The UN Convention on Biological Diversity defines biotechnology as:

any technological application that uses biological systems, living organisms, or derivatives thereof, to make or modify products or processes for specific use.

And doesn't urine fall under the category of being a derivative of a living organism?

Published recently in the Journal of Micromechanics and Microengineering, Singapore physicists at the Institute of Bioengineering and Nanotechnology (IBN) led by Dr Ki Bang Lee, have developed a paper battery that is small, cheap to fabricate, and which ingeniously uses the urine as the power source. Using 0.2 ml of urine, they generated a voltage of around 1.5 V with a corresponding maximum power of 1.5 mW. Dr. Lee says,

"Our urine-activated battery would be integrated into biochip systems for healthcare diagnostic applications. These fully-integrated biochip systems have a huge market potential."

Imagine using your urine to power the battery that runs in, say, your blood-sugar test kit. Could be a convenient alternative when travelling, for example, wouldn't it?