When a glucose solution is poured into the white cubes, the Walkman begins to play.
When an isotonic drink is poured in, a propeller starts to spin.
In the summer of 2007, the Sony-developed bio battery was announced in newspapers, magazines,
and TV reports, and evoked a strong response. Carbohydrates (glucose) are broken down to release
energy and generate electricity.
This bio battery, which is based on mechanisms used in living organism, is not only friendly to the
environment but also has great potential for use as an energy source.
         This prototype bio battery has achieved
the world’s highest power output of 50
mW*2 when employed for a passive
type*1 system.
These research results were published
at the 234th American Chemical Society
National Meeting & Exposition in August
2007 and earned respect from an academic
point of view.
         Sony successfully demonstrated bio battery
powered music playback with a memory
type Walkman and passive speakers
(which operate on power supplied by the
Walkman) by connecting four bio battery
units in series. The case of this bio battery,
which is made from an organic plastic
(polylactate), is designed to be reminiscent
of a living cell.
       Plants create both carbohydrates and oxygen
by photosynthesis from carbon dioxide and
water. Animals take up those carbohydrates and
oxygen and utilize them as an energy source
and release carbon dioxide and water. Then this
cycle starts again.
Since the carbon dioxide is recycled in this system,
the amount of carbon dioxide in the atmosphere
does not increase. If electrical energy could
be directly acquired from this cycle, we could
obtain more environmentally friendly energy
than that from fossil fuels.
Furthermore, renewable energy sources such
as glucose (which is present in plants and
therefore abundantly available) have an extremely
high energy density. One bowl of rice (about
100 grams) is equivalent to 160 kilocalories,
which corresponds to the energy about 64 AA
alkaline dry cells.
Therefore, this bio battery, which is based on
Energy for activity, that is the ATP and thermal
energy commonly used in the living organism,
can be obtained from the exchange of the
electrons and protons through these two enzymatic
To take advantage of this living organism
mechanism, the energy for activity from inside
the organism must be removed outside the
organism as electrical energy.
           That is, when the
electrons and protons move from enzyme to
enzyme, it is necessary to extract just the electrons
and divert them through a separate path.
Thus Sony used an electron transport mediator
so that electrons could be exchanged smoothly
between the enzymes and the electrodes
that are the entrance and exit to that detour.
The principles of the bio battery are based on
the energy conversion mechanism in living
organisms. However, in order to create the
bio battery, several technologies needed to be

        These include immobilization of
enzymes that are normally incompatible with
carbon and metal electrodes, electrode structures,
and electrolytes.
mechanisms used in living organisms, is not
only friendly to the environment but is also likely to be of practical use as an energy source.
Sony has focused on these advantages since 2001
and has developed an electrical power generation
device that uses mechanisms similar to
those in living organisms.