Tokyo (Japan) – Cue up the Matrix jokes because Sony has developed a biological battery that runs on glucose. The so-called “bio battery” converts the sugar into electricity with the help of enzymes, oxygen and water. Sony researchers proved the batteries work by stringing four of them together and powering a Walkman.

The small battery is a cube measuring 39 mm (about 1.5 inches) on each edge and holds about 40 cc of sugar, enzymes and water. The battery casing is made from vegetable-based polylactate plastic while the enzymes used are glucose dehydrogenase and diaphorase.

The enzymes digest the glucose and release hydrogen ions, along with free electrons. The hydrogen and electrons then absorb oxygen to form water. Altogether, Sony says the process produces 50 mW of electricity per battery.

Sony promises to market sugar-powered batteries sometime in the future.