DynaButtons: Fast Interactive Soft Buttons with Analog Control

While mechanical buttons are ubiquitous, their haptic response is fxed, reducing interface fexibility and precluding an avenue for rich feedback. Here, we describe a new type of dynamic button, or DynaButton, which can vary its visual and haptic response via rapid shape change. To achieve this, we made several advances in the performance of embedded electroosmotic pumps: we increased core pump speed >300% over prior work, demonstrated closed-loop control, and investigated analog output that varies in response to pressure and force inputs. We validated our system with a physical characterization and performed a series of stimuli recognition studies to validate the expressivity and discriminability of three regimes of button interaction.