Tap and Swipe Smartphone Gestures Indicating Hand Tremor and Finger Joint Range in Motion

Conditions such as multiple sclerosis or arthritis impair normative hand function by diminishing motor control and limiting finger range of motion (ROM), respectively. Day-to-day variation of these symptoms makes it difficult for physicians to track clinically relevant changes in function. This is worsened in populations that lack general access to healthcare. A smartphone holds the potential to be used as a frequent self-screening platform for changes in hand function. We use a custom smartphone application for detecting deviations in force control due to tremors and differences in finger ROM through simple tapping and swiping gestures. We conduct a 17-participant cross-sectional study, which includes two participants with known hand tremors. From the smartphone data during tap-and-hold, we see that people with hand tremors demonstrate less touchscreen force control than normative subjects. During the swiping task, we find a statistically significant moderate correlation between the path length of the swiping gesture and the maximum proximal interphalangeal joint flexion angle of the index finger. We find that different processing methods for the swiping data can reveal additional correlations with metacarpophalangeal flexion. These results are a promising start for the smartphone as an accessible screening tool for tremors and changes in finger ROM.