Publications

The output of an ultrasonic wave-driven nanogenerator (NG) has been found to depend on the excitation conditions and geometry. Incidence angle tests indicate that the effective area of an NG determines the amount of power that can be generated. The output power of an NG is also directly related to its distance from the ultrasonic source. A sinusoidal profile of the electrical output was observed when an NG was moved inside a long tube filled with water with the ultrasonic source located at one end. This is due to the oscillation of the wave intensity inside the tube as a function of the distance from the excitation source.

Since the world's first triboelectric nanogenerator (TENG) was proposed in 2012, numerous TENG-based devices and equipment have sprung up in various fields. In particular, TENG has great potential in the field of human-health care due to its small size, self-powered and low cost. With the continuous deepening of TENG research, its structure, function and technical concept are becoming more and more abundant. In order to summarize the progress and development status of TENG in health care, based on the different types of applications subdirection, this paper reviews the TENG-based research work of this field in recent eight years. The characteristics of various types of TENG-based applications and their corresponding technologies are introduced and analyzed, under the comparison of their structure and performance. This review is dedicated to provide reference and inspiration for the future development and innovation of TENG for health care.

Vibration is one of the widespread phenomena in our surroundings, and a lot of research has been conducted to harvest it; however, due to its low frequency and random directions, there are few solutions to achieve omnidirectional energy harvesting. Based on a tower spring, this paper proposes an omnidirectional hybrid triboelectric–electromagnetic nanogenerator (OD-HNG) to harvest the omnidirectional vibration energy. The triboelectric nanogenerators (TENGs) are designed into a multilayered structure to enhance space utilization, and the electromagnetic generator (EMG) unit is hybridized to increase the output of OD-HNGs further. Benefiting from the design of the tower spring, the OD-HNG can respond to the external excitation in both vertical and horizontal directions, and its operational bandwidth is extended, allowing it to perform omnidirectional and broadband vibration energy harvesting very effectively. When OD-HNG is installed on a bicycle at a regular riding speed, a 1000 μF capacitor can be charged to 1.75 V in 20 s and has been successfully used as the power supply of portable electronic devices, ambient temperature monitors, and self-powered systems. More significantly, by harvesting the vibration energy from the vehicle-mounted environment, the OD-HNG can power portable electronic devices and environmental sensors continuously. These characteristics show that the tower spring-based OD-HNG is capable of very effective omnidirectional and broadband vibration energy harvesting and provides a good candidate for harvesting low-frequency vibration energy on a large scale.

Activated carbon-supported sulfided molybdenum catalysts were tested in transformation of ethanol to ethyl acetate. The catalytic activity of MoS x /C catalysts was found to depend strongly on preparation procedure. Surface atomic ratio of S/Mo on these catalysts was different and the catalyst with the ratio of S/Mo = 2.2 had better catalytic properties. For the purpose of enhancement of catalytic activity, the treatment of activated carbon support by HN0 3 had been applied. Physicochemical characterization showed that the pretreatment was effective in obtaining a highly dispersed molybdenum species on the surface of the catalyst, which led to an increase in conversion of ethanol.

Triboelectric nanogenerator (TENG) has presented the huge potential application in distributed energy field which can realize the conversion from dispersed mechanical energy to electric energy. However, the natural characteristic of pulse output for conventional TENG, which means high crest factor, is defective for directly driving electronics. Here, a strategy to convert the pulse alternate current of TENG into a direct current with low crest factor is achieved through introducing a phase difference design into the structure of TENG. As a result, a direct current with a crest factor of 1.07 is obtained in a rotational free-standing TENG (RF-TENG) array at optimum phase difference, where 3D digital printing technology is used to accurately control the parameter of phase difference. Moreover, an adaptable contact mode structure between tribolayer and electrode improves the durability of the RF-TENG array, which can present a stable performance after working 1.2 million cycles. This work provides a combined strategy to obtain a long-lifetime and low crest-factor TENG for its large-scale application in energy harvesting.

Liquid and gas flow sensors are important components of the micro total analysis systems (μTAS) for modern analytical sciences. In this paper, we proposed a self-powered triboelectric microfluidic sensor (TMS) by utilizing the signals produced from the droplet/bubble via the capillary and the triboelectrification effects on the liquid/solid interface for real-time liquid and gas flow detection. By alternating capillary with different diameters, the sensor's detecting range and sensitivity can be adjusted. Both the relationship between the droplet/bubble and capillary size, and the output signal of the sensor are systematically studied. By demonstrating the monitoring of the transfusion process for a patient and the gas flow produced from an injector, it shows that TMS has a great potential in building a self-powered micro total analysis system.

Abstract Wind energy is one of the most promising renewable energy sources, but harvesting low frequency breeze wind energy is hardly achieved using traditional electromagnetic generators (EMGs). Triboelectric nanogenerators (TENGs) provide a new approach for large‐scale collection of distributed breeze wind energy (usually 3.4–5.4 m s −1 ). Herein, by coupling the TENG and EMG, a swing‐structured hybrid nanogenerator with improved performance and durability is designed. The dielectric brush and air gap designs can minimize the material wear and continuously supply the tribo‐charges. Under external triggering, systematic comparisons are made about the output characteristics of TENG and EMG. The rectified peak power and average power of TENG are respectively, 60 and 635 times higher than those of EMG at moderate coil turn numbers, showing that TENG is much more effective than EMG for harvesting low‐frequency distributed energy (high entropy energy). Furthermore, the hybrid nanogenerator and array device are hung on tree branches to demonstrate the effective harvesting of breeze wind energy, delivering total rectified peak power densities of 2.07 and 1.94 W m –3 for single and array devices, respectively. The applications of powering portable electronics reveal the huge prospects of hybrid nanogenerator in self‐powered environmental monitoring toward forest/park fire warning systems.

Ultrasound (US)-triggered sonodynamic therapy (SDT) based on semiconductor nanomaterials has attracted considerable attention for cancer therapy. However, most inorganic sonosensitizers suffer from low efficiency due to the rapid recombination of electron-hole pairs. Herein, the Cu2-xO-BaTiO3 piezoelectric heterostructure was fabricated as a sonosensitizer and chemodynamic agent, simultaneously, for improving reactive oxygen species (ROS) generation and cancer therapeutic outcome. Under US irradiation, the Cu2-xO-BaTiO3 heterojunction with a piezotronic effect exhibits high-performance singlet oxygen (1O2) and hydroxyl radical (•OH) generation to enhance SDT. Moreover, it possesses Fenton-like reaction activity to convert endogenous H2O2 into •OH for chemodynamic therapy (CDT). The integration of SDT and CDT substantially boosts ROS generation and cellular mitochondria damage, and the in vitro and in vivo results demonstrate high cytotoxicity and tumor inhibition on murine refractory breast cancer. This work realizes improvement in cancer therapy using piezoelectric heterostructures with piezotronic effects.

We introduce a solution-based electrodeposition technique that selectively deposits copper only at the contacts between nanowires/nanobelts/nanotubes and the electrodes, while leaving the device surfaces clean. This was achieved using a copper nitrate bath with low covering power. Our method demonstrates an effective, parallel process for achieving stable electric and mechanical contacts for one-dimensional nanomaterial-based devices on a large scale.

Stretchable electronics are of great significance for the development of the next-generation smart interactive systems. Here, we propose an intrinsically stretchable organic tribotronic transistor (SOTT) without a top gate electrode, which is composed of a stretchable substrate, silver nanowire electrodes, semiconductor blends, and a nonpolar elastomer dielectric. The drain-source current of the SOTT can be modulated by external contact electrification with the dielectric layer. Under 0-50% stretching both parallel and perpendicular to the channel directions, the SOTT retains great output performance. After being stretched to 50% for thousands of cycles, the SOTT can survive with excellent stability. Moreover, the SOTT can be conformably attached to the human hand, which can be used for tactile signal perception in human-machine interaction and for controlling smart home devices and robots. This work has realized a stretchable tribotronic transistor as the tactile sensor for smart interaction, which has extended the application of tribotronics in the human-machine interface, wearable electronics, and robotics.

A triboelectric-pyroelectric-piezoelectric hybrid cell, consisting of a triboelectric nanogenerator and a pyroelectric-piezoelectric nanogenerator, is developed for highly efficient mechanical energy harvesting through multiple mechanisms. The excellent performance of the hybrid cell enhances the energy-harvesting efficiency significantly (by 26.2% at 1 kΩ load resistance), and enables self-powered sensing, which will lead to a variety of advanced applications.

All-solid-state flexible supercapacitors based on a carbon/MnO2 (C/M) core–shell fiber structure were fabricated with high electrochemical performance such as high rate capability with a scan rate up to 20 V s–1, high volume capacitance of 2.5 F cm–3, and an energy density of 2.2 × 10–4 Wh cm–3. By integrating with a triboelectric generator, supercapacitors could be charged and power commercial electronic devices, such as a liquid crystal display or a light-emitting-diode, demonstrating feasibility as an efficient storage component and self-powered micro/nanosystems.

Abstract The development of the Internet of Things (IoT) indicates that humankind has entered a new intelligent era of the “Internet of Everything”. Thanks to the characteristics of low‐cost, diverse structure, and high energy conversion efficiency, the self‐powered sensing systems, which are based on the Triboelectric Nanogenerator (TENG), demonstrate great potential in the field of IoT. In order to solve the challenges of TENG in sensing signal processing, such as signal noise and nonlinear relations, Machine Learning (ML), which is an efficient and mature data processing tool, is widely applied for efficiently processing the large and complex output signal data generated by TENG intelligent sensing system. This review summarizes and analyzes the adaptation of different algorithms in TENG and their advantages and disadvantages at the beginning, which provides a reference for the selection of algorithms for TENG. More importantly, the application of TENG is introduced in multiple scenarios, including health monitoring, fault detection, and human‐computer interaction. Finally, the limitations and development trend of the integration of TENG and ML are proposed by classification to promote the future development of the intelligent IoT era.

Abstract Solid‐state sodium batteries (SSSBs) are promising electrochemical energy storage devices due to their high energy density, high safety, and abundant resource of sodium. However, low conductivity of solid electrolyte as well as high interfacial resistance between electrolyte and electrodes are two main challenges for practical application. To address these issues, pure phase Na 3 Zr 2 Si 2 PO 12 (NZSP) materials with Ca 2+ substitution for Zr 4+ are synthesized by a sol‐gel method. It shows a high ionic conductivity of more than 10 −3 S cm −1 at 25 °C. Moreover, a robust SSSB is developed by integrating sodium metal anodes into NZSP‐type monolithic architecture, forming a 3D electronic and ionic conducting network. The interfacial resistance is remarkably reduced and the monolithic symmetric cell displays stable sodium platting/striping cycles with low polarization for over 600 h. Furthermore, by combining sodium metal anode with Na 3 V 2 (PO 4 ) 3 cathode, an SSSB is demonstrated with high rate capability and excellent cyclability. After 450 cycles, the capacity of the cell is still kept at 94.9 mAh g −1 at 1 C. This unique design of monolithic electrolyte architecture provides a promising strategy toward realizing high‐performance SSSBs.