This work introduces a new kind of metamaterial called handed shearing auxetics (HSAs). Auxetic materials are those with a negative Poisson's ratio, meaning that they expand perpendicularly when pulled in tension (unlike most materials which contract when pulled). Shearing auxetics expand with a bias rather than just isotropically expanding. By adding chirality to a shearing auxetic pattern, we can create new structures that have a strong coupling between twisting and extension, as well as structures with selective stiffness based on the pairing of chirality. We have demonstrated the potential of HSAs by using it to create a compliant linear actuator and as a soft robotic manipulator without the need for pneumatic actuation.
Through this new material, we are able to create robust soft robotic hands that can withstand puncture, classify materials by size and stiffness, and even sort recyclables.