Publications

Abstract The biophysical characteristics of the extracellular matrix, such as nanotopography and bioelectricity, have a profound influence on cell proliferation, adhesion, differentiation, etc. Recognition of the function of a certain biophysical cue and fabrication of biomaterial scaffolds with specific properties would have important implications and significant applications in tissue engineering. Herein, nanotopographic and piezoelectric biomaterials are fabricated and the combination effect of and individual contribution to proliferation, adhesion, and neuron‐like differentiation of rat bone marrow‐derived mesenchymal stem cells (rbMSCs) are clarified via nanotopography and piezoelectricity. Piezoelectric polyvinylidene fluoride with nanostripe array structures is fabricated, which can generate a surface piezoelectric potential up to millivolt by cell movement and traction. The results reveal a more favorable effect on neuron‐like differentiation of rbMSCs from the combination of piezoelectricity and nanotopography rather than nanotopography alone, whereas nanotopography can increase cellular adhesion. This research provides a new insight into designing biomaterials for the potential application in neural tissue engineering.

Nanowires, sandwiched nanoribbons, and nanotubes of SnO2 are synthesized using elevated temperature synthesis techniques, and their structures are characterized in detail by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition to the normal rutile structured SnO2, it has been possible to form an orthorhombic superlattice-like structure in the present study. The orthorhombic structure can form in a thin nanowire, coexist with the normal rutile structured SnO2 in a sandwiched nanoribbon, or occur in the form of nanotubes. This result is distinct from that for bulk SnO2 where pressures in excess of 150 kbar are required to form the orthorhombic form. The orientation relationship between the orthorhombic SnO2 and the rutile structured SnO2 is determined to be [001]o || [102̄]t and (100)o || (010)t for the nanowires and sandwiched nanoribbons, and [001]o || [3 ]t and (110)o || (451)t for the nanotubes. Although the growth direction of the rutile structured SnO2 nanowires is along [101]t, two growth directions are found to occur in the nanostructures having the orthorhombic SnO2 structure. They are [010]o for nanowires and [1̄10]o for the sandwiched nanoribbons and nanotubes. The results in this study and the observation of orthorhombic SnO2 may result from the formation of the products in an oxygen deficient environment.

Abstract Extremely soft and thin electrodes with high skin conformability have potential applications in wearable devices for personal healthcare. Here, a submicrometer thick, highly robust, and conformable nanonetwork epidermal electrode (NEE) is reported. Electrospinning of polyamide nanofibers and electrospraying of silver nanowires are simultaneously performed to form a homogeneously convoluted network in a nonwoven way. For a 125 nm thick NEE, a low sheet resistance of ≈4 Ω sq −1 with an optical transmittance of ≈82% is achieved. Due to the nanofiber‐based scaffold that undertakes most of the stress during deformation, the electric resistance of the NEE shows very little variation; less than 1.2% after 50 000 bending cycles. The NEE can form a fully conformal contact to human skin without additional adhesives, and the NEE shows a contact impedance that is over 50% lower than what is found in commercial gel electrodes. Due to conformal contact even under deformation, the NEE proves to be a stable, robust, and comfortable approach for measuring electrocardiogram signals, especially when a subject is in motion. These features make the NEE promising for use in the ambulatory measurement of physiological signals for healthcare applications.

An optical-fiber–nanowire hybridized UV–visible photodetector (PD) is reported. The PD is designed to allow direct integration in optical communication systems without requiring the use of couplers via fiber-welding technology. The PD works in two modes: axial and off-axial illumination mode. By using the piezo-phototronic effect, the performance of the PD is enhanced/optimized by up to 718% in sensitivity and 2067% in photoresponsivity.

Abstract A useful direction to solve the energy problem is the effective repeated use of biomaterial for mechanical energy collection and sensing applications. Here, a feather‐based single‐electrode triboelectric nanogenerator (F‐STENG) by only sputtering copper atoms on the feathers are presented. The feather of F‐STENG, as a natural material, has environmental friendliness, which is different from the polymer materials of other triboelectric nanogenerators. F‐STENG has super durability due to its feather structure self‐healing property. The device has a high output voltage of 90 V and an output current of 3.5 µA. After breaking and self‐healing lots of times, the output performance is also 80% of the original. F‐STENG has a high sensitivity to temperature, humidity, and wind speed, and the sensitivity is 0.50 V °C −1 , ‐0.98 V RH −1 , and 1.67 μA m −1 s −1 . The output power of F‐STENG is 0.62 mW g −1 , which can realize global positioning and photographing to solve the module energy consumption problem. F‐STENG provides an effective way for the application of self‐powered sensors and equipment in military, industrial, transportation, and daily life.

Abstract Triboelectric nanogenerators (TENGs) are attractive in powering sensors for smart power grids. Herein, a TENG based on a rotational magnetic ball is presented to harvest the magnetic energy of transmission lines. The magnetic ball rolls in a spherical shell under the alternating magnetic field generated by the transmission line. The centrifugal force produced during the rotation is used to drive a TENG unit (ten times the weight of the magnetic ball and shell) to generate electricity with the assistance of coil springs. The device can maintain the stability of the output performance under high current shocks; meanwhile, the open‐circuit voltage, output power, and operating frequency of a single TENG unit can reach 1.5 kV, 6.67 mW, and 20 Hz, respectively. Furthermore, a wireless alarm system for monitoring the temperature and dip angle of transmission lines is successfully driven by this device. This work demonstrates an efficient and nontraditional strategy for harvesting magnetic energy through TENG, which is applied to power‐distributed and self‐powered sensors for monitoring transmission lines.

Mechano-electric conversion fibers (MECFs) represent a groundbreaking innovation in smart textiles, integrating the high-efficiency mechanical energy conversion of triboelectric nanogenerators (TENGs) with superior wearability and comfort inherent in textile materials....

[This retracts the article DOI: 10.3892/etm.2019.7722.].