Self-touch gestures (e.g., nuanced facial touches and subtle finger scratches) provide rich insights into human behaviors, from hygiene practices to health monitoring. However, existing approaches fall short in detecting such micro gestures due to their diverse movement patterns. This paper presents μTouch, a novel magnetic sensing platform for self-touch gesture recognition. μTouch features (1) a compact hardware design with low-power magnetometers and magnetic silicon, (2) a lightweight semi-supervised framework requiring minimal user data, and (3) an ambient field detection module to mitigate environmental interference. We evaluated μTouch in two representative applications in user studies with 11 and 12 participants. μTouch only requires three-second fine-tuning data for each gesture, and new users need less than one minute before starting to use the system. μTouch can distinguish eight different face-touching behaviors with an average accuracy of 93.41%, and reliably detect body-scratch behaviors with an average accuracy of 94.63%. μTouch demonstrates accurate and robust sensing performance even after a month, showcasing its potential as a practical tool for hygiene monitoring and dermatological health applications. Code is available at https://wangmerlyn.github.io/muTouch/.

翻译：自触摸手势（例如细微的面部触摸和轻微的抓挠）为人类行为提供了丰富的洞察，从卫生习惯到健康监测。然而，现有方法因其多样的运动模式而难以检测此类微手势。本文提出了μTouch，一种用于自触摸手势识别的新型磁感知平台。μTouch具有以下特点：（1）采用低功耗磁力计和磁性硅的紧凑硬件设计；（2）需要最少用户数据的轻量级半监督框架；（3）用于减轻环境干扰的环境磁场检测模块。我们在两项具有11名和12名参与者的用户研究中，通过两个代表性应用评估了μTouch。μTouch每个手势仅需三秒的微调数据，新用户在使用系统前所需时间少于一分钟。μTouch能以平均93.41%的准确率区分八种不同的面部触摸行为，并以平均94.63%的准确率可靠检测身体抓挠行为。即使在一个月后，μTouch仍表现出精确且鲁棒的感知性能，展示了其作为卫生监测和皮肤健康应用实用工具的潜力。代码发布于 https://wangmerlyn.github.io/muTouch/。