Architected Piezoelectric Metamaterial with Designable Full Nonzero Piezoelectric Coefficients

Piezoelectric metamaterials have received extensive attention in fields of robotics, nondestructive testing, energy harvesting, etc. Natural piezoelectric ceramics possess only five nonzero piezoelectric coefficients due to the crystal symmetry of 8mm, which has limited the development of related devices. To obtain nonzero piezoelectric coefficients, previous studies mainly focus on assembling piezoelectric ceramic units or multiphase metamaterials. However, only part of the nonzero piezoelectric coefficients or locally piezoelectric electromechanical modes are achieved. Additionally, it still remains challenge for manipulating the piezoelectric coefficients in a wide range. In this work, full nonzero piezoelectric coefficients are obtained by symmetry breaking in architected piezoelectric metamaterial. The piezoelectric coefficients are designable over a wide range from positive to negative through manipulating the directions of the three-dimensional architected lattice. The architected metamaterials exhibit multiple positive/inverse piezoelectric modes, including normal, shear, and twist deformation in different directions. Finally, a smart gradient architected piezoelectric metamaterial is designed to take advantage of this feature, which can sense the position of the normal and shear force. This work paves the way for the control of piezoelectric metamaterial in a wide range with designable full nonzero piezoelectric coefficients, thereby enabling application potential in the fields of intelligent actuation and sensing.