Research Article Just Accepted
Giant piezotronic effect in ferroelectric field effect transistor
Nano Research
Available online: 01 July 2024
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The piezotronics effect utilizes a piezopotential to modulate and control current in piezo-semiconductors. Ferroelectric materials, as a type of piezoelectric materials, possess piezoelectric coefficients that are significantly larger than those found in conventional piezoelectric materials. Here, we propose a strain modulated ferroelectric field-effect transistor (St-FeFET) utilizing external strain instead of gate voltage to achieve ferroelectric modulation, which eliminates the need for gate voltage. By applying a very small strain (0.01%), the St-FeFET can achieve a maximum on-off current ratio of 1250% and realizes a gauge factor (GF) of 1.19 × 106, which is much higher than that of conventional strain sensors. This work proposes a new method for realizing highly sensitive strain sensors and presents innovative approaches to the operation methods of ferroelectric field-effect transistors as well as potential applications for coupling of strain sensors and various devices across different fields.

Research Article Online First
Triboelectric nanogenerator integrated with a simple controlled switch for regularized water wave energy harvesting
Nano Research
Published: 27 April 2024
Abstract PDF (9.4 MB) Collect

Ocean is full of low-frequency, irregular, and widely distributed wave energy, which is suitable as the energy source for maritime Internet of Things (IoTs). Utilizing triboelectric nanogenerators (TENGs) to harvest ocean wave energy and power sensors is proven to be an effective scheme. However, in random ocean waves, the irregular electrical energy output by general TENGs restricts the applications. At present, achieving regularized water wave energy harvesting relies on rather complex mechanical structure designs, which is not conducive to industrialization. In this work, we proposed a novel mechanical controlled TENG (MC-TENG) with a simple controlled switch to realize the regularization function. The structural parameters of the MC-TENG are optimized, and the optimal output voltage, output current, and transferred charge respectively reach 1684.2 V, 85.4 μA, and 389.9 nC, generating a peak power density of 38.46 W·m−3·Hz−1. Under real water wave environment, the output of the MC-TENG is regularized and keeps stable regardless of any wave conditions. Moreover, the potential applications of the MC-TENG are demonstrated in powering environmental temperature, humidity, and wind speed sensors. This work renders a simple approach to achieve effective regularized ocean wave energy harvesting, promoting the TENG industrialization toward practical application of maritime IoTs.

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
Abstract PDF (13.5 MB) Collect

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
Abstract PDF (3.1 MB) Collect

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
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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
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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
Abstract PDF (22.3 MB) Collect

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
Abstract PDF (7 MB) Collect

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
Abstract PDF (12.8 MB) Collect

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
Abstract PDF (16.7 MB) Collect

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.

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