Experimental results point out that the said copolymer electret film is a polar material, i. e. there exist both oriented dipoles and deposited space charges in the film after charging.

The combination of heat and charge releases electrons, which accelerate through the tube and strike a positively charged electrode at the other end.

It relies on the same principle employed in lithium-ion batteries-moving sodium or potassium ions between electrodes during charging and discharging-but does it much more cheaply.