Batteries come in all shapes and sizes, and power the modern world, from the tiny hearing aid and gadgets like wrist watches, smartphones, laptops and camera, to large entities like cars and trucks! Irrespective of their shape, size and function, the working principle behind all batteries is pretty much uniform: two electrodes – an ‘anode’ attracting negative ions and a ‘cathode’ attracting positive ions – connected by an electrolyte, undergo redox reactions to help convert other forms of energy into electrical energy. When the circuit is completed, the terminal voltage across the anode and cathode drives the flow of electrons / ions across the electrodes generating an electric current. Now, scientists at IIT Kharagpur have come up with an ingenious prototype of a microbial fuel cell, which is not only environmentally friendly and flexible enough to be fabricated in any size or shape desired, but can also be made using commonly available materials. The scientists used electrodes made from paper and filled it with a mixture of bacteria and organic fuel, to construct the novel ‘bio-battery’. They further used commercially available eyeliner as a conductive ink for providing electrical conductivity to the paper-based cathode and anode. The eyeliner contained carbon nanoparticles as well as iron oxide (Fe3O4) which provided the conductivity. Additionally, a Whatman filter paper was used for both supporting the electrodes as well as for separating multiple such microbial fuel cells from each other. The bacteria stored within these biocompatible electrodes, in their active form, can chemically oxidize the organic fuel to generate a current. Such a microbial fuel cell can be rapidly powered up and can provide up to 12.5 watts per cubic metre of power. Microbial fuel cells like these can, in principle, be used for fabricating a plethora of tailor-made electrodes for use in various kinds of power consuming devices.