It's still early days for e-readers, and consumers can only choose between a few chunky-looking models. But by next year, Plastic Logic, based in Cambridge, U.K., will start selling a sleek e-reader that's the size of a standard sheet of paper and as thin as about six credit cards, and weighs less than a pound. The design of the device could help win over some customers, but Steven Glass, head of user experience at Plastic Logic, believes that the user interface developed for the device will play just as crucial a role.

On Wednesday, Plastic Logic will demo its new interface for the first time, at the All Things Digital D7 conference, in San Diego. The interface includes a touch screen to let users add notes to documents and save them even when the documents are transferred to another device or computer.

As with both the Kindle and the Sony Reader, Plastic Logic's display is built using E-ink: black and white microcapsules are suspended in a liquid and controlled using an electric charge. When a charge is applied, the microcapsules assume their position and form black text on a white background. However, in Plastic Logic's reader, the E-ink is deposited on a lightweight plastic backplane instead of on a glass backplane. Plastic Logic says that the plastic backplane allows for a larger reading area without adding more weight or bulk, and this makes the device more robust.

Plastic Logic hopes to further distinguish its reader from Amazon's Kindle and the Sony Reader by targeting those who read business documents created using Microsoft Office and Adobe Acrobat, as well as image files and standard e-reader files. The goal is to eliminate "the huge stack of papers that people take with them when they travel," says Glass. Many people need to sort through thousands of documents quickly, he adds, and want to mark them up by circling or underlining items or by adding notes.

In a demonstration at Plastic Logic's Mountain View, CA, facility last week, Glass showed off the upcoming reader. After the device starts up, the left side of the screen shows documents, including newspapers and books, organized in several different ways. For example, it shows the most recently transferred documents; a series of drop-down folders, similar to those of the file manager on personal computers; and a calendar with documents assigned to specific days. The right side of the screen shows icons for different documents, with their titles below. The interface also supports a search function, and when that is selected, a keyboard pops up on the screen for entering text.

When reading a document, a person "turns" the page by flicking a finger across the screen, and she can skip to a page number using a hidden toolbar that pops out of the right side of the screen when that side is touched. Depending on the size of the document, the page numbers are presented either one at a time or in groups of 10, such as 50 through 59. Tapping the screen further breaks it down to individual pages. Because marking up documents is an important feature of the interface, users can see, on these page numbers, which pages have been altered or bookmarked and can skip directly to them.

While the Plastic Logic home page interface allows for more flexibility than that of the Kindle, which offers limited ways to find documents, it appears less elegant and is slightly more cluttered.