The modified Smartphone has a small vibration sensor that looks for the acoustic and vibrational differences between the three types of touch.
For example, a fingertip could help select an object while a knuckle tap could act like the right-click on a computer mouse and open up a submenu.
"A big problem with touchscreens right now is that they are very simplistic, relative to the capability of our hands," Harrison said.
"We could do so much more," he said.
He said that the sensor is a standard piece of electronics, which could be added to any Smartphone's main circuit board.
"The real magic is in the software, this artificial intelligence that lives in the heart of the phone," he added.
He has launched a company called Qeexo to sell his creation.