The batteries are printed using a silk screen printing process in which a rubber lip presses the organic semiconductor materials through a screen onto a flexible substrate. The lithographic-like technique uses templates to pattern layer upon layer–each about the width of a human hair–of battery components until enough bulk has been achieved for a particular application.

Printable batteries for smart cards would weight less than 1 gram and measure less that 1-mm thick. The organic materials produced 1.5 volts per cell, like conventional batteries, but use no harzardous chemicals like the heavy metals in conventional rechargeable and alkaline batteries.

via EETimes.com – Paper-thin batteries set to arrive by 2010.

If you can print power sources like this for batteries, think of how you could weave these into clothing. Anything from the frivolous — totally cool fashion that would glow, light-up, move, etc. to practical uses — spy cam shirt, chemical detectors, audio identifiers. If these can be solar powered, or even better, use our body heat for power, then it would be something.