Electrostatic Layer Jamming Variable Stiffness Enhanced by Giant Electrorheological Fluid

The traditional electrostatic layer jamming (ELJ) utilizes air as the dielectric, which leads to the ELJ system that can withstand less voltage. A novel electrostatic layer jamming based on giant electrorheological fluid (ELJ-GERF) for soft robotics is proposed in this paper. The principle of ELJ-GERF is to use electrostatic attraction to squeeze the flexible planar electrodes to generate friction and then engage jamming, where GERF acts as the dielectric. Three specimens for variable tensile stiffness applications, namely ELJ-GERF, ELJ-AIR, and ELJ-OIL, are fabricated by adding giant electrorheological fluid, air, and silicone oil. Tensile experiments are conducted to investigate the stiffness adjustment characteristics of these specimens. Advantages of ELJ-GERF are indicated by the experimental results. ELJ-GERF has a more than 4 times faster response time than well-known pneumatic layer jamming. Compared to ELJ, the stiffness variation range of ELJ-GERF is enhanced by more than 1.7 times under DC voltage and more than 1.9 times under AC voltage. And the decay rate of the output force of the ELJ-GERF is reduced by a factor of nearly 3 at DC voltage. Moreover, the ELJ-GERF system has better stability at AC voltage and can withstand about 6.7 times higher breakdown voltages. We found that the GERF particles have an important effect on the variable stiffness performance of ELJ-GERF and that the application of AC voltage can further improve the stiffness of the specimen. The stiffness of ELJ-GREF increased nearly four times at 5000V applied. The same enhancement exists for the ELJ-AIR and ELJ-OIL.