The advancement of digital microfluidics technology has been pivotal in academic research and engineering applications. However, the prevailing limitation is that traditional voltage sources generate an excess of joule heat, adversely impacting droplet operation. Moreover, the power supply equipment required by digital microfluidics limits its applications. Here, we propose a self-powered microdroplet manipulation (SMDM) via triboelectric nanogenerator (TENG), which presents a capability for splitting and mixing different kinds of droplets. Fundamentally, SMDM is based on the electroosmotic flow principle, thereby enabling droplet splitting in the range of from 2 μL to 630 μL. Notably, for droplet splitting in the range of from 5 μL to 60 μL, the TENG only requires a power output ranging from 2.704 mW to 6.084 mW. In addition, SMDM demonstrates proficiency in droplet mixing, which achieves complete mixing of 10 μL droplets in 60 s, and 30 μL droplets in a mere 53 s. Therefore, leveraging the strengths of the TENG, a self-powered microdroplet manipulated system is designed for digital microfluidics. It carries significant advantages over the traditional voltage source, including self-powered, low-joule heat, increased safety, and enhanced portability. This research provides a new solution for portable applications of digital microfluidics.

Since the abstract is indexed in many databases it should be self-contained without any undefined abbreviations or any cited references. For the ultrathin two-dimensional (2D) materials and lateral heterojunction, the formation of unstable but elastic ripples is commonly observed but is rarely studied, especially their correlations with different material properties. To fill the knowledge gap in this field, this work systematically explores transition metal dichalcogenides (TMDCs) in a single component and lateral heterojunction with a series of ripple structures. The ripple formation energy is quantitatively classified into the initial elastic strain stage and fracture threshold stage based on Fermi-like Distribution. Electronic structures reveal that the formation of ripples is accompanied by electron accumulations from flat surfaces to ripples. By comparing the Unilateral, Decaying, and Bilateral Ripples in 2D lateral heterojunction, we confirm that Fermi-like distribution is still valid regardless of the shape of the ripples, where the thermodynamic and electronic properties are modulated by ripples-induced uneven strain. The main features of optical properties are not affected while the sensitivity to ripple-induced strains is distinguished. More importantly, the phonon properties further demonstrate the potential of ripples in promoting thermal conductivity, which are strongly correlated with the optical branch of anion vibrations. This work provides important theoretical guidance for the design and optimization of high-performance optoelectronic devices based on TMDC heterojunctions.

Ocean wave energy is a significant and promising source of renewable energy. However, the energy harvesting is challenging due to the multi-directional nature of waves. This paper proposes a magnetic-field-assisted triboelectric nanogenerator (MFA-TENG) for harvesting multi-directional wave energy. By incorporating a magnetic field, the planar motion of the pendulum is converted into spatial motion, increasing the triggering of multilayered TENG (M-TENG) and enhancing the output energy of the MFA-TENG. Experimental results demonstrate that the output energy of the MFA-TENG is increased by 73% by utilizing the magnetic field. Moreover, a spring model based on the origami-structured M-TENG is established to analyze the effect of different equivalent stiffnesses on the performance of the M-TENG, aiming to obtain optimal output performance. The results showcase the impressive output performance of the M-TENG, generating outputs of 250 V, 18 μA, and 255 nC. Furthermore, the proposed MFA-TENG effectively harvests multi-directional wave energy under water-wave driven conditions. This study significantly enhances the ability of the MFA-TENG to harvest multi-directional wave energy and presents a promising approach for self-powered marine monitoring in the future.

With the arrival of the era of artificial intelligence (AI) and big data, the explosive growth of data has raised higher demands on computer hardware and systems. Neuromorphic techniques inspired by biological nervous systems are expected to be one of the approaches to breaking the von Neumann bottleneck. Piezotronic neuromorphic devices modulate electrical transport characteristics by piezopotential and directly associate external mechanical motion with electrical output signals in an active manner, with the capability to sense/store/process information of external stimuli. In this review, we have presented the piezotronic neuromorphic devices (which are classified into strain-gated piezotronic transistors and piezoelectric nanogenerator-gated field effect transistors based on device structure) and discussed their operating mechanisms and related manufacture techniques. Secondly, we summarized the research progress of piezotronic neuromorphic devices in recent years and provided a detailed discussion on multifunctional applications, including bionic sensing, information storage, logic computing, and electrical/optical artificial synapses. Finally, in the context of future development, challenges, and perspectives, we have discussed how to modulate novel neuromorphic devices with piezotronic effects more effectively. It is believed that the piezotronic neuromorphic devices have great potential for the next generation of interactive sensation/memory/computation to facilitate the development of the Internet of Things, AI, biomedical engineering, etc.

The performance degradation and even damage of the e-textiles caused by sweat, water, or submersion during all-weather health monitoring are the main reasons that e-textiles have not been commercialized and routinized so far. Herein, we developed an amphibious, high-performance, air-permeable, and comfortable all-textile triboelectric sensor for continuous and precise measurement of epidermal pulse waves during full-day activities. Based on the principle of preparing gas by acid-base neutralization reaction, a one-piece preparation process of amphibious conductive yarn (ACY) with densely porous structures is proposed. An innovative three-dimensional (3D) interlocking fabric knitted from ACYs (0.6 mm in diameter) and polytetrafluoroethylene yarns exhibit high sensitivity (0.433 V·kPa⁻¹), wide bandwidth (up to 10 Hz), and stability (> 30,000 cycles). With these benefits, 98.8% agreement was achieved between wrist pulse waves acquired by the sensor and a high-precision laser vibrometer. Furthermore, the polytetrafluoroethylene yarn with good compression resilience provides sufficient mechanical support for the contact separation of the ACYs. Meanwhile, the unique skeletonized design of the 3D interlocking structure can effectively relieve the water pressure on the sensor surface to obtain stable and accurate pulse waves (underwater depth of 5 cm). This achievement represents an important step in improving the practicality of e-textiles and early diagnosis of cardiovascular diseases.

The separation of photogenerated electron–hole pairs is vitally important for photocatalysis, which can be effectively promoted by polarization field. However, it only manifests in piezoelectric/pyroelectric/ferroelectric materials that have a non-centrosymmetric structure. Here, we demonstrate that the polarization enhanced photocatalysis (with wide spectra from ultraviolet (UV) light to visible light) can be achieved in centrosymmetric semiconductors, such as δ-MnO₂ and TiO₂ nanosheets integrated nanoflowers, by using the strain-gradient-induced flexoelectric polarization that is always overlooked in polarization-enhanced catalysis. Under ultrasonic and illumination excitation, the organic pollutants (methylene blue (MB), etc.) can be effectively degraded within 30 min with excellent stability and repeatability. Compared with photocatalysis, the flexo-photocatalytic performance of above centrosymmetric semiconductors is substantially increased by 85%. Moreover, the factors related to flexo-photocatalysis such as material morphology, mechanical stimuli source, and adsorption are explored to deeply understand the mechanism of flexo-photocatalysis. This work opens up a way for high-performance photocatalysis in centrosymmetric semiconductors.

In this work, we successfully prepared vertically aligned NaNbO₃ nanotube (NN-NT) with trapezoidal shapes, in which the orthorhombic and monoclinic phases coexisted. According to the structure analysis, the NN-NT/epoxy composite film had excellent flexoelectric properties due to the lattice distortion caused by defects and irregular shape. The flexoelectric effect is the greatest in the vertical direction in the flexible NN-NT/epoxy composite film, and the flexoelectric coefficient ( ${\mu }_{12}^{\mathrm{\prime }}$) is 2.77 × 10⁻⁸ C·m⁻¹, which is approximately 5-fold higher than that of the pure epoxy film. The photovoltaic current of the NN-NT/epoxy composite film increased from 39.9 to 71.8 nA·cm⁻² in the direction of spontaneous polarization when the sample was bent upward due to the flexoelectricity-enhanced photovoltaic (FPV) effect. The flexoelectric effect of the NN-NT/epoxy composite film could modulate the photovoltaic response by increasing it by 80% or reducing it to 65% of the original value. This work provides a new idea for further exploration in efficient and lossless ferroelectric memory devices.

The development and utilization of marine blue energy has become the focus of current research. A drawstring triboelectric nanogenerator with modular electrodes (DS-TENG) is proposed to harvest wave energy. Motion displacement and water wave adaptability are improved by using the drawstring structure in the DS-TENG. Furthermore, the modular electrode design is applied to improve the durability and replaceability of the generation units. The rationality of the structure is verified by theoretical analysis, and performance experiments on the fundamental output, displacement and frequency, durability and application are carried out. The DS-TENG can achieve output performance of 98.03 nC, 3.63 μA, 238.50 V and 923.92 µW at 150 mm and 1.0 Hz. In addition, the performance drops by 6.11% after 110,000 cycles for DS-TENG durability. This paper will provide reference for the design of TENG that adapts to a wide range of wave heights.

The development of automation industry is inseparable from the progress of sensing technology. As a promising self-powered sensing technology, the durability and stability of triboelectric sensor (TES) have always been inevitable challenges. Herein, a continuous charge supplement (CCS) strategy and an adaptive signal processing (ASP) method are proposed to improve the lifetime and robustness of TES. The CCS uses low friction brushes to increase the surface charge density of the dielectric, ensuring the reliability of sensing. A triboelectric mechanical motion sensor (TMMS) with CCS is designed, and its electrical signal is hardly attenuated after 1.5 million cycles after reasonable parameter optimization, which is unprecedented in linear TESs. After that, the dynamic characteristics of the CCS-TMMS are analyzed with error rates of less than 1% and 2% for displacement and velocity, respectively, and a signal-to-noise ratio of more than 35 dB. Also, the ASP used a signal conditioning circuit for impedance matching and analog-to-digital conversion to achieve a stable output of digital signals, while the integrated design and manufacture of each hardware module is achieved. Finally, an intelligent logistics transmission system (ILTS) capable of wirelessly monitoring multiple motion parameters is developed. This work is expected to contribute to automation industries such as smart factories and unmanned warehousing.

Raindrops contain abundant renewable energy including both kinetic energy and electrostatic energy, and how to effectively harvest it becomes a hot research topic. Recently, a triboelectric nanogenerator (TENG) using liquid–solid contact electrification has been demonstrated for achieving an ultra-high instantaneous power output. However, when harvesting the energy from the dense raindrops instead of a single droplet, a more rational structure to eliminate the mutual influence of individual generation units is needed for maximize the output. In this work, a “solar panel-like” bridge array generators (BAGs) is proposed. By adopting array lower electrodes (ALE) and bridge reflux structure (BRS), BAGs could minimize the sharp drop in the peak power output for large-scale energy harvesting devices. When the area of the raindrop energy harvesting device is 15 × 15 cm², the peak power output of BAGs reached 200 W/m², which is remarkable for paving a potential industrial approach for effective harvesting raindrop energy at a large scale.