The pigment, pyrrolo-pyrrole, is used to create the red color of auto paints. The pigment itself is not electrically conductive, but a joint research team from Toyo Ink and the university discovered that when nitrogen is mixed in with the pyrrolo-pyrrole, the mixture exhibits a sudden 100, 000-fold increase in conductivity when it comes in contact with hydrogen.

The researchers realized that this property could be exploited to design a hydrogen sensor. The sensor they built is made by first fabricating a transparent electrode with a comb-like shape using a metal-oxide compound fixed to the surface of a glass substrate, and then coating the electrode with a paste made from a mixture of pyrrolo-pyrrole and nitrogen.

Toyo Ink intends to focus on marketing the paste, selling the compound via a subsidiary. But it also plans to license the technology to makers of autoparts and measuring instruments.

Because the pigment is inexpensive and readily available, hydrogen sensors made this way promise to cost just around 10% of conventional devices, which cost 2,000 (US$19) to 3,000 yen apiece.