Estimating Friction Modulation From the Ultrasonic Mechanical Impedance

Ultrasonic surface-haptic touchscreens produce compelling tactile sensations directly on the users’ fingertips. The stem from modulation of friction produced by acoustic radiation pressure, which reduces contact between skin and glass plate. During this process, some vibrations are partly absorbed tissues, resulting in a conspicuous change vibration amplitude plate upon with finger, manifests as net system mechanical impedance. In article, we leverage observable impedance to estimate levitation frictional force. self-sensing method utilizes model first principles governing physical interaction skin, relies multi-scale theory. accurately describes experimental influence observed (i.e., amount energy reflected) can be used coefficient ($R^2=0.93$). These results provide additional evidence partial mechanism at play ultrasonic friction-modulation. This finding useful for designing energy-efficient devices design suggestions using forces.