Stretchable pumps for soft machines

Machines made of soft materials bridge life sciences and engineering1. Advances in soft materials have led to skin-like sensors and muscle-like actuators for soft robots and wearable devices1–3. Flexible or stretchable counterparts of most key mechatronic components have been developed4,5, principally using fluidically driven systems6–8; other reported mechanisms include electrostatic9–12, stimuli-responsive gels13,14 and thermally responsive materials such as liquid metals15–17 and shape-memory polymers18. Despite the widespread use of fluidic actuation, there have been few soft counterparts of pumps or compressors, limiting the portability and autonomy of soft machines4,8. Here we describe a class of soft-matter bidirectional pumps based on charge-injection electrohydrodynamics19. These solid-state pumps are flexible, stretchable, modular, scalable, quiet and rapid. By integrating the pump into a glove, we demonstrate wearable active thermal management. Embedding the pump in an inflatable structure produces a self-contained fluidic ‘muscle’. The stretchable pumps have potential uses in wearable laboratory-on-a-chip and microfluidic sensors, thermally active clothing and autonomous soft robots.A stretchable polymer pump that uses electric fields to accelerate ions in dielectric liquids can generate flow even when bent into different conformations, offering applications in soft robotics.