Phase-transforming mechanical metamaterials with dynamically controllable shape-locking performance

Abstract

Active mechanical metamaterials with customizable structures and deformations, active reversible deformation, dynamically controllable shape-locking performance and stretchability are highly suitable for applications in soft robotics and flexible electronics, yet challenging in integrating them due to their mutual conflicts. Here, we introduce a class of phase-transforming mechanical metamaterials (PMMs) that integrate the above properties. Periodically arranging basic actuating units according to the designed pattern configuration and positional relationship, PMMs can customize complex and diverse structures and deformations. Liquid-vapor phase transform provides active reversible large deformation while silicone matrix offers stretchability. The contained carbonyl iron powder endows PMMs with dynamically controllable shape-locking performance, thereby achieving magnetically assisted shape-locking and energy-storing in different working modes. We build theoretical model and finite element simulation to guide the design process of PMMs, so as to develop a variety of PMMs with different functions and suitable for different applications, such as programmed PMM, reconfigurable antenna, soft lens, soft mechanical memory, biomimetic hand, biomimetic flytrap and self-contained soft gripper. PMMs are applicable to achieve various 2D deformations and 2D to 3D deformations and integrate multiple properties, including customizable structures and deformations, active reversible deformation, rapid reversible shape-locking, adjustable energy-storing and stretchability, which could open a new application avenue in soft robotics and flexible electronics.

Powerful UAV manipulation via bioinspired self-adaptive soft self-contained gripper

“…As shown in Fig. 2A, when the temperature of the low–boiling point liquid inside the UCTA increases by Δ T from the initial temperature T 0 , the phase transition of the low–boiling point liquid inside the actuator causes a pressure change Δ P ( 48 ), where P v ( T ) is the saturation vapor pressure of the low–boiling point liquid at temperature T ΔP=Pnormalvfalse(T0+normalΔTfalse)−Pnormalvfalse(T0false)…”

“…We fill the UCTAs with an appropriate amount of low–boiling point liquid (Novec 7000) and soft resistance wires, forming a voltage-driven self-contained system, thus eliminating the need for a set of bulky pneumatic pumps. When applying voltage to the resistance wires inside the UCTAs, the low–boiling point liquid in the UCTAs undergoes a phase transition from liquid to gas, which is known as a liquid-gas phase transition driving mechanism ( 47 , 48 ). This increases the pressure inside the UCTAs and results in a winding deformation similar to tendril plants ( Fig.…”

“…When voltages are applied to the soft resistance wires, the low–boiling point liquid undergoes a phase transition from liquid to gas. The liquid-gas phase transition mechanism ( 47 , 48 ) can generate high pressure (>200 kPa), which can make UCTAs to generate winding deformations. Hence, by eliminating the requirement for multiple bulky pumps, the mechanism opens the door to the application of UCTAs in UAV manipulation/grasping.…”

Soft Electrohydraulic Bending Actuators for Untethered Underwater Robots

“…With the rapid development of soft materials and smart materials [13][14][15][16][17], underwater soft robots [18][19][20][21][22] have attracted widespread attention. Soft robots [23][24][25][26] have inherent softness and can produce larger deformations, so they are more adaptable, efficient, and safe.…”