A PDMS/Silicon Adhesion Control Method at Millimeter-Scale Based on Microvibration

Switchable surface adhesion at a small scale is crucial for robot end-effector design, allowing the manipulation of small objects such as semiconductors, optical lenses, and precision mechanical parts. In this work, a detailed characterization of a millimeter-scale (1-5 mm) adhesion modulation method is performed, demonstrating its effectiveness for switching adhesion on small, lightweight objects with smooth surfaces. This modulation phenomenon arises from the viscoelastic behavior when PDMS interacts with a rigid surface and is controlled via microvibration. A maximum apparent adhesion enhancement of 2400% and a reduction of 50% are achieved with a 1 mm-diameter PDMS hemisphere vibrating at a 30 mu m amplitude and a 700 Hz frequency. The effects of different parameters, including size, actuation amplitude/frequency, surface roughness, and material properties, on adhesion performance are carefully measured and analyzed. A monotonic increase in maximum adhesion is observed with increased device size and surface smoothness, while nonlinear relationships of other factors are generalized with a numerical model. A long working lifespan and high endurance are also observed during the characterization. This work serves as a practical reference for the further design of small-scale soft grippers, highlighting its continuous, large modulation range, simple structure, and flexible control.