Alveolar-Inspired Negative-Pressure Soft Actuators with Integrated Actuation–Sensing

Abstract

Soft actuators show promise for soft robotics, wearables, and biomedical devices. However, existing pneumatic actuators rely on positive pressure actuation, yielding bulky, complex systems. This study presents a negative-pressure-driven soft actuator inspired by alveolar respiration. A double-layer membrane composed of a high-porosity alveolar-mimicking layer (AML) and a dense structural layer (DSL) was fabricated via an ethanol-induced porogenic method. Under negative pressure, AML microbubbles expand, driving macroscopic directional bending, constrained by the DSL. The effects of the curing temperature and ethanol content on the pore structure, mechanical properties, and deformation behavior were systematically studied. Integrated actuation sensing was achieved by depositing a carbon nanotube conductive coating on the alveolar-inspired negative-pressure-driven (AND) soft actuator surface. The AND soft actuator exhibits reversible deformation within 0.0 to −0.1 MPa and has been demonstrated in soft crawling robots, shape-programmable reconfiguration, and negative-pressure-triggered switches. This study offers a bioinspired negative-pressure actuation strategy, opening a route to high-performance integrated soft actuators.