Publications

Vertically aligned ZnO−ZnS heterojunction nanowire (NW) arrays were synthesized by thermal evaporation in a tube furnace under controlled conditions. Both ZnO and ZnS are of wurtzite structure, and the axial heterojunctions are formed by epitaxial growth of ZnO on ZnS with an orientation relationship of [0001]ZnO//[0001]ZnS. Vertical ZnS NW arrays have been obtained by selectively etching ZnO−ZnS NW arrays. Cathodoluminescence measurements of ZnO−ZnS NW arrays and ZnS NW arrays show emissions at 509 and 547 nm, respectively. Both types of aligned NW arrays have been applied to convert mechanical energy into electricity when they are deflected by a conductive AFM tip in contact mode. The received results are explained by the mechanism proposed for nanogenerator.

Although butterfly wings and water strider legs have an anti-wetting property, their working conditions are quite different. Water striders, for example, live in a wet environment and their legs need to support their weight and bear the high pressure during motion. In this work, we have focused on the importance of the surface geometrical structures in determining their performance. We have applied an atomic layer deposition technique to coat the surfaces of both butterfly wings and water strider legs with a uniform 30 nm thick hydrophilic Al(2)O(3) film. By keeping the surface material the same, we have studied the effect of different surface roughness/structure on their hydrophobic property. After the surface coating, the butterfly wings changed to become hydrophilic, while the water strider legs still remained super-hydrophobic. We suggest that the super-hydrophobic property of the water strider is due to the special shape of the long inclining spindly cone-shaped setae at the surface. The roughness in the surface can enhance the natural tendency to be hydrophobic or hydrophilic, while the roughness in the normal direction of the surface is favorable for forming a composite interface.

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Cardiovascular diseases are the leading cause of death globally; fortunately, 90% of cardiovascular diseases are preventable by long-term monitoring of physiological signals. Stable, ultralow power consumption, and high-sensitivity sensors are significant for miniaturized wearable physiological signal monitoring systems. Here, this study proposes a flexible self-powered ultrasensitive pulse sensor (SUPS) based on triboelectric active sensor with excellent output performance (1.52 V), high peak signal-noise ratio (45 dB), long-term performance (107 cycles), and low cost price. Attributed to the crucial features of acquiring easy-processed pulse waveform, which is consistent with second derivative of signal from conventional pulse sensor, SUPS can be integrated with a bluetooth chip to provide accurate, wireless, and real-time monitoring of pulse signals of cardiovascular system on a smart phone/PC. Antidiastole of coronary heart disease, atrial septal defect, and atrial fibrillation are made, and the arrhythmia (atrial fibrillation) is indicative diagnosed from health, by characteristic exponent analysis of pulse signals accessed from volunteer patients. This SUPS is expected to be applied in self-powered, wearable intelligent mobile diagnosis of cardiovascular disease in the future.

Abstract Here, a strain‐insensitive, durable, and visualized ultraviolet (UV) detectible multilayered artificial UV shielding skin (MUVS‐skin) is demonstrated. The electrospinning of polyurethane nanofibers and electrospraying of TiO 2 nanoparticles are alternatingly conducted to assemble the MUVS‐skin. The results show that the stability of UV shielding property under different strains (50%, 100%, 150%, and 200%) is enhanced as more layers are assembled. The ultraviolet protection factor of the strain‐free MUVS‐skin (119 µm) is 10 810 and reaches to 5685 at 200% strain. Moreover, the effective transmittance (at 365 nm) of MUVS‐skin (119 µm) after being stretched for 10 000 cycles at 200% strain is only 0.125%. This stable UV shielding property is ascribed to the low‐level variation in the porosity of the multilayered structure, which originates from the enhanced slippage between adjacent layers. Furthermore, ultraviolet A (UVA) and ultraviolet B (UVB) can be precisely detected as the luminescence of blue and red for the MUVS‐skin integrates with a phosphor layer (MUVS‐skin/P). Owing to the excellent stable UV shielding property, visualized UV detection and durability against cyclic deformation, this MUVS‐skin/P might be extensively applied to the smart wearable artificial skin and protective clothing.

The open‐circuit voltage of a triboelectric nanogenerator (TENG) increases with the tribo‐charge density and the separated distance between two tribo‐surfaces, which can reach several thousand volts and is much higher than the working voltage required by most electrical devices and energy storage units. Therefore, improving the effective efficiency of TENGs requires reducing the output voltage and enhancing the transferred charges. Here, a multilayered‐electrode‐based TENG (ME‐TENG) is developed in which the output voltage can be managed by controlling the charge flow in a process of multiple ( N ) steps, which results in N times lower voltage but N times higher total charge transport. The ME‐TENG is demonstrated to work in various modes, including multichannel, single‐channel, and double‐tribo‐surface structures. The effects of insulator layer thickness and total layer number on the output voltage are simulated by the finite element method. The output voltage can be modulated from 14 to 102 V by changing the insulator layer number between two adjacent working electrodes, based on which the 8‐bit logic representations of the characters in the ACSII code table are demonstrated. The ME‐TENG provides a novel method to manage the output power and has potential applications in self‐powered sensors array and human–machine interfacing with logic communications.

Adiponectin is increasingly recognized as a potential therapeutic agent for the treatment of diabetes and other metabolic diseases. It circulates in plasma as homotrimers and higher‐order oliogomers of homotrimers. To facilitate the production of active recombinant adiponectin as a therapeutic tool, we designed a single‐chain globular domain adiponectin (sc‐gAd) in which three monomer sequences are linked together in tandem to form one contiguous polypeptide. Here, we present the crystal structure of human sc‐gAd at 2.0 Å resolution. The structure reveals a similar trimeric topology to that of mouse gAd protein. Trimer formation is further rigidified by three calcium ions.

Vertically grown cadmium sulfide (CdS) nanowire (NW) arrays were prepared using two different processes: hydrothermal and physical vapor deposition (PVD). The NWs obtained from the hydrothermal process were composed of alternating hexagonal wurtzite (WZ) and cubic zinc blende (ZB) phases with growth direction along WZ ⟨0001⟩ and ZB [111]. The NWs produced by PVD process are single crystalline WZ phase with growth direction along ⟨0001⟩. These vertically grown CdS NW arrays have been used to converting mechanical energy into electricity following a developed procedure [Z. L. Wang and J. Song Science 312, 242 (2006)]. The basic principle of the CdS NW nanogenerator relies on the coupled piezoelectric and semiconducting properties of CdS, and the data fully support the mechanism previously proposed for ZnO NW nanogenerators and nanopiezotronics.

The triboelectric properties of the tribolayers are essential factors affecting the current density of triboelectric nanogenerators (TENGs). To enhance the current density, composites have been developed to tune their triboelectric properties. Previous studies have reported enhanced TENG performance with composite materials, primarily based on their composition, while chemical interactions between the components have been less analyzed. In this study, we report a novel approach to improve the current density of a TENG by introducing dipole-dipole interactions between a nylon filter membrane and graphene oxide (GO) through hydrogen bonds. The Raman spectroscopy confirmed the occurrence of the interactions resulting from hydrogen bonding. The enhancing mechanisms of hydrogen bonds were further analyzed by Kelvin probe force microscope (KPFM) measurement, which demonstrated that hydrogen bonding could influence the surface potential of the coated GO, leading to increased output of the nylon/GO@NFM TENG (NGN-TENG). Our results show that an ultrahigh current density of 1757 mA·m-2 was obtained with a 2 x 2 cm2 NGN-TENG. Additionally, we demonstrated the feasibility of using the NGN-TENG as a motion sensor to sense finger motions. These findings suggest that the introduction of hydrogen bonds in TENG composites can provide a promising route for improving their performance.

A self-powered and self-modulated infrared wireless communications system is developed via integrating a triboelectric nanogenerator and mechanical modulation protocols.

'Passive Pumping' published in 'Encyclopedia of Nanotechnology'