How to Write on Thin Air

June 17, 2009 — -- Wouldn't it be handy if you could write yourself a note in midair and have it safely stored where you could retrieve it later? Someday soon you may be able to do just that with nothing more than your cell phone.

Researchers at Duke University have created what they are calling a "PhonePoint Pen" that uses a modern cell phone's built-in accelerometer to detect writing in thin air, and then automatically send a note to a designated e-mail account. There are still some bugs to work out, but the researchers believe they've proven that the idea really works.

"We are convinced that this is feasible and this will become something that people will use," Romit Roy Choudhury, assistant professor of electrical and computer engineering at Duke, said in a telephone interview.

Roy Choudhury said he began toying with the idea while he was still a grad student in 2005, back in the days of technological antiquity when the most common form of writing a personal reminder was with a sticky note.

"I used to keep forgetting things, and I thought there should be some way of jotting something down while I'm walking down the street, like calling someone when I get home," Roy Choudhury said. "By the time I get home, I've forgotten about it."

"The existing technology wasn't all that great," he added. "And the idea struck me that maybe it's possible that I could have a pen with an accelerometer and I could just write in the air with the pen."

The accelerometer would detect the movement of the pen, and "then and I could press a button or something and the writing would get e-mailed to my mailbox. But getting a pen with an accelerometer was hard."

Fast forward three years and Roy Choudhury is an assistant professor of electrical and computer engineering at Duke. A lot had happened during that brief period, including the inclusion of accelerometers in state-of-the-art cell phones.

That's the feature that allows an image on the screen of an iPhone to change between portrait and landscape formats as the phone is rotated.