Biomimetic Fingertips: Friction Modulation Through Surface-Responsive Texture Triggered by Microvibration Sensing

Human fingertips naturally wrinkle in wet conditions, enhancing friction and grip. Inspired by this biological adaptation, we present a biomimetic robotic fingertip capable of dynamically modulating friction through controlled changes in surface texture. The design incorporates shape memory alloy (nitinol) actuators within a silicone fingertip structure and employs a piezoelectric vibration sensor for real-time surface detection and classification. Our system achieves surface type classification accuracy exceeding 94% and can dynamically alter surface texture in response to detected conditions. Experimental results demonstrate that the fingertip can increase friction coefficients by up to 66.4% relative to the inactive state under the same load with moderate actuation speed (0.58 s). Compared with conventional robotic grippers that rely solely on increased grip force, our approach offers an adaptive, integrated alternative, potentially beneficial in delicate manipulation tasks involving slippery and fragile surfaces within robotic applications.