Xerox hopes plastic ink leads to printed chips

A team of researchers at Xerox Corp. has discovered a way to print plastic transistors using a semiconductive ink, paving the way for flexible displays and low-cost RFID (radio frequency identification) chips, Xerox announced Friday.

Other companies are working on ways to print chips using inkjet printing technology or other methods of depositing liquid on a surface. Most of those techniques have required manufacturing environments at high temperatures or high pressures, but Xerox has developed a way to print transistors at room temperature, said Beng Ong, a Xerox fellow, in a press release.

The new technique builds on a polythiophene semiconductor developed by Ong's team last fall. Polythiophene is an organic compound that resists degradation in open air better than other semiconductor liquids and also exhibits self-assembling properties.

Ong's team has now found a way to take the polythiophene semiconductor and process into a liquid that can form ordered nanoparticles. When the particles are put into liquid form, they form an ink that can be used to print the three key components of a circuit: a semiconductor, a conductor, and a dielectric, Xerox said.

The CMOS (complementary metal-oxide semiconductor) technology used to build most chips today is expensive, and requires a solid base such as silicon to manufacture circuits. Xerox hopes this technology can be used to build displays that can be rolled up, bent around a corner, or otherwise stretched in ways not currently possible.

Backers of RFID technology are also looking for a way to build low-cost chips that can be used to track inventory in warehouses and grocery stores. Companies such as Wal-Mart Stores Inc. are looking for ways to improve their inventory management techniques with these chips, but the cost of putting an RFID chip in every product sold through a company as large as Wal-Mart is prohibitive.

Ong presented his findings to the Material Research Society spring conference in San Francisco Friday, and was unavailable for comment.