Recent progress on flexible nanogenerators toward self-powered systems

The advances in wearable/flexible electronics have triggered tremendous demands for flexible power sources,where flexible nanogenerators,capable of converting mechanical energy into electricity,demonstrate its great potential.Here,recent progress on flexible nanogenerators for mechanical energy harvesting toward self-powered systems,including flexible piezoelectric and triboelectric nanogenerator,is reviewed.The emphasis is mainly on the basic working principle,the newly developed materials and structural design as well as associated typical applications for energy harvesting,sensing,and selfpowered systems.In addition,the progress of flexible hybrid nanogenerator in terms of its applications is also highlighted.Finally,the challenges and future perspectives toward flexible self-powered systems are reviewed.

Flexible energy storage devices for wearable bioelectronics

With the growing market of wearable devices for smart sensing and personalized healthcare applications,energy storage devices that ensure stable power supply and can be constructed in flexible platforms have attracted tremendous research interests.A variety of active materials and fabrication strategies of flexible energy storage devices have been intensively studied in recent years,especially for integrated self-powered systems and biosensing.A series of materials and applications for flexible energy storage devices have been studied in recent years.In this review,the commonly adopted fabrication methods of flexible energy storage devices are introduced.Besides,recent advances in integrating these energy devices into flexible self-powered systems are presented.Furthermore,the applications of flexible energy storage devices for biosensing are summarized.Finally,the prospects and challenges of the self-powered sensing system for wearable electronics are discussed.

Bistable Piezoelectric Flutter Energy Harvesting with Uncertainty

The analytical formulation of piezoelectric flutter energy harvesting using a bistable material,while considering uncertainties in the model is presented in this paper.Bistable laminates provide the advantage of large deflection due to the nonlinear snap-through characteristics when exposed to external loading,and can therefore provide a suitable base for piezoelectric material in energy harvesting applications.A piezoelectric material that is bounded on the surface of bistable laminates,subjected to external loading,generates large strains and hence relatively higher electrical output energy,in comparison with the case where piezoelectric material is bonded on a regular surface,with analogous loading conditions.Although information regarding the external loading,material characteristics of the bistable laminate and the piezoelectric material,boundary conditions,and overall electrical circuit efficiency can be defined for analytical purposes,the exact model of the system is not readily accessible.The unavoidable uncertainties in the material,loading,and efficiency of a complex system call for a probabilistic approach.Hence,this paper provides a formulation that considers uncertainty bounds in obtaining a realistic model.Optimal Uncertainty Quantification(OUQ) is used in this paper,which takes into account uncertainty measures with optimal bounds and incomplete information about the system,as a well-defined optimization problem according to maximum probabilities,subjected to the imposed constraints.The OUQ allows the inspection of the solution for a span of uncertain input parameters,as a reliable and realistic model.

用于集成型光电检测系统的高性能平面微型超级电容器阵列

薄膜微电容(TF-MSC)因其适合作为能量存储设备,集成在个人健康监测或实时环境检测等便携式电子产品中,而引起了越来越多的关注.然而,能量存储单元和检测单元的不同制造方式使得此类集成器件的制备变得复杂,同时也给材料的选择带来限制.为了打破这一限制,本文基于可同时应用于储能和可见光检测的Sb_(2)S_(3)多功能薄膜,制备了由叉指型TF-MSC阵列驱动的集成型光电检测装置.TF-MSC以原位沉积的Sb_(2)S_(3)@聚苯胺(PANI)薄膜作为负极,活性炭作为正极,在0.25 mA cm^(−2)下的电容值为18.44 mF cm^(−2),且在1 mA cm^(−2)下经7000次充放电循环后仍可保持97%的比电容.由于Sb_(2)S_(3)@PANI薄膜的可扩展和可编辑性,由多个TF-MSC面内集成的TF-MSC阵列,表现出成倍增加的储能能力和广泛的应用潜力.与TF-MSC阵列集成在同一基底上的垂直或横向Sb_(2)S_(3)光电探测器,在较宽的光强度范围下可获得快速响应.因此,这种多功能集成器件在便携式监控设备中具有广泛的应用前景.

Harvesting vibration energy by a triple-cantilever based triboelectric nanogenerator

Triboelectric nanogenerators （TENG）, a unique technology for harvesting ambient mechanical energy based on triboelectric effect, have been proven to be a cost-effective, simple and robust approach for self-powered systems. Here, we demonstrate a rationally designed triple-cantilever based TENG for harvesting vibration energy. With the assistance of nanowire arrays fabricated onto the surfaces of beryllium-copper alloy foils, the newly designed TENG produces an open-circuit voltage up to 101 V and a short-circuit current of 55.7 ~tA with a peak power density of 252.3 mW/m2. The TENG was systematically investigated and demonstrated as a direct power source for instantaneously lighting up 40 commercial light-emitting diodes. For the first time, a TENG device has been designed for harvesting vibration energy, especially at low frequencies, opening its application as a new energy technologv.