An interaction technique for smartwatches based on estimating the moving amount of the thumb

We present ThumbSlide, which is one-handed thumb interaction technique for smartwatch. This technique realizes continuous manipulation by estimating the moving amount of the thumb. Combining with any determining operation (e.g., clench of the hand), our technique enables the user to select a target by only the hand that is wearing a smartwatch. Our system estimates the moving amount of the thumb by muscles' expansion caused by its movement. The muscle expansion is measured by a specially designed wrist-worn sensor device. Moreover, the device can recognize the clench of the hand as a change of the wrist's contour. In this paper, we show the implementation of ThumbSlide, the experimental data of muscles' expansion caused by movement of the thumb, and the estimation accuracy in the moving amount of the thumb.