ScraTouch: Extending Interaction Technique Using Fingernail on Unmodified Capacitive Touch Surfaces
summary
ScraTouch distinguishes fingernail versus fingertip by reading shunt current from unmodified capacitive surfaces without kernel or hardware changes, using the macOS MultitouchSupport private framework and a max-shunt-current threshold taken in tens of milliseconds (0–80 ms). Recognition yields about 97% accuracy (equal error rate ≈3%). A point-and-select study finds overall performance equal to fingertip baseline, switching commands are slower due to pitch-angle changes, and ScraTouch is on average 29% faster than a 500 ms long press.
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chapters (7)
- 0:00ScraTouch: Extending Interaction Technique Using Fingernail on Unmodified Capacitive Touch Surfaces
- 0:27Extending touch inputs using different parts/posture of hand
- 0:57Extending interaction using fingernails on capacitive touch surfaces
- 2:26Working principle
- 3:14Distinguishing between finger and nail Data Collection Experiment
- 3:45User Evaluation
- 5:06Results: error rates Error rate of unintended mode activation (finger/nail)
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