Water contains an abundance of energy in various forms, although very little of this energy is being harnessed, though there are a lot of techniques to harvest water energy.

On a larger scale, a Nanowerk report specified that there are traditional hydro energy and tidal force harvesting plants. On a larger scale, devices harvesting water motion energy on a particular surface, such as triboelectric nanogenerators and water droplets.

In this regard, rain can be considered prolific as a sustainable energy source, such as scavenging from wind or solar.

As a result, droplet-driven energy harvesting devices, which provide a simple construction with low-cost materials equipment, have been given considerable attention from the global research community.

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Droplet-Driven Energy

Aside from energy harvesting applications, the droplets' behavior is an essential phenomenon in modern science.

Water droplet-related studies are increasing substantially in many scientific fields for their wide applications in basic sciences like biotechnology and bioengineering, the fluid mechanism at micro- and nanolevel, and condensation processes.

Current technologies like self-cleaning glass or solar cells, air conditioning, heat transformation, and ventilation greatly rely on the characteristics of the water droplets.

A recent review published in Advanced Energy Materials discusses thoroughly different methods for harvesting water droplets with their potential in the future for different applications.

Nanogenerators Classified

In this research, the authors report structure device variations with modification depending on performance enhancement and application with the most recent advancement in fabrication processes, not to mention material selections.

They also comprise a performance analysis and deal with the limitations of present device fabrication. The researchers begin by discussing the water droplets' physical properties, the water droplets' interaction with dielectric surfaces, their effect on the covers of nanogenerators, droplets-based nanogenerators, surface engineering for nanogenerators based on droplets, solid/liquid interface for energy harvesting, which is detailed in a report published in the Applied Energy journal, and the significance of water droplets-based nanogenerators in present studies.

Based on the team's working mechanism, for instance, how droplets interact with the dielectric materials, many basic types of droplet-based nanogenerators can be classified.

Triboelectric and Tribovoltaic Effects

This classification comprises most of the reported water droplet-based nanogenerators explained in the literature.

Essentially, the triboelectric impact is the build-up of an electric charge between a pair of materials through contact and separation.

In this circumstance, these nanogenerators' basic working principle is based on the water droplet's contact and separation with the dielectric layers.

Moreover, tribovoltaic refers to a phenomenon in which quantum energy is released when an atom-to-atom bond is formed at the dynamic interface of two contacting materials.

For example, the tribovoltaic can be produced at the liquid-semiconductor interface by moving a water droplet over a silicon surface.

Nanostructure Materials

Nanostructured materials can produce electricity interacting with water; a phenomenon called the "hydrovoltaic impact."

Here, a flowing droplet's kinetic energy on a nanostructured surface can be used to produce a streaming potential due to the electrical double layer-based electrokinetic effect.

Based on the three fundamental impacts, researchers are examining water droplets-based energy harvesting with different mechanisms, structures, and materials modifications to fabricate better-performing nanogenerators.

Related information about harvesting energy is shown on Texas Instruments' YouTube video below:

 

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