Rational Design of Cellulosic Triboelectric Materials for Self‑Powered Wearable Electronics

With the rapid development of the Internet of Things and flexible electronic technologies,there is a growing demand for wireless,sustainable,multifunctional,and independently operating self-powered wearable devices.Nevertheless,structural flexibility,long operating time,and wearing comfort have become key requirements for the widespread adoption of wearable electronics.Triboelectric nanogenerators as a distributed energy harvesting technology have great potential for application development in wearable sensing.Compared with rigid electronics,cellulosic self-powered wearable electronics have significant advantages in terms of flexibility,breathability,and functionality.In this paper,the research progress of advanced cellulosic triboelectric materials for self-powered wearable electronics is reviewed.The interfacial characteristics of cellulose are introduced from the top-down,bottom-up,and interfacial characteristics of the composite material preparation process.Meanwhile,the modulation strategies of triboelectric properties of cellulosic triboelectric materials are presented.Furthermore,the design strategies of triboelectric materials such as surface functionalization,interfacial structure design,and vacuum-assisted self-assembly are systematically discussed.In particular,cellulosic self-powered wearable electronics in the fields of human energy harvesting,tactile sensing,health monitoring,human–machine interaction,and intelligent fire warning are outlined in detail.Finally,the current challenges and future development directions of cellulosic triboelectric materials for self-powered wearable electronics are discussed.

A New Soil Infiltration Technology for Decentralized Sewage Treatment:Two-Stage Anaerobic Tank and Soil Trench System

The low removal effciency of total nitrogen(TN) is one of the main disadvantages of traditional single stage subsurface infiltration system,which combines an anaerobic tank and a soil filter field.In this study,a full-scale,two-stage anaerobic tank and soil trench system was designed and operated to evaluate the feasibility and performances in treating sewage from a school campus for over a one-year monitoring period.The raw sewage was prepared and fed into the first anaerobic tank and second tank by 60% and 40%,respectively.This novel process could decrease chemical oxygen demand with the dichromate method by 89%-96%,suspended solids by 91%-97%,and total phosphorus by 91%-97%.The denitrification was satisfactory in the second stage soil trench,so the removals of TN as well as ammonia nitrogen(NH+4-N) reached 68%-75% and 96%-99%,respectively.It appeared that the removal effciency of TN in this two-stage anaerobic tank and soil trench system was more effective than that in the single stage soil infiltration system.The effuent met the discharge standard for the sewage treatment plant(GB18918-2002) of China.

Preparation and thermal-mechanical property evaluation of cellulose insulation paper with differing nano-SiC contents

Cellulose insulation paper is the main component of oil-paper insulation systems in oilimmersed transformers.However,the poor thermal conductivity and thermal stability of the cellulose can lead to thermal ageing.It is critical to address this issue by improving the performance of cellulose,nano-SiC-modified cellulose models were established by molecular simulation,while nano-SiC composite papersheets were prepared based on the simulation results,and the effects of different contents of nano-SiC on the papersheets were investigated.Macroscopically,doping nano-SiC particles can enhance the thermal stability of cellulose;compared with the unmodified papersheet,the thermal conductivity and tensile strength of the modified papersheets are increased by 44.3%and 42.8%,respectively.The degree of polymerisation of the modified papersheet decreased more slowly than that of the unmodified papersheet under accelerated thermal ageing,showing that the modified papersheet has better anti-ageing properties.Microscopically,with the addition of nano-SiC,the simulations showed that the mean square displacement of the cellulose decreases dramatically and the distribution of the free volume becomes difficult to disperse,which corresponds to the decrease in porosity in the experiments.As a result,this research provides a way for improving the thermal-mechanical properties of cellulose that has practical application significance.

Utilizing Multilayer Design of Organic-Inorganic Hybrids to Enhance Wearable Strain Sensor in Humid Environment

Flexible strain wearable sensors have attracted considerable attention due to their advantages of low cost, lightweight, high sensitivity and good flexibility. However, the strain sensors are easy to be damaged in an extreme humidity environment or by the wearer’s sweat in the process of use, resulting in detection disorder or even a short circuit. Furthermore, preparation of sensors with stable properties under extreme environments is one of the most important research directions. To fill this gap, a flexible sensor was prepared by using polyurethane and carbon nanotubes, then modified by polydopamine and 1H,1H,2H,2H-perfluorodecane-mercaptan. A typical tunnel model was used to explain the working mechanism of the sensor, the sensitivity of the sensor is also explained and evaluated by the tunneling theory. The results show that the sensor has good sensitivity (the sensor has a stable sensing signal output under a strain range from 2% to 300%) and stability over 8500 cycles. At the same time, the sensor has good superhydrophobicity, the water contact angle reaches 152°, and it is still stable in a humid environment. Moreover, this sensor shows excellent performance in monitoring human joint motion (such as finger, elbow, wrist and knee) and physiological signals (such as speaking and drinking). This work provides an effective design method for the sensor which can be applied in a high humidity environment.

Advanced biomass materials: progress in the applications for energy, environmental, and emerging fields

The world is currently grappling with many crises,including climate change,environmental pollution,resource scarcity,and rampant resource consumption.To address these issues,it is necessary to seek solutions that are low-carbon,environmentally friendly,and cost-effective.One promising avenue for addressing these challenges is through the use of biomass-based materials,which have many unique advantages,including renewability,biodegradability,and abundance.