Figure 1: CapStones are tangible blocks that allow the underlying capacitive touch screen to identify blocks and to sense how they are arranged in 3D.

Recent research proposes augmenting capacitive touch pads with tangible objects, enabling a new generation of mobile applications enhanced with tangible objects, such as game pieces and tangible controllers. In this paper, we extend the concept to capacitive tangibles consisting of multiple parts, such as stackable gaming pieces and tangible widgets with moving parts. We achieve this using a system of wires and connectors inside each block that causes the capacitance of the bottom-most block to reflect the entire assembly. We demonstrate three types of tangibles, called CapStones, Zebra Dials and Zebra Sliders that work with current consumer hardware and investigate what designs may become possible as touchscreen hardware evolves.

Figure 2: A single Zebra Slider allows users to adjust brightness. A second Zebra Slider allows also adjusting contrast.

Figure 3: A single Zebra Dial allows users to adjust the brightness of the underlying image. Placing a second Zebra Dial on top allows adjusting brightness and contrast.


Talk at CHI 2012


Chan, L., Mueller, S., Roudaut, A. and Baudisch, P. CapStones and ZebraWidgets: Sensing Stacks of Building Blocks, Dials and Sliders on Capacitive Touch Screens. In Proceedings of CHI 2012, pp. 2189-2192.
 PDF (6.6MB) |  Slides + Videos (198.5MB)