Simon Voelker, Kosuke Nakajima, Christian Thoresen, Yuichi Itoh, Kjell Ivar Øvergård, Jan Borchers
In Proceedings of ITS '13, ACM, 101 - 104
Publication year: 2013



Capacitive multi-touch displays are not designed to detect passive objects placed on them-in fact, these systems usually contain filters to actively reject such touch data. We present a technical analysis of this problem and introduce Passive Untouched Capacitive Widgets (PUCs). Unlike previous approaches, PUCs do not require power, they can be made entirely transparent, they are detected reliably even when no user is touching them, and they do not require internal electrical or software modifications of the touch display or its driver. We show the results from testing PUCs on 17 different off-the-shelf capacitive touch display models, and provide initial technical design recommendations.

The Team

PUCs is a research project by Simon Voelker and Jan Borchers from the Media Computing Group, Kosuke Nakajima and Yuichi Itoh from the Osaka University, and Christian Thoresen and Kjell Ivar Øvergård from the University College of Southeast Norway. It is funded in part through the German B-IT Foundation and through the MACS project.


 author = {Voelker, Simon and Nakajima, Kosuke and Thoresen, Christian and Itoh, Yuichi and \Overg{\aa}rd, Kjell Ivar and Borchers, Jan},
 title = {{PUCs: Detecting Transparent, Passive Untouched Capacitive Widgets on Unmodified Multi-touch Displays}},
 booktitle = {Proceedings of the 2013 ACM International Conference on Interactive Tabletops and Surfaces},
 series = {ITS '13},
 year = {2013},
 isbn = {978-1-4503-2271-3},
 location = {St. Andrews, Scotland, United Kingdom},
 pages = {101--104},
 numpages = {4},
 url = {},
 doi = {10.1145/2512349.2512791},
 acmid = {2512791},
 publisher = {ACM},
 address = {New York, NY, USA},
 keywords = {capacitive multi-touch, passive widgets, tabletop interaction, tangible user interfaces, transparent widgets},