W. Guo, Prof. X. Pu, Prof. Z. L. Wang School of Nanoscience and Technology University of Chinese Academy of Sciences Beijing 100049, China Full PaPer

Stretchable, Transparent, and Thermally Stable Triboelectric Nanogenerators Based on Solvent-Free Ion-Conducting Elastomer Electrodes

The viable application of soft electronics/robotics relies on the development of power devices which are desired to be flexible, deformable, or even self-healable. We report here a shape-adaptive, ...

Shape-Adaptive, Self-Healable Triboelectric Nanogenerator with Enhanced Performances by Soft Solid-Solid Contact Electrification.

Soft ionic conductors show great promise in multifunctional iontronic devices, but currently utilized gel materials suffer from liquid leakage or evaporation issues. Here, a dry ion-conducting elastomer with dynamic crosslinking structures is reported. The dynamic crosslinking structures endow it with combined advantageous properties simultaneously, including high ionic conductivity (2.04 × 10-4 S cm-1 at 25 °C), self-healing capability (96% healing efficiency), stretchability (563%), and transparency (78%). With this ionic conductor as the electrode, two soft iontronic devices (electroluminescent devices and triboelectric nanogenerator tactile sensors) are realized with entirely self-healing and stretchable capabilities. Due to the absence of liquid materials, the dry ion-conducting elastomer shows wide operational temperature range, and the iontronic devices achieve excellent stability. These findings provide a promising strategy to achieve highly conductive and multifunctional soft dry ionic conductors, and demonstrate their great potential in soft iontronics or electronics.

Panpan Zhang

Papers

Stretchable, self-healing, conductive hydrogel fibers for strain sensing and triboelectric energy-harvesting smart textiles

Stretchable, Transparent, and Thermally Stable Triboelectric Nanogenerators Based on Solvent-Free Ion-Conducting Elastomer Electrodes

Shape-Adaptive, Self-Healable Triboelectric Nanogenerator with Enhanced Performances by Soft Solid-Solid Contact Electrification.

Dynamically Crosslinked Dry Ion-Conducting Elastomers for Soft Iontronics.

Multifunctional Self-Charging Electrochromic Supercapacitors Driven by Direct-Current Triboelectric Nanogenerators