Publications

Abstract Transdermal drug delivery (TDD) systems with feedback control have attracted extensive research and clinical interest owing to their unique advantages of convenience, self‐administration, and safety. Here, a self‐powered wearable iontophoretic TDD system that can be driven and regulated by the energy harvested from biomechanical motions is proposed for closed‐loop motion detection and therapy. A wearable triboelectric nanogenerator (TENG) is used as the motion sensor and energy harvester that can convert biomechanical motions into electricity for iontophoresis without stored‐energy power sources, while a hydrogel‐based soft patch with side‐by‐side electrodes is designed to enable noninvasive iontophoretic TDD. Proof‐of‐concept experiments on pig skin with dyes as model drugs successfully demonstrate the feasibility of the proposed system. This work not only extends the application of TENG in the biomedical field, but may also provide a cost‐effective solution for noninvasive, electrically assisted TDD with closed‐loop sensing and treatment.

Although electrocoagulation technology has been widely researched in wastewater treatment, high energy consumption and electrode passivation are still the main challenges for its widespread applications. Here, we propose a self-powered electrocoagulation system based on a triboelectric nanogenerator (TENG) with alternating current (AC) outputs to solve these two issues, and thus enhance the removal efficiency of organic pollutants. Compared with the direct current source, the AC power source can reduce the electrode passivation, produce more aluminum hydroxide compounds after consuming an equal amount of charges, and thus improve the degradation efficiency. Moreover, the removal efficiency can be further enhanced by decreasing the frequency AC, in which a 5.7-fold improvement was achieved at 0.2 Hz compared to DC at 1.8 Hz. Inspired by the low frequency of ocean wave water, we developed a self-powered AC-electrocoagulation system to directly drive the electrocoagulation reaction by harvesting water wave energy, which can effectively remove 94.8% of xylenol orange and 98.8% of water-oil emulsion, and thus completely address the problem of energy consumption. This study further promotes the application of self-powered electrochemical systems in treating environmental pollution.

Abstract Because of the shortage of fossil energy and the rapid development of Internet of things nowadays, renewable and clean energy is becoming valuable and necessary. One renewable energy source, triboelectric nanogenerators (TENGs), has been proved to effectively harvest energy from vibration, walking, and even sphygmus. TENGs based on contact–separation mode are foremost and fundamental, and the input stimuli for TENGs are strictly limited by constant amplitude and uniaxial direction of motion, which limits many practical applications. Therefore, it is extremely meaningful to develop a kind of TENG to collect random energy, which ubiquitously exists in the ambient environment. Here, an elastic rubber is placed inside the structure of an elastic TENG (E‐TENG). With this novel structure, the output signals of the TENG are almost independent of the amplitude of the external stimuli due to the elasticity of rubber. Moreover, the E‐TENG shows good performance on angle detection without the limitation of the direction of stimuli. It is believed that the E‐TENG will contribute to developing next‐generation flexible TENGs and self‐powered sensors in the future.

Coaxial fiber-shaped Zn-ion hybrid supercapacitors (CFZHSCs) with high power/energy density, long cycle life, splendid mechanical stability, and high safety are promising electrochemical energy storage devices for flexible and wearable electronics. However, the poor electrochemical performance of Zn anode severely restricts their practical application. To address this challenge, a highly reversible fiber-shaped Zn anode with controlled deposition morphology is developed based on theoretical calculation guided design of highly zincophilic 3D metal-organic-frameworks derived carbon with N- and OH-containing functional groups (N,O-MOFC) scaffold, by regulating electroplating chemistry of the initial nucleation and crystal growth time of zinc metal. Benefitting from fast ion diffusion ability of the hierarchically nanostructured 3D Zn/N,O-MOFC anode on the carbon nanotube fiber (CNTF), the assembled CFZHSCs device achieves a large volumetric specific capacitance of 128.06 F cm-3 and a high volumetric energy density of 57.63 mWh cm-3, surpassing the state-of-the-art FZHSCs device. More impressively, the efficient rechargeable capability of the fiber-shaped Zn anode also enables an adequately stable CFZHSCs device with the capacitance retention of 99.20% after 10,000 charge/discharge cycles and remarkable mechanical flexibility. As a conceptual demonstration of system integration, the as-fabricated CFZHSCs device is integrated with triboelectric nanogenerator (TENG) yarn to achieve the self-powered textile-based monitoring systems to stably detect temperature variation.

The phenomenon of contact electrification (CE) has been known for thousands of years, but the nature of the charge carriers and their transfer mechanisms are still under debate. Here, the CE and triboelectric charging process are studied for a metal-dielectric case at different thermal conditions by using atomic force microscopy and Kelvin probe force microscopy. The charge transfer process at the nanoscale is found to follow the modified thermionic-emission model. In particular, the focus here is on the effect of a temperature difference between two contacting materials on the CE. It is revealed that hotter solids tend to receive positive triboelectric charges, while cooler solids tend to be negatively charged, which suggests that the temperature-difference-induced charge transfer can be attributed to the thermionic-emission effect, in which the electrons are thermally excited and transfer from a hotter surface to a cooler one. Further, a thermionic-emission band-structure model is proposed to describe the electron transfer between two solids at different temperatures. The findings also suggest that CE can occur between two identical materials owing to the existence of a local temperature difference arising from the nanoscale rubbing of surfaces with different curvatures/roughness.

'Polyethylene Carbonate (PEC)' published in 'Encyclopedia of Nanotechnology'

It is highly desirable to measure fluid pressure and its pulsations through portable, handheld instruments and test kits, which allow a rapid, low-cost, and reliable quantification about liquid status, especially for cheaper, faster, and smarter point-of-care testing (POCT). Here, we proposed a portable self-powered smart fluid pressure sensor based on a liquid piston triboelectric nanogenerator (LP-TENG) with specific coupled materials. By analyzing the characteristic signals due to the triboelectrification effect, electrostatic induction, and theory of ideal gas equation, the developed sensor is able to determine the fluid’s pressure and flowing status quantitatively (e.g., moving direction, flow rate, blockages, pipe bursts, leakage, etc.). Here, a simply fabricated device has a sensitivity of 0.07 kPa/mm with a pressure range from 0 kPa to 30 kPa, which is superior to most commercial sensors. Furthermore, the electric performance can reach a resolution ratio of 0.18 kPa, which is adequate to accurately identify the blood pressure (BP) level. Consequently, the self-powered LP-TENG is capable of real-time monitoring the fluid status, which can fit the need for diagnosing and detecting the BP level as a reliable POCT device in healthcare products, as well as other broad potential applications in manufacturing, transportation, and civil service.

Contact electrification has been extensively investigated and harnessed, yet quantifying the triboelectrification capacity of liquid phase materials remains elusive due to their non-fixed shape and complex flow dynamics. Here, we report a novel gas-regulated flow strategy to stabilize liquid columns, effectively decoupling fluid kinetics from electrification processes. By optimizing material selection, electrode configurations, and flow regimes, we established a standardized triboelectric series encompassing 50 diverse liquids, including organic solvents and ionic solutions. Our results reveal that liquid-phase triboelectrification is synergistically governed by molecular functional groups, ionic species, and concentrations. Specifically, hydroxyl groups and dilute ion concentrations promote charge transfer, whereas alkyl groups and excessive ions exert a suppressive effect. This study elucidates that liquid-solid electrification arises from a sophisticated interplay of electron transfer, molecular polarization, ion adsorption/screening, which collectively dictate charge redistribution. By providing a quantitative triboelectric matrix, this work facilitates the design of high-efficiency energy harvesters and safer industrial liquid-handling systems, advancing the fundamental understanding of liquid-interface physics.

Abstract Triboelectric nanogenerators (TENGs), a promising energy harvesting technology for distributed power sources, faces inevitable issues regarding long‐term wear and durability. However, current low‐wear TENGs are impaired by lower performances due to low charge density. Here, both issues are addressed using a double charge supplement TENG (DCS‐TENG). Adding two low friction charge brushes allows the DCS‐TENG to achieve a high surface charge density (76.5 µC m −2 ) and power density (697.5 mW m −2 Hz –1 ), setting a new record among previously reported low‐wear TENGs. Moreover, the device exhibits unprecedented durability with an attenuation of only 5% after continuous operation for 110 h (3 960 000 cycles). Using a customized energy management module, a 3 × 7 hygrothermograph array, a high‐power vehicle's radar and accelerometer modules are stably powered, demonstrating the DCS‐TENG's strong electrical load capacity. This strategy provides a facile and effective path to conjointly boost power output and durability of TENGs, taking them to the next level for practical applications.