Publications

Abstract Tribovoltaic nanogenerator (TVNG) mainly collects energy from sliding motions of two semiconducting materials, but it cannot effectively react to the pressure change in the vertical direction. Here, a piezo‐tribovoltaic nanogenerator (P‐TVNG) is proposed by integrating piezoelectric and tribovoltaic effects to collect energy from both the sliding motion and the variation of applied pressure. Hence, this P‐TVNG can gain extra performance improvement on the top of the original output limit of TVNG. The maximum output power density of P‐TVNG is up to 3.61 W m −2 , which is 28.9 % higher than the highest record of the TVNG using similar materials. Additionally, the piezo‐module can work as a separated sensory component by switching the circuit, which can monitor and analyze various working parameters of TVNG. A series of dynamic characteristics of TVNG during its operation have been identified, including the hysteresis between output current and applied pressure, the influence and incompatibility of interface stress to output performance, and so on. As a multifunction of devices, this P‐TVNG system is possible to be applied in semiconductor industry, smart manufacturing, and many other fields. This work improves the performance of the TVNGs while extending its functionality, which broadens the application field of TVNG devices.

We report a systematic investigation about the mechanism of pH sensing using SnO2 nanobelt field effect transistors (FETs). The FETs, based on single SnO2 nanobelts, are channel-limited and with proper contact passivation; the pH sensing was conducted with sodium phosphate solutions through integrated microfluidics. The responses of the FET channel conductance to pH were measured at different gate voltages: a linear pH dependence was observed in the linear transport "on" state, while an exponential dependence was observed in the subthreshold regime. Measurements at the same pH but different ion concentrations demonstrated that the FET's pH sensitivity decreases logarithmically with the ion concentration. The effect of APTES-functionalization was evaluated by comparing the pH responses of the same device with and without the surface modification. The APTES functionalization results in a slight enhancement of the pH sensitivity and a large suppression of the noise level, leading to marked improvement in the signal-to-noise ratio. The results indicate that the pH sensing is based on a screened field-effect response of the FETs to the surface protonation/deprotonation on the nanobelt. This study provides several useful guidelines for optimizing the sensor performance for chemical and biomolecular detection.

Abstract An agglomeration phenomenon characterized by nanoparticle dispersion is a decisive factor that reflects the degree of the maintained overall performance of nanofluids and other nanocomposites. However, the quantitative characterization and non‐destructive measurement for nanofluid dispersion (NFD) still remain challenged. Herein, an in situ NFD measurement system based on a variable frequency liquid–solid triboelectric nanogenerator (VFLS‐TENG) is developed. This work utilizes VFLS‐TENG as a passive probe and proposes an equivalent capacitance circuit model for detecting NFD based on the electric double layer model at liquid–solid interfaces. In the circuit model, a quantitative calculation process for both particle size and spacing is introduced through parameter identification using the Quantum Genetic and Levenberg–Marquardt hybrid algorithm, and parameter separation using the Runge–Kutta algorithm. The results demonstrates a good agreement with the traditional methods, among which the measured particle size is more accurate than the hydrodynamic diameter of dynamic light scattering by 28.6% with a high sensitivity of 1667 nm nF −1 . The proposed method is capable of measuring the effective charge on the nanoparticle surface in situ, and simultaneously obtaining the particle size and spacing for the online monitoring NFD, thus further facilitating the controllable preparation during the nano‐composites modification, and quantitative optimization of nanofluid design performance.

Due to the simple installation and convenient maintenance, the floating water wave energy harvesting devices have significant economic advantages. Mass power density is the most important index to evaluate the advancement of floating wave energy harvesting devices. Herein, a self-adaptive rotating triboelectric nanogenerator (SR-TENG) with a compound pendulum and a functional gear-set is provided for wave energy harvesting. First, a compound pendulum structure with a low center of gravity and high moment of inertia is obtained by the geometric design and mechanical study. Besides, compared with the previous triboelectric nanogenerator with one-way clutch, SR-TENG can harvest twice the kinetic energy utilization through the functional gear-set. Importantly, depending on the structure design, the SR-TENG obtains the average mass power density of 45.18 mW kg-1 under low frequency driving conditions, which is about 10 times the reference electromagnetic generator with a similar structure and size. This result shows that the SR-TENG has a significant advantage in small water wave energy harvesting. These findings provide an important example of the floating water wave energy harvesting devices.

International audience

We report the systematic study of catalyst-free syntheses of InAs nanowires on Si substrates with various growth parameters and surface treatments. Nanowire morphology and crystal structure were studied using scanning electron microscopy and transmission electron microscopy. High-resolution cross-sectional transmission electron microscopy studies reveal heteroepitaxy of InAs[111] nanowires on Si(111) substrate with clean and sharp interface. Single nanowire field-effect transistor measurements of InAs nanowires under optimal growth conditions indicate a typical electron concentration of 1018–1019 cm–3 and mobility of around 1000 cm2/V·s. III/V on Si devices with InAs nanowire array on p-Si show a broadband photodetection up to wavelength of 3.5 μm.

Triboelectric nanogenerator (TENG) technology has emerged as a new mechanical energy harvesting technology with numerous advantages. This paper analyzes its charging behavior together with a load capacitor. Through numerical and analytical modeling, the charging performance of a TENG with a bridge rectifier under periodic external mechanical motion is completely analogous to that of a dc voltage source in series with an internal resistance. An optimum load capacitance that matches the TENGs impedance is observed for the maximum stored energy. This optimum load capacitance is theoretically detected to be linearly proportional to the charging cycle numbers and the inherent TENG capacitance. Experiments were also performed to further validate our theoretical anticipation and show the potential application of this paper in guiding real experimental designs.

A highly-efficient, flexible piezoelectric PZT thin film nanogenerator is demonstrated using a laser lift-off (LLO) process. The PZT thin film nanogenerator harvests the highest output performance of ∼200 V and ∼150 μA·cm−2 from regular bending motions. Furthermore, power sources generated from a PZT thin film nanogenerator, driven by slight human finger bending motions, successfully operate over 100 LEDs. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

'Pulsed HIFU' published in 'Encyclopedia of Nanotechnology'