Students from Northwestern University managed to use pencils and regular paper to create functional sensor devices. They created two types of sensors - strain sensors and chemical vapor sensors.

The students had a discussion about the conductive properties of graphene. They realized that when you draw a line on a piece of paper with a pencil, the pencil's graphite sheds numerous graphene sheets. They started exploring what these graphene sheets can be used for... and, well,  you can read more here:

http://www.graphene-info.com/researchers-use-pencil-and-paper-create-strain-and-chemical-sensors