Once celebrated for cameras that made their own prints, Polaroid Corp. plans to update the concept this year by selling a portable printer for images on cell phones and digital cameras. And like those old Polaroid instant-film cameras, the new printers should have a wow factor: they require no ink, because they employ a thermal printing technology from startup Zink Imaging Inc. The 8-ounce printers, a bit bigger than a deck of cards, are due to go on sale around back-to-school time for about $150, Polaroid and Zink announced Monday at the International Consumer Electronics Show. Once connected to a phone or camera by Bluetooth wireless or the USB port, the printers need less than a minute to churn out 2-inch-by-3-inch pictures, which can be peeled off a backing and used as stickers. Sheets of paper for the device will cost about 40 cents each, less if bought in bulk. The Zink technology, which uses heat to activate minuscule dye crystals embedded in the photo paper, won raves at the influential Demo conference a year ago. But until the CES announcement, Zink had not lined up any partners who would bring its technology to market. Polaroid is a natural fit, and not just because of its photo-printing history. Zink was founded in 2005 by private investors who bought many technologies from Polaroid as it was coming out of bankruptcy. Now Zink and Polaroid are based in the same complex in Waltham, Mass. Zink also announced that Tomy Co. would be its partner in Japan. Prices and availability dates were not disclosed. Another mobile printer with thermal paper debuted at CES, though it is much larger and designed for business people. The $300 Printstik from Canada-based Planon Systems Solutions Inc. is less than 2 pounds but prints in black and white, in the familiar 8 1/2-by-11-inch paper dimension. After a connection via USB cord or Bluetooth wireless, the Printstik can churn out paper copies to ease the task for people who tire of reading text on the small screens on devices like BlackBerrys.