A hybrid energy utilization technology using solar energy for desalination and extracting electricity from an evaporation induced salinity gradient is presented.

body is actually a tremendous storehouse of energy that is generated from body heat and motion. [15][16][17][18][19] Power generation from breathing, heating, blood transport, arm motion, typing, and walking could reach to over 100 W for a 68 kg adult's daily activities (Figure 1). [20] Thus, converting 1% of power from the human body may be enough to support the work of most portable electronics.In the past two decades, researchers have developed several energy conversion devices based on piezoelectricity, electrostaticity, triboelectricity, or thermoelectricity that can directly harvest the mechanical or thermal energy and convert it into electric energy (these conversion devices are so-called nanogenerators (NGs)). [21][22][23][24][25] The first nanogenerator (NG) based on ZnO was invented by Prof. Wang in 2006; after that, various NGs were developed to harvest the mechanical or thermal energy with the output performance increasing gradually. [26] These NGs are easy-to-construct flexible devices since most materials for these devices are polymers and nanomaterials. Generally, the flexible devices assembled by film materials can be stretchable and bendable in one direction. But their lack of air-permeability, poor 3D deformation, and low damage tolerance limit their application, especially for wearable electronics. Therefore, fiberbased energy conversion devices have been designed. [27] These fiber-based devices can also be knitted to yarn or fabric in the clothing system to build up a large area electronic system. [28,29] The energy generation and internal charging can be realized by means of a self-powered system that harvests the energy from natural sources around the human body to sustain the wearable electronics. [30][31][32] The search for functional materials that possess good conversion efficiency, as well as great mechanical and environmental stability, combined with a novel device design might push these devices to meet the requirement of a practical application. In the past decade, numerous contributions have been offered to improve the performance of fiber-based energy conversion devices (FBECD) and extend its application. This review specifically summarizes FBECD with different energy conversion mechanisms including piezoelectricity, electrostaticity, triboelectricity, and thermoelectricity in recent processes (Figure 2). The functional materials, fiber fabrication techniques, and device design strategies for different classes of FBECDs are covered in the article. We also introduce an overview of the fiber-based self-powered system and sensors and 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...

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. Moreover, a hollow microstructure (HM) with higher deformation than solid microstructures and great potential for improving the pressure sensitivity of self-powered sensors has never been investigated. Here, for the first time, we demonstrated a noncontact heartbeat and respiration monitoring system based on a flexible HM-enhanced self-powered pressure sensor, which possesses the advantages of low cost, a high dynamic-pressure sensitivity of 18.98 V·kPa, and a wide working range of 40 kPa simultaneously. Specific superiority of physiological detection under a high pressure is also observed. Continuous reliable heartbeat and respiration information is successfully detected in a noncontact mode and transmitted to a mobile phone.

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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 PM0.3 removal with an efficiency of 99.712% under low pressure drop (38.1 Pa) and high quality factor of 0.154 Pa–1. Furthermore, a recyclable multifunctional healthcare mask is constructed by integrating the HPFM-based nanogenerator, which realizes efficient PM0.3 filtering and wireless real-time human respiration monitoring simultaneously. More importantly, the performance of this mask is still relatively stable even at 100%RH humidity and 92 °C temperature conditions for 48 h, which infers that it can be reused after disinfection. The strategy of fabricating HPFM provides an approach to obtain charge-rich stable electret materials, and the design of multifunctional masks demonstrates their potential application for future personal protection and health monitoring devices.

Implantable ultrasonic energy harvesters that scavenge wireless mechanic energy from ultrasound own remarkable potential in advanced medical protocols for neuroprosthetics, wireless power, biosensor, etc. The main challenge for this kind of device is to achieve high‐efficiency energy conversion in a weak ultrasonic pressure field. Here, a multilayered piezoelectret with strain enhanced piezoelectricity by introducing a parallel‐connected air hole array in an interdielectric layer sandwiched between a pair of electrets for an efficient ultrasonic energy harvester is presented. This device delivers a remarkable peak output power around 13.13 mW and short‐circuits current around 2.2 mA when implanted into tissues at 5~10 mm under an ultrasonic probe setup at 25 mW cm−2, which is higher than the required power threshold of bioelectronic devices and current threshold of nerve stimulation. Furthermore, the feasibility of supplying power to implantable bioelectronics and working as neuroproteins for peripheral nerve stimulation are both demonstrated. It is anticipated that this highly efficient, easily fabricated, and biocompatible device will potentially enable applications for multifunctional and advanced implantable bioelectronics in the next generation of diagnosis and therapy.

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