Magnetically tunable adhesion of composite pads with magnetorheological polymer gel cores

Tunable and reversible dry adhesion has important applications in transfer printing, precision manufacturing, and intelligent robotics. In this paper, a novel composite pad is fabricated whose adhesion can be adjusted rapidly and reversibly by the magnetic field. The composite pad consists of a cylindrical polydimethylsiloxane (PDMS) shell and a magnetorheological polymer gel (MRPG) core. The mechanical properties of the MRPG core in the pads are sensitive to the magnetic field. So the adhesion of the composite pad can be changed due to the interface stress modulation by the magnetic field. The interface stress is calculated by using the finite element method to study the mechanism of magnetically controllable adhesion. The results show the smaller the edge stress, the larger the adhesion. So composite pads with four different core shapes are prepared to optimize the structure design. Pad-bump has the largest magnetically tunable adhesion interval. The adhesion of composite pads on uneven surfaces is also tested and the results show the adhesion of composite pads with soft cores is improved compared to the solid core pad. Finally, a magnetic field controlled pick-and-place demonstration experiment shows that the composite pad array has great application potential in magnetically controlled grabbing and release.