  We have observed that a rotating liquid soap film generates electricity when
placed between two non-contact electrodes with a sufficiently large potential
difference. In our experiments suspended liquid film (water + soap film) is
formed on the surface of a circular frame, which is forced to rotate in the
$x-y$ horizontal plane by a motor. This system is located at the center of two
capacitor-like vertical plates to apply an external electric voltage difference
in the $x-$direction. The produced electric current is collected from the
liquid film using two conducting electrodes that are separated in the
$y-$direction. We previously reported that a liquid film in an external
electric field rotates when an electric current passes through it, naming it
the liquid film motor (LFM). In this paper we report a novel technique, in
which a similar device can be used as an electric generator, converting the
rotating mechanical energy to electrical energy. The liquid film electric
generator (LFEG) is in stark contrast to the LFM, both of which could be
designed similarly in very small scales like micro scales with different
applications. Although the device is comparable to commercial electric motors
or electric generators, there is a significant difference in their working
principles. Usually in an electric motor or generator the magnetic field causes
the driving force, while in a LFM or LFEG the Coulomb force is the driving
force. This fact is also interesting from the Bio-science point of view and
brings a similarity to bio motors. Here we have investigated the electrical
characteristics of such a generator for the first time experimentally and
modelled the phenomenon with electroconvection governing equations. A numerical
simulation is performed using the local approximation for the charge-potential
relation and results are in qualitative agreement with experiments.
