Multiplying the Stable Electrostatic Field of Electret Based on the Heterocharge-Synergy and Superposition Effect.

Owing to magic charge storage behavior, an electret can exhibit an external electrostatic field, which is widely used in numerous domains such as electronics, energy, healthcare, and environment. However, the theory of the charge storage mechanism still needs further development to enhance the performance and stability of the electret. Herein, a stable charge storage model known as the heterocharge-synergy model (HSM) in electrets is proposed and verified, and the electrostatic field superposition effect of electrets is also proved.

High-Performance Dielectric Elastomer Nanogenerator for Efficient Energy Harvesting and Sensing via Alternative Current Method.

Soft, low-cost, high-performance generators are highly desirable for harvesting ambient low frequency mechanical energy. Here, a dielectric elastomer nanogenerator (DENG) is reported, which consists of a dielectric elastomer capacitor, an electret electrostatic voltage source, and a charge pump circuit. Under biaxial stretching, DENG can convert tensile mechanical energy into electrical power without any external power supply.

Trap-Induced Dense Monocharged Perfluorinated Electret Nanofibers for Recyclable Multifunctional Healthcare Mask.

Recently, wearable and breathable healthcare devices for air filtering and real-time vital signs monitoring have become urgently needed since virus and particulate matter (PM) cause serious health issues. Herein, we present a trap-induced dense monocharged hybrid perfluorinated electret nanofibrous membrane (HPFM) for highly efficient ultrafine PM removal with an efficiency of 99.712% under low pressure drop (38.

Electrospun Polytetrafluoroethylene Nanofibrous Membrane for High-Performance Self-Powered Sensors.

Polytetrafluoroethylene (PTFE) is a fascinating electret material widely used for energy harvesting and sensing, and an enhancement in the performance could be expected by reducing its size into nanoscale because of a higher surface charge density attained. Hence, the present study demonstrates the use of nanofibrous PTFE for high-performance self-powered wearable sensors. The nanofibrous PTFE is fabricated by electrospinning with a suspension of PTFE particles in dilute polyethylene oxide (PEO) aqueous solution, followed by a thermal treatment at 350 °C to remove the PEO component from the electrospun PTFE-PEO nanofibers.

Fiber-Based Energy Conversion Devices for Human-Body Energy Harvesting.

Following the rapid development of lightweight and flexible smart electronic products, providing energy for these electronics has become a hot research topic. The human body produces considerable mechanical and thermal energy during daily activities, which could be used to power most wearable electronics. In this context, fiber-based energy conversion devices (FBECD) are proposed as candidates for effective conversion of human-body energy into electricity for powering wearable electronics.

Boosting the Efficient Energy Output of Electret Nanogenerators by Suppressing Air Breakdown under Ambient Conditions.

By virtue of simple fabrication, low cost, and high conversion efficiency, nanogenerators play a key role in promoting the development of self-powered systems and large-scale mechanical energy harvesting. Efforts have been ongoing for improving the output power of nanogenerators by maximizing their surface charge density via surface modification or structure optimization. Nevertheless, because of inevitable air breakdown during the operation process, enhancing charge density is not retainable, which is the most crucial limitation for the output performance of nanogenerators.

Flexible THV/COC Piezoelectret Nanogenerator for Wide-Range Pressure Sensing.

Flexible pressure sensors possess promising applications in artificial electronic skin, intelligence robot, wearable health monitoring, flexible physiological signal sensing, etc. Herein, we design a flexible pressure sensor with robust stability, high sensitivity, and large linear pressure region on the basis of tetrafluoroethylene-hexafluoropropylene-vinylide (THV)/cyclic olefin copolymer (COC) piezoelectret nanogenerator. According to the theoretical analysis for piezoelectret nanogenerators with imbalanced charge distribution, THV and COC are utilized to promote the electric field inside the piezoelectret for output voltage enhancement.

Highly Efficient Water Harvesting with Optimized Solar Thermal Membrane Distillation Device.

Water distillation with solar thermal technology could be one of the most promising way to address the global freshwater scarcity, with its low cost and minimum environmental impacts. However, the low liquid water productivity, which is caused by the heat loss and inadequate heat utilization in solar-thermal conversion process, hinders its practical application. Here, a compact solar-thermal membrane distillation system with three structure features: highly localized solar-thermal heating, effective cooling strategy, and recycling the latent heat, is proposed.

Noncontact Heartbeat and Respiration Monitoring Based on a Hollow Microstructured Self-Powered Pressure Sensor.

Advances in mobile networks and low-power electronics have driven smart mobile medical devices at a tremendous pace, evoking increased interest in household healthcare, especially for those with cardiovascular or respiratory disease. Thus, flexible battery-free pressure sensors, with great potential for monitoring respiration and heartbeat in a smart way, are urgently demanded. However, traditional flexible battery-free pressure sensors for subtle physiological signal detecting are mostly tightly adhered onto the skin instead of working under the pressure of body weight in a noncontact mode, as the low sensitivity in the high-pressure region can hardly meet the demands.

Output optimized electret nanogenerators for self-powered long-distance optical communication systems.

High-speed optical communication systems are built for real-time, massive and remote information exchange. However, any power outage will paralyse the systems and cause a huge loss. Here we constructed a self-powered long-distance optical communication system (SLOCS) utilizing output enhanced parallel connected electret nanogenerators (NGs) as a backup power for the power outage.

Sensitivity-Enhanced Wearable Active Voiceprint Sensor Based on Cellular Polypropylene Piezoelectret.

Wearable active sensors have extensive applications in mobile biosensing and human-machine interaction but require good flexibility, high sensitivity, excellent stability, and self-powered feature. In this work, cellular polypropylene (PP) piezoelectret was chosen as the core material of a sensitivity-enhanced wearable active voiceprint sensor (SWAVS) to realize voiceprint recognition. By virtue of the dipole orientation control method, the air layers in the piezoelectret were efficiently utilized, and the current sensitivity was enhanced (from 1.

Scalable salt-templated synthesis of two-dimensional transition metal oxides.

Two-dimensional atomic crystals, such as two-dimensional oxides, have attracted much attention in energy storage because nearly all of the atoms can be exposed to the electrolyte and involved in redox reactions. However, current strategies are largely limited to intrinsically layered compounds. Here we report a general strategy that uses the surfaces of water-soluble salt crystals as growth templates and is applicable to not only layered compounds but also various transition metal oxides, such as hexagonal-MoO3, MoO2, MnO and hexagonal-WO3.

Two-Dimensional Layered Heterostructures Synthesized from Core-Shell Nanowires.

Controlled stacking of different two-dimensional (2D) atomic layers will greatly expand the family of 2D materials and broaden their applications. A novel approach for synthesizing MoS2 /WS2 heterostructures by chemical vapor deposition has been developed. The successful synthesis of pristine MoS2 /WS2 heterostructures is attributed to using core-shell WO3-x /MoO3-x nanowires as a precursor, which naturally ensures the sequential growth of MoS2 and WS2 .