Micro-Architectured Electro- Elasto- Kinematic Muscles (MEEKs)

Fig2Electro-active polymers (EAP) such as dielectric elastomers can reproduce biomimetic functions requiring micro-scale actuation such as color and texture change, or tunable wetting and adhesion. For these applications, large actuation strains and energy density are required. Recent studies with fiber reinforced elastomers demonstrated the ability to obtain anisotropic in- and out-of-plane actuation in macro-scale elastomer membranes. We design a new class of fiber micro-architected elastomers capable of anisotropic actuation in the two orthogonal in-plane directions under isotropic electrostatic field. We reinforce the two sides of a pre-stretched VHB film with parallel arrays of stiff ultra-high molecular weight polyethylene fibers.  By controlling the spacing and bias angle between the fibers, we create diamond shaped unit cells of 100-300 um size, and demonstrate a wide range of kinematics showing maximum extension of 26% at 45o and maximum contraction of -6.3% at 65o at maximum efficiency of 15%. We call these devices Micro-architected Electro- Elasto- Kinematic muscles (MEEKs).  We expect this principle to be suitable for micro-actuation and smart skins where anisotropy can be advantageous.