Soft Robotics Metamaterials

We are currently developing pneumatic metamaterials for the fast actuation of soft robots and their safe operation with the surrounding environment. 

One example is a soft pneumatic actuator with zero-power locking for shape retention in both extension and bending, some of the most common modes of operation. This functionality enables to reduce energy costs and avoid unexpected collapse due to bursts from prolonged pressurization or puncture. The underpinning mechanism is the integration of a pneumatic transmitter and a multistable guider, which are programmed to interact for balanced load transfer, flexural and extension steering, and progressive snapping leading to state locking.  

Another example leverages snap-through buckling in thin elastic shells for fast response of soft pneumatic valves and actuators. Here, we intentionally impart a large axisymmetric imperfection to the thin shell to make the shell response departing from bifurcation buckling, i.e., the classical dimple-like shape of perfect shells, to snap-through buckling localized at the site of the imperfection. Pairing an imperfect shell with a spherical into a soft bi-shell valve enables a shell-snapping interaction that can convert a slowly dispensed volume input into a fast volume output. 

Some Related Publications

Rahman S, Wu L, El Elmi A, Pasini D, Zero-power shape retention in soft pneumatic actuators with extensional and bending multistability, Advanced Functional Materials , Vol 33, 2304151, 2023. (PDF)

Qiao C, Liu L, Pasini D, Bi-shell valve for fast actuation of soft pneumatic actuators via shell snapping interaction, Advanced Science, Vol 8, 2100445, 2021. (PDF)

Qiao C, Liu L, Pasini D, Elastic thin shells with large axisymmetric imperfection: from bifurcation to snap-through buckling, Journal of the Mechanics and Physics of Solids, Vol 141, 103959, 2020. (PDF)