HACKENSACK, N.J. — Once upon a time, portable gadgets were so cumbersome that man needed a bag — or at least generous cargo pants — to cart his high-tech arsenal.

As anyone who recently purchased the now-obsolete iPod Mini knows, two years is ancient history in the hyper-speed world of personal gizmos, where MP3 players, cell phones and PDAs get smaller and more feature-rich seemingly every day.

"It is not even science fiction to imagine something like MP3 players embedded in your ear,'' said Donald Sebastian, senior vice president for research and development at New Jersey Institute of Technology in Newark.

Sebastian can easily envision a world where MP3 players are worn as pendants or integrated into headphones, and cell phones resemble earplugs. That world is almost here.

Since the mid-1990s, everything from inkjet printer heads to air bags and pacemakers has incorporated micro-electro-mechanical-systems (also known as MEMS) — levers, switches and other mechanical devices that measure in the millionths of a meter.

Microchips, which are produced by transcribing information onto silicon molecules using light and radiation beams as "pencils,'' have become smaller and more complex each year, Sebastian said.

The player, available in 30- and 60-gigabyte versions, can hold up to 15,000 songs, 25,000 photos or 150 hours of video. And, it's less than half an inch thick — 10 percent thinner than its predecessor, the iPod Photo, introduced last year.

Creative Labs' $400 Zen Vision is a 3-by-5-inch portable media center with a 30GB hard drive and a 3.7-inch color screen. The device holds up to 120 hours of videos, 10,000 photos or 15,000 MP3s.

Motorola's Razr V3 cellphone, which can browse the Web, play videos and snap photos, is less than 14 millimeters thick. James Burke, Motorola's senior director of product operations, can envision a future where super-thin phones also serve as primary digital cameras and media players.

Sebastian predicts that adding features into increasingly thin packages will become easier over the next decade as more devices incorporate nano-scale technology. With nano-scale technology, microchips are created by writing on silicon with atomic precision.

If so, the relevant question companies must ask is: "How small do consumers want their electronics?'' said Peter Shankman, CEO of the high-tech public relations firm The Geek Factory. "The term is just small enough.

They also want phones with large buttons and screens, Burke said. "Smaller isn't always better,'' he said, adding that one of Motorola's smallest phones didn't appeal to consumers, in part, because it was too small.

"You want things that fit in your pocket, but you don't want the ‘Zoolander' phone,'' said Starros George, a 21-year-old Palisades Park, N.J., resident, referring to the inch-long micro-cell phone Ben Stiller's character uses in the 2001 comedy.

"I wouldn't want to take the chance of a very small device breaking,'' said Stanley Chan, 20, of Palisades Park, who was shopping with George and another friend, Dino Georgiou, at the Garden State Plaza in Paramus, N.J.

Sebastian sees a future where losing devices won't be a problem. Many of us may live to see a future where information is stored inside atoms, he said, making gadgets so microscopically small that they could be grafted into a person's nervous system and controlled via thought.

• iPod: The latest incarnation of the hugely popular gadget can store up to 15,000 songs, 25,000 photos or 150 hours of video and is less than half an inch thick. $299 to $399.

• iPod Nano. The superhero of MP3 players at the moment. Thinner than a pencil, and able to play 500 to 1,000 songs or store about 25,000 photos. $199 to $249.

• Motorola ROKR cell phone: This 2-by-4-inch cell plays 100 MP3s from Apple's iTunes, takes pictures, records video and, of course, makes calls. $249.99 (with contract).

• Nikon's Coolpix S1 digital camera: Just 0.75 inches thick, this 5.1-megapixel model has a digital zoom, exclusive "face-priority'' auto focus and red-eye removal. $379.95.

• Delphi MyFi XM2GO portable XM satellite radio. Features: antenna, home kit, vehicle kit and more than 150 channels. $349.99. Price does not include subscription fee of $9.95 a month.

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