We argue that the key to touch-enabling very small devices is to use touch on the device backside 
One more advantage of nanoTouch the authors missed is that touching the back side of a small device is much more comfortable than touching that of a larger one.
 P. Baudisch and G. Chu, "Back-of-Device Interaction Allows Creating Very Small Touch Devices," submitted to CHI2009, Boston, MS, April 4-9, 2009.
PS: I found another nanotouch site. It says that
Placing the Nanotouch on the right hand thumb, as the user massages their index finger with their thumb "Nanotouch" makes the cursor move on the screen.
The concept is funny, but no more information I can have.