Highly Compressible Integrated Supercapacitor–Piezoresistance‐Sensor System with CNT–PDMS Sponge for Health Monitoring

Rapid improvement of wearable electronics stimulates the demands for the matched functional devices and energy storage devices. Meanwhile, wearable microsystem requires every parts possessing high compressibility to accommodate large‐scale mechanical deformations and complex conditions. In this work, a general carbon nanotube–polydimethylsiloxane (CNT–PDMS) sponge electrode is fabricated as the elementary component of the compressible system. CNT–PDMS sponge performs high sensitivity as a piezoresistance sensor, which is capable of detecting stress repeatedly and owns great electrochemical performance as a compressible supercapacitor which maintains stably under compressive strains, respectively. Assembled with the piezoresistance sensor and the compressible supercapacitor, such highly compressible integrated system can power and modulate the low‐power electronic devices reliably. More importantly, attached to the epidermal skin or clothes, it can detect human motions, ranging from speech recognition to breathing record, thus showing feasibility in real‐time health monitor and human–machine interfaces.     

Rational Design of a Flexible CNTs@PDMS Film Patterned by Bio‐Inspired Templates as a Strain Sensor and Supercapacitor

Flexible devices integrated with sensing and energy storage functions are highly desirable due to their potential application in wearable electronics and human motion detection. Here, a flexible film is designed in a facile and low‐cost leaf templating process, comprising wrinkled carbon nanotubes (CNTs) as the conductive layer and patterned polydimethylsiloxane (PDMS) with bio‐inspired microstructure as a soft substrate. Assembled from wrinkled CNTs on patterned PDMS film, a strain sensor is realized to possess sensitive resistance response against various deformations, producing a resistance response of 0.34%, 0.14%, and 9.1% under bending, pressing, and 20% strain, respectively. Besides, the strain sensor can reach a resistance response of 3.01 when stretched to 44%. Furthermore, through the electro‐deposition of polyaniline, the CNTs film is developed into a supercapacitor, which exhibits a specific capacitance of 176 F g^?1 at 1 A g^?1 and a capacitance retention of 88% after 10 000 cycles. In addition, the fabricated supercapacitor shows super flexibility, delivering a capacitance retention of 98% after 180° bending for 100 cycles, 95% after 45° twisting for 100 cycles, and 98% after 100% stretching for 400 cycles. The superior capacitance stability demonstrates that the design of wrinkled CNTs‐based electrodes fixed by microstructures is beneficial to the excellent electrochemical performance.     

Printable Fabrication of a Fully Integrated and Self‐Powered Sensor System on Plastic Substrates

Wearable and portable devices with desirable flexibility, operational safety, and long cruising time, are in urgent demand for applications in wireless communications, multifunctional entertainments, personal healthcare monitoring, etc. Herein, a monolithically integrated self‐powered smart sensor system with printed interconnects, printed gas sensor for ethanol and acetone detection, and printable supercapacitors and embedded solar cells as energy sources, is successfully demonstrated in a wearable wristband fashion by utilizing inkjet printing as a proof‐of‐concept. In such a “wearable wristband”, the harvested solar energy can either directly drive the sensor and power up a light‐emitting diode as a warning signal, or can be stored in the supercapacitors in a standby mode, and the energy released from supercapacitors can compensate the intermittency of light illumination. To the best of our knowledge, the demonstration of such a self‐powered sensor system integrated onto a single piece of flexible substrate in a printable and additive manner has not previously been reported. Particularly, the printable supercapacitors deliver an areal capacitance of 12.9 mF cm^?2 and the printed SnO₂ gas sensor shows remarkable detection sensitivity under room temperature. The printable strategies for device fabrication and system integration developed here show great potency for scalable and facile fabrication of a variety of wearable devices.     

A Highly Responsive Organic Image Sensor Based on a Two‐Terminal Organic Photodetector with Photomultiplication

Highly responsive organic image sensors are crucial for medical imaging applications. To enhance the pixelwise photoresponse in an organic image sensor, the integration of an organic photodetector with amplifiers, or the use of a highly responsive organic photodetector without an additional amplifying component, is required. The use of vertically stacked, two‐terminal organic photodetectors with photomultiplication is a promising approach for highly responsive organic image sensors owing to their simple two‐terminal structure and intrinsically large responsivity. However, there are no demonstrations of an imaging sensor array using organic photomultiplication photodetectors. The main obstacle to a sensor array is the weak‐light sensitivity, which is limited by a relatively large dark current. Herein, a highly responsive organic image sensor based on monolithic, vertically stacked two‐terminal pixels is presented. This is achieved using pixels of a vertically stacked diode‐type organic photodetector with photomultiplication. Furthermore, applying an optimized injection electrode and additionally stacked rectifying layers, this two‐terminal device simultaneously demonstrates a high responsivity (>40 A W^?1), low dark current, and high rectification under illumination. An organic image sensor based on this device with an extremely simple architecture exhibits a high pixel photoresponse, demonstrating a weak‐light imaging capability even at 1 µW cm^?2.     

集成化质量管理系统的设计开发

通过对我国制造业所面临的主要质量改进问题的分析,以笔者开发的集成化质量管理系统为基础,阐述了面向制造业的集成化计算机辅助质量管理系统的设计开发方法。所开发的系统实现了质量管理工具和方法的集成应用,为制造业持续质量改进提供了一个基础管理平台。     

分形几何和动力系统中的一些问题

本文是Zhou与Feng,Nonlinearity,2004的续篇,对自相似集的结构和动力系统提出一些较为深入的问题。     

An All‐Freeze‐Casting Strategy to Design Typographical Supercapacitors with Integrated Architectures

The emergence of flexible and wearable electronics has raised the demand for flexible supercapacitors with accurate sizes and aesthetic shapes. Here, a strategy is developed to prepare flexible all‐in‐one integrated supercapacitors by combining all‐freeze‐casting with typography technique. The continuous seamless connection of all‐in‐one supercapacitor devices enhances the load and/or electron transfer capacity and avoids displacing and detaching between their neighboring components at bending status. Therefore, such a unique structure of all‐in‐one integrated devices is beneficial for retaining stable electrochemical performance at different bending levels. More importantly, the sizes and aesthetic shapes of integrated supercapacitors could be controlled by the designed molds, like type matrices of typography. The molds could be assembled together and typeset randomly, achieving the controllable construction and series and/or parallel connection of several supercapacitor devices. The preparation of flexible integrated supercapacitors will pave the way for assembling programmable all‐in‐one energy storage devices into highly flexible electronics.     

A Highly Aligned Nanowire‐Based Strain Sensor for Ultrasensitive Monitoring of Subtle Human Motion

Achieving highly accurate responses to external stimuli during human motion is a considerable challenge for wearable devices. The present study leverages the intrinsically high surface‐to‐volume ratio as well as the mechanical robustness of nanostructures for obtaining highly‐sensitive detection of motion. To do so, highly‐aligned nanowires covering a large area were prepared by capillarity‐based mechanism. The nanowires exhibit a strain sensor with excellent gauge factor (≈35.8), capable of high responses to various subtle external stimuli (≤200 µm deformation). The wearable strain sensor exhibits also a rapid response rate (≈230 ms), mechanical stability (1000 cycles) and reproducibility, low hysteresis (<8.1%), and low power consumption (<35 µW). Moreover, it achieves a gauge factor almost five times that of microwire‐based sensors. The nanowire‐based strain sensor can be used to monitor and discriminate subtle movements of fingers, wrist, and throat swallowing accurately, enabling such movements to be integrated further into a miniaturized analyzer to create a wearable motion monitoring system for mobile healthcare.     

Actively Perceiving and Responsive Soft Robots Enabled by Self‐Powered,Highly Extensible,and Highly Sensitive Triboelectric Proximity‐ and Pressure‐Sensing Skins

Robots that can move, feel, and respond like organisms will bring revolutionary impact to today's technologies. Soft robots with organism‐like adaptive bodies have shown great potential in vast robot–human and robot–environment applications. Developing skin‐like sensory devices allows them to naturally sense and interact with environment. Also, it would be better if the capabilities to feel can be active, like real skin. However, challenges in the complicated structures, incompatible moduli, poor stretchability and sensitivity, large driving voltage, and power dissipation hinder applicability of conventional technologies. Here, various actively perceivable and responsive soft robots are enabled by self‐powered active triboelectric robotic skins (tribo‐skins) that simultaneously possess excellent stretchability and excellent sensitivity in the low‐pressure regime. The tribo‐skins can actively sense proximity, contact, and pressure to external stimuli via self‐generating electricity. The driving energy comes from a natural triboelectrification effect involving the cooperation of contact electrification and electrostatic induction. The perfect integration of the tribo‐skins and soft actuators enables soft robots to perform various actively sensing and interactive tasks including actively perceiving their muscle motions, working states, textile's dampness, and even subtle human physiological signals. Moreover, the self‐generating signals can drive optoelectronic devices for visual communication and be processed for diverse sophisticated uses.