Every electronic device, from laptops to toothbrushes, has one thing in common: a printed circuit board, or PCB. These flat boards, usually green in color, carry the copper wires and electronic ...

Cellulose residues, which have hardly been used to date, can be pressed into hard circuit boards after “hornification.” They don't have to be totally waterproof.

They are the "heart" of every electronic device, from laptops to electric toothbrushes: printed circuit boards, also known as ...