DuoTouch is a passive attachment for capacitive touch panels that adds tangible input while minimizing content occlusion and loss of input area. It uses two contact footprints and two traces to encode motion as binary sequences and runs on unmodified devices through standard touch APIs. We present two configurations with paired decoders: an aligned configuration that maps fixed-length codes to discrete commands and a phase-shifted configuration that estimates direction and distance from relative timing. To characterize the system's reliability, we derive a sampling-limited bound that links actuation speed, internal trace width, and device touch sampling rate. Through technical evaluations on a smartphone and a touchpad, we report performance metrics that describe the relationship between these parameters and decoding accuracy. Finally, we demonstrate the versatility of DuoTouch by embedding the mechanism into various form factors, including a hand strap, a phone ring holder, and touchpad add-ons.

翻译：DuoTouch是一种用于电容式触摸屏的被动式附件，可在最小化内容遮挡和输入区域损失的同时增加实体输入功能。该附件通过两个接触触点与两条导电路径，将运动编码为二进制序列，并借助标准触摸API在未经改装的设备上运行。我们提出了两种配备配对解码器的配置方案：对齐配置将固定长度编码映射为离散指令，移相配置则通过相对时间关系估算方向与距离。为评估系统可靠性，我们推导出采样受限条件下的理论边界，该边界关联了驱动速度、内部路径宽度与设备触摸采样率。通过在智能手机和触摸板上开展技术评估，我们报告了描述这些参数与解码精度关系的性能指标。最后，我们通过将DuoTouch机制嵌入多种形态因子（包括手部绑带、手机指环支架及触摸板附加组件）展示了该系统的多功能性。