Inexpensive printed sensors, transistors, and memory devices that aren’t as speedy or as high-capacity as silicon devices could enable the widespread use of sensors in places that aren’t cost-effective today. Disposable devices could monitor and store information about the temperature of drugs, the safety of food during shipping, or air quality.
Researchers at the Palo Alto Research Center (PARC), which is owned by Xerox, have been developing a suite of materials for making printed electronics, including sensors and transistors. This week at the Printed Electronics USA conference in Santa Clara, California, PARC announced details about two partnerships to develop products based on its research prototypes. PARC will work with Norwegian company Thin Film Electronics to make higher-capacity printed memory devices that incorporate the research center’s printed transistors. And PARC is working with Soligie of Savage, Minnesota, to develop products based on its printed temperature sensors.
Much of the excitement around printed electronics has centered on the potential to replace silicon electronics in complex devices such as display screens so that they can roll up. For these types of applications, researchers are working to match silicon’s performance in materials that are just as fast and efficient, but flexible and inexpensive.
These more sophisticated printed electronics may be a few years from commercialization. “We want to go to market in simpler applications to prove that printed electronics can work today,” says Davor Sutija, CEO of Thin Film. The company’s 20-bit printed memory devices will be in toys early next year.
Products integrating these postage-stamp-sized memory devices will include playing cards paired with online games. Kids will use the cards to transfer their playing history between a PC and a handheld device. For a toy or a game that requires only a small amount of memory, using silicon-based memory like flash is impossibly expensive. “When you’re only storing a small amount of data in lots of places, the cost threshold is right for printed electronics that cost a few cents,” Sutija says.
Thin Film’s memory devices are made on long reels of plastic using roll-to-roll printing, the same basic process used to churn out newspapers. They sandwich a layer of electrically sensitive polymer between top and bottom layers of wire-like electrodes that are perpendicular to one another. Where the electrodes cross, it creates a charge-storage device called a capacitor. When a small voltage is applied to the capacitor, the orientation of the polymer in the capacitor changes; this change in orientation makes the “1” and the “0.”