Electronic Design

So You Won't Turn Off Your Cell Phone? Don't Worry—The Paint Will

Nanotubes, those hollow cylinders that are oh so tiny but oh so useful, no doubt will make great contributions to mankind someday. We could wind up with semiconductor technologies that make today's deep-submicron devices look bloated. Imagine what that could do for implantable medical diagnostic systems and prostheses. Such breakthroughs may rival in importance one development that could come even sooner—blocking the ringing of cell phones in inappropriate places like movie theaters and concert halls.

The nanotubes that may make this wondrous feat possible aren’t the manufactured carbon cylinders commonly used in the electronics industry. Instead, they’re naturally occurring alumina-silicate tubes found in halloysite clay. NaturalNano Inc., a nanotechnology and advanced materials company that looks for ways to commercialize naturally occurring nanomaterials, has developed a metalization technique to coat the outside or fill the inside of the halloysite nanotubes to block, or greatly reduce, RF signals.

The Rochester, N.Y., company says that experimental trials of a spray-on coating embedded with the copper-filled nanotubes demonstrated a significant ability to do just that. The passive technique doesn’t involve jamming, which is illegal in the U.S. It presumably would be much less expensive than conventional RF shielding methods that require labor-intensive installation of costly conductive shielding material, especially in a retrofit situation.

To complement its technology, NaturalNano recently licensed technology from AMBIT Corp., of Ashland, Mass., that would let building managers selectively override the RF blocking. An indoor antenna would pick up the cell-phone or other signals and send them through a filter to an outdoor antenna for broadcast. Received signals would go through a reversed process. Building management could turn the AMBIT system on and off as well as control the frequencies allowed in and out.

Imagine that—a paint that could block cell-phone signals from disturbing a movie you just paid eight bucks or more to see, or a show or concert that you may have paid $100 or more to attend. Instead of a slide that reminds people to turn off their cell phones, theater operators could put up a message that tells people their cell phones won’t work during the movie. Fantastic!

Of course, you’ll see lots of complaints. While the First Amendment doesn’t give you the right to falsely yell fire in a crowded theater, surely the Constitution gives you the right to receive a phone call. I’ve seen the bleatings already. One guy on the Internet said his child had a serious allergic reaction and his babysitting grandmother had to call the theater. Far be it from me to criticize someone’s mother. But if your mother or any other sitter can’t handle such a problem, should she be alone with the child anyway? And if it is an emergency, could you get back to your home quicker than the EMTs could?

But what about doctors who need to receive calls summoning them to the hospital to save a life? Hey, I have great respect for doctors. I must. I’m putting enough of their kids through college. But doctors aren’t on call every night. When they are, they shouldn’t go to the movies. And if there’s an emergency inside the theater? Simple. Wire up the override system to automatically open up all frequencies if an alarm sounds.

Michael Riedlinger, president of NaturalNano, stresses that his company isn’t a paint manufacturer. But it is open to working with companies that could commercialize this RF shielding technique. The fact that NaturalNano licensed the AMBIT technology is ample evidence of that.

Riedlinger also emphasizes that the company’s scientists have identified more than 200 applications for the halloysite nanotubes, which have inside diameters of about 20 to 40 nm. Ultracapacitors may not be far off. And depending on what material they’re filled or coated with, the nanotubes could be used for extended-release delivery of anything from drugs to fragrances to sunscreen to pesticides, he says.

I'm sure that many of the other 199 or so applications will greatly improve the human condition in some way. But the application that I hope is commercialized first is the one that prevents theatergoers everywhere from ever having to listen someone’s idea of a cute ring tone.

NaturalNano
www.naturalnano.com

AMBIT Corp.
www.ambitcorp.com

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