Publications
CONFERENCE (INTERNATIONAL) Passive Attachments for Back-of-Device Interaction via Binary Touch Sequences
Kaori Ikematsu, Kunihiro Kato (Tokyo University of Technology)
The ACM Symposium on User Interface Software and Technology (UIST2025)
September 27, 2025
We present passive attachments for smartphones that generate binary touch sequences to enable expressive input without external power or modifications to operating systems. In this approach, user actions transmitted via a finger-actuated conductor, such as pressing a button, rotating a dial, or sliding a knob, generate binary sequences based on the arrangement of conductive and non-conductive segments on the attachment. Our system interprets these sequences either by analyzing them and recognizing discrete commands or by comparing relative activation timing between spatially offset conductive segments to detect continuous inputs. The proposed approach requires only two single-line capacitive sensors and minimal on-screen contact points, thereby reducing visual occlusion and wiring complexity. We demonstrate our approach through its application to a back-of-device interface.
Paper :
Passive Attachments for Back-of-Device Interaction via Binary Touch Sequences
(external link)