A Touchpad Phone Augmentation



  • User Researcher
  • Interaction Designer
  • Prototype Development


  • Physical Medium Prototyping
  • 3D Printing
  • Windows Phone API
  • .NET WPF Framework

Design Process


Smartphone interaction is largely touch-based through direct contact with the front display. This leads to issues such as: “fat finger syndrome”, high precision necessary for small targets, and frequent submenu usage for simple tasks.


Inspired by my own frustrations with existing smartphone interactions caused by the problems listed above, I sketched out possible alternative interactions that do not involve a direct touch with the display.



Intrigued by the possibilities of using the back of the phone for interaction, I started sketching ideas on how we can use it for common interactions such as: precise selection, scrolling, panning, and more.


Physical Medium Sketch

In order to get a realistic sense of how this novel interaction would feel in the hand, I created a physical medium sketch using two smartphones held back-to-back.

It turns out that this interaction did not feel as natural as I had expected from my sketches, and the range of comfortable motion is very limited. Furthermore, after asking for feedback on my interaction ideas, I realized I should try to think about how this new touch surface can allow for new ways to interact with the phone, rather than trying to replicate existing gestures.



Back to the drawing board! This time I focused my attention on creating expert poweruser techniques that can enhance smartphone interactions in new and faster ways for users who aren’t satisfied with existing interaction paradigms. These include: quick mode switching, multi-tasking, context menus, and mode toggling.



My prototype consisted of two smartphones, one being the regular front display, and the back one acting as a touchpad. They were held together using a custom 3D printed case. While the dimensions were clunkier than ideal, it provided a realistic environment where I can test actual interactions using this new augmentation.

I created a set of mini applications that highlight the possibilities that the “Backpad” provides its user as shown in the video below. They were developed using .NET and the Windows Phone API.