Fully Transparent Shape-Changing Display With Adjustable Key Travel for Enhanced Touchscreen Typing

Touchscreen devices often suffer from high typing error rates in the absence of physical keys. Shape-changing displays, which recreate physical keys on the screen, offer a promising solution. While the travel of physical keys plays an important role in the typing experience, it has received limited attention in previous work. To investigate the impact of on-screen physical keys with varying key travel on typing performance and user preferences, we developed a fully transparent shape-changing display that delivers adjustable key travel on touchscreens. The engineered portable microfluidic pressure-control system regulates the driving pressure, thereby adjusting the key travel to provide personalized passive tactile feedback. Using this platform, we conducted a user study in which participants typed with a two-thumb posture under four different key travel conditions, including the zero-travel condition. The results demonstrate that shape-changing keys significantly reduce typing error rates compared with flat keys, while revealing significant inter-individual variability in both performance and preference. These findings highlight the role of adjustable key travel in meeting diverse user needs and enabling adaptive touchscreen interaction.