Chris Harrison at Carnegie Mellon University in Pittsburgh says the screen can distinguish between touches from the knuckle, fingertip and even a fingernail, and initiate different phone action based on the hand part used, NewScientist.com reported.
Harrison's modified Samsung Galaxy S3 smartphone senses the acoustic and vibrational differences between the three types of touch.
"A big problem with touchscreens right now is that they are very simplistic, relative to the capability of our hands," Harrison says. "We could do so much more."
For example, he says, a fingertip could select an object, while a knuckle tap could work like the right-click on a computer mouse and open up a sub-menu.
The sensor is a standard piece of electronics that can be added to the main circuit board of any smartphone, he says. What makes it work is his FingerSense software.
"The real magic is in the software, this artificial intelligence that lives in the heart of the phone," said Harrison, who is already in talks with some major phone manufacturers about his system.