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Stretchable electrodes have a crucial impact on the development of flexible electronic systems. Most conventionally blended nanocomposite electrodes are incapable of achieving high stretchability, breathability, or durability. In this work, a highly conductive, breathable, and stretchable epidermal electrode (SEE) is demonstrated by designing a hierarchically interactive nano-network that is composed of elastic polymer nano-fibers and multi-level silver nano-wires (AgNWs). The elastic polymer nano-fibers act as a continuous scaffold, and multi-level AgNWs embedded in the nano-fibers form branched conductive pathways. This structure enables high conductivity of the SEE at 4800 S cm-1 (at a significantly low AgNW content of 1.59 vt%), with high stretchability and excellent durability. For example, the SEE remained conductive even at a high strain of 500%, and it also maintained its initial resistance even after 30 000 cycles of strain at 50% or being washed with water for 100 000 cycles. The SEE was prepared by a facile in situ nonequilibrium fabrication process, and can easily be produced into an elastic circuit on a large scale, which provides a foundation for integrated and multifunctional electronic skins. The SEE possesses superior mechanical conformability and permeability of gas and liquid, and therefore, it was successfully applied in measuring electrocardiogram signals and thermal therapy, and exhibited highly robust and comfortable performances even while being washed with water or undergoing complex deformations.

In this work, a novel solid-liquid interfacing triboelectric field based electroluminescence (SL-TEL) was proposed. When a droplet impacting on the SL-TEL device surface, specific textured green SL-TEL emit on the two cross-overlapped areas. As a coupling effect of solid-liquid interfacing triboelectrification and electroluminescence, the SL-TEL is essentially a type of electroluminescence excited by changing triboelectric field of droplet impact or wave scour. It relies on converting mechanical energy of liquid to visual light energy utilizing an intermediate triboelectric field without any electric power consumption. The SL-TEL device simply consist of three thin flexible layers, which is greatly simplifying the electroluminescent device structure and showing strong advantages of simple structure such as easy to integration and excellent stability. Experiments show that sequential liquid motions of droplet impinging on solid surface excite a corresponding dynamic series of electroluminescence patterns. The features of the electroluminescence also reveal the characteristics of liquid and the solid surface, such as contour edge of liquid spreading, capillary convergence of liquid at the apex (advancing and receding), and so on, which is capable of both sensing liquid leakage and displaying the dynamic information of droplets impacting motions.

Wearable and portable electronics for water environment application are of paramount significance, however restricted by its power source component. It remains a great challenge to simultaneously achieve ultra stretchability and high electric output performance for most energy harvesters in water. Herein, we report a high-performance stretchable liquid-solid contact electrification-based nanogenerator (S-LSNG) that enables water wave energy harvesting and subtle motion monitoring in water by an in-situ charged nanocomposite membrane. Notably, the effectively charged PTFE nanoparticles (100 nm) in this novel membrane can highly promote the output of S-LSNG. For the first time, the excellent stretchability (tensile strain, 200%), high output performance (open-circuit voltage of 120 V and short-circuit current of 18 μA) and ultra-thin device structure (300 μm) were achieved simultaneously for a liquid-solid contact electrification-based nanogenerator. Besides, the output performance of S-LSNG barely changed even after 100000 submerging-emerging cycles. In addition, the application of motion monitoring for human body in water was also demonstrated, such as single finger motion sensing and complex motion sensing of multiple-fingers. Because of the excellent stretchability, output performance and durability, the S-LSNG would be extensively applied to a sustainable energy supplier for the stretchable and wearable electronics in water.

Harvesting water wave energy presents a significantly practical route to energy supply for self-powered wireless sensing networks. Here we report a networked integrated triboelectric nanogenerator (NI-TENG) as a highly adaptive means of harvesting energy from interfacing interactions with various types of water waves. Having an arrayed networking structure, the NI-TENG can accommodate diverse water wave motions and generate stable electric output regardless of how random the water wave is. Nanoscaled surface morphology consisting of dense nanowire arrays is the key for obtaining high electric output. A NI-TENG having an area of 100 × 70 mm2 can produce a stable short-circuit current of 13.5 μA and corresponding electric power of 1.03 mW at a water wave height of 12 cm. This merit promises practical applications of the NI-TENG in real circumstances, where water waves are highly variable and unpredictable. After energy storage, the generated electric energy can drive wireless sensing by autonomously transmi...

Triboelectric nanogenerator (TENG) is a newly emerged technology for harvesting mechanical energy, which has the promise for various practical applications. Here, we introduce a new principle of TENG in which induced current is generated between two coplanar electrodes because of different dielectric fillers of distinct permittivities. The manipulation of permittivity of dielectric materials for TENG is first reported, demonstrating a novel route in designing high-performance TENGs. When repeatedly contacting with an object, a TENG having lateral dimensions of 21 mm × 10 mm can produce an open-circuit voltage of 58.5 V and a short-circuit current of 44.7 μA. The instantaneous output power density can reach up to 708 μW. Besides, the new design incorporates all electrodes into a single plane, greatly simplifying the structure, promoting robustness, and providing a viable solution for device miniaturization.

We investigate the nonvolatile holographic storage characteristics of near-stoichiometric LiNbO3:Fe:Mn crystals with different Li2O contents. Experimental results indicate that the optimal value of Li2O content is about 49.6 mol%. Nonvolatile sensitivity S′ considerably improved to 0.15 cm/J because of the use of near-stoichiometric LiNbO3:Fe:Mn with 49.6 mol% Li2O.

We report a flexible and area-scalable energy-harvesting technique for converting kinetic wave energy. Triboelectrification as a result of direct interaction between a dynamic wave and a large-area nanostructured solid surface produces an induced current among an array of electrodes. An integration method ensures that the induced current between any pair of electrodes can be constructively added up, which enables significant enhancement in output power and realizes area-scalable integration of electrode arrays. Internal and external factors that affect the electric output are comprehensively discussed. The produced electricity not only drives small electronics but also achieves effective impressed current cathodic protection. This type of thin-film-based device is a potentially practical solution of on-site sustained power supply at either coastal or off-shore sites wherever a dynamic wave is available. Potential applications include corrosion protection, pollution degradation, water desalination, and wireless sensing for marine surveillance.

A biocide-free antifouling method on wetted insulating surfaces, enabled by the oscillation of electric potential generated by an integrated triboelectric wave harvester (I-TEWH) is reported. Distinct from previous studies that reported antifouling on conducting surfaces by applying an additional power source, this method achieves antifouling on insulating surfaces with zero-power consumption. The electric potential in the vicinity of a protected surface oscillates in large amplitude as a result of periodically accumulated free electrons on an underlying electrode. The dynamic flow of the free electrons is driven by the I-TEWH that converts ambient wave energy by solid–liquid interface triboelectrification. As a consequence, the oscillating electric potential disturbs the inherent charge distribution on microbes due to electrostatic induction, preventing their initial adhesion onto the protected surface and thus prohibiting the subsequent formation of macroorganisms. Significant anti-adhesion efficiencies of as high as 99.3%, 99.1%, and 96.0% are achieved for negative-gram bacteria (Escherichia coli), positive-gram bacteria (Staphylococcus aureus), and diatoms (bacillariophyceze), respectively, on a smooth surface. The antifouling efficiency on a roughened surface with micro/nanostructures can be further enhanced by another 75%. This approach can be potentially utilized in coastal constructions, offshore facilities, and vessels that are either moving or stationary in port.

It has been suggested to use LiNbO3:Fe, Mn crystal for solving the problem of information volatility during the read-out process with all-optical facilities, but the minute order response time is far from the requirements for the real-time information processing. We present the nonvolatile holographic storage properties of LiNbO3:Hf, Fe, Mn. The response time is shortened to 5.0 s, and the sensitivity S' is enhanced to 0.22 cm/J in this triply doped crystal. The experimental results show that the HfO2 doping threshold is 5.0 mol.%. Thus it seems that we have found a useful tetravalent dopant for LiNbO3:Fe, Mn that can obviously improve the nonvolatile holographic recording sensitivity.