How to Write on Thin Air

Cell texting

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."

Accelerometer Detects Movement of Pen

"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.

Cell Phone as the Magic Pen

As an assistant professor, Roy Choudhury had a gaggle of creative students at his disposal, and he suggested they try to figure out how to use a cell phone as the magic pen he had wanted in college.

At first, it was kind of a game, he admits, but Sandip Agrawal, an electrical and computer engineering senior, and Ionut Constandache, a grad student, made rapid progress.

One cell phone manufacturer, Nokia, donated "a bunch" of phones, and the students found that if they held the phone like a pen, grasped between the thumb and the forefinger, they could control it's movements well enough for it to recognize letters of the alphabet.

They had to be pretty big letters, about six inches tall, and the user had to learn how to write with no frame of reference other than an imaginary blackboard, but it worked well enough to jot down a phone number, or an address, or where the car was parked at the airport.

Phone Can Recognize Script

That's progress, but it's not good enough. The researchers now say they've figured out how to make the phone recognize script, and translate that into text before sending it to a designated e-mail account.

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