Triboelectric nanogenerators are an energy harvesting technology that relies on the coupling effects of contact electrification and electrostatic induction between two solids or a liquid and a solid. Here, we present a triboelectric nanogenerator that can work based on the interaction between two pure liquids. A liquid–liquid triboelectric nanogenerator is achieved by passing a liquid droplet through a freely suspended liquid membrane. We investigate two kinds of liquid membranes: a grounded membrane and a pre-charged membrane. The falling of a droplet (about 40 μL) can generate a peak power of 137.4 nW by passing through a pre-charged membrane. Moreover, this membrane electrode can also remove and collect electrostatic charges from solid objects, indicating a permeable sensor or charge filter for electronic applications. The liquid–liquid triboelectric nanogenerator can harvest mechanical energy without changing the object motion and it can work for many targets, including raindrops, irrigation currents, microfluidics, and tiny particles. Triboelectric nanogenerators harvest energy by contacting two solids or a liquid and a solid. Here the authors use a conductive liquid membrane as a permeable electrode to demonstrate triboelectrification via liquid–liquid contact by passing liquid droplets through a liquid membrane to generate power.

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Power generation from the interaction of a liquid droplet and a liquid membrane.

The tropical convection experiment COPT 81 (Convection Profonde Tropicale) was carried out near Korhogo (Northern Ivory Coast) during May and June 1981. The June 22 squall line was observed using meteorological and electrical equipment. The frontal part was characterized by a heavy precipitation core associated with strong convection. It was followed by a region of weak precipitation and a wide area of stratiform rain. The characteristic of this squall line resides in the two-dimensional structure of the observed three-dimensional wind fields, with intense convection ahead of the heavy precipitation core. Electrical measurements indicate that electrostatic field changes, at ground level, occurred in the weak precipitation zone and in the stratiform precipitation region. No particular electrical activity was observed in the most convective but shallow part of the squall line. A classical dipole structure appeared within the stratiform area. The stationary electrical structure was coherent with the stationary dynamics and precipitation pattern of the squall line.

The June 22 tropical squall line observed during COPT 81 experiment: Electrical signature associated with dynamical structure and precipitation

[1] The accumulation of charges on cloud particles by the charge transfer of ions and attachment of electrons in the atmosphere of Venus is investigated in the present work. Three cloud layers between 45 and 70 km exist in the atmosphere of Venus. Ions and electrons are produced by the interaction of galactic cosmic rays with the neutral molecules. Ion to particle and electron to particle attachment coefficients are calculated. The charge balance equations include ion-ion recombination, ion-electron recombination, electron attachment to neutrals, electron detachment from negative ions, and attachment of electron and charge transfer from ions to particles. It is found that the ion concentrations are reduced by a maximum of a factor of 5 by charging of the particles, while the earlier studies showed a maximum reduction of about an order of magnitude due to the differences in the surface area of the particles. A similar result is observed in the calculation of electrical conductivity. Both monodisperse and polydisperse distribution of particles are considered. The conductivity was reduced by a factor of 3 when using the monodisperse distribution of particles, while the maximum reduction observed was a factor of 2 when using the polydisperse distribution. This result implies that the monodisperse particle distribution overestimates the effect of particles on the atmospheric conductivity. The ratio of negative to positive charges is found to be very large in the middle and upper cloud layers. The low abundance of the aerosols and high conductivity of the atmosphere appear to rule out lightning activity in the 40 to 70 km altitude region.

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Highly charged cloud particles in the atmosphere of Venus

Capture success of spider webs has been associated with their microstructure, ornamentation, and wind-induced vibrations. Indirect evidence suggests that statically charged objects can attract silk thread, but web deformations induced by charged insects have not yet been described. Here, we show under laboratory conditions that electrostatically charged honeybees, green bottle flies, fruit flies, aphids, and also water drops falling near webs of cross-spiders (Araneus diadematus) induce rapid thread deformation that enhances the likelihood of physical contact, and thus of prey capture.

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Spiderweb deformation induced by electrostatically charged insects.

Various insects, especially social insects, possess electric charges. Erickson (1982, 1983) shows their involvement in the odor receptor efficiency of honey bee antenna. Also, the author suggests t...

Measurement of Electric Charges Carried by Bees: Evidence of Biological Variations

Two ground-based instruments were designed and built in order to accomplish the present research. The first, based on the principle of the induction ring, measures the electric charge as well as the size of the individual raindrops. The other is a novel raingage providing the instantaneous value of the rainfall rate: a U-shaped tube turns the rainwater flow into an airflow more easily measured by a sensitive airflow meter. The adjustable range has been set between 1 and 100 mm h−1. Six spring showers were investigated. Individual electric charges between 5 and 100 pC have been measured on raindrops up to 4 mm in diameter. The data reduction shows that each shower must be studied separately, using several parameters. Under these conditions, there are two distinct types of precipitation, according to the sign of the charge excess they provide. The total charge carried down by each shower is primarily determined by the greater number of drops of one sign as compared to the other sign. Cross-correlat...

Serge Despiau

Papers

Rainfall Rate and Electric Charge and Size of Raindrops of Six Spring Showers