Device uses motion of single droplet to generate power

Researchers from Vestfold University College in Norway have created a simple, efficient energy-harvesting device that uses the motion of a single droplet to generate electrical power.

According to a statement, the new technology could be used as a power source for low-power portable devices, and would be suitable for harvesting energy from low-frequency sources such as human body motion, claim the authors of a paper in Applied Physics Letters.

The harvester is said to produce power when an electrically conductive droplet (mercury or an ionic liquid) slides along a thin micro-fabricated material called an electret film, which has a permanent electric charge built into it during deposition.

Cyclic tilting of the device causes the droplet to accelerate across the film’s surface; the maximum output voltage (and power) occurs when the sliding droplet reaches its maximum velocity at one end of the film.

A prototype of the fluidic energy harvester is said to have demonstrated a peak output power at 0.18 microwatts, using a single droplet 1.2mm in diameter sliding along a 2μm-thick electret film.