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Research Article Issue
Scalable rolling-structured triboelectric nanogenerator with high power density for water wave energy harvesting toward marine environmental monitoring
Nano Research 2023, 16 (9): 11646-11652
Published: 14 August 2023
Downloads:29

In the context of advocating a green and low-carbon era, ocean energy, as a renewable strategic resource, is an important part of planning and building a new energy system. Triboelectric nanogenerator (TENG) arrays provide feasible and efficient routes for large-scale harvesting of ocean energy. In previous work, a spherical rolling-structured TENG with three-dimensional (3D) electrodes based on rolling motion of dielectric pellets was designed and fabricated for effectively harvesting low-frequency water wave energy. In this work, the external shape of the scalable rolling-structured TENG (SR-TENG) and internal filling amount of pellets were mainly optimized, achieving an average power density of 10.08 W∙m−3 under regular triggering. In actual water waves, the SR-TENG can deliver a maximum peak power density of 80.29 W∙m−3 and an average power density of 6.02 W∙m−3, which are much greater than those of most water wave-driven TENGs. Finally, through a power management, an SR-TENG array with eight units was demonstrated to successfully power portable electronic devices for monitoring the marine environment. The SR-TENGs could promote the development and utilization of ocean blue energy, providing a new paradigm for realizing the carbon neutrality goal.

Open Access Research Article Issue
Wearable energy harvesting-storage hybrid textiles as on-body self-charging power systems
Nano Research Energy 2023, 2: e9120079
Published: 01 June 2023
Downloads:1400

The rapid development of wearable electronics requires its energy supply part to be flexible, wearable, integratable and sustainable. However, some of the energy supply units cannot meet these requirements at the same time, and there is also a capacity limitation of the energy storage units, and the development of sustainable wearable self-charging power supplies is crucial. Here, we report a wearable sustainable energy harvesting-storage hybrid self-charging power textile. The power textile consists of a coaxial fiber-shaped polylactic acid/reduced graphene oxide/polypyrrole (PLA-rGO-PPy) triboelectric nanogenerator (fiber-TENG) that can harvest low-frequency and irregular energy during human motion as a power generation unit, and a novel coaxial fiber-shaped supercapacitor (fiber-SC) prepared by functionalized loading of a wet-spinning graphene oxide fiber as an energy storage unit. The fiber-TENG is flexible, knittable, wearable and adaptable for integration with various portable electronics. The coaxial fiber-SC has high volumetric energy density and good cycling stability. The fiber-TENG and fiber-SC are flexible yarn structures for wearable continuous human movement energy harvesting and storage as on-body self-charging power systems, with light-weight, ease of preparation, great portability and wide applicability. The integrated power textile can provide an efficient route for sustainable working of wearable electronics.

Research Article Issue
Physical mechanisms of contact-electrification induced photon emission spectroscopy from interfaces
Nano Research 2023, 16 (9): 11545-11555
Published: 20 April 2023
Downloads:81

Photon emission during contact electrification (CE) has recently been observed, which is called as CE-induced interface photon emission spectroscopy (CEIIPES). Physical mechanisms of CEIIPES are essential for interpreting the structure and electronic interactions of a contacted interface. Using the methods of density functional theory (DFT) and time-dependent DFT (TDDFT), it is confirmed theoretically that the spectrum of emitted photons is contributed from electron transfer and transition during CE. Specifically, the excited electrons from higher energy state in one material may transfer to a lower energy state of another material followed by a transition; and/or some unstable excited electrons at a higher energy level of one material may transit to a lower energy state of itself, both of which result in CEIIPES. Furthermore, the CE-induced interface absorption spectrum (CEIIAS) has been demonstrated, due to the intermolecular electron transfer excitation.

Research Article Issue
A bioinspired, self-powered, flytrap-based sensor and actuator enabled by voltage triggered hydrogel electrodes
Nano Research 2023, 16 (7): 10198-10205
Published: 30 March 2023
Downloads:70

Because of its adaptive interfacial property, soft sensors/actuators can be used to perform more delicate tasks than their rigid counterparts. However, plant epidermis with a waxy cuticle layer challenges stable and high-fidelity non-invasive electrophysiology since the conventional electrodes are invasive, easily detached from plants, and require complicated setup procedures. Here, we report a bioinspired sensor and actuator created by using a conformable electrode interface as an electrical modulation unit on a Venus flytrap. Our conformable electrode, by employing an adhesive hydrogel layer, can achieve the merits of low impedance, stretchable, biocompatible, reusable, and transparent enough for normal chlorophyll activity to occur. Owing to the high sensitivity of a flytrap to a triggering mechanical stimulation, a plant sensor matrix based on flytraps has been demonstrated by capturing the stimulated action potential (AP) signals from upper epidermis, which can orient honeybee colonies by their touch during collecting nectar. Moreover, via frequency-dependent AP modulation, an autonomous on-demand actuation on a flytrap is realized. The flytrap actuator can be controlled to responsively grasp tiny objects by the modulated signals triggered by a triboelectric nanogenerator (TENG). This work paves a way of developing autonomous plant-based sensors and actuators toward smart agriculture and intelligent robots.

Research Article Issue
Miniaturized retractable thin-film sensor for wearable multifunctional respiratory monitoring
Nano Research 2023, 16 (9): 11846-11854
Published: 08 February 2023
Downloads:134

As extremely important physiological indicators, respiratory signals can often reflect or predict the depth and urgency of various diseases. However, designing a wearable respiratory monitoring system with convenience, excellent durability, and high precision is still an urgent challenge. Here, we designed an easy-fabricate, lightweight, and badge reel-like retractable self-powered sensor (RSPS) with high precision, sensitivity, and durability for continuous detection of important indicators such as respiratory rate, apnea, and respiratory ventilation. By using three groups of interdigital electrode structures with phase differences, combined with flexible printed circuit boards (FPCBs) processing technology, a miniature rotating thin-film triboelectric nanogenerator (RTF-TENG) was developed. Based on discrete sensing technology, the RSPS has a sensing resolution of 0.13 mm, sensitivity of 7 P·mm−1, and durability more than 1 million stretching cycles, with low hysteresis and excellent anti-environmental interference ability. Additionally, to demonstrate its wearability, real-time, and convenience of respiratory monitoring, a multifunctional wearable respiratory monitoring system (MWRMS) was designed. The MWRMS demonstrated in this study is expected to provide a new and practical strategy and technology for daily human respiratory monitoring and clinical diagnosis.

Research Article Issue
Scalable one-step wet-spinning of triboelectric fibers for large-area power and sensing textiles
Nano Research 2023, 16 (5): 7518-7526
Published: 12 January 2023
Downloads:45

Textile-based electronic devices have attracted increasing interest in recent years due to their wearability, breathability, and comfort. Among them, textile-based triboelectric nanogenerators (T-TENGs) exhibit remarkable advantages in mechanical energy harvesting and self-powered sensing. However, there are still some key challenges to the development and application of triboelectric fibers (the basic unit of T-TENG). Scalable production and large-scale integration are still significant factors hindering its application. At the same time, there are some difficulties to overcome in the manufacturing process, such as achieving good stretchability and a quick production, overcoming incompatibility between conductive and triboelectric materials. In this study, triboelectric fibers are produced continuously by one-step coaxial wet spinning. They are only 0.18 mm in diameter and consist of liquid metal (LM) core and polyurethane (PU) sheath. Due to the good mechanical properties between them, there is no interface incompatibility of the triboelectric fibers. In addition, triboelectric fibers can be made into large areas of T-TENG by means of digital embroidery and plain weave. The T-TENGs can be used for energy harvesting and self-powered sensing. When they are fixed on the forearm can monitor various strokes in badminton. This work provides a promising strategy for the large-scale fabrication and large-area integration of triboelectric fibers, and promotes the development of wearable T-TENGs.

Research Article Issue
Thermal-mechanical-electrical energy conversion system based on Curie effect and soft-contact rotary triboelectric nanogenerator
Nano Research 2023, 16 (2): 2502-2510
Published: 08 November 2022
Downloads:44

Untapped thermal energy, especially low-grade heat below 373 K from various sources, namely ambient, industries residual, and non-concentrated solar energy, is abundant and widely accessible. Despite that, there are huge constraints to recycle this valuable low-grade heat using the existing technologies due to the variability of thermal energy output and the small temperature difference between the heat source and environment. Here, a thermal-mechanical-electrical energy conversion (TMEc) system based on the Curie effect and the soft-contact rotary triboelectric nanogenerator (TENG) is developed to recycle thermal energy in the mid-low temperature range. According to the phase transition mechanism between ferromagnetic and paramagnetic, disk-shaped ferromagnetic materials can realize stable rotation under external magnetic and thermal fields, thus activating the operation of TENGs and realizing the conversion of thermal energy and electrical energy. During the steady rotation process, an open-circuit voltage (VOC) of 173 V and a short-circuit current (ISC) of 1.32 µA are measured. We finally obtained a maximum power of 4.45 mW in the actual working conditions, and it successfully charged different capacitors. This work provides a new method for mid-low temperature energy harvesting and thermal energy transformation and broadens the application of TENG in the field of thermal energy recovery.

Research Article Issue
Wearable and humidity-resistant biomaterials-based triboelectric nanogenerator for high entropy energy harvesting and self-powered sensing
Nano Research 2022, 15 (7): 6213-6219
Published: 07 May 2022
Downloads:57

Triboelectric nanogenerator (TENG) provides a new solution to the energy supply by harvesting high entropy energy. However, wearable electronic devices have high requirements for flexible, humidity-resistant, and low-cost TENG. Here, environment-friendly and multi-functional wheat starch TENG (S-TENG) was made by a simple and green method. The open-circuit voltage and short-circuit current of S-TENG are 151.4 V and 47.1 μA, respectively. S-TENG can be used not only to drive and intelligently control electronic equipment, but also to effectively harvest energy from body movements and wind. In addition, the output of S-TENG was not negatively affected with the increase in environmental humidity, but increased abnormally. In the range of 20% RH–80% RH, S-TENG can be potentially used as a sensitive self-powered humidity sensor. The S-TENG paves the way for large-scale preparation of multi-functional biomaterials-based TENG, and practical application of self-powered sensing and wearable devices.

Research Article Issue
Knitted self-powered sensing textiles for machine learning-assisted sitting posture monitoring and correction
Nano Research 2022, 15 (9): 8389-8397
Published: 16 February 2022
Downloads:122

With increasing work pressure in modern society, prolonged sedentary positions with poor sitting postures can cause physical and psychological problems, including obesity, muscular disorders, and myopia. In this paper, we present a self-powered sitting position monitoring vest (SPMV) based on triboelectric nanogenerators (TENGs) to achieve accurate real-time posture recognition through an integrated machine learning algorithm. The SPMV achieves high sensitivity (0.16 mV/Pa), favorable stretchability (10%), good stability (12,000 cycles), and machine washability (10 h) by employing knitted double threads interlaced with conductive fiber and nylon yarn. Utilizing a knitted structure and sensor arrays that are stitched into different parts of the clothing, the SPMV offers a non-invasive method of recognizing different sitting postures, providing feedback, and warning users while enhancing long-term wearing comfortability. It achieves a posture recognition accuracy of 96.6% using the random forest classifier, which is higher than the logistic regression (95.5%) and decision tree (94.3%) classifiers. The TENG-based SPMV offers a reliable solution in the healthcare system for non-invasive and long-term monitoring, promoting the development of triboelectric-based wearable electronics.

Research Article Issue
Hybridized triboelectric-electromagnetic nanogenerators and solar cell for energy harvesting and wireless power transmission
Nano Research 2022, 15 (3): 2069-2076
Published: 28 September 2021
Downloads:92

Energy harvesting and power transmission is a significant challenge for the self-powered technologies towards mobile electronic devices. Here, we propose a hybridized energy harvester to complement each other's strengths for simultaneously scavenging multiple types of energy and then wirelessly transmit the power. The harvester consists of electromagnetic-triboelectric nanogenerator units for collecting rotational energy and a commercial water-proof flexible solar cell. At a rotation rate of 500 rpm, the output current of electromagnetic-triboelectric nanogenerator units can reach about 630 mA through energy management. Moreover, the power harvested by hybridized energy harvester can be wirelessly transmitted up to a distance of about 100 cm in real time to charge mobile phone, anemometer, and hygrometer based on self-resonant coils. The hybridized energy harvester with wireless power transmission has potential applications in large-scale energy collection, long-distance wireless power transmission and sustainably driving mobile electronic devices.

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